Cotton Pests and Plant Protection Methods

## **Chapter 8**

## Pest Insects and Their Biological Control

*Gozde Busra Eroglu*

## **Abstract**

Cotton is an industrial plant with a high commercial value. It is used in various fields such as textile, food (cotton oil), gunpowder industry, paper, and furniture production. One of the most important problems encountered during cotton production is insects that feed on cotton and cause economic loss. The intensive amount of pesticides is used by the producers for the control of pest insects. As insects gain resistance to pesticides over time, the amount of chemical pesticides applied is gradually increasing. Chemical products are quite harmful to both living things and the environment. For this reason, there is a need to popularize biological control methods instead of using pesticides to control pests. In this chapter, detailed information about insect species causing damage to cotton and biological control methods is given.

**Keywords:** cotton pests, damage, biological control, pesticide

## **1. Introduction**

Cotton, *Gossypium hirsutum* (Linnaeus) is an important cultivated plant in the mallow family (Malvaceae), originated from India [1, 2]. Cotton is one of the oldest and most common agricultural products in the world. The fiber of cotton is used in the textile industry, cottonseed is used in the oil industry, and the pulp obtained after oil extraction is used in the feed industry [3]. The use of cotton in various commercial areas contributes to the economy of many countries and has an important place in both exports and employment [4]. It is an agricultural product that employs millions of people and earns money in the production, processing, and marketing, which is grown in temperate and subtropical regions of more than 60 countries. In addition, cotton is a very important economic base in developing and underdeveloped countries, and it is a product that provides foreign exchange income for these countries [1, 4]. Especially in recent years, organic cotton and organic textile products have become preferred by consumers [5]. However, factors affecting the economic importance of cotton in the field of plant protection are pests, diseases, and weeds. These factors reduce cotton yield by about 30% [6]. The use of plenty of water and fertilizer in the cultivation of cotton, which is a plant with abundant green parts, makes the plant attractive to harmful insects [3]. In cotton production, harmful insects are encountered in every period from sowing to the end of harvest. In cases where the pest population exceeds the economic damage threshold, the

yield loss in cotton is 15–20% [7]. There are 96 insect and mite species known as the main pest and other pests in cotton [8]. While chemical control should be the last method to be applied in the control against these pests, it is frequently referred to by the producers [9]. Since the fiber obtained from cotton is not a direct nutrient, the absence of pesticide residue problem allows the use of pesticides more widely than other herbal products in the fight against pests [10]. For many years, the most common method used by manufacturers to prevent product loss has been chemical control [11]. Although chemical control is seen as an easy-to-apply and successful method of controlling pests in the short term, it causes crucial problems in a long time. Chemical pesticides cause the insects to gain resistance over time, and the beneficial insects in nature die because they are not specific to the target organism [12, 13]. In addition, after application, it accumulates in the soil and mixes with the air and water, harming both plants and other vertebrates. Over time, it accumulates in the human body and causes many diseases. This situation causes the deterioration of the ecological balance and also harms the health of living things. In addition, chemical residues remaining on products, prepared for export, cause rejection of products by many countries. Thus, the need to develop biological control methods to be used as an alternative to chemical products in the control of agricultural pests has arisen.

Biological control is the use of predators, parasitoids, or pathogens to control the population of the target organism. In biological control, predators and parasitoids are methods based on the use of beneficial insects against the target organism, while pathogens consist of microorganisms that cause disease or death of the target organism. These microorganisms originate from fungi, nematodes, bacteria, protozoa, and viruses and are bioinsecticides that can reduce harmful insect populations below the economic damage threshold in a short time [14]. Studies on widespread use of these pathogens have gained importance because, unlike chemical substances, they are specific to the host, do not cause harm to nontarget organisms, do not leave residues in nature, and are environmentally friendly and reliable [15]. For this reason, as in other products, cultural measures and biological control should be the first preferred control methods in cotton [3]. Chemical control should be used as the last alternative. It is more important in terms of biological control to protect the natural enemies present in the grown cotton [16]. In order to keep pests below the economic damage threshold, natural enemies and friendly microorganisms should be given an opportunity.

In this chapter, harmful insects that feed on cotton plants and cause economic loss and biological control methods applied against them are given.

## **2. Cotton pest insects**

The pest insects' variety and density vary according to the development stage of the cotton plant and the geography where it grows. In this section, insects that cause economic loss by feeding on cotton are classified under two headings as main pests and other pests.

#### **2.1 Main pest insects**

Insects that are the main pests of cotton are: cotton aphid (*Aphis gossypii*), cotton jassid (*Amrasca bigutulla*), tobacco thrips (*Thrips tabaci*), cotton leafhoppers (*Empoasca*

### *Pest Insects and Their Biological Control DOI: http://dx.doi.org/10.5772/intechopen.101980*

*decipiens* and *Asymmetrasca decedens*), two-spotted spider mite (*Tetranychus urticae*), and white tobacco fly (*Bemisia tabaci*) [9]. These insects cause great economic losses in cotton by invading cotton planted areas, especially in summer [17].

## *2.1.1 Cotton aphid, A. gossypii glover (Hemiptera: Aphididae)*

Adult individuals of the pest, which have an average maturity of 7 days, have the ability to procreate offspring immediately. Since aphids reproduce by parthenogenetic reproduction, they have the ability to form large colonies in a short time [9]. This insect damages cotton in several different ways. Plant sap of cotton is rich in sugar, yet low in protein. For this reason, aphids need to take large amounts of sap to obtain sufficient protein. Excess sugar is secreted in the form of honeydew and makes the crop and fruit sticky. Black mold fungi (*Cladosporium* spp.) thrive in this plant sap, contaminating fruit and ornamental plants while making them unsuitable for the market. At the same time, photosynthesis in leaves decreases, which affects the production of cotton [18]. However, nymphs and adults take nutrients from the plant and disrupt the balance of growth hormones. As a result, plant growth is slowed by deformed leaves or pest infestation. In addition, being a vector of plant viruses, it causes different diseases to be transmitted to cotton [19]. This aphid species can transmit more than 70 different viruses, including the cucumber mosaic virus [18]. *A. gossypii* has many natural enemies and these are very effective in reducing the population of the pest. In the basic development period, it is very important for biological control that a large number of useful insects such as Coccinellid (bride beetles) pass to cotton after the wheat harvest. However, in order to preserve this existing natural enemy balance and to be effective, the field should be controlled very well during this period and care should be taken not to disturb the natural balance by avoiding unnecessary spraying. The most effective natural enemies of cotton aphids are especially *Chrysoperla carnea* and Coccinellid larvae. In addition, *Fusarium subglutinosa*, which is an entomopathogenic fungus, is effective in reducing the aphid population from time to time [9, 20].

### *2.1.2 Cotton jassid,* Amrasca bigutulla *Ishida (Hemiptera: Cicadellidae)*

*Amrasca bigutulla* is one of the most damaging species to the cotton plant. It feeds on cotton in both nymph and adult stages by sucking the sap of the cotton plant due to its absorbent and piercing mouth structure. They cause damage to the plant with the poisonous saliva it leaves on the plant during feeding [21–25]. Intense infestation of *A. bigutulla* on cotton causes leaves to turn yellow, curl up, and fall off. In addition, the secretions that insects leave on cotton cause mold formation on the plant. In this case, it restricts the amount of light reaching the photosynthetic surfaces of the plant and reduces the yield [25]. These harmful species cause an epidemic in cotton plants almost every year [26]. Natural enemies (ladybugs, predatory lygaeid insects, and various mantises) and neem oil are widely used as a method of control [27].

### *2.1.3 Tobacco thrips,* T. tabaci *Lindeman (Thysanoptera: Thripidae)*

*T. tabaci* grow in dry environments rather than moist environments, and in the years when the spring is dry, their density is quite high and the damage increases. It feeds on the underside of the leaves.  The places where the pest feeds on the plant take a silvery color after a while. In heavy contamination, the leaves of cotton seedlings curl, turn brown, and fall off. If the growth point of the plant is damaged, a forked plant occurs [29]. Reduction in fruit branches in the lower parts of the damaged plant causes a decrease in yield. In addition, delays in harvesting occur in heavy damage [30]. Tobacco thrips have many effective natural enemies. Natural enemies are effective in reducing the population of the pest. The *Orius* species (*Orius albidipennis*, *Orius niger*, *Orius horvathi*) are among the most effective natural enemies [9].

## *2.1.4 Cotton leafhoppers,* Empoasca decipiens *Paoli and* Asymmetrasca decedens *Paoli (Hemiptera: Cicadellidae)*

Cotton leafhoppers, which are seen in dense populations in the early period in cotton fields, feed on the vegetative and generative parts of the cotton plant by sucking, affect the development of the plant negatively, and cause shedding especially in the generative organs [31]. It is known that hairless and broad-leaved cotton varieties are more adversely affected by the population growth of leafhoppers [32, 33]. In addition to the sucking damage, it gives to the plant, cotton leafhoppers are also harmful because of toxic secretions into the plant body. The toxic substances cause hypertrophy in the phloem tissue cells of the leaf and blockages in sap transport. Biological control of cotton leafhoppers is done with the use of natural enemies. Among these natural enemies, the most successful are: *C. carnea*, *Deraeocoris* spp., *Geocoris* spp., *Nabis* spp., and *Paederus kalalovae* [9].

## *2.1.5 Two-spotted spider mite,* Tetranychus urticae *Koch (Acarina: Tetranychidae)*

*Tetrancyhus urticae* Koch (Acari: Tetranychidae), also called the two-spotted red spider, is an important polyphagous pest species that are frequently found in agricultural areas where crop production is carried out in the world [34, 35]. The two-spotted spider mite is found in all parts of the plant. However, it especially prefers fresh and strong leaves and lives under these leaves. It is densely located on the underside of the leaves, especially where the petiole and leaf blade meet, and passes from there to other parts of the cotton plant. As a result of the feeding of the pest, yellow spots interspersed on the upper surface of the leaves, which are its characteristics. Later, the yellow spots turn red due to the damage of the chlorophyll substance, which gives the leaf its green color. This redness increases and covers the entire leaf surface or a part of the leaf homogeneously, and the leaves dry out before time [36, 37]. Another feature of the pest is the nets they form due to the substances they secrete during their feeding. The abundance of the nets also indicates that the pest population is dense [9]. The economic loss caused by mites in the plant can reach significant dimensions depending on the population, and these mites can hardly be controlled even with the use of intensive pesticides. Although success can be achieved with biological control elements in the control of these mites in greenhouse cultivation in the world, producers in many places prefer chemical pesticides in the control of this pest. The extensive use of these chemical drugs has caused this mite to develop resistance primarily to organophosphorus, mitochondrial electron transport inhibitors, growth regulators, and many specific acaricides [34, 38]. In the biological control of *Tetrancyhus urticae*, ethanol extracts obtained from sage, rosemary, yarrow, and cumin plants are used to remove the

harmful species from the plant [39]. In addition, the two-spotted spider mite has many effective natural enemies. Of these species, *Scolothrips longicornis* and *Stethorus* spp. are specialized predators of the pest. For this reason, if pest control is required, specific acaricides should be used to protect beneficial species [9].

## *2.1.6 White tobacco fly,* B. tabaci *Gennadius (Hemiptera: Aleyrodidae)*

*B. tabaci* has become one of the most important cotton pests due to its high reproduction rate and resistance to many chemical pesticides [40]. Whitefly larvae need a lot of protein to grow, so they consume large amounts of plant sap. Since the sap contains a large amount of sugar, the excess sugar is excreted as honeydew. As the larva grows, the amount of freshwater excreted also increases. The damages caused by whiteflies to cotton plants are as follows [41]:

However, dark mold can also develop on the leaves, as a result of which the amount of photosynthesis and transpiration is reduced in cotton plants [41, 42]. The consumption of plant sap by whiteflies and the secretion of fresh juice also reduces the esthetic value of the crop. This is a very important problem, especially in ornamental plants. Besides, larvae inject enzymes into the plant, altering the plant's normal physiological processes [43, 44]. Many effective natural enemies are used in the control of *B. tabaci*. Natural enemies of this species include the predators such as *Amblyseius* spp., *Euseius rubini* (Acarina: Phytoseiidae), *C. carnea* (Neuroptera: Chrysopidae), and *Serangium parcecetosum* (Coleoptera: Coccinellidae); parasitoids such as *Encarsia fomosa*, *Encarsia lutea*, and *Eretmocerus mundus* (Hymenoptera: Aphelinidae); as well as entomopathogens such as *Aschersonia* spp., *Beauveria bassiana*, *Paecilomyces* spp., and *Verticillium lecanidae* [45–49]. In different studies conducted around the world, potential entomopathogenic bacterial species that can be used in pest control have also been determined. Among them, *Enterobacter cloacae*, *Acinetobacter radioresistens*, and *Erwinia persicinus* are promising bacteria for biocontrol of *B. tabaci* [50–52]. However, today there is no entomopathogenic bacterial species that is effective on whiteflies and can be converted into commercial form.

## **2.2 Other pest insects**

Under this section of "other pest insects," information is given about the insects that cause significant damage to the cotton plant by causing epidemics in some years. These insects are cotton bollworm (*Helicoverpa armigera*), pink bollworm (*Pectinophora gossypiella*), Egyptian bollworm (*Earias insulana*)*,* cutworms (*Agrotis ipsilon* and *Agrotis segetum*)*,* beet armyworm (*Spodoptera exigua*), cotton leafworm, (*Spodoptera littoralis*)*,* flower thrips (*Frankliniella intonsa* and *Frankliniella occidentalis),* and plant bedbugs (*Creontiades pallidus, Lygus gemellatus, Lygus pratensis,* and *Lygus italicus*).

### *2.2.1 Cotton bollworm,* Helicoverpa armigera *Hübner (Lepidoptera: Noctuidae)*

*Helicoverpa armigera* is an important group that causes millions of dollars of damage every year in the world [53]. Since the adults usually lay their eggs on fresh leaves, the damage starts on the leaves first. The larvae cause product loss by eating only the veins of the leaves and even eating some of the veins. In the following period, the larvae turn to the upper part of the plant and begin to feed on the flower bud, seed, and capsule. Since edible flowers generally cannot form seed capsules, crop yield is directly affected. After the seed capsules are formed, damage occurs as a result of the larvae feeding by piercing the capsules [54, 55]. In areas with high populations, they can cause significant damage, requiring replanting. *H. armigera* has a number of natural enemies found in the orders Hymenoptera, Diptera, Coleoptera, Hemiptera, and Neuroptera. Although parasitoids and predators have the ability to keep their hosts under pressure, they are not sufficient for the control of pests due to their insufficient number in nature [56]. There are 2 commercial preparations that are widely used in the world for the microbial control of *H. armigera*: *Bacillus thrungiensis* [57] and nucleopolyhedrovirus (NPV). These belong to the baculovirus group. However, it was reported that *H. armigera* developed resistance against *B. thrungiensis* [58, 59]. For this reason, studies on the development of baculovirus-derived products have been focused on the control of *H. armigera* [60–68].

#### *2.2.2 Pink bollworm,* Pectinophora gossypiella *Saund (Lepidoptera: Gelechiidae)*

The larvae of *Pectinophora gossypiella* feed on the comb, flower, and cocoon parts of the cotton plant, and the larvae eat pollen and anther, especially in the flower, preventing fertilization of the plant [69]. In addition, the larvae feeding on cotton seeds secrete a substance during feeding and this substance creates twin seeds by sticking 2 seeds together. In years when the pest density in the cocoon is high, blind cocoon formation is observed and the damage rate can reach up to 80% [70]. The small size of *P. gossypiella* eggs allows the pest to be easily suppressed by natural enemies. The most well-known natural enemies are: *Pyemotes ventricosus*, (Acarina: Pyemotidae), *Exeristes roborator* (Hymenoptera: Ichnoumonidae), Chrysocharis sp. (Hymenoptera: Eulophidae), Habrocytus sp. (Hymenoptera: Pteromalidae), and *Pediculoides ventricosus*. (Acarina: Piemotidae) [71, 72].

#### *2.2.3 Egyptian bollworm,* E. insulana *Boisduval (Lepidoptera: Noctuidae)*

*E. insulana*, which is an important pest in cotton, directly affects the yield and quality of a cotton plant. This pest causes damage to shoots, combs, flowers, and cocoons. The larva that emerges from the egg while the cotton plant is in its development period is fed by eating the bud. Then it pierces the shoot and enters the stem and continues to feed in the stem [9]. In the comb area of the cotton, the larvae generally penetrate the top of the comb and enter and cause damage. Larvae in more advanced stages can do their damage by piercing the comb from the side. Damaged combs are poured. *E. insulana* does its main damage in the cotton boll. The newly hatched larvae usually enter the lower half of the cocoon and expel the dung. The larva also feeds on undeveloped fiber and grains. More than one larva can be found in a cocoon. Cocoons damaged by prickly worms usually do not open, and the damaged bolls create a suitable environment for the growth of bacteria that cause angular leaf spot disease (*Xanthomonas malvacearum*). When there is no control during the epidemic years, it

### *Pest Insects and Their Biological Control DOI: http://dx.doi.org/10.5772/intechopen.101980*

can cause up to 90% damage [73]. Natural enemies are mainly used in the biological control of the *E. insulana*. Predatory insects, especially in the *Orius* genus, are quite successful in controlling the population density of *E. insulana* [9].

## *2.2.4 Cutworms,* A. ipsilon *Hufnagel,* Agrotis segetum *Schiffer (Lepidoptera: Noctuidae)*

Cutworms larvae damage cotton seedlings by cutting them. It damages cotton plants by cutting from the two-leaf period, which is the basic development period, to the 6-8-leaf period, and cuts the young plants from the soil surface. However, they can also cut underground under conditions where the soil is soft and the soil moisture is low. Especially large larvae pull the cut plants under the ground and eat their leaves. They do damage by taking turns. Damage is greater in late planting areas and rainy spring months. Damage may occur to a degree that requires replanting [9]. Biological control agents, including fly and wasp parasites, disease organisms, and predatory beetles, continually reduce cutworm populations [74]. However, entomopathogenic nematodes are used successfully in the control of cutworms living under the ground [75, 76].

## *2.2.5 Beet armyworm,* S. exigua *Hübner (Lepidoptera: Noctuidae)*

*S. exigua* larvae are mostly seen in cotton in the early period. Especially after the first hoe, it passes from weeds to cotton plants and its damage is important in this period. They are seen more intensely after the rainy spring months. The first instar larvae that have just hatched from the egg coexist collectively at first. Then, larvae consume the epidermis of the leaf, making it like a membrane. It prevents the growth of the plant by damaging the leaves and tip shoots of small cotton plants. The damage in the leaf is in the form of large holes with regular edges. If the plant is in the combing period, it will also be harmful to leaves, shoots, and combs. However, they do not eat the combs completely, and they gnaw them out from the outside, although they rarely get inside the comb. In addition, it can be damaged in the flower and cocoon of the cotton plant. However, this damage to the pest is not significant. During the epidemic years, it causes significant damage to the median by eating the top shoots and leaves of the cotton in a way that the middle vein remains or completely [9]. In its biological control, formulations originating from entomopathogenic bacteria *Bacillus thrungiensis* isolate, and toxin proteins produced by this isolation are used successfully [77–80]. However, baculovirus has been used successfully in commercial products [81, 82].

## *2.2.6 Cotton leafworm,* Spodoptera littoralis *Boisduval (Lepidoptera: Noctuidae)*

*Spodoptera littoralis* larvae mostly damage the leaf part of the cotton plant. The newly hatched *S. littoralis* larvae feed in such a way that only the large veins of the leaf remain.  In this case, the leaf takes on a sieve-like appearance. As it grows, it feeds on other leaves and punctures the leaves. In the following periods, they feed on buds and cocoons and cause these parts to shed or dry. Inside the cocoons, the insect's excrement and the holes they create can be seen. Predators (*C. carnea*, *Nabis pseudoferus*) and parasitoids (*Microplitis rufiventris*) are used successfully in biological control [83]. In addition, the use of the bacterial endochitinase enzyme from *Bacillus thuringiensis* has recently been used to control many bacteria-resistant *S. littoralis*

larvae [84]. However, Azadirachtin obtained from the neem tree is an effective herbal solution for the control of *S. littoralis* larvae [85].

## *2.2.7 Flower thrips,* F. intonsa *Trybom,* F. occidentalis *Pergande Thysanoptera: Thripidae*

Flower thrips, especially in late planting cotton fields, in case the population is very high, adults feed on flowers and larvae feed mostly on the cocoons, causing shedding of flowers and newly formed bolls and early opening of mature bolls. However, no economic damage is caused in the cotton fields of our country. Species belonging to this genus are harmful, especially by sucking on the flowers and flower buds of the cotton plant. In addition, large and mature cocoons cause the formation of cocoons that do not fully open and are called "Crispy cocoons" as a result of the suction damage that occurs in dense populations [9]. In the biological control of flower thrips, predatory insects of the genus *Dicyphus* and *Orius* and the fungus *Metarhizium anisopliae* have been used successfully [86, 87].

## *2.2.8 Plant bedbugs,* Creontiades pallidus *Rumb,* Lygus gemellatus *Herrich-Schaffer,* L. pratensis *Linnaeus,* Lygus italicus *Wagner (Hemiptera: Miridae)*

Plant bedbugs feed by sucking all the organs of the cotton plant due to their stinging and sucking mouth structures. The absorbed place deformed as a result of the toxic substance secreted and then turns black. If the damage occurs on the leaves, the leaf tissue dies over time in the place where it is absorbed. The leaves become perforated or segmented. These pest larvae do their main damage by feeding on generative organs [88]. Most of the scallops, flowers, and small bolls that are damaged by the suction are shed. As a result of casting, a decrease in the product occurs, as well as a delay in maturation. In sucked cocoons, the seed weight decreases. This reduces the seed yield [89]. In addition to generative organ casting, they also cause deformities such as abnormal comb formation, elongation of plant height, and an increase in the number of nodes on the branches. Predators (*C. carnea*, *Nabis pseudoferus*) and parasitoids (*Leiophron deciphiens*) are used in the biological control of plant bedbugs [9].

## **3. Conclusions**

With the increasing importance of cotton plants both in commercial and domestic use, harmful insect species found in cotton fields and their damage to the product have started to gain more importance. Both the suitability of the leaf surface (especially the hairless cotton leaf) and the high irrigation rate of cotton attract harmful insects. For this reason, there are at least 20 agricultural pest insect species on the cotton plant. When cotton producers see the presence of harmful insects on the product, they prefer the use of chemical pesticides in terms of ease of application in a short time. However, the use of chemical products has long-term negative effects on natural enemies (predators and parasites), other nontarget invertebrates and vertebrates, the environment, nature, and human health. Besides, unnecessary and excessive use of chemical pesticides causes harmful species to resistance. Therefore, the use of chemical drugs should be reduced as much as possible, and biological control agents should be preferred instead. Predator and parasitoid species are used quite successfully for

## *Pest Insects and Their Biological Control DOI: http://dx.doi.org/10.5772/intechopen.101980*

the biological control of cotton pests. In addition, studies on the preparation and marketing of commercial formulations of entomopathogenic microorganisms continue all over the world. In recent years, consumers have started to prefer organic products for all products. In the food and clothing sectors, products containing organic cotton (especially baby clothes) are preferred. For this reason, the development of biological control agents and the cultivation of natural enemies should be supported, and producers should be encouraged to apply them in nature. In particular, the licensing procedures required for placing organic biopesticides on the market involve a very difficult process in some countries. Facilitation of this process by the relevant ministries of agriculture is one of the most important factors that will increase large-scale biopesticide production.

## **Author details**

Gozde Busra Eroglu Faculty of Science, Department of Molecular Biology and Genetics, Erzurum Technical University, Erzurum, Turkey

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## **Chapter 9**

## Influence of Abiotic Factors on Whitefly Population Abundance in Cotton

*Abhijit Ghosal*

## **Abstract**

Whitefly started to infest cotton soon after planting in favourable weather condition. During November planting mean whitefly population were highest (6.9 whiteflies per 3 leaves) and slowly declined in successive planting dates. It was found that number of population were above ETL during the month of December, January and February. Maximum population were recorded in the month of February depending on the growth stage of the crop. Maximum temperature beyond 35°C, minimum temperature below 8°C and moderate to high rainfall was very much detrimental to successful population build up. The most favourable temperature was ranged in respect of min. temperature and max. temperature was ranged 12–30°C. Simple regression value reflects whitefly population were influenced to the tune of 70.8%, 69.5%, 35.3% and 75.4% in November, December, January and February month respectively. Whitefly population were negatively correlated with temperature (max. and min.), rainfall and relative humidity (max. and min.); while, positively correlated with sunshine hours, but during November planting relative humidity (max. and min.) was positively correlated and sunshine hours were negatively correlated. Thus adjustment of planting dates may be adjusted or suitable plant protection measure may be introduced according to the weather forecast.

**Keywords:** abiotic factors, cotton, population abundance, whitefly

## **1. Introduction**

Crop productivity primarily gets highly influenced by biotic and abiotic stress. Several biotic fauna influence the growth of which insects are the most limiting factor to obtain the desired yield. On the other hand abiotic factors play an important role for the biotic stress abundance. Survival and thriving at extreme physical conditions require peculiar adaptations and plastic responses. Among abiotic factors, temperature and humidity stand out as the most important ones constraining abundance and distribution of insect. Furthermore, it is well documented that abiotic factors, regulate the ecology of insect communities. Although effects of temperature on survival, development, and reproduction of insects have been exhaustively explored over several decades, there is still a lot of interest on how temperature and other abiotic factors set the limits of distribution and define abundance of insect species.

Cotton, (*Gossypium hirsutum* L.) is the important cash crop in India due to its high industrial demand. Despite of huge share in areas the productivity of cotton (290 kg/ha) is still very lower than even the world average productivity. It is anticipated that this low production is mainly attributed due to infestation of pest problem. An array of insect pests has been reported to infest the crop rendering the low yield. About 162 species of insects has been known to occur in cotton at various stages of growth, of which 8 are key pests [1]. Among the sap feeders whitefly emerged as most dangerous due to its wide potency to act as vector of plant viruses.

Cotton leaf curl is suggested as a major factor in the decline in cotton production worldwide [2]. Whitefly is active throughout the year on different host plants depending upon the regional and ecological condition, though the activity of this pest is more in dry season. Likewise other insect pest biology of whitefly population is greatly influenced by abiotic factors both positively and negatively as explored by several workers [3]. Sing et al. [4] studied the effect of microclimate on population dynamics of whitefly in cotton and concluded that whitefly population were negatively associated with temperature but directly associated with relative humidity. It is important to understand the relation between the weather parameters and insect population fluctuation to predict and develop a strategic model of pest management in the changing climate. In search of that conclusion the present work has been oriented to study the impact of weather parameters on population of whiteflies in cotton in West Bengal condition.

## **2. Materials and methods**

Field experiment was conducted in experimental plots of Bidhan Chandra Krishi Viswavidyalaya, Kalyani, Nadia, West Bengal, India during rabi season of 2012–2013 and 2013–2014 in randomised block design with three replication. Cotton (var. Bollguard-II) was raised in plots (10 m × 5 m) under recommended package of practices with 50 cm × 50 cm spacing in different days sowing at monthly interval starting from 1st November onwards till February [5]. The field was left as such without any plant protection intervention. Whitefly population were recorded from three leaves per plant top, middle and bottom canopies (randomly sampled tagged 10 plants per plot) from each plot were enumerated at weekly interval [6]. The meteorological data during the study periods was also recorded from the AICRP on Agro-meteorology, Directorate of Research, BCKV, Kalyani, Nadia to establish the correlation and regression co-efficient between whitefly population and weather factors.

The abiotic factors i.e. maximum temperature (X1), minimum temperature (X2), maximum relative humidity (X3), minimum relative humidity (X4), total rainfall (X5) and sun shine hours (X6) and population of whitefly (Y) were arranged as a weekly interval. The inter action between the population in one hand and meteorological data on the other hand had been worked out through correlation, regression and multiple regressions analysis. The data thus obtained were analysed statistically followed by Fisher's method of analysis of variance [7]. Simple and multiple regression analysis (X1, X2, X3, X4, X5, X6) were worked out and the data were detailed out based on spectrum of regression analysis and equation as Y = a + b1X1+ b2X2 + b3X3+ b4X4+ b5X5+ b6X6. Where, b1…b6 are the regression coefficient of X1 ….X6.

## **3. Result and discussion**

The population build up of whiteflies in relation to abiotic factors were ascertained through the correlation studies along with simple and multiple regression analysis. The result showed that the population of whitefly was found in its first peak (9.7 whiteflies per three leaves) on 3rd week of December, when max. Temperature was- 26.1°C, min. Temperature was- 12.4°C, RH% was ranged between—61.5–91%, sunshine hour was—4.8 h and with zero rainfall. There were 10.2 whiteflies per three leaves were recorded in 3rd week of January and this was considered as the second peak. The population were greatly fluctuated with the fluctuation of mean temperature and relative humidity (RH%). Whitefly population stroked its highest and third peak during 2nd week of February (6th standard week) with max. Temperature 29.9°C and 13.4°C min. Temperature, relative humidity ranged 87% max.—43.5% min. and with sunshine hours—8 h. Gradually the population decreased with the subsequent advance of crop age (**Figure 1**). Population of whitefly illustrated non significant negative correlation with the max. Temperature (r = −0.18), min. Temperature (r = −0.30), rainfall (−0.003) and sunshine hours (r = −0.16); while positive correlation with max. Relative humidity (r = 0.54) and min. Relative humidity (r = 0.04). Maximum relative humidity showed significant correlation with the population load during November planting (pooled) (**Table 1**). Cumulative effect of weather parameters designated that 70.8% population (R2 = 0.708) can be explained by the cumulative effect of the weather parameters (**Table 2**).

The number of whitefly population varied from 0.7 to 13.2 per three leaves during December planted cotton (Pooled) (**Figure 2**). Maximum whitefly population (13.2 per three leaves) was recorded during 2nd week of February; at this stage the max. Temperature was- 29.9°C, min. Temperature was- 13.4°C, max. Relative humidity was-87%, min. Relative humidity was- 43.5%, sunshine hours was 8 h and without any rainfall. But, during 7th standard week the population suddenly lowered down (7.8 whiteflies per three leaves) which was apprehended due to sudden forms of torrential rain during that week. The population again started rebuilding from 8th standard week (9.4 whiteflies per three leaves) with a comfortable weather. After 2nd week of

*\*\*Correlation significant at 0.01 level.*

#### **Table 1.**

*Correlation studies b/w incidence of whitefly and weather parameters.*

*\*\*Correlation significant at 0.01 level.*

#### **Table 2.**

*Regression equation showing quantitative relationship between B. tabaci (Y) and meteorological parameter.*

### *Influence of Abiotic Factors on Whitefly Population Abundance in Cotton DOI: http://dx.doi.org/10.5772/intechopen.103006*

March the population were in a trend to decrease with steady increase of temperature up to the rest of the experiment. The correlation coefficient (r) showed negative trend with maximum and minimum temperature (r = −0.03 and − 0.21, respectively), max. and min. Relative humidity (r = −0.16 and − 0.20, correspondingly) with population of whitefly. Sunshine hours showed positive correlation (r = 0.42) with the whitefly population build up. The effect of weather parameters during the period of infestation failed to establish any significant correlation (**Table 1**). The combined contribution of the weather factors was 69.5% (**Table 2**).

**Figure 3** depicts the incidence pattern of *B. tabaci* during January planted cotton (Pooled). Infestation was initiated (0.5 whiteflies per three 3 leaves) during 3rd standard week after the initiation of third leaf. It was noted that whitefly population were gradually in upward trend with the advances of crop stage and thereby hits its maximum peak (12.6 whiteflies per three 3 leaves) during 9th standard week (1st week of March), with max. temperature—30.8°C, min. temperature—15.3°C, max. RH—88%, min. RH—45%, sunshine hours—8.2 h and zero rainfall. During 10th standard week and afterwards the population were getting dwindled off with the increase of temperature. All the weather parameters were negatively correlated with whitefly population during December planting (pooled) except sunshine hours (r = 0.30) (**Table 1**). But none of the parameters showed significant relation. Only 35.3% population were influenced by the existing weather factors at this period (**Table 2**).

Effect of climatic factors on the incidence of *B. tabaci* in February planted cotton (Pooled) is presented in **Figure 4**. The number of whitefly population were varied from 0.5 to 4.2 per three leaves during the course of study. It was observed that max. Temperature above 35°C was unfavourable to the population load. Maximum whitefly population (4.2 per three leaves) was recorded during 1st week of March (max. temperature was—30.8°C, min. temperature was—15.3°C, max. relative humidity was—88%, min. relative humidity was—45%, sunshine hours was 8.2 h and zero rainfall). But, during 12th standard week the population suddenly fall down (1.8 whiteflies per three leaves) which was detained due to sudden forms of torrential rain during that week associated with high temperature. After that the population were in a trend to shrink with steady increase of temperature and rainfall up to the rest of the experiment.

**Figure 3.** *Population dynamics of whitefly in relation with weather parameters in January planted cotton (pooled)*

#### **Figure 4.**

*Population dynamics of whitefly in relation with weather parameters in February planted cotton (pooled)***.**

Lowest population were recorded in 20th standard week. Minimum temperature (−0.73), min. relative humidity (−0.54) and rainfall (−0.57) exhibited significant effect on the population of whiteflies (**Table 1**). 75.4% population of whitefly were influenced by the weather factors during this period of investigation (**Table 2**).

## **4. Effect of different dates of sowing on the incidence of whitefly**

Wide fluctuation of population were noted in different dates after planting, which was varied from 0.9–7.5 mean whiteflies per three leaves. Lowest population were recorded in 21 DAS, and then slowly but steadily increased with the advance of crop age up to 63 DAS. These findings may be ascertained due to the favourable stage of the crop for successful multiplication of whitefly. It was recorded that population maintained uniform pattern of incidence during 49 DAS to 98 DAS. Accordingly the population were in decreasing trend and thus during 119 DAS only 2.6 numbers of whiteflies were recorded from three leaves (**Table 3**).

Each and every biological organisms are responsive towards the climatic factors. Biology of herbivore insects are greatly influenced by the weather parameters as these parameters exerted direct impact on the life cycle as well as the plant itself in which the insect used to feed and grow have potential impact on the population build up of the particular insects. It is apparent from this experimental findings that whitefly population were influenced by the weather parameters in different dates of planting of cotton. Population of whitefly in four different planting dates at monthly interval from November to February showed that the population of whiteflies decreased in successive planting. Population build up of whiteflies were high during spring season, as whitefly population were strongly affected by high temperature as well as low temperature; though the population of whitefly were greatly varied with the favourable growth stages of the crop. It was recorded that max. temperature beyond 35°C and min. temperature below 8°C was very detrimental for the population build up. The most favourable temperature was ranged in respect of min. temperature and max. temperature was 12–30°C depending on the favourable vegetative stage of the crop. Dry period greatly favoured the

## *Influence of Abiotic Factors on Whitefly Population Abundance in Cotton DOI: http://dx.doi.org/10.5772/intechopen.103006*

#### **Table 3.**

*Effect of dates of sowing on the incidence of whitefly (*B. tabaci*) in cotton.*

population build up, while rainfall exerted negative effect on the population size because the population of whiteflies were washed out as well as mortality of adult population were noticed. Our result is in confirmation with the findings of Sing et al. [4] and Banjo et al. [8]. It was also observed that population of whiteflies were maximum in 63 days after sowing and maintained its uniform pattern of incidence up to 98 days after sowing, which suggests that whiteflies prefer to feed the crop at early growth stages of the crop. Similar findings were reported by Meena et al. [9]. Correlation matrix of whitefly population and weather factors showed few sort of inconsistency based on the weather parameters recorded on that growing period of the crop. Whitefly population were negatively correlated with maximum and minimum temperature, relative humidity and rainfall; while positively correlated with sunshine hours; which were in agreement with Kataria et al. [10] and Latif and Akhter [11]. During November planting (pooled) maximum and minimum relative humidity was positively correlated with the population dynamics of whitefly, whereas, rainfall showed non significant positive correlation with the whitefly population during December planted cotton (pooled); which was at par with the result of Dahiya et al., [12]. Fluctuation in correlation between weather parameters and whitefly population build-up in different planting dates may be due to inconsistency of weather parameters as an effect of global warming in recent days or may be associated with the other ecological factors influencing whitefly incidence.

## **5. Conclusion**

In the changing climate it is much very difficult to manage the pest in field condition. The interaction of crop and herbivore are greatly influenced by the meteorological parameters. Now a days thus pest forecasting has gained an importance in world agriculture which strongly depends on the study of population of the biotic species build up in relation with the abiotic factors like temperature, rainfall, humidity etc. In our present study we have noticed that the population of *B. tabaci* were negatively correlated with maximum and minimum temperature, relative humidity and rainfall; while positively correlated with sunshine hours during November plating while the population showed non significant positive relation with the rainfall during December planting, which denotes that during winter season the light rainfall helps to increase the soil temperature as well as temperature of the micro climate of the field. Temperature is the key meteorological factor in relation to population abundance of whitefly. It is apparent that the population build up of whiteflies in Indian context was favourable in between the temperature range 12–30°C depending on the favourable vegetative stage of the crop, early growth stages of the plant favours the population build up. Thus plant protection measure should be adopted during the early growth phase depending on the temperature, humidity and rainfall. At high temperature and moderate to high rainfall as the population of the whiteflies get affected thus avoid spraying the crop.

## **Author details**

Abhijit Ghosal Sasya Shyamala Krishi Vigyan Kendra, Ramakrishna Mission Vivekananda Educational and Research Institute, Kolkata, West Bengal, India

\*Address all correspondence to<EMAIL_ADDRESS>
© 2022 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

## **References**

[1] Dhawan AK. Cotton pest scenario in India: Current status of insecticides and future perspectives. Agrolook. 2000;**1**(1):75-85

[2] Singh, J., Sohi, A. S., Brar, D. S., Denholm, I., Russel, D. and Briddon, R. 1999. Management of cotton leaf curl viral disease in India. In: Proceeding of the ICAC-CCRI Regional Consultation, Insecticide Resistance Management in Cotton. Central Cotton Research Institute, Multan, Pakistan, pp-277-278

[3] Rameshbabu S, Meghwal ML. Population dynamics and monitoring of sucking pests and bollworms on bt cotton in humid zone of Southern Rajasthan. The Bioscanning. 2014;**9**(2):629-632

[4] Sing S, Niwas R, Saini RK, Khichar ML. Effect of microclimate on population dynamics of whitefly in cotton. Journal of Insect Science. 2006;**19**(2):209-212

[5] Selvaraj S, Ramesh V. Seasonal abundance of whitefly, *Bemisia tabaci* Gaennadius and their relation to weather parameters in cotton. International Journal of Food and Agricultural Veterinary Sciences. 2012;**2**(3):57-63

[6] Prasad NVVSD, Rao NHP, Mahalakshmi MS. Population dynamics of major sucking pests infesting cotton and their relation to weather parameters. Annals of the Plant and Protection Sciences. 2008;**18**(1):49-52

[7] Fisher RA. Statistical Methods for Research Workers. London: Oliver and Boyd (Edinburgh); 1934. p. 198

[8] Banjo AD, Hassan AT, Jackal LEN, Dixon AGO, Ekanayake IJ. Developmental and behavioural study of spiralling whitefly (*A. dispersus*) on three cassava (*Manihot esulanta* crantz) genotypes. Journal of Crop Research. 2003;**26**(1):145-149

[9] Meena NK, Kanwat PM, Meena A, Sharma JK. Seasonal incidence of jassids and whiteflies on okra, *Abelmoschus esculentus* (L.) Moench in semi-arid region of Rajasthan. Annals of the Agricultural Biological Research. 2010;**15**(1):25-29

[10] Kataria SK, Singh PB, Kaur J. Population dynamics of whitefly, *Bemisia tabaci* Gennadius and leaf hopper, *Amrasca biguttula biguttula* Ishida in cotton and their relationship with climatic factors. Journal of Entomology Zoological Studies. 2017;**5**(4):976-983

[11] Latif MA, Akhter N. Population dynamics of whitefly on cultivated crops and its management. International Journal of Bio-resources Stress Management. 2013;**4**(4):576-581

[12] Dahiya KK, Kumar D, Chander S. Influence of abiotic factors on leafhopper and whitefly population buildup in Bt-cotton hybrids. Indian Journal of Entomology. 2013;**75**(3):194-198

## Machinery for Plant Protection in Cotton Crop

*Manjeet Singh Makkar and Santosh Kumar Gangwar*

## **Abstract**

Spraying is very tedious and time consuming operation. There is a need of an efficient, precise and high capacity machine for spraying. The pesticide with conventional sprayers is not so effective because non-uniform spray and of lesser width of coverage. Distribution of pesticide is not uniform especially at the underside of the leaves. The pest can be controlled effectively if pesticides are applied properly at the right rate, right time and on the target by right equipment. In field crops like cotton the pest attacks is on the lower side of the leaves during vegetative as well as reproductive stages of the cotton crop. The sprays with conventional sprayer do not enter at the bottom of the plant canopy and at lower side of the leaves. Different type of sprayers are being developed especially for the control of white fly in cotton crop. These sprayers can also be used for crops like sugarcane, potato etc. Air assisted electrostatic sprayer, Auto rotating gun type sprayer, Multipurpose high clearance sprayer and even drones are now a days used for spraying in cotton crop. Multipurpose high clearance sprayer mostly preferred by the farmers has three types of spraying arrangements namely auto rotate gun, boom type and drop up type nozzles can work at all stages of the crop and saves time, labor and cost of operation as well as it reduces drudgery of the operation. Selection of nozzle is also important for these type of sprayers. Automatic controller can be fitted on these sprayers for adjusting the discharge and to reduce missing or overlapping of spray.

**Keywords:** spraying, high clearance sprayer, auto rotate gun sprayer, electrostatic spraying, drone, weeding etc.

## **1. Introduction**

Leading cotton producing countries worldwide in 2020–2021 are China with the production of 6.42 million metric tons followed by India with 6.16 million metric tons accounting for about 58% of the world cotton production [1]. Over the past several years, plantings of transgenic crops producing insecticidal proteins from the bacterium Bacillus thuringiensis (Bt) have helped to control several insect pests and reduced the need for insecticides. Broad-spectrum insecticides kill arthropod natural enemies that provide biological control of pests. The decrease in use of insecticide [2] sprays associated with Bt crops could enhance bio-control services [3]. Although, Bt. cotton provides effective protection against cotton bollworms, but sucking pests namely whitefly, jassid, aphid and mealy bug are the most serious in Bt. cotton and

they cause maximum damage.  Affected leaves and seed cotton turns black due to development of sooty mold on the plants. Regular, supervision of the crop is must for detection of whitefly incidence. If possible proper coverage of underside of leaves during the insecticidal spray may effectively reduce the whitefly population in cotton crop.

Chemical application by sprayer is a common field operation in crop production. Different types of sprayers namely; manual operated, tractor operated boom sprayer, auto-rotated gun sprayer, self-propelled high clearance boom sprayer, air assisted boom sprayer, air assisted electrostatic sprayer and unmanned aerial vehicle (UAV) based sprayer are available for spraying on cotton crop. Special devices, such as the portable knapsack sprayer, have been designed for manual operation has only one nozzle, which is fixed on a lance. Sprayers for crop protection can be divided as vehicle-mounted, trailed types and portable type sprayers. Vehicle-mounted sprayers generally use wider booms attached with nozzles for horizontal or vertical spraying. Horizontal boom sprayers are used to spray in field crops, while vertical boom sprayers are used to spray for vineyards and orchards. Both type of sprayers utilize air in which the nozzles spray into the air stream of a fan flow, which carries and distributes the droplets into the vineyards and orchards. Spray booms can also be mounted on drones, airplane or helicopter for application to spray on large fields.

Nozzle selection and efficient operation of sprayers is must for the better control of the pest on cotton crop. The success of control over insect-pest, diseases and weed depends upon use of proper spraying technologies (spray machine & spray method) [4]. Agrochemical may be applied at various crop growth stages of cotton during the entire crop seasons by different sprayers technology commercially available in the market. Sprayers may be designed as attachments to tractor or self-propelled power unit. Numerous types of sprayers are available i.e. knapsack sprayers, auto rotating gun sprayer, air assisted boom sprayer and tractor mounted boom sprayers, multipurpose high clearance spryer, and recent new advance developed sprayer i.e. air assisted electrostatics sprayer, Drone (UAVs) sprayer etc.

In China and some other countries, use of UAV spraying with low altitude and low volume is increasing for the application of chemical to control insect, pest and disease in different crops. It saves time, energy and drudgery of operation with less chance of contact chemical to operator skin also avoid soil structure damage by controlling traffic over field surface.

## **2. Sprayers**

Sprayer is a machine dispersal of fluids chemical in the form of spray droplets by using hydraulic or gaseous or centrifugal energy are commonly known as sprayers. Specification of all purpose sprayer are:

1.High clearance for tall crops.

2.Enough wide, light, flexible boom, adjustable in height.

3.Non corrosive construction to enable the sprayer to be used for all type chemical.

4.Boom section control valve.

Different types of sprayers available for the protection of cotton crop are explained below;

## **2.1 Knapsack sprayer**

Generally, knapsack sprayers are utilized for spraying on low height crops, vegetables and plant up to 1.5 meters in height (**Figure 1**). Different types of knapsack sprayers produce different impacts on agriculture in terms of the plant protection. Knapsack sprayers are indispensable agricultural equipment for small and marginal farmers for pest control because of affordability and ease of operation [5]. But this device has some limitations. It causes fatigue to operating person and hence cannot be used for longer time. The hand operated knapsack sprayer needs a lot of effort to move the lever up and down to generate the pressure inside the sprayer. The machine consists of lever-operated hydraulic pump to produce the desired pressure up to 3.0 kg cm−2. It has hollow cone type nozzle mounted on a handheld lance of 1500 mm long with effective discharge of 1.3 lmin−1 and having a 16-liter chemical spray tank. The field capacity of this sprayer is 0.08 hah−1. The droplet size and percent coverage area of knapsack sprayer is as 347.85 μm, and 22.29%. The bio efficacy to control whitefly in cotton crop with the knapsack sprayer is varies between 65 and 70%.

## **2.2 Auto rotate gun type sprayer**

An auto rotate gun sprayer was developed for the control of whitefly *(Bemisia tabaci)* in cotton crop. An auto rotate gun type sprayer [6] with two gun type nozzle (Make: Teejet) was developed in Department of Farm Machinery and Power, PAU, Ludhiana in collaboration with the industry (**Figure 2**). It has tractor mounted, boom with guns,

**Figure 1.** *Knapsack sprayer in cotton crop.*

**Figure 2.** *Auto rotate gun type sprayer.*

dc motor, hydraulic piston type pump and spray tank (600 liter). Spacing between the two guns is kept 9 m. Each gun rotates 120 degree of rotation to cover about 30 m of span or working width of sprayer at liquid pressure of 35–40 kg cm−2. These guns can be operated independently if required. There are two rotation settings (30 and 40 RPM) for each gun. The auto rotate gun sprayer were control as 85–95% whitefly nymphs in cotton crop. The droplet of auto rotate gun type sprayer having size of 250–330 micron [7]. Auto rotate gun type sprayer was preferred by the farmer as it may be used for effective spraying at earlier stage of crop and saves time, labor and cost of operation as well as it reduces drudgery of the operation.

## **2.3 Multipurpose self-propelled high clearance sprayer**

A high clearance self-propelled 4 wheel drive high clearances drive tractors with spraying system is developed (**Figure 3**) and popularized by Punjab Agricultural University (PAU), Ludhiana, India [8]. It has three types of spraying arrangements namely auto rotate gun, boom type and drop up type nozzles which is operated by a single pump. The spray machine consists of a hydraulic pump, spray tank (1000 liters), pressure gauge and hydraulic assistance for controlling the boom. The pump can be operated at 800 rpm to develop desired pressure up to 35 kg cm−2.

Boom and drop-up nozzle mechanism consists of 14 hallow cone nozzles on boom and 13 hallow cone drop-up nozzles (Make: Teejet) mounted on foldable 9.8 m wide boom with 67.5 cm nozzle spacing. Boom nozzles are used to spraying on top side of plant canopy and other drop-up nozzles which is used to spray inside the crop canopy up to 65–75 cm below from the boom and within the row or underside of leaf through adjustable drop-up arrangement of nozzle to target whitefly residing locations. The height of boom can be adjusted up in the range of 30–250 cm according to the crop height with the help of a hydraulic assistance provided.

*Machinery for Plant Protection in Cotton Crop DOI: http://dx.doi.org/10.5772/intechopen.103834*

**Figure 3.** *Multipurpose high clearance sprayer.*

The auto rotate gun type attachment has two guns (Make: Teejet) placed at 9.5 m apart on each end of its boom and it has coverage radius of 10 m per nozzle at limiting pressure of 35 kg cm−2 This gun performs 1200 rotation to cover about 20 m of swath or working width. These guns can be operated independently if required. There is a provision for adjusting vertical height of boom from target which makes it suitable to spraying for different crops at different crop growth stage.

The auto rotate gun boom type nozzles and drop up nozzles performed batter as 92–95% whitefly nymphs are killed by these spraying attachments as compared to knapsack sprayer. Auto rotate gun, drop up nozzles and boom type nozzle performed batter as 65–75% whitefly adults are killed by these type of spraying attachments as compared to knapsack sprayer as control by which only 50–65% whitefly adults are killed. Droplet size (micron) is in the range by high clearance boom type (320–380), drop up (200–320), auto rotate gun type (250–330). High clearance was preferred by the farmer as it can work at all stages of the crop and saves time, labor and cost of operation as well as it reduces drudgery of the operation.

These multipurpose high clearance sprayer can be further modified to improve self-propelled high clearance sprayer with four-wheel drive system having narrow width tires and four-wheel steering system to facilitate the operation of these sprayers in other crops like rice, wheat etc. It has two types of spraying arrangements namely boom type and drop up type nozzles which is operated by a single pump.

Safety guide lines for tractor driver to operate PAU-Multi-purpose high clearance sprayer

## **2.4 Drop up with air-assisted boom sprayer**

The sprayer machine is tractor operated and attached with three-point linkage system of tractor. Power requirement of drop-up air assisted boom sprayer (**Figure 4**) is 30–35 hp. and hydraulic pressure pump of sprayer is run by PTO power of tractor. The machine consists of water tank, hydraulic pressure pump, one blower fan, foldable and height adjustable boom with air assisted and drop-up type nozzles. High-density polyethylene made water tank which have enough water holding capacity of 600 liters to minimize frequent refilling of tank resulting improve field efficiency of machine. A hydraulic pump pressure in range 15–35 kg cm−2 bar is used to archive desire pressure range for efficient operation of drop-up and air assisted nozzle. Power from tractor PTO to hydraulic pump with gear ratio1:1.6 transmitted through a v-belt drive arrangement. The pump has one suction pipe diameter of 32 mm, three outlets port of

**Figure 4.** *Operational view of drop-up-air assisted boom sprayer.*

## *Machinery for Plant Protection in Cotton Crop DOI: http://dx.doi.org/10.5772/intechopen.103834*

diameters 12.7 mm and one overflow pipe with a pressure control lever and a pressure gauge.  Two pressure pipes with individual "on" and "off" valve were used to connect the outlets of pump to inlets pipe of drop-up and air assisted nozzle. Another one pressure pipe is used to fill water tank which connected with the suction pipe of water tank. The blower has two air stream discharge pipes diameter of 110 mm connected with air assisted nozzle boom through flexible PVC pipe diameter of 110 mm. The diameters of air discharge pipe were same as the diameter of air assisted boom pipe and this air stream opening around air assisted nozzle which improves the atomization of liquid for good spray pattern. A foldable and height adjustable boom is mounted on the rear side of spray frame which are made of 40 × 40 × 4 mm angle iron bar. The total width of boom is as 9500 mm which have five sections two each side left and right with one middle fixed section. The height of boom is adjusted from 1000 mm up to 2500 mm from the ground surface.

## **2.5 Back pack type air assisted electrostatic sprayer**

Mobile Back Pack type (MBP) air assisted Electrostatic Sprayer powered by a 5.0 HP engine with an on-board compressor and spray gun can also be used for cotton crop (**Figure 5**). The engine power the air compressor and the compressor produces pressurized air which passes through conducting hose and used to atomize and propel the liquid spray. The electrostatic sprayer is equipped with a 15 liters tank which is hang on the operator's back. For charging the spray particles in the nozzle, two 9.0 V rechargeable batteries have been provided. Air and liquid enter separately at the outmost of nozzle. Just before leaving the nozzle, the air hit the liquid stream to atomize it into spray droplets that passed through the charging ring. Spray deposition on the upper side and underside of leaves by electrostatic sprayer is 80 and 85% more than knapsack sprayer respectively. Average drift loss of electrostatic sprayer is approx.

**Figure 5.** *Back pack type air assisted electrostatic sprayer.*

50% lesser as compared to knapsack sprayer. Bio efficacy of the sprayer is given as percentage of insects killed by the operation of spraying [9]. Overall bio-efficacy of electrostatic sprayers i.e. 80–85% is comparatively higher than conventional sprayer.

## **2.6 Drone (unamend aerial vehicles)**

In modern agriculture, Unmanned Aerial Vehicles (UAVs) have been used for field mapping, surveillance, farm management etc. It is also used for remote sensing, visual inspection of crop and soil conditions etc. This technology has utility in agriculture and forestry not only for taking observation and sensing but it can also be used in spraying application. Pesticides are applied in agricultural crop fields to increase output, improve quality and decrease cost of production. However, extended direct or indirect contact with these chemicals can cause various diseases to human such as cancer, complications in the respiratory system, neuro-logical diseases, asthma, allergies, hypersensitivity, and hormone disruption. According to World Health Organization (WHO) there are 3 million cases of pesticide poison every year and up to two lakhs twenty thousand deaths in developing countries. This problem may be reduced by the use of drone to carry out the task of spraying pesticides/herbicide.

The octa-copter type UAV with configuration of 8 propellers and its self-weight about 12 kg can be used for spraying as shown in **Figure 6**. The UAV have maximum take-off weight capacity up to 28 kg and its flying time 15–20 minutes with two lithium polymer batteries having capacity of 16,000 mAh. The UAV have two flight mode i.e. GPS and manual. A GPS receiver can locate UAV's exact location and altitude can be maintained by barometer. The range of remote controller has 1.5 km maximum transmission distance to control the UAVs. The UAV remote control system operates at 2.4 GHz radio wave frequency. Telemetry consisted of a radio modem and one ground control station which provide real time information during the flight. The UAV sprayer system consisted of 5–10 liters capacity tank and four flat fan nozzles having spray angle 110° were used in UAV sprayer and fitted beneath propeller. Swath width of UAV sprayer is upto 3 m with four nozzles. Transparent PVC pipes with an inner diameter of 8 mm is used; while a small independently 12 volts' electric power pump was used to develop desire pressure of 3.0 kg cm−2. Remote control system is used to drive the pump, vary its speed and also autonomous of UAV through the electronic system and GPS. For this function, a pulse width modulation (PWM) system is used, in which the radio signal sent from the receiver adjusts the flow rate of the spraying system. Using this, the flow rate of the nozzles can be varied between 0.10–0.25 l/min at the minimum to maximum pump speed.

**Figure 6.** *UAVs sprayer in cotton crop.*

*Machinery for Plant Protection in Cotton Crop DOI: http://dx.doi.org/10.5772/intechopen.103834*

The bio-efficacy of drone sprayer varying between 70 and 80% to control pest in cotton crops [10]. The water application rate also lies in range of 20–50 liter per hectare. Application of pesticides with the help of UAV has advantage of its use for any crop of any season also, in covering large areas quickly. UAV (drone) allows the farmer to take advantage of very small windows of opportunity such as weather conditions or pest growth cycle. UAVs do not cause soil compaction and crop damage. Now, many countries including India has their own regulations and guidelines for the use of drone in agriculture. Recently, Government of India has released standard operating procedures (SOP) for use of drone with pesticides for the crop protection and for spraying soil and crop nutrients in agriculture, forestry, non-cropped areas etc [11].

## **2.7 Cost on spraying**

Actual field capacity of high clearance sprayer was found as 1.78 ha/h as compared to 0.80 ha/h for gun type sprayer and 0.08 for knapsack sprayer. Similarly cost, labour and time saving by using high clearance sprayer was 66, 95 and 95% respectively as compared to knapsack sprayer. Breakeven point for the multi-purpose high clearance sprayer was calculated 300 ha/year.

## **3. Selection of nozzles for various application**

Most of the nozzle manufactures give discharge of nozzles at various operating pressures and on the basis of the purpose of use. However, nozzles should be selected on the basis of the type of spray job, i.e. spraying of insecticide, weedicide, fungicide

**Figure 7.** *Types of nozzle commercially available.*

etc. Uniform distribution of chemical depends on the constant speed and proper nozzle selection and efficient operation of sprayers is must for the better control of the insect and pest on cotton crop. The success of control over insect-pest, diseases and weed may depends upon selection of appropriate spraying machinery (spray machine and spray method).

Flat fan nozzle is used for uniform coverage application such as for weed spraying (**Figure 7**).  Solid cone nozzles are used when a high pressure penetrating spray is required as for the control of whitefly in cotton. Use hallow cone nozzle which deliver 600 ml of spray material per minute for efficient pest control. Nozzle performance changes as spray materials erode the nozzle tip. Brass tips show wear about one third as fast as aluminum tip; stainless steel and some of the new plastic tips show wear only one-quarter as fast as brass. Nozzle wear is more significant in first 50 hours of use, depending on the abrasiveness of the spray material. Hence, nozzle performance should be periodically tested for changes in flow rate and spraying pressures used and for changes in spray pattern owing to nozzle tip wear.

## **4. Calibration of sprayers**

Societal and environmental distresses as well as economics require precision application of only enough chemical to accomplish pest control. Conventional spraying technology depending on gravity force and spray droplet inertial forces often achieves less than 50 per cent deposit of the total spray volume on the plant targets and actual quantity reaching the insect or disease pest can be as low as 0.01% of the total spray volume. Hence, Air-assisted with electrostatic technology is better to achieve more penetration of spray and more uniform distribution on the plant canopies, particularly on the lower side of leaves. Calibration of the sprayer is very important to determine the effectiveness of spraying and elimination of the over-spraying. Sprayer requires too much care in calibration as various parameters affect the eventual spray concentration per acre are:

The insecticides recommended for control of sucking pests like whitefly, jassid etc., should be sprayed using 300–375 liters spray solution per hectare a with the manually operated knapsack sprayer. For calibration of a sprayer to control whitefly, let us suppose that dose of insecticides is recommended as 1500 ml/ha. Measure the nozzle discharge by collecting the liquid coming out from each nozzle in ml/min. Calculate total volume collected from 18 nozzles, let it was10 l/min. The sprayer travels at a forward speed of 4 kmh−1. When the sprayer nozzles are spaced 67.5 cm apart on the boom and carried 50 cm above the crop canopy, the application will be uniform. Field efficiency of the sprayer is to be assumed as 50% (using Eq. (1)).

*Machinery for Plant Protection in Cotton Crop DOI: http://dx.doi.org/10.5772/intechopen.103834*

$$\mathbf{A} = \mathbf{D} \* \mathbf{1} \otimes \mathbf{c} \otimes \mathbf{c} / \mathbf{F} \* \mathbf{S} \* \mathbf{N} \* \mathbf{E} \tag{1}$$

Where, A = Application rate (l/ha) of spray, D = Pump Discharge (l/min), F = Forward Speed (m/min), S = Spacing between Nozzles (m), N = No. of Nozzles, E = Field efficiency.

To find the quantity of water required for spraying, fill the spray machine tank with measured quantity of water and spray in field. After spraying, measure the area sprayed and record amount of water consumed in that area. Calculate the amount of water required per hectare by the following equation (Eq. (2)):

$$\mathbf{Q} = \mathbf{V} \* \mathbf{r} \mathbf{o} \mathbf{o} \mathbf{o} \mathbf{o} / \mathbf{A} \tag{2}$$

Where, Q = Amount of water required (l/ha), V = Volume of water consumed (liter), A = Sprayed area (m−2).

## **5. Automatic spray control system**

Various commercial spray controllers use section control technology to auto-turn boom-section valves to ON/OFF. This technology has a potential to reduce overlapping application resulting in savings on inputs. There are two type of spray control technology available first is Automatic Section Control (ASC) and second is Boom Section Control (BSC). The ASC technology has reduced over-application of pesticides to a large extent as compared to manual control system. Applying pesticides below a desired rate may lead to yield loss. Owing to its potential to save farm inputs, its ease of usage, and improved efficacy, the ASC technology has become increasingly popular. At this rate, this technology will gradually become a part of sprayer control systems. Based on this background, it is imperative to integrate factors such as speed and flow rate with the functioning of self-propelled sprayer in order to prevent the hazards of non-uniform spraying. Varios system and part of the technology are explained below.

#### **5.1 Spray controller**

The spray controller system consists of a manifold, electronic control unit (console), proximity sensor, pressure sensor, and water hose pipes (**Figure 8**). Manifold is composed of several components including flow meter, liquid strainer, electric regulating valve with bypass mode, and pressure relief valve (**Figure 2a**). These components ultimately control the spray application rate by adjusting the liquid flow rate. Flow meter is used to measure the actual rate of flow in a system and the value of system's real time flow rate is displayed on electronic control unit in a digital readout form. A liquid strainer is fitted to filter or separate out unwanted solid matter from the liquid stream. Regulating motor rated 3 rpm which is the most accepted motor used to regulate the liquid flow rate in automated systems was used. Motor opens the valve to the maximum flow in about 6 seconds and pressure relief valves in about 10 seconds. The pressure relief valve (PRV) is designed to open at a predetermined set pressure used to control or limit the pressure which otherwise may results in process upset or system failure. The pressure is relieved by allowing the pressurized liquid to flow from an auxiliary passage out of the system.

#### **Figure 8.**

*Manifold with 3 way section and its components (b) electric control unit (ECU) (c) proximity sensor (d) pressure transducer (10 bar).*

The function of the electronic control unit (ECU) was to control the spray boom sections during real-time applications and to switch on/off the spray. The selected ECU had a provision to control five boom sections in real-time. The number of active boom sections was set to three in ECU as only 3 boom sections were used. A small display provided on ECU delivered all real time information regarding sprayer. This system had a provision to run in auto and manual modes. The parameters like ontarget application rate, number of tips on each boom sections, tip spacing, nozzle used were calibrated on ECU before the field operation.

A proximity transducer was fixed on rear tyre of high clearance boom sprayer to measure the forward speed. It works by sensing a metal object mounted in front of sensor face. The control system monitors the traveling speed and adjusts the amount of pesticide sprayed for a unit area accordingly for precise spraying applications. The analogue pressure transducer is mounted at valve manifold to monitor the overall liquid pressure. A pressure transducer generates an electrical signal which is displayed on electronic control unit (ECU) indicating the pressure imposed in the system. Pressure transducer used in this study is able to measure pressure up to 10 bar.

#### **5.2 Installation and calibration of the automatic spray control system**

A frame casing was fabricated using the angle-irons and G.I. sheet to house the manifold and sensors of the automatic spray control system. This complete unit was mounted on the high clearance sprayer such that the delicate parts were protected from the harsh operating conditions. The block diagram of the setup used to configure the automatic sprayer control system is shown in **Figure 9**.

Once the system was successfully installed, calibration was necessary to ensure its effective operation. To this end, different sensors and other electronic parts of the system were optimally calibrated. The proximity/speed sensor installed near the rear wheel of high clearance sprayer counts the number of wheel rotations (**Figure 10a**). It is calibrated by the spray controller (ECU) to provide the exact speed and spray area readings. For calibration, the tractor was made to run over a 100-meter distance i.e., point A to point B in the field after activating the calibration step of the automatic spray control system

**Figure 9.**

*Block diagram of an automatic spray control system.*

*A view of (a) proximity sensor installed at rear wheel and (b) calibration step screen on electronic control unit.*

and pulses generated by the speed sensor were counted. Once the desired distance was covered, the speed calibration number was displayed on the screen (**Figure 10b**). It was saved in console memory and calibration procedure was completed.

The pressure transducer was calibrated by adjusting the pressure displayed by the ECU to the actual pressure value. To this end, an accurate manual pressure gauge was placed in the spray line close to the spray nozzles to measure the actual pressure in the system. Then, in-auto mode calibration step was activated to calibrate the installed pressure transducer and the displayed pressure was adjusted. Once the actual pressure matched the displayed pressure, calibration was initiated. The newly recorded value of maximum rating of pressure transducer, which lies between "0–10", was displayed and saved in memory after calibration.

The calibration of flow meter sensor was performed by setting the console in auto mode and activating calibration step wherein the flow meter pulses are calculated on

the basis of a known volume of fluid passing through the flow meter. To achieve this, calibration step was activated and the sprayer pump was started. During calibration, a known volume of fluid (360 liters) was sprayed and monitored. Once the entire volume had been sprayed, the ECU was instructed to stop counting pulses. Based on the pulse count obtained, the flow meter was calibrated.

## **6. Spraying tips with safety precautions**

Agro-chemicals are toxic to both humans and animals. However, the harm to humans and non-target animal species can be reduced, if necessary precautions are taken. Insecticides will cause maximum harm, if inhaled or ingested or if they are in direct contact with the skin. Pesticide particles can also be inhaled with the air, while they are being sprayed. Another risk is the contamination of drinking-water, food or soil with insecticide particles. Precautions should also be taken during transport, storage and handling of pesticides and spray equipment. Spray equipment should be regularly cleaned and maintained to prevent leaks. People who work with pesticides should receive proper training in their safe use. Some spraying tips along with safety precautions before, during and after spraying are mentioned below;

Before spraying:

During spraying:

After spraying:

## **7. Conclusions**

The following conclusions have been drawn regarding the plant protection equipment used for cotton crop;

*Cotton*

## **Author details**

Manjeet Singh Makkar\* and Santosh Kumar Gangwar Punjab Agricultural University, Ludhiana, India

\*Address all correspondence to<EMAIL_ADDRESS>
© 2022 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

*Machinery for Plant Protection in Cotton Crop DOI: http://dx.doi.org/10.5772/intechopen.103834*

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[2] Consumption of chemical pesticides in various states/uts during 2016-2017 to 2020-2021 [Internet]. 2022. Available from: http://ppqs.gov.in/statisticaldatabase [Accessed: 03-01-2022]

[3] Lu Y, Wu K, Jiang Y, Guo Y, Desneux N. Widespread adoption of Bt cotton and insecticide decrease promotes biocontrol services. Nature. 2012;**487**(7407):362-365. DOI: 10.1038/ nature11153

[4] Kumar A, Kumar R, Aman VS, Karwasra N. Optimization of nozzle characteristics for different type of sprayers. International Journal of Pure & Applied Bioscience. 2020;**8**(2):273-281

[5] Narang MK, Mishra A, Kumar V, Thakur SS, Singh M, Mishra PK. Field evaluation of manual spraying technology against white flies on cotton crop in south-West Punjab. Agricultural Engineering Today. 2015;**39**(1):29-33

[6] Kumar S, Singh M, Manes GS, Singh NK. Development of auto rotate gun sprayer for the control of whitefly (*Bemisia tabaci*) in cotton crop. Journal of Cotton Research and Development. 2020;**34**(2):211-217

[7] Kumar S, Singh M, Arora J, Manes GS. Comparative field evaluation of auto-rotate gun sprayer for control of *Bemisia tabaci* in a cotton crop. African Entomology: Journal of the Entomological Society of Southern Africa. 2020;**28**(2):300-311

[8] Kumar S, Singh M, Manes GS, Pathania M. Development and evaluation of PAU multi-purpose sprayer to control whitefly *(Bemisia tabaci*) in cotton. The Indian Journal of Agricultural Sciences. 2020;**90**(6):1160-1165

[9] Singh M, Ghanshyam C, Mishra PK, Chak R. Current status of electrostatic spraying technology for efficient crop protection. AMA, Agricultural Mechanization in Asia, Africa and Latin America. 2013;**44**(2):46-53

[10] Parmar R, Singh S, Singh M. Bio-efficacy of unmanned aerial vehicle based spraying to manage pests. The Indian Journal of Agricultural Sciences. 2021;**91**(9):109-113

[11] Indra Mani. Standard Operating Procedures (SOP) for use of drone with pesticides for the crop protection and for spraying soil and crop nutrients in agriculture, forestry, non-cropped areas etc. Document released by Department of Agriculture and Farmers welfare, Ministry of Agriculture and Farmers Welfare, Govt of India in December 2021

Section 4