Physiological plant disorder diseases. Improving drainage will help to alleviate this problem. Hail can cause damage to soft skinned fruits, and may also allow brown rot or other fungi to penetrate the plant. Brown spot markings or lines on one side of a mature apple are indicative of a spring hailstorm. Plants affected by salt stress are able to take water from soil, due to an osmotic imbalance between soil and plant. Poor growth and a variety of disorders such as leaf discolouration (chlorosis) can be caused by a shortage of one or more plant nutrients. Poor plant uptake of a nutrient from
Plant tolerance to herbivory Using simulated herbivory allows for the control of environmental variables, but replicating natural herbivory is difficult, causing plants to respond differently from imposed and natural herbivory (Tiffin and Inouye 2000). Growing plants in the control environment of the greenhouse may also affect their response as it is still a novel environment to the plants. Even if the plots are grown in natural settings, the methods of excluding or including herbivores, such as using cages or pesticides, may also affect plant tolerance (Tiffin and Inouye 2000). Lastly, models have predicted that manipulated herbivory may actually result in less precise estimates of