plankton. n. 1. (Biology) the organisms inhabiting the surface layer of a sea or lake, consisting of small drifting plants and animals, such as diatoms.Compare nekton. [C19: via German from Greek planktos wandering, from plazesthai to roam].lankton is a primary food source for many animals, and consists of bacteria, protozoans, certain algae, cnidarians, tiny crustaceans such as copepods, and many other organisms. Microscopic aquatic organisms that float near the surface of water.
Descriptions of Common Tomato Diseases. 1  Anthracnose - small, circular, slightly sunken spots... 2  Bacterial Canker - wilting, browning plants and bird's-eye fruit spots. 3  Bacterial Spot - small, dark, slightly raised dots on fruit... 4  Bacteria Wilt - entire plant dies rapidly after browning... 5  Blossom End Rot - spot on bottom of fruit turns black and...
Diseases can be classified into two groups. The first are those caused by infectious microorganisms that include fungi, bacteria, viruses and nematodes. These diseases are contagious and can spread from plant to plant in a field, often very rapidly when environmental conditions are favorable.ungi are the most common cause of infectious plant diseases and can be very destructive. Diseases of tomatoes caused by bacteria, viruses, and nematodes are described in Extension Fact Sheet EPP-7626. Non-infectious diseases of tomato are covered in Extension Fact Sheet EPP-7627.