Transmission of Plant Diseases by Insects

Plant diseases appear as necrotic areas, usually spots of various shapes and sizes on leaves, shoots, and fruit; as cankers on stems; as blights, wilts, and necrosis of shoots, branches and entire plants; as discolorations, malformations, galls, and root rots, etc. Regardless of their appearance, plant diseases interfere with one or more of the physiological functions of the plant (absorption and translocation of water and nutrients from the soil, photosynthesis, etc.), and thereby reduce the ability of the plant to grow and produce the product for which it is cultivated. Plant diseases are generally caused by microscopic organisms such as fungi, bacteria, nematodes, protozoa, and parasitic green algae, that penetrate, infect, and feed off one or more types of host plants; submicroscopic organisms such as viruses and viroids that enter, infect, spread systemically and affect the growth of their host plants; parasitic higher plants which range from about an inch to several feet in size...