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SYMPTOMS OF NEMATODE INFECTIONS

A classic symptom associated with infection by some nematodes is the formation of root GALLS (see arrow). Root knot nematode (Meloidogyne sp.) causes this kind of symptom. The nematode tunnels into the root and sets up housekeeping. As the nematode feeds, its saliva stimulates the plant root cells to divide excessively and expand to larger than normal size. This leads to gall formation. In addition, growth of abnormal cells can lead to collapse of the plant's food and water-conducting tissue (i.e., phloem and xylem). This in turn can lead to wilt symptoms and discolorations of foliage that are typical of nutrient deficiencies (e.g., yellowing or reddening).