Diseases of pepper (
Root-knot nematode
The southern root-knot nematode, Meloidogyne incognita, is a soil borne plant parasitic nematode that is found in sandy and sandy loam soils in Arizona. The nematode is an obligate parasite that must feed on host roots to complete its life cycle. It has a very wide host range.
As M. incognita larvae enter the plant root, feed and mature, the surrounding cells of the plant root increase in size and divide causing swellings, often referred to as galls, on the roots (photo 1). Multiple infections cause swellings in roots that look like knots in a rope (photo 2). The flow of nutrient and water is restricted, and plants wilt quickly when water becomes limiting. If plants are infected when young, they are often severely stunted and chlorotic (photo 3). Under optimum conditions of plenty of moisture and warm temperatures, M. incognita completes a life cycle in less than 30 days.
Because of the nematode's wide host range, control is difficult. Cotton, sorghum, corn, and beans, among many other crops, are all hosts and should not be rotated with peppers when M. incognita is a problem. Rotations to alfalfa and oats, which are not hosts, are effective, especially in multiple year rotations. Preplant soil fumigation with 1,3 dichloropropene or metam-sodium is also effective in reducing early infections, but data on yield increase is not yet available in Arizona. Soil solarization is an option for small areas that can be effectively tarped for at least 6 weeks in summer. More information on control strategies and solarization can be obtained from:
http://cals.arizona.edu/yavapai/anr/hort/byg/archive/soilsolarization.html
http://edis.ifas.ufl.edu/pdffiles/CV/CV11200.pdf
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February 24, 2003