Diseases of olive (
Root-knot nematode
Root-knot nematodes, which include several species in the genus Meloidogyne, infect many different plants. They are widespread in Arizona, and are usually found in sandy or sandy loam soils. Root-knot nematode is an obligate parasite that must complete its life cycle in a plant host, but eggs are persistent and can remain inactive in the absence of a host and/or in fallow soil for months or years.
As nematodes 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. The flow of nutrients and water is restricted, and plants may show premature decline. Newly transplanted trees that were infected in the nursery may decline rapidly (photo 1).
The only way to prevent nematode infections is to use a clean planting medium for nursery stock and make sure all transplants are free of infestation. If trees are infected when planted, there is no way to control disease. Once infested transplants contaminate soil at the planting site, it is impossible to completely eradicate the nematodes, and replacement plants may become infected. Oleander and pines are tolerant and are among the very few choices for replanting infested sites.
More information can be obtained from:
http://edis.ifas.ufl.edu/CV112
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May 16, 2003