The occurrence of nematodes in onion planting

Abstract

Several nematode species were found in the State of São Paulo, Brazil, attacking roots of onion; namely, Meloidogyne incognita, M. javanica, M. thamesi, and Pratylenchus brachyurus. The last species seemed to be much more serious a detriment to onion production than the other ones. Symptoms exhibited by the attacked plants, particularily in seedlings, were: reduction of the aerial part and root system, chlorosis, magnesium and other element deficiencies, galls and necrosis on the roots and multilated roots. Control measures considered most economic are presented. They include: fumigation of the seed beds, crop rotation and repeated disturbance of the soil principally during hot-dry periods.