Control ofDitylenchus dipsaci in garlic by bulb and soil treatments

Garlic bulbs heavily infected withDitylenchus dipsaci were chemically treated to control the nematode. Treatment with ethoprop resulted in greatest reduction of nematodes early in the season; oxamyl provided good control; methomyl was ineffective. Treating the soil with aldicarb or phenamiphos was also effective. Later in the season, nematode populations increased with all treatments and crop damage was severe. In a soil heavily infested with this pathogen, nematode populations in the untreated plots were initially low but had increased rapidly 100 days after planting, resulting in total loss of plants by the end of the season. Excellent control was obtained by treating the soil with methyl bromide (MB) or solar heating with transparent polyethylene sheets prior to planting, although MB treatment caused severe stunting of the plants. Treatment with ethylene dibromide (EDB) controlled the pathogen initially, but later in the season the population level increased. The yields (kg/m²) were: untreated, 0; solar heating, 2.325; EDB, 0.813; and MB, 1.152.