Chemical treatments and soil solarization for the control of the stem nematode, Ditylenchus dipsaci on onion

Abstract

Trials on the control of Ditylenchus dipsaci were carried out in 1997-1998 on onion in sandy soil in southern Italy. Plots were solarized from mid July to the beginning of September 1997. Nematicides were applied in early January, the fumigants, and the day of planting, on 21 Januaty 1998, and one month later the non volatiles. There were combinations which included integration of soil solarization with chemicals and different chemicals at various times of application. All treatments statistically increased the marketable yield of onion bulbs with respect to the control, but no dramatic differences occurred among treatments. In pallicular, it appeared that integration of soil solarization with chemical treatments did not always improved the results obtained by each single treatment. Metam sodium, metam potassium, fenamiphos either granular or microcapsulated or the experimental Bayer granular nematicide were equally effective as single preplant applications. Their performance was not improved when after soil fumigation further application of non-volatile nematicides followed at planting and at one month after planting. Marketable bulbs represented in all treated plots between 90 and 100% of the total yield. Soil populations of D. dipsaci at the end of the experiment were erratic and not much different from the untreated control.