Soil fumigation of sultana vines

Abstract

Soil supporting mature sultana vines at 23 sites on loam and sandy loam soils in the Merbein district was fumigated with 92.2 per cent w/w 1,2-dibromo-3-chloropropene at the rate of 2 1/2 gallons an acre. Significant yield increases were recorded at four sites in the second season after treatment, and at eight sites in the third season. Significant increases generally were of the order of twice the cost of treatment, or better. All sites were infested with citrus nematode, numbers ranging from an average of about 2,000 per 500 grams of soil on some sites to more than 20,000 on others. There was no relation between numbers of nematodes in the soil and vine yield. Soil counts indicated a substantial reduction in nematode numbers due to fumigation, but counts made at the end of the third season suggested that numbers in treated soil were increasing rapidly. No reason for the yield response was apparent-response was not related to mean untreated yield, to soil type, or to numbers of nematodes in the soil.