Chemical control of Globodera pallida (Stone) Behrens and potato (Solanum tubersoum L. var Floresta) yield

Abstract

In a field planted with the variety Floresta of potato (Solanum tuberosum) and infested with nematodes (Globodera pallida,Stone 1973; Behrens 1975),  the effect of fenamifos and forato on nematode control and crop yield was evaluated. The nematicides were applied at sowing or at sowing and hilling. Forty five days after treatment application, fenamifos at sowing reduced in 58 % (p=0,0023) the cyst number per 200 g of soil. The lowest (p= 0.0087) root nematode population, 189 juveniles per 100 g of roots, was found in the plants of the plots treated with the mix of fenamifos-forato at sowing. When fenamifos was applied at sowing and hilling, the cyst population decreased by 25 % from 45 to 155 days after planting, resulting in the lowest growth rate. The initial cyst density of 0.6 per gram of soil in the untreated control resulted in a 48 % reduction in yield. On average, the nematicide treatments yielded 5.6 tm ha^-1 more (p= 0.0537) than the untreated control, and the application of fenamifos at planting and hilling and of the mix of fenamifos-forato at sowing yielded 10.7 (p= 0.0131) and 6.2 tm ha^-1 (p= 0.0455) more than the untreated control, which represented a net gain of $2743, $6383 and $3625 ha^-1, respectively.  Yield increases varied from 19 to 106 %, being higher when the application was made at planting and hilling.