FIELD CONTROL OF LOOSE SMUT IN BARLEY WITH THE SYSTEMIC FUNGICIDES VITAVAX AND PLANTVAX

Abstract

Vitavax (2,3-dihydro-5-carboxanilido-6-methyl-1,4-oxathiin) applied as a seed treatment at a rate of 113 g per 45.4 kg of barley seed gave complete control of loose smut under field conditions. The seed treatment increased yield significantly in Parkland where smut in untreated plots was 49%. In York, with 16% smut in plants grown from untreated seed, yield increases were not significant. A higher dosage (227 g) also controlled smut but appeared to cause some toxicity. Seed treatment had no apparent effect on the malting quality of the seed subsequently harvested.Plantvax (2,3-dihydro-5-carboxanilido-6-methyl-1,4-oxathiin-4,4 dioxide) applied as a soil treatment at the rates of 5.6 kg/ha and 11.2 kg/ha also resulted in effective loose smut control in York barley but did not result in increased yield. There were indications that yield was depressed at the higher rate in York and at both rates in the variety Herta.There were also indications that treatments with either chemical had a slight effect on height, date of maturity, weight per hectoliter and 1,000-kernel weight. Seed treatment at planting time did not prevent infection of barley florets by loose smut spores 55 to 60 days after planting.