Controlling powdery mildew - fungicides and spray timing.

摘要

The efficacy of Cabrio (pyraclostrobin; 40 ml/100 litres), Filan (boscalid; 100 g/100 litres), Flint (trifloxystrobin; 15 g/100 litres), Legend (quinoxyfen; 200 ml/100 litres), Microthial Disperss (sulfur; 400 g/100 litres) and Prosper (spiroxamine; 60 ml/100 litres) against powdery mildew [caused by Erysiphe necator] on grape (cv. Chardonnay) was evaluated in Adelaide Hills, South Australia, during 2009-10. Seven spray programmes, in which 6 sprays were applied in the season, were compared. The first sprays were applied at the 4-leaf stage (late October) and the final sprays were applied at the pre-bunch closure stage (5 January 2010). The effects of the spray programmes on the development of powdery mildew was investigated on 24 February 2010. The spray programmes slightly varied in terms of control efficacy, as the severity of powdery mildew on bunches was <=5% in most treatments at 7 weeks after the final application. Fungicide programmes that included Cabrio, Filan, Flint, Legend or Prosper applied just before or during flowering provided good control of the disease. The programme that included 2 early applications of sulfur, the Filan and Cabrio mixture at the early flowering stage, a sulfur spray at capfall stage, and a final 2 applications of sulfur was the least effective.