Calculation of an infestation loss relation for second brood of the grape berry moth (Eupoecilia ambiguella Hbn.) by means or regression
1990
Kast, W.K. (Staatliche Lehr- und Versuchsanstalt fuer Wein-und Obstbau, Weinsberg (Germany, F.R.)) | Munder, H.
In a single case, the great variance of yield prevents accurate identification of the loss caused by grape caterpillar. From 160 paired observations of yield and infestation investigated in 1985-1988 in a Riesling vineyard, a relation of 0.13 per cent loss per 1 per cent infestation was calculated. An experiment using marked infested grapes proved similar results (0.1 per cent loss per 1 per cent infestation). From data given by a paper of Schruft, relation from 0.07 to 0.08 per cent were calculated. Sugar content increases only little from 0 to 0.04 per cent. Intensity of loss is influenced by the specific Botrytis pressure, varying by means of variety and environmental factors. A damage threshold of 4-7 per cent infestation was calculated dependent on the accounted costs
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