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United States Department of Agriculture

Agricultural Research Service

Research Project: Production Management Research For Horticultural Crops in the Gulf South

Location: Southern Horticultural Research

Title: Fungicide applications affect fruit diseases and quality of muscadine grape (Vitis rotundifolia Michx.)

Author
item Smith, Barbara

Submitted to: American Phytopathology Society
Publication Type: Abstract Only
Publication Acceptance Date: April 20, 2013
Publication Date: June 10, 2013
Citation: Smith, B.J. 2013. Fungicide applications affect fruit diseases and quality of muscadine grape (Vitis rotundifolia Michx.). American Phytopathology Society. 103:S2.135-136.

Technical Abstract: Fungicides can significantly reduce losses due to disease in the yield and quality of muscadine grapes. In three studies fungicides were applied individually or as part of a full season schedule from early bloom until harvest of three muscadine cultivars. The objective was to compare the effect of a full season treatment of 9 - 12 fungicide applications applied on a 10 day interval to fewer applications of individual fungicides on disease incidence, yield, and berry quality. Foliar and berry diseases were rated on visual scales. Sugars, acids, ellagic acid, and resveratrol content were determined by HPLC. In study 1, the highest berry yields were from the myclobutanil, azoxystrobin, and full season treatments; and the lowest bitter rot and Macrophoma rot scores and lowest resveratrol levels were from the azoxystrobin and full season treatments. In study 2, four applications of the individual azoxystrobin, myclobutanil, or cyprodinil & fludioxonil mixture treatments applied at 30 day intervals were as effective in reducing total berry diseases as the full season treatment. In study 3, the cyprodinil & fludioxonil mixture alternated with azoxystrobin resulted in the lowest total berry disease scores. These data indicate that the number of fungicide applications can be reduced to as few as four without an increase in berry rot diseases, and that when fruit diseases of muscadine grapes are controlled, levels on the beneficial phytoalexin, resveratrol, decrease.

Last Modified: 9/10/2014
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