Blevins,* P.K.1, Straw, R.A.2
1. Extension Agent, Virginia Cooperative Extension, Washington County, Abingdon, Virginia 24210
2. Extension Specialist, Virginia Cooperative Extension-Southwest Virginia AREC, Glade Spring, Virginia 24340
Disease control in fresh market tomatoes is a major factor limiting the adoption of organic production methods by growers in Southwest, Virginia. Six bio-fungicides were compared to a conventional standard [Bravo (3 pts/acre) alternated with Manzate (2 lbs/acre) plus Tanos (8 oz/acre) plus BCS Copper (64 oz/ acre) for the first four weekly sprays, and Bravo alone thereafter] and an untreated check (UTC) for relative effectiveness in controlling diseases such as early blight. The biological materials and rates applied were, Storox (1% solution), Biophos (2% solution), Prophyte (4 pts/acre), Serenade Max (3 lbs/acre), BCS Copper (2qts/acre), and Serenade Max (3lbs/acre) plus BCS Copper (2qts/acre). All treatments were made on a weekly basis. The tomato variety Mountain Fresh Plus was used in a drip irrigated, trellised, plasti-culture system. Fruit was harvested and graded and placed into one of the following grades: Jumbo, Extra Large, Large, Medium, Small, No. 2, or Cull. Yield data and disease ratings were analyzed using ANOVA techniques and means were separated using Duncans Multiple Range Test. There were no statistical differences in yield of total marketable fruit. The UTC plot produced the greatest number of Jumbo fruit, while the Serenade/BCS Copper produced the lowest. Storox has been a material that local organic growers have relied on for disease control. In terms of disease control, all treatments including the UTC were better statistically than Storox, which had leaf area damage ratings in excess of 40%. This study suggests that there are differences in the relative effectiveness of these bio-fungicides for disease control. However, in this case it did not significantly impact total marketable yield. If harvest had continued, yield differences would have been expected due to defoliation by early blight.