Abstract

Organic farming is currently the fastest growing agricultural sector worldwide. However, diseases and weeds are among the major factors limiting its expansion. The use of cover crops has been shown to reduce weeds and minimize soil-borne pathogen populations through increased organic matter deposition, which also improves soil structure and porosity. Reflective and colored plastic mulches have also been shown to reduce vector borne diseases on many vegetable crops, including tomato. Such measures to combat disease depend on other variables and are generally site-specific. Two experiments were conducted to evaluate the effects of the winter cover crops, crimson clover, rye, hairy vetch, and Austrian winter peas and reflective polyethylene mulch with or without biofungicides on severity of diseases and fruit yield of tomato. Plant height, fruit weight, number of fruits per plant and the type of foliar and fruit diseases observed including their severity were determined. Tomato fruit rot incidence was significantly lower in tomato plants grown following hairy vetch and Austrian winter pea compared to plants in fallow plots. Reflective polyethylene mulch was significantly (p = 5%) better than control (no mulch) for fruit yield, number of fruits/plant and plant height. However, plants on reflective polyethylene mulch showed significantly more severe bacterial spot disease. Application of spent mushroom compost under polyethylene mulch significantly enhanced tomato fruit yield and number of fruits/plant compared to the biofungicide Root Guardian^®, but increased bacterial spot severity compared to Plant Guardian^®. The results of this study indicated that winter cover crops enhance yields of tomato by minimizing disease while reflective polyethylene mulch and spent mushroom compost are conducive to growth and fruit yield in field-grown organic tomato.

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