Impact of reduced fungicide and tillage on foliar blight, fruit rot, and yield of processing tomatoes

The effect of reduced tillage, soil-surface crop residue maintenance, and reduced fungicide input on processing tomato yield and disease incidence was studied in 1990 to 1992. Fall-seeded rye was desiccated in strips in early spring; the remainder, after 1.2 m of growth. Strips were zone tilled (ZT) 35 cm deep with no soil inversion. The ZT system permitted desiccated inter-row rye residue to persist throughout the summer, providing approximately 90% cover of the soil surface. Tomatoes were transplanted into the prepared strips. The ZT system did not affect marketable yield or percent fruit with mold (1991 to 1992); but it decreased (1990), increased (1991), and did not affect (1992) defoliation caused by early blight (EB) compared to a conventional tillage production system using a moldboard plow, disk, or both. The fungicide, Brave 720 (chlorothalonil), was applied as follows: none, weekly, or a full or reduced rate at intervals according to the disease forecasting model, TOM-CAST. Fungicide treatment did not enhance marketable yield compared to that of the unsprayed treatment. TOM-CAST-based treatments did not consistently provide control of defoliation compared to that in plots sprayed weekly. However, compared to weekly sprays, select forecast-generated spray schedules required 45 to 80% fewer applications to limit fruit mold incidence caused by Alternaria solani (EB), Colletotrichum coccodes (anthracnose), and Rhizoctonia solani (soil rot). Conservation tillage practices, soil-surface residue maintenance, and reduced fungicide input were integrated without compromising yield and management of disease, affording advantages of sustained farmland productivity.