Information on chemical plant protectants for disease control on greenhouse vegetables must be used in the context of a "Total Disease Control Program." For example, many diseases are controlled by sanitation (no smoking, fumigating soil, using disease-free seed and seedlings, removing all dead plant parts, and washing hands and equipment before moving from one house to another), use of resistant varieties, crop rotation, seed treatment, exclusion of aphids from fall crops, and cultural practices. Always use top-quality seed or plants obtained from reliable sources. Seed are ordinarily treated by the seed producer for the control of seed decay and damping-off. However, tomato seed also should be treated with Clorox to reduce the risk of tobacco mosaic virus and certain bacterial diseases.

Most foliar diseases can be reduced or controlled by maintaining relative humidity under 90%, by keeping the air circulating in the house, and watering in such a manner to avoid wetting leaves.

Spraying with fungicides should be done as to ensure coverage of all plant surfaces. We recommend the use of high-pressure and high-volume equipment or subliming products (Exotherm Termil). Application should start prior to or as soon as the disease first appears and continued on a 7- to 14-day schedule as needed. Before starting the spray schedule, be sure to obtain a diagnosis of the disease in order to use the proper material. This information may be obtained through your local N.C. Cooperative Extension center.

CAUTION: The risk of pesticide exposure in the greenhouse is high; use protective clothing laundered daily or after each exposure; ventilate house during application and use appropriate respirator. Always use the chemical as directed on the label.

Note: This information was adapted from the Southeastern Vegetable Handbook in 2017.

• Plant Disease Factsheets
• North Carolina Agricultural Chemicals Manual

For assistance with a specific problem, contact your local N.C. Cooperative Extension center.

Charles Averre, S. F. Jenkins, Paul B. Shoemaker

Recommendations of specific chemicals are based upon information on the manufacturer's label and performance in a limited number of trials. Because environmental conditions and methods of application by growers may vary widely, performance of the chemical will not always conform to the safety and pest control standards indicated by experimental data. All recommendations for pesticide use were legal at the time of publication, but the status of registration and use patterns are subject to change by actions of state and federal regulatory agencies.