Growers can reduce the chance of disease infestation on greenhouse vegetable crops by incorporating a strict sanitation program and minimizing plant exposure to moisture. Sanitation and moisture management are key factors in controlling diseases on greenhouse food crops, said Michigan State University plant pathologist Mary Hausbeck.
By Dave Kuack:
By Dave Kuack:
“Preventing greenhouse diseases starts with sanitation,” she said. “I can walk into a greenhouse head house and predict how many disease problems I’m going to find just by what I see in the head house area. Is it clean? Is it neat and orderly? Sanitation is a mindset. It either carries through from the head house to the growing areas or it doesn’t.”
Hausbeck said growers should try to do a thorough job of removing any plant debris that may be left in the greenhouse, including “pet” plants that may be left in hallways or in the corners of the greenhouse.
“When a grower is making a changeover to another crop there shouldn’t be any other plants left in the greenhouse,” she said. “That is the safest approach.”
Hausbeck said growers should also make sure there is a weed-free perimeter that goes all the way around the outside of the greenhouse.
“There should not be any weeds growing around the greenhouse,” she said. “Growers need to have a critical eye to make sure there is nothing around the greenhouses that can harbor pests or diseases. Ideally all of that needs to be removed.”
Moisture management
Hausbeck said growers should make every effort to limit plant exposure to moisture.
“This includes moisture in the air—relative humidity, moisture on the foliage—leaf wetness, and moisture in the growing medium,” she said. “Moisture is a big driver for disease prevention and control. Growers should limit the amount of moisture by decreasing the relative humidity, watering during the time of day when the foliage can dry rapidly or not getting the foliage wet at all and not overwatering the plant root system. These are things that are important when growing ornamentals and are helpful when growing vegetables. It’s moisture more than temperature. When the humidity is 85 percent and higher, growers should do what they can to reduce the moisture in the growing environment and be vigilant for moisture-loving diseases such as Botrytis to develop.”