Pathogens are always present in the greenhouse and are a continuous challenge for growers. The combination of plant material, moisture and certain environmental conditions can favor plant root diseases. Here are some helpful suggestions to improve your success for healthy plant material.
Keep a clean house
Root pathogens can take up residence in your greenhouse from dirty plant containers, benches, hoses and walkways. If you re-use containers, pots and trays, be sure to sanitize these adequately before introducing and re-using in your greenhouse. Traffic from outside into your greenhouse can also introduce potential pathogens. Many growers install sanitation mats to sanitize shoes and boots at the doorway. Also, if you don’t do so already, it’s a good idea to sanitize sections of your greenhouse after a crop cycle to keep pathogens in check, and they are less likely to be transferred from crop to crop.
Pull those weeds
Weeds can harbor thrips, aphids, whiteflies and occasionally fungus gnats and shore flies. These insects are vectors for plant pathogens. Remove weeds from under benches, outside the greenhouse near vents or stock plants. By removing weeds, you remove unwanted pests that are sources for pathogen introduction.
Watering
Adjust irrigation to the type of growing medium used, container type and the crop grown. Allow the growing medium surface to dry between watering as this reduces algae growth, which limits problems with shore flies, fungus gnats and restricts the activity of certain soil pathogens. The general rule is to irrigate early in the day and refrain from applications after noon, unless the crop is wilting. Early day watering allows foliage to dry and temperature of the growing medium to rise to a normal level. Irrigate to ‘run-through’ to be sure each container receives the same quantity of water. This prevents ‘spotty’ wet/dry containers and reduces salt build-up in the growing medium.
Relative humidity
If moisture collects on the glass or poly inside the greenhouse, the greenhouse contains excessive moisture and the relative humidity is too high. Periodic venting of the greenhouse introduces fresh air to lower relative humidity and reduce condensation. This allows the growing medium to dry out faster and can alleviate uneven drying from one container to the next. Adding ‘horizontal air-flow’ fans improves air circulation to accelerate the drying rate of the growing medium surface.
Crop Growth Problems
Look for changes in crop growth. Are there any patterns or color changes in plant foliage? Light green foliage and chlorotic growth often indicate nutritional and pH related problems. These symptoms may also be from overwatering, cool temperatures and the onset of root diseases. Examine the root systems of affected and non-affected plants. Healthy plant roots should be white with small, ‘fuzzy’ root hairs. If roots are limited in quantity and gray in color, plants may be infected with a root pathogen. If root disease is present, use chemical treatments to control the suspected pathogen as instructed on the product label.
PRO-MIX Biofungicide growing media products include a natural bacteria that suppresses Fusarium, Pythium and Rhizoctonia by producing antibiotics, competing for resources and stimulating the plants natural defense mechanisms. When PRO-MIX Biofungicide is used in combination with sound environmental practices, disease incidence is reduced and best plant results are achieved. For more information about PRO-MIX Biofungicide, contact Premier Tech’s Horticulture team at www.pthorticulture.com