Sanitation Is the Key to Prevent Diseases in High Tunnels

At the end of the growing season, it is imperative that growers remove all plants (with roots when possible) and any dropped fruit to limit the likelihood of infection from overwintering sources of inoculum. If a grower is planning to compost their high tunnel debris, they should locate their compost and/or cull piles far away from their production areas to prevent windblown spores from infecting the high tunnel crops in the coming year.

Weeds are a scourge in any production system, and when encountered in high tunnels, their impact may be greatly amplified. Weeds will impede airflow in high tunnels, promoting plant diseases like gray mold and powdery mildew. Weeds also compete with crops for light, water, and nutrients and are known to harbor a variety of pests and diseases that may reduce overall crop yield or even cause crop loss. Weeds like crop residue should be physically removed from the high tunnel at the end of the growing season to limit sources of inoculum for the next year.

Tools and equipment used in the high tunnel should be cleaned and sanitized to prevent the introduction of pests, diseases, and weed seeds into the high tunnel environment next season. Products containing hydrogen peroxide and peracetic acid are often labeled for use on hard non-porous surfaces to kill pathogens that may infect horticultural crops. Before using any product to clean or sanitize equipment, ensure that the product is properly labeled for use in your state.

Used wooden stakes often serve as a source of inoculum in fields and in high tunnels. Bacterial diseases like bacterial speck, bacterial spot, and bacterial canker can often be introduced into production areas on used wooden stakes. Wooden stakes crack and check during exposure to the elements, and the small fissures in the wood serve to collect bacteria and fungal spores. When these "used" wooden stakes are deployed to support crops, the plant foliage will inadvertently come in contact with the stake resulting in infection. At the conclusion of each growing season, consider burning or burying all wooden stakes that were used during the previous growing season. Only use new wooden stakes when supporting vegetable crops in the field and/or high tunnel systems.