Plant Pathology Infobytes

October 14, 1998
Smart Starts for the Next Vegetable Garden

Activities have slowed for most vegetable gardeners. That's understandable, but don't forget -- the seasons not over until fall garden "clean-up" has been completed.

Why is attention to this detail so important? Experienced gardeners know that carrying out a program of fall or early winter sanitation through garden clean-up is an important disease control step for the next crop. It will also help reduce over-wintering numbers of some insect pests as well.

Destruction of crop debris left over from the past gardening season should be step number one in your sanitation program. Many disease microorganisms live through the winter in old plants, cull piles, or plant stubble left in the garden. Getting rid of this carryover material is an important sanitary step in reducing vegetable disease problems caused by many fungi, bacteria, and other pests.

Recommended practices include removal and destruction of stalks (with root systems when possible), stems, vines, and other debris as soon as possible following last harvest. When root-knot nematodes were a problem, destruction of old root systems will remove thousands of nematodes and eggs from the garden site.

As a general rule, debris from diseased plants should not be added to compost piles, since temperatures reached are not always sufficient to kill nematode eggs and other plant disease microbes.

When possible, remaining stubble and surface litter should be plowed under to a depth of at least six inches before planting the next crop. This helps in vegetable disease control because debris which is buried breaks down a lot faster than stubble and litter left on the soil surface. As this debris decays, many of the disease microbes eventually deteriorate. Also, when diseased material is beneath the soil surface, it's a lot less likely to be a source of disease inoculum.

Plowing to bury debris is an effective way to reduce the amount of southern blight on tomatoes, peppers, and other susceptible vegetables. Southern blight sclerotia (dark brown to tan colored reproductive structures about the size of mustard seed) are formed on diseased stalks and unless turned under through deep plowing will remain near the soil surface to attack susceptible crops the next season. Sclerotia survive in soil for seven years or longer, thus burial through plowing is an important means of managing this disease.

Additional information on sanitation and other disease control measures is covered in the "Garden Tabloid," available at the County Extension Office County Extension Office. Check with us to obtain a free copy of this informative gardening publication.


Written by the late Dr. Frank Killebrew

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