Plant Pathology Infobytes

January 25, 1996
Sunny Day Vegetable Garden Projects

Planting time is still several weeks away for most vegetable gardeners. However, if you're really dedicated and ready for a few sunny day gardening projects, consider some of the following. They'll really pay-off in terms of fewer disease and other pest problems after your garden is up and going next spring.

Chore number one should be destruction and burial of last season's crop debris. Since many disease and insect pests live through the winter in old plants, cull piles, or plant stubble left in the garden, destruction of crop debris should be an annual project. This is a great way to cut down on early season disease pressure and you'll have less blight in your cabbage, broccoli, green beans, tomatoes, and other crops.

You'll want to remove and destroy old stalks (with root systems when possible), stems, vines, and other debris. If root-knot nematodes were a problem, destruction of old root systems will remove thousands of nematodes and eggs from the garden site.

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.

Remaining stubble and surface litter should be plowed under at least six inches before planting. This is effective because as debris decays, the disease microorganisms eventually deteriorate, and reduce the amount of fungus and bacterial inoculum that could cause problems in future crops.

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.

How about those tomato stakes and bean support poles lying over in a corner in the garden? Before reusing, it's a good idea to disinfect them, since many disease-causing microorganisms are able to survive the off-season on stakes, poles, cages, and other plant support structures. To reduce the risk of disease, tomato stakes and cages can be disinfected by washing to remove soil, followed by dipping or spraying with a 10% bleach solution (one gallon of household bleach in nine gallon of water works great) prior to reuse.

Site selection is always an important decision for home gardeners, but it's an even more critical consideration for those gardeners who plant extra early. To reduce chances of damping-off, root rot, and other problems associated with wet soils, choose a well-drained site.

If drainage is a problem, plant on raised beds to promote drainage and faster warming of soil. These conditions encourage faster seed germination, seedling emergence, and young plants more resistant to seedling disease infection. Similarly, transplants are less susceptible to root disease problems when grown in raised beds.

If you haven't already done so, collect soil samples to determine fertility needs. Plants which are fertilized according to recommen- dations based on a soil test are not as likely to have disease problems as plants which are low in nutrition or receive an imbalance of nutrients. Fertilizers may not prevent diseases, but a healthy, well-fertilized plant is less susceptible to disease than one growing in soil lacking required nutrients.

While collecting a soil sample for fertility analysis, why not collect a duplicate sample to check for the presence of parasitic nematodes which feed on the roots of many garden plants. Collecting soil samples for nematode analysis should be a routine part of a vegetable production program.

Collect at least 20 cores from six to eight inches deep per 5000 square feet of production area. Mix this soil thoroughly and place about one pint in a nematode soil sample bag or in a plastic freezer bag and seal. Mark the sample number on the collection container and complete the form (available at the County Extension Office) which will need to accompany the samples to the processing laboratory.

Bring the samples to the County Extension Office for mailing to the Nematode Laboratory at Mississippi State University. There is no charge for analysis of the sample for nematodes. Expect to receive sample results in approximately two weeks.

Please contact us at the County Extension Office if you need additional information on other ways to get ready for the 1996 gardening season.


Written by the late Dr. Frank Killebrew

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