Plant Pathology Infobytes

February 2, 1998
Don't Let El Nino Put A Damper On Your Spring Gardening Season

Rain, rain, and more rain! If the southern version of El Nino hangs around into the spring gardening season, home vegetable production could be difficult in 1998.

Diseases, and most other pests which attack vegetable crops, are more difficult to control under rainy conditions, so gardeners will likely have their hands full trying to take care of early season disease problems such as seedling diseases, and other wet weather disorders such as blights, leaf spots, and wilts.

The following tips should reduce the severity of vegetable diseases under El Nino growing conditions. But, even if we don't experience an unusually wet spring, these practices are great ways to help prevent diseases in any season.

  • Seed rot and seedling disease are more common in wet springs. Soil fungi, such as Rhizoctonia and Pythium, attack seed after planting and cause seed rot and poor stands. Or, these fungi attack young seedlings as they emerge, causing root and stem rots. Green bean seeds and seedlings are common victims, but most all types of vegetable seeds and seedlings are susceptible to attack. How do you prevent seed rot and seedling disease? If you are an early season gardener, avoid placing seeds too deep, or delay planting until soil has warmed.
  • Another way to obtain and maintain a healthy stand of vegetable seedlings is to use the "raised row" planting approach. Soils in raised rows are better drained, warmer, and encourage faster seed germination, seedling emergence, and young plants more resistant to seedling disease infection. Raised row gardening can be an especially valuable disease control technique if your garden area isn't especially well-drained.
  • Plant seeds treated with a fungicide to further help reduce seed, root and stem rots. Vegetable seeds are coated with fungicides to control seed rot and seedling diseases. Fungicide treated seeds are especially worthwhile in circumstances where vegetables are to be planted in cool or wet soils. Often seeds bought from dealers are already treated - indicated by a reddish or green color - but ask to be sure. The most commonly used materials are products containing captan or thiram fungicides. Seeds not already treated commercially can be coated with fungicide by the gardener. Large seeded crops such as corn or beans can be treated by placing seed and fungicide in a jar and gently shaking or rotating the container until all seeds are evenly coated. As little as 1/4 to 1/2 teaspoonful of captan or thiram per pound of seed may be all that is needed to accomplish this. Smaller seeds may be treated right in the seed packet by shaking a small amount of fungicide with the seed. Be sure to wash equipment and hands after handling fungicide and treated seeds.
  • If nitrogen fertilizers are applied, avoid use over-use, since excessive nitrogen can favor seedling diseases caused by Rhizoctonia.
  • Plant at recommended seeding rates, since dense plantings stay wet longer because of reduced air circulation and poor sunlight penetration. This leads to bacterial and fungal leaf spots and blights.
  • After a stand of healthy seedlings is up and growing, observe the garden daily for evidence of leaf spot or other disease symptoms, and begin a fungicide spray program at the first sign of disease symptoms. Or, better still, start your fungicide application program before diseases are observed if weather conditions are favorable for disease development. This can be a big step in preventing a possible overnight buildup of diseases that reduce yield and quality of garden vegetables.

Anthracnose, rust, mildew - are these foreign words in your gardening vocabulary? Look for coverage on how you can prevent these and other garden disease problems in future articles. Our aim is to help you produce a healthy crop of vegetable this season, so feel free to give us a call at the County Extension Office any time you have gardening questions.


Written by the late Dr. Frank Killebrew

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