For 20 years, scientists have been exploring the possibility that compost may help control some diseases. The addition of compost has reduced disease levels in potting mixes. Damping off and root rot diseases were reduced significantly with the addition of compost. Compost added to alfalfa fields resulted in healthier root systems and thicker plant stands. Phytophthora, a serious disease in soybeans and numerous other plants, has been reduced through the addition of compost and other cultural practices. Rhizoctonia, rootknot nematodes, and bacterial spot were reduced on experimental plots of peas and beans. Compost added to tomato fields reduced early blight, bacterial leaf spot, and nematodes. Other research has shown reduced mosaic virus spread by white fly and control of crown rot in tomatoes.
Gardeners who have regularly used compost in their gardens know the benefits of compost. The addition of compost to the soil reduces the need for fertilizer, conserves soil moisture, and may actually help in disease control. The possible reduction in disease problems is another excellent reason to begin your own compost pile. A word of warning, before adding your own compost to the garden, make sure it is mature and fully composted. Immature compost pulls nitrogen away from plants until it is mature. Also, do not add diseased plant material to the compost pile. Compost science and soil microbiology are just beginning to unlock the secrets of compost's actions.
This article originally appeared in the June 9, 1995 issue, p. 81.