The Garden Corner By Sharon Allen, Master Gardener This article, which begins my second year of writing for the newspaper, will offer a few suggestions that you can use to help control plant diseases in your gardens. It is not a particularly exciting topic, but I hope that you find it useful.
Keep the garden clean. Keeping your garden free of diseased material is an effective method of disease control. Carry a bag as you walk around your garden and put diseased material (whether they are leaves, vegetables, or entire plants) into it when spotted. Do not compost diseased material unless your compost pile heats up to 1600F. Place plants suspected of having viruses into sealed containers and dispose of with the household trash.
Prune for disease control. One of the reasons for pruning plants is to control diseases. Cut off any leaves or stems that you suspect are diseased, preventing the spread of disease within the plant and checking the spread to other plants.
Keep tools clean. Clean pots and tools that come into contact with diseased plants. Scrape off the soil (not into the garden) and dip them into a 10 percent bleach solution (one part bleach to nine parts water.) It is also a good idea to soak seedling flats, since they can harbor disease causing organisms.
Rotate your crops. Grow your crops in a different part of the garden each year to avoid the buildup of disease organisms. Many garden pests survive winter and can reinfest the following year if the same thing (or plant from the same family) is grown in the same place. Carrots, dill, fennel, and parsley belong to the Umbellifrae family; tomatoes, eggplants and peppers are in the nightshade family; and beans and peas are in the legume family, for example. Crop rotation does not work for every disease, since some diseases (verticillum wilt fungus attacks nearly 300 different species) have many host plants.
An additional benefit of crop rotation is preventing nutrient disorders. Plants are selective in their use of nutrients and can deplete the soil of specific ones. A wider variety of nutrients will be removed if different types of plants are grown in a given location, balancing soil fertility.
Control disease carriers. Diseases can be spread by insects, splashing or running water, wind, and bits of soil carried on shoes and tools. In some cases, if you control the disease carrier then the disease will not occur. Cucumber beetles, which spread bacterial wilt, will require more control if the object is to prevent disease rather than merely insect damage. A floating row cover can be helpful if used when the seeds are planted and removed later for insect pollination. Humans can transfer disease too. People can infect their tomatoes with tobacco mosaic virus if they handle the plants after touching tobacco products infected with tobacco mosaic virus.
For answers to gardening problems, write to Sharon Allen at 110 North Plum Street, Vermillion, SD 57069 or reach her through the internet at firstname.lastname@example.org.