Extension Communications
3614 Administrative Services Building
Ames, Iowa 50011-3614
(515) 294-9915
2/15/99
Contacts:
Rebecca Roorda, ISU Plant Pathology, (515) 294-1741
Mark Gleason, Plant Pathology Extension, (515) 294-0579
Elaine Edwards, Extension Communication Systems, (515)
294-5168
Yard and Garden Column for the Week Beginning Feb. 19
Planning A Healthy Vegetable Garden
By Rebecca Roorda
Plant pathology graduate student
Iowa State University
While looking out on the wintry landscape, the thoughts of Iowa gardeners can't help but turn to the planting and growing season ahead. Curled up in chairs with a stack of gardening magazines and seed catalogs, we imagine the rows and patches of delicious fresh vegetables we will nurture and eat in the months ahead. It's time to plan what will be planted. To satisfy the urge to work with the soil, many of us will start a few (or many) seeds on a sunny windowsill, under lights in our basements or, if lucky, in a greenhouse. Others will rely on purchased seedlings. For all of us, planning is half the fun.
But what to plant? The same varieties planted before or something new and different? Did you have trouble with the tomatoes, did the radishes rot or peppers perish? Don't give up. There are ways to encourage healthy plants in the home garden if you follow a few simple guidelines.
Healthy plants begin with healthy seeds and seedlings. Without good quality seeds, the chances of having a good crop of the favorite vegetable is lowered. Many diseases can be transmitted through seeds, so it is important to start out with disease-free seeds. Make sure you buy seeds and seedlings from a reputable source. To reduce the chance that diseases present in or on the seeds will develop, many commercially-available garden seeds are treated with fungicides and other chemicals. If you save your seeds, most will benefit from storage in a cool and dry place with conditions that are unfavorable to many common diseases and limited seed deterioration.
Some varieties of plants are more resistant to diseases than others. Look for varieties that are resistant to diseases common in Iowa. In tomatoes you will often see initials such as VFN or VFFN after the name of the variety. These initials mean the variety is resistant to the diseases Verticillium wilt, Fusarium wilt (two Fs mean resistance to two races of Fusarium wilt) and to root knot nematodes, tiny wormlike creatures that can infest the roots of some plants. Some plant tags and seed catalogues are better than others at providing information about disease resistance, so you may need to search out this information. If you have varieties that have worked well in the past, go ahead and continue to use them. Advice from your gardening neighbors can be helpful too, especially if you are a new gardener. Most gardeners are happy to let you know what they plant, and may even be willing to share extra seedlings. Extension publications are available that give lists of many vegetable varieties that have done well in Iowa.
But what if you want to try something new and can't find any information on disease resistance? Gather as much information as you can, go ahead and try it, and see what happens. Try to plant something new in your garden every year. Sometimes the experiment is a success, and sometimes you may not get much of a crop. The failures are sometimes caused by an unexpected disease and sometimes the plant is simply not suited to the growing conditions in the garden. No matter what the outcome, you can always learn from the experience and have fun.
Don't try to squeeze too many plants into your garden. Follow the recommendations for spacing of plants in the garden. Crowded conditions are usually more favorable to disease development than more open plantings where air can circulate and limit moisture buildup on leaves and around the plants.
It is always tempting to put in a few more plants because they look so small when they are set out. It is easy to forget how large some plants get by mid-August. If you crowd too many plants into the space, you not only have disease problems but also have trouble picking the produce amid the tangle of foliage. Thin your seedlings if they are too close together. The ones left will reward you with a better, healthier crop.
Don't forget good garden management including crop rotation, sanitation and mulching. As you plan your garden for spring, put that patch of tomatoes in a different spot than last year. Some diseases are soil borne and once established, can increase in the soil as long as their host plant is available. For example, Fusarium wilt infects plants of the nightshade family, which includes tomatoes, peppers, eggplant and potatoes, so it is a good idea to rotate these crops.
Some diseases survive in dead leaves, stems and roots, so cleaning up or thoroughly tilling under garden debris is important, especially if last year's crop had a disease. While composting is a good way to conserve organic matter, if you don't have a "hot" compost pile, it is better to burn garden debris, if allowed, or otherwise dispose of it away from your garden area to prevent disease transmission from last year's plants. Proper use of mulches, especially with tomatoes and their relatives, can prevent soil and soilborne disease organisms from splashing up on plant leaves, but be aware that mulching squash provides excellent hiding places for squash bugs. Finally, plan to keep your plants appropriately fed and watered. A vigorous plant can survive disease better than one weakened from lack of water or nutrients. Maybe this is the year to invest in a soaker hose to make watering easier.
There are no guarantees that your garden won't have disease problems. After all, diseases can be affected by conditions beyond our control, such as the weather. But if you follow these recommendations, you can go a long way toward limiting the diseases that are likely to infect your garden.
ml: isugarden
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