Question: J. S. Woodbridge
I had a lot of disease problems in my vegetable garden this year. I harvested very few disease-free, large heirloom tomatoes, but I did have a pretty good crop of cherry tomatoes. I don't like to use any pesticides in my garden. Do you have any tips for next year's garden?
There is a great deal you can do to reduce disease problems in your vegetable garden without using pesticides. Here are several ways to cut the need for pesiti cides:
First, make a diagram of all of the plants and their location. Avoid planting related plants in the same location the following year. This practice is called crop rotation. For instance, avoid planting plants in the solena ceous family -- tomatoes, peppers, eggplants or potatoes -- in the same location two years in a row.
Disease organisms often affect plants in the same family and can build to higher levels in the soil over time and become more problematic.
It is especially important that you practice crop rotation when growing heirlooms because of their increased susceptibility to disease.
Clean out all diseased fruit and plants from your vegetable garden at the season's end. Diseased plants can provide a source for infection of next year's crop. Discard the diseased plants and fruit. If you compost them, use that compost for ornamental beds away from your vegetable garden. It's wise to cut up the plant residue into smaller pieces to speed the composting process.
Grow vegetables on raised beds or in appropriate sized containers. Raised beds allow for proper soil drainage and aeration and can reduce soil-borne diseases. Avoid the use of overhead irrigation, which provides extended periods of leaf moisture. This can encourage foliar and fruit disease. Water vegetables with a gentle flow near the base of plants.
Raised beds along with adequate and even watering, can reduce fruit cracking on some heirloom tomatoes.
Space plants properly to allow for proper air flow and leaf drying. Crowding can increase plant stress as well as humidity levels that may favor certain leaf diseases.
Avoid over-fertilization. Excessive use of quick-release fertilizers can induce rapid growth and can enhance disease and insect problems.
Make certain to have your soil tested and adjust pH and fer tility to match the needs of your garden plants.
Grow plants vertically in cages or on trellises to keep leaves and fruit dry and reduce splash from disease spores in the soil. The use of mulches around plants can also reduce splashing and prevent weed growth.
Select vegetable and fruit varieties that have resistance to many of our common diseases. Letters on seed packets such as V, F, or N represent resistance to common soil born diseases and nematodes. Hybrid vegetable varieties have greater vigor and disease resistance than many heirloom varieties.
We discuss alternative pest and disease strategies at our county Master Gardener classes and other educational workshops . For more information on programs near you, log on to www.rce.rutgers.edu and to www.ifplantscouldtalk.rutgers.edu for educational slide shows, videos and graphics.