Master Gardener: Growing vegetables

The goal of most vegetable gardeners is to have a good harvest of tasty vegetables. We may have to tolerate low levels of plant disease, but here are a few strategies to keep the plant diseases in your garden at a tolerable level.

Before beginning to start your plants or set plants in the garden, make sure that all pots and tools are clean and won�t spread diseases. Remove all dirt and plant debris and clean everything with a 10% bleach solution before using.

Purchase seed from a reputable source and look for disease resistant or tolerant varieties for disease problems you have had in the past. If saving your own seed, collect seed only from healthy plants. If you suspect your seed may be contaminated, soak in a 1:4 bleach solution for 1 minute and rinse in running water for 5 minutes just before planting.

If starting seeds indoors, use new potting mix with new pots or pots cleaned with 10% bleach. Keep soil moist but not soggy and keep good air movement around plants. If starting seeds in the garden wait until the soil is warm enough to plant.

If you are going to start your garden from transplants that you purchase, purchase healthy transplants from a local reputable grower. Inspect all transplants prior to purchase, Reject any plant with dark, discolored or soft sunken spots on leaves, stems or roots. Roots should be a nice white color.

Be sure to rotate crops so that no member of the same plant family has been grown in that spot for 2 to 4 years. Different plant families include the cabbage family, tomato family, squash family, bean family and onion family.

Watch for problems with disease in your garden whenever you are in the garden, but at least weekly. Fungi and bacteria thrive in humid conditions. Do not work in plants when leaves are wet. Fungi and bacteria spread under these conditions. Use drip irrigation or if you water overhead with a sprinkler, do it early in the day so that the plant dries quickly in the sun. Space plants for good air movement so plants dry quickly after rain or dew. Stake vining plants like cucumber, bean, and tomato. Mulch to cover the soil with plastic or organic mulch like straw or woodchips.

Weed management is import because weeds crowd the crop and increase humidity on leaves and fruit. Weeds also steal nutrients and water from the plant and many pathogens can survive on weeds and then move into the crop.

Diseases are easier to deal with if identified early. Completely remove plants that are infected with a virus or aster yellows. Pinch off leaves infected with leaf spots and remove them from the garden, but never remove more than 1/3 of the plant�s leaves. Remove rotten fruit from the garden and also remove diseased plants. Do not compost diseased plants unless your compost pile get hot (above 148 degrees) so the plants completely break down.

To determine problems with your plants, use the online diagnostic tool “What’s wrong with my plant?” or send a sample to the U of MN Plant Disease Clinic to identify pest problems.

This information was taken from a U of MN handout by Michelle Grabowski, UMN, Extension Educator.