Using good cultural practices throughout the growing season can reduce many common diseases in the vegetable garden to a tolerable level.
- Purchase disease free seeds and transplants.
- Plant in a location where no plant of the same family has been grown for 2 to 4 years.
- Create conditions that favor plant growth and limit fungi and bacteria by using proper plant spacing, staking, mulching and watering.
- Look for disease problems early in the season.
- Remove infected plant parts from the garden.
You can manage garden diseases
Spots, rots, wilts and other plant problems often appear in the vegetable garden.
Below are a few strategies to keep plant diseases at a tolerable level.
Remember the goal is a good harvest of tasty vegetables. It's okay to tolerate low levels of plant disease.
Start out right
- Look for disease resistant or tolerant varieties of disease problems you have seen in the past.
- Purchase seed from a reputable source.
- If saving your own seed, collect seed only from healthy plants.
- If you suspect seed may be contaminated, soak in 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.
- Provide good air movement around plants.
- If starting seeds in the garden, wait until the soil is warm enough to plant.
Remove all dirt and plant debris from
- Used pots.
- Garden tools.
- Plant supports, like trellises and cages.
Clean everything with a 10% bleach solution before using in the garden. (Mix 1 cup bleach to 9 cups water.)
- 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.
Plant in a location where no member of the same plant family has been grown for 2 to 4 years. For instance, don't plant tomatoes in the same place you grew eggplant 2 years ago.
The bean family includes:
- Black-eyed peas
- Green beans
- Green peas
- Lima beans
- Pinto beans
- Sugar snap peas
- String beans
The cabbage family includes:
- Bok choy
- Collard greens
- Mustard greens
The onion family includes:
- Red onions
- Yellow onions
The squash family includes:
- Acorn squash
- Butternut squash
- Winter squash
The tomato family includes:
- Chili peppers
- Green, yellow and red peppers
- Ground cherries
Managing disease throughout the season
- Fungi and bacteria thrive in humid conditions.
- Use drip irrigation or water with a sprinkler 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 completely cover the soil with plastic or organic mulch like straw or woodchips
- Do not work in plants when leaves are wet. Fungi and bacteria easily spread under these conditions.
- Weeds crowd the crop and increase humidity on leaves and fruit.
- Weeds steal nutrients and water from the plant, resulting in plant stress.
- Many pathogens can survive on weeds and then move into the crop.
- Completely remove plants infected with a virus or aster yellows.
- Pinch off leaves infected with leaf spots and remove them from the garden. Never remove more than 1/3 of a plant's leaves.
- Remove rotten fruit from the garden to prevent spread to developing fruit. Do not harvest rotten and ripe fruit together or rot may spread in the refrigerator.
- At the end of the growing season completely remove diseased plants.
- Diseased plant material can be composted if the compost pile gets hot (148°F or more) and the plants completely break down.
- If the garden is very large, bury plant debris to begin the decay process and rotate to a different plant family the following year.
Reviewed in 2020