When growing vegetables, at some point, all gardeners encounter disease problems of one kind or another. Early blight on tomatoes, powdery mildew on squash, black rot on broccoli, or damping off on your seedlings, just to name a few. While each of these diseases have very specific life cycles, they can all be managed through a good combination of cultural tactics.
Use these tactics in your own vegetable garden to reduce disease issues and achieve bountiful, high-quality harvests year after year.
Monitoring, Planning, & Diagnosis
- Scout often and address issues as soon as they are noticed.
- Most disease issues cannot be corrected, only prevented. By addressing the issue as soon as it is noticed, you can prevent it from spreading.
- Plan to address issues if they have been observed in the past.
- If you've had issues with Septoria leaf spot on tomatoes the past two years, its very likely to occur again. Be prepared.
- Accurately identify the problem. You can only treat it appropriately if you know what the problem is.
- Not all things that look like a disease are caused by a microorganism like fungi or bacteria.
- Learn how to distinguish biotic and abiotic issues in this article: Biotic vs. Abiotic - Distinguishing Disease Problems
Prevention Through Crop Selection & Rotation
- Practice good crop rotation.
- Disease-causing microorganisms can only be a problem if they have the right environmental factors and the right host. By removing the host species and planting something that cannot be a host, the fungi, bacteria, or other organisms cannot become a problem.
- Select varieties with disease resistance.
Maintain Optimal Plant Health & Growing Conditions
- Water and fertilize to maintain plants in a vigorous condition.
- Provide ideal growing conditions.
- Plants growing in too much shade (less than 6 hours of direct sunlight a day) or poor soil are more likely to have disease issues.
- Avoid fluctuations in water levels, whether too much or too little. This stress can make plants more susceptible to disease issues.
Water & Moisture Management
- Keep foliage dry. Most disease-causing microorganisms, like fungi, require water to proliferate. Dry foliage helps slow or prevent their growth.
- Avoid overhead watering. Soaker hoses, drip irrigation, or watering at the base of the plant all help keep the foliage dry.
- Don't work in the garden when the foliage is wet (from rain or heavy dew). You can accidentally spread diseases.
Sanitation & Cultural Practices
- Practice good sanitation. Clean tools and start seeds in clean containers.
- Eradicate weeds. They can often serve as alternate hosts for diseases.
- Remove and destroy diseased plant material. Especially at the end of the growing season after the first frost.
- Disease-causing microorganisms can sometimes overwinter on plant debris (as spores, for example) and re-infect plants next year.
- Don't compost disease-infested materials.
- Utilize mulch to reduce soil splashing.
- Stake or trellis vining or rambling plants to reduce contact with the soil.
Chemical Control (when needed)
- Using fungicides appropriately. Fungicides may be used to protect new plant tissue and prevent pathogen infection and spread.
- They rarely help eliminate the disease-causing agents (or their symptoms)
- Fungicide applications should always be used in combination with other management tactics.
- Remember to always read and follow pesticide labels.
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