By Sara Toler
There’s nothing more discouraging than watching healthy tomato plants suddenly develop yellow leaves, dark spots, and dying branches just as they’re beginning to produce fruit. In Michigan, tomato blight is one of the most common garden challenges due to our warm, humid summers. The good news is that with a few preventative steps and proper care, you can greatly reduce your chances of losing your harvest.
What is Tomato Blight?
Tomato blight is a fungal disease that attacks leaves, stems, and sometimes fruit. Michigan gardeners most commonly deal with Early Blight and Late Blight. Early blight usually begins on the lower leaves, creating brown spots with distinctive circular rings. As the disease spreads upward, leaves turn yellow and eventually die.
Late blight is more aggressive and can quickly destroy entire plants. It often appears during cool, wet weather and causes dark, water-soaked spots on leaves and stems.
Prevention is the Best Medicine
The easiest way to beat blight is to prevent it before it starts.
- Plant tomatoes in full sun where air circulates freely.
- Space plants at least 24–36 inches apart.
- Mulch around plants with straw or shredded leaves to keep soil from splashing onto the leaves.
- Water at the base of the plant instead of overhead to keep foliage dry.
- Rotate your tomato planting location every year, avoiding the same garden bed for at least three years.
Keep Your Plants Healthy
Healthy tomato plants are naturally more resistant to disease.
Prune the lower leaves so they don’t touch the soil, and remove suckers if plants become overcrowded. Stake or cage tomatoes to improve airflow and keep fruit off the ground. Fertilize moderately—too much nitrogen encourages lush foliage that stays wet longer and is more susceptible to disease.
Remove Diseased Leaves Immediately
If you notice brown or spotted leaves, remove them as soon as possible. Dispose of infected leaves in the trash rather than composting them, since fungal spores can survive and spread. At the end of the growing season, remove all tomato plant debris from your garden to reduce disease next year.
Consider Resistant Varieties
Many modern tomato varieties are bred with resistance to common diseases. When shopping for seeds or transplants, look for varieties labeled as resistant to early blight or other fungal diseases. While no tomato is completely immune, resistant varieties often stay productive much longer.
Organic and Natural Options
Organic gardeners can use copper-based fungicides or biofungicides as preventative treatments before disease becomes severe. These products work best when applied early and according to label directions—they cannot cure leaves that are already infected.
A Healthy Garden Starts with Good Habits
Michigan’s weather may create ideal conditions for tomato blight, but good gardening practices can make all the difference. Proper spacing, watering techniques, mulching, pruning, and crop rotation work together to keep plants healthy throughout the season.
A little prevention now can reward you with baskets of fresh, delicious tomatoes all summer long. Happy gardening from all of us at Grow Jackson!
