CLEVELAND, Ohio -- August can be a glorious month in Northeast Ohio. The weather is wonderful, hopes are still high for the Cleveland Browns preseason and maybe even the Guardians postseason, and the bounty of the vegetable garden is at its peak.
But then tomato plants that were thriving suddenly start struggling, threatening a season's worth of work and anticipation. As the calendar turned to August, I received two reader emails that exemplify the roller coaster ride of growing tomatoes at home.
The first email came from reader Tim in Richmond Heights, whose container garden using five-gallon buckets was featured in this space just a few weeks ago. His container-grown tomato plants were loaded with green fruit, including heirloom seeds from a friend's family in Italy. Tim reports that the peppers, zucchini, and cucumbers are still doing great, but the tomato plants are another story.
Tim writes, "The leaves on just about all 20 tomato plants have been turning yellow. First, I thought over-watering, but I used my water gauge and that didn't seem to be it." Then he suspected the hot temperatures, but tomatoes generally like warm air and soil. He concludes, "So the poor guys must have a disease of some kind."
He went on to describe that the leaves at the bottom of the plants were turning yellow and had brown spots, and the problem was working its way up the stems.
From Tim's photos and description, the likely cause is fusarium wilt, which is a soil-borne fungus that infects tomato roots and blocks water movement. A guide from the University of Maryland Extension explains that symptoms often begin with yellowing of the oldest leaves, followed by wilting and browning. Splitting the stem lengthwise reveals brown streaks, and which Tim sadly confirmed in his plant stems.
After a tomato plant is infected with fusarium wilt, there is no cure. Not only that, but the fungus persists in the soil for several years, so replanting tomatoes in the same spot will lead to reinfection, even after a few years of crop rotation.
Dead plants should be destroyed by throwing them in the trash or burning them, depending on the rules in your area. Do not compost them; the fungus can survive the relatively low heat of home compost piles and reinfect future plants.
Because the soil remains infected, the area should be planted in future seasons with plants that are not susceptible to fusarium wilt, like squash and beans. If the tomato plants are in containers, like reader Tim's, another option is to empty the infected soil into a non-vegetable garden area, sterilize the containers with a mild bleach solution, and start over with new soil.
Experts also recommend planting fusarium-resistant tomato varieties, which marked with an "F", in future years. However, fusarium-resistant plants are the result of many generations of selective breeding, so heirloom tomatoes will not have this quality.
Tim decided to trim off yellowing leaves and hope for some ripe fruit before the plants give out, which is a gamble I have also taken in past growing seasons. But long-term, the best prevention is clean soil and disease-resistant plants.
The harmless nutrient deficiency
The second email came from Teri in North Collinwood, whose first red tomatoes of the season looked perfect until she turned them over. The "blossom ends" were sunken and dark, which is a classic symptom of blossom end rot.
According to a helpful tip sheet from Michigan State University Extension, blossom end rot is caused by calcium deficiency in the developing fruit. However, don't rush outside to pour milk on your tomatoes (which is a popular home remedy on social media). The real culprit is inconsistent watering or waterlogged soil, which interferes with calcium movement in the plant. Temperature extremes and excessive nitrogen fertilizer can also contribute to the condition.
While the damage makes affected fruits unappetizing, the rot doesn't spread between plants, and healthy fruits on the same plant can still be enjoyed. In fact, tomatoes that develop later in the season often turn out fine if watering is kept consistent. Of course excessively rainy periods in Northeast Ohio make this advice almost impossible to follow, but regular watering during dry spells will help.
Teri also noted that her volunteer cherry tomatoes were thriving, which is not surprising, because smaller-fruited varieties are less prone to blossom end rot. And in general, with all the challenges that tomatoes in Northeast Ohio face, cherry or grape varieties can be a great way to maximize tomato output while minimizing heartbreak.
Diagnosing tomato problems
If your tomatoes are struggling, the University of Maryland Extension offers a helpful online tool, Key to Common Problems of Tomatoes, which uses lots of photos and simple descriptions to match symptoms to likely causes such as diseases, pests, or environmental stress. Iowa State University Extension's guide on Managing Tomato Diseases, Disorders, and Pests is another excellent resource.
Tomato problems can be discouraging, especially when they appear just as the fruit is ripening, but each challenge teaches us something for next season. And even in a tough year, there are usually a few healthy tomatoes to savor.