(5/23) Now is the time most vegetable gardeners are getting ready to set out tomato plants or have already done so with protection. In this first of two articles, we will look at some commonly encountered tomato diseases with suggestions for remedy and prevention.
Bottom end or blossom end rot can occur early in the season as ugly black and brown sunken-in bottoms on the fruit. This malady is due to a lack of calcium, an element critical to fruit development. Calcium lack can be due to drought, inconsistent watering, too alkaline a soil, or high temperatures. Calcium may be present in the soil, but an excess of nitrogen and
potassium salts due to over fertilization can prevent the plantís being unable to take up the calcium it needs. Either condition can lead to bottom end rot. Always get a soil test to determine soil condition. Kits are available at the Extension Office. To prevent or remedy this woe, keep plants well mulched and evenly watered at the soil level, not on the leaves which
promotes other fungal woes. Try adding a calcium supplement (follow label directions) or place 1 to 2 tablespoons of hydrated lime over the root zone and water thoroughly.
Another tomato woe is yellow shoulder, usually found on tomatoes located along the outside perimeter of a plant. Yellow shoulder tomatoes have hard yellow-green places that never get red or ripe. This woe can develop when prolonged hot sun strikes the fruit, increasing
temperatures on the tops of the fruit. This in turn leads to inhibited lycopene production causing the tops to stay hard, green or yellow. A contributing cause has to do with the chlorophyll that gives plants their green color. Excessive heat prevents chlorophyll from breaking down. When ripening green tomatoes are in direct hot sun for hours on end, chlorophyll hangs on.
That, together with a lack of lycopene, leads to yellow shoulder. It can be remedied or prevented by maintaining good leaf cover over the fruit. Avoid overzealous leaf or sucker pruning since that exposes developing fruit to the sun. Some varieties are more prone to this problem than others. Grow hybrid varieties bred to avoid it. Heirloom tomatoes are more prone to this
Overly dry conditions cause another woe - skin cracks that develop after periods of high rainfall or too much watering. Very dry conditions alleviated by lots of rain or excessive watering can cause some varieties to crack around the top or split top towards bottom. Getting too much water too fast causes both. The tomato inside grows faster than its outside, so
expanding skin cracks to relieve the pressure. Maintain even moisture levels and mulch plants well to prevent this woe and consider crack-resistant varieties.
The last woe for this discussion is called cat facing. Not sure why a cat gets picked on for this woe since the resulting deformation does not look like a cat face to me. Anyway, it is a sign of poor pollination resulting from tomato flowers being exposed to cold night
temperatures, usually below 50 degrees F. The blossom end is shrunken in, somewhat deformed, and scabby looking, not rotted like blossom end rot. The only remedy is to protect young flowering plants during cold snaps or set plants out later in warmer weather.
While not exactly considered a tomato woe, it is extremely important to know what type of tomato you are growing. Ever wonder why some tomatoes grow 6 feet tall and others stay smaller, or why you get so many tomatoes all at once? If you can answer these questions, you already know whether your tomato plant is a determinate or indeterminate variety. Determinate
varieties, also called "bush" tomatoes, are bred to be compact in height (approximately 4 feet) and can be grown in containers. Determinate plants stop growing when fruits set and ripen their entire crop at nearly the same time, usually over a two-week period, and then die. They should NOT be pruned or suckered as this severely reduces the amount of potential fruit.
Examples are Rutgers, Roma, Celebrity (called a semi-determinate by some), and Marglobe.
Indeterminate tomatoes, also called "vining" tomatoes, continue to bloom, set new fruit, and ripen mature fruit simultaneously throughout the growing season until frost. Near the end of the growing season, removing new flowers and immature fruit can help speed ripening of existing mature fruit. Indeterminate plants can reach heights of up to 10 feet although 6 feet is
considered the norm. As a result, these plants are not for containers since they require substantial caging or staking for support. I grow mine in large homemade wire cages and never sucker the plants. My plants easily reach over 6-7 feet and have lush growth that protects their fruit from sun-based woes and pecking birds. Grown in cages, fruit stays cleaner, and no plant
tying and staking are needed. Yields are large. Building big tomato cages is a bit of an outlay initially, but well-made cages last many years. Indeterminate examples are Big Boy, Better Boy, Beef Master, most "cherry" types, Early Girl, and most heirloom varieties.
Experiment to see what type of plants you prefer to grow now that you know what can cause tomato woes.
Read other articles on growing herbs, vegetables and fruit