Tomato plant problems
From Allotments4All
What's Wrong With My Tomatoes?
Q: What causes a big black spot on the blossom-end of my fruit?
A: The problem is called Blossom-End Rot (BER) and is caused by a lack of calcium within the fruit. When calcium reaches low levels in the tomato, the fruit simply dies back at the bottom leaving the characteristic black or brown spot. Calcium is present in most soils in adequate amounts. The problem is that the plant cannot absorb enough calcium through its roots because of dry soil conditions. That's because calcium is taken up by the roots along with water. If, for some reason, water uptake is restricted, calcium uptake will stop.
What can you do about it? Have your soil tested to make sure you have enough calcium in the soil. If you don't, add either limestone (if the soil's acidity level or pH is below 6.0) or gypsum. If calcium levels are adequate, the most important control measure is to maintain optimum soil moisture. Whenever tomato plants are allowed to experience the slightest bit of water stress, you are causing BER. To maintain good soil moisture, try using a mulch of straw, leaves, or even grass clippings to prevent evaporation.
Tomatoes need about one inch of water per week as a minimum. If you do not get this through rainfall, you will need to apply the water As a rough estimate, each tomato plant needs approximately 3-5 gallons of water each week. If you use a mulch, this amount may be cut in half. When watering, don't lightly sprinkle the ground. Apply the water so it enters the ground and moves through the soil to a depth of 8-12 inches. Shallow watering only encourages shallow rooting which leaves tomato plants more prone to wilting.
Q: My tomato plants look great in the morning and then they wilt in the afternoon. I have a lot of green fruit that need to ripen...will these plants live to produce ripe fruit?
A: There are two pathogenic fungi that can cause wilts in plants: Fusarium and Verticillium. When you purchase seed or tomato plants, look at the variety name and the letters that follow. Most varieties are VFN resistant, which means they are resistant to Verticillium, Fusarium, and nematodes. Use varieties that are VFN resistant.
The other possible cause for late afternoon wilting is known as walnut wilt. The roots of walnut trees secrete a chemical that is very toxic to tomato plants and will cause them to wilt when they are stressed in the heat of the day. Planting tomatoes in locations where there are no walnut trees is the only answer.
Q: In May and June, dark brown to black leaf spots developed on the leaves of my tomato plants. Some were as large as an inch in diameter. What caused these spots?
A: Leaf spots can be caused by fungi that are parasites on your tomato plants. The two most common diseases are early blight and Septoria leaf spot. Spots caused by early blight can get as large as an inch in diameter and will have a bullseye appearance. Septoria leaf spots are dark at first and then become more gray in the center as they age. Both of these diseases will cause the leaves of the plant to fall off prematurely. These fungi are mostly a problem during prolonged periods of wet weather.
Q: My tomato fruit looked beautiful but after I harvested them, several developed sunken circular areas that eventually rotted. What caused this to happen?
A: Sunken circular areas on tomato fruit are typical symptoms of a disease known as anthracnose, which is caused by a fungus. Although this fungus may attack both green and red fruit, symptoms do not develop until the fruit ripen. A perfectly good looking tomato will often develop these sunken areas during storage. This disease is typically a problem on tomato fruit that are sitting on the ground and when there have been prolonged periods of wet weather.
Q: How do I control diseases in the future on my tomatoes?
A: 1) The first control measure is to purchase or produce disease-free transplants. Don't purchase tomato plants that have spots on them or that are yellowing or wilting.
2) Consider the location in your garden: it is best not to plant tomatoes in the same area in consecutive years.
3) Research has shown that placing straw, plastic, or paper mulches around the base of the tomato plants will help reduce development of disease. Mulching will provide a physical barrier between your tomato fruit and any disease organisms that may be lurking in the ground.
4) If disease is present on your tomato plants, spread of the disease can be reduced by using fungicides that are available from home garden stores.
Q: Every year, I seem to have lots of green tomatoes on my plants when the first frost comes. What can I do with these unripe fruit?
A: Often, the first killing frost of the season may be followed by weeks of mild weather. First, try protecting the plants from frost. When a frost is forecast, cover the plants. Try using an old sheet, a plastic tarp, or even a floating row cover material like reemay. Place it over the plants in the late afternoon and take it off the next morning after temperatures have risen above freezing.
This will also be a good time to root prune the plants. Root pruning means taking a spade and pressing it into the soil about 6-8 inches. Do this in a circle, one foot from the base of the plant. By doing this you will sever parts of the root which will usually hasten ripening.
When frosts are becoming more regular, it's time to cut the plants at the base and take them to a cool location, like a basement or garage. Hang the plants from the rafters and you will see the fruit slowly ripen. The fruit will not be as tasty as those in the summer, but they will be better than what you will find in the supermarket.
Instead of removing the whole plant, harvest all tomatoes of good size and place them in paper bags in a cool location. Tomatoes do not need light to ripen and should never be placed on a windowsill! Place the tomatoes in a single layer in the bags. Tomatoes stacked on top of each other are more likely to be damaged. When placing the fruit in the bags, try to separate them based on ripeness (i.e., put all fruit of a similar ripeness in the same bag). Check the bags regularly and remove fruit as it ripens.
