Overwatering generally makes the plant look almost like it's rotting, as in drooping and turning soggy brown. My guess is it is having Nitrogen problems. Any type of vegetable fertilizer you buy at the store should work fine.
Consistent Watering: During the early stages of growth and fruit development, tomatoes need consistent moisture. Aim to water deeply but infrequently to encourage deep root growth. This typically means watering once every 1-2 weeks, depending on rainfall and temperature.
Yes. Too much water is the primary reason that tomatoes split. It happens because all that water makes the tomato's flesh grow faster than its skin can grow, and eventually the skin bursts. This often happens when there's a lot of rain after a period of dry weather.
If you dice your tomatoes, salt them, then set them in a strainer or colander set over a bowl to collect the juices, you'll end up with chunks of tomato that are not only less watery (as the salt will draw liquid out), but also more flavorful and denser/meatier in texture.
Symptoms on leaves - curling & distortion
Symptoms: upward rolling of the leaves. This is a common occurrence in mid-summer and is associated with high temperatures and moisture stress. Some tomato varieties, including heavily pruned determinate-type varieties, are more prone to leaf roll.
When nitrogen is deficient leaves are small and pale green to yellow in color. Symptoms are first seen in the old leaves and gradually progress to new growth. The plant appears thin and upright. With severe deficiency the old leaves become completely yellow or turn brown before dropping from the plant.
Depending on the amount of damage, the plant should recover in one to two weeks.
Tomatoes love the sunshine. A position in full sun (that means an average of at least eight hours a day) gives the best results in most areas, though if you're in a hot climate you can get away with dappled shade.
Ripening Fruit
Starting in mid-August, blossoms on large-fruited varieties will not mature and ripen before the end of the season. Remove blossoms and small fruit to encourage ripening of the remaining tomatoes. Reduce or stop watering about mid- to late-August to stress the plant and encourage ripening.
The good news is that most plants will bounce back between 7-14 days if they're given proper care (which includes rehydration). If this isn't possible because major damage was done or little healthy root system exists then expect about 2 weeks until improvement can be seen.
Soil that contains a lot of sand doesn't hold water well and dries quickly. Because of this, tomato plants growing in sandy soil may need to be watered more often, about every three or four days. Clay soil, on the other hand, holds water well. Plants growing in clay soil usually only need to be watered once a week.
Some growers prefer to use a high-phosphorus fertilizer, indicated by a larger middle number. You can also keep things simple with a fertilizer especially formulated for tomatoes – usually with a ratio like 3-4-6 or 4-7-10. Most importantly, don't over-fertilize. Too little fertilizer is always better than too much.
NASA research found that previsible signs of stress can be detected by measuring the chlorophyll content based on light energy reflected from the plant. The Observer detects stress up to 16 days before deterioration is visible to the eye. Early detection provides an opportunity to reverse stress and save the plant.
Symptoms and Diagnosis
With mild water deficiency, plants are usually slow-growing and stunted. Some plant leaves turn from shiny to dull at first signs of stress. Grasses, which are the first to show the loss of water in the landscape, will show signs of wilt.
Try saving stressed tomatoes from heat or early blight using shade, vermicompost tea, and removing blighted leaves.
Symptoms in tomato plants are the upward curling of leaves, yellow (chlorotic) leaf margins, smaller leaves than normal, plant stunting, and flower drop. If tomato plants are infected early in their growth, there may be no fruit formed. Infected plants may appear randomly throughout the garden.
MY TOMATO PLANTS HAVE FLOWERS, BUT THEY DON'T SET FRUIT (BLOSSOM DROP) Tomatoes can be a little finicky! Outdoors, they may not set fruit if days are too hot or too cool, if nights are too warm or too cool, if the soil is too wet or too dry, and so on.
Watering tomato plants every day will prevent them from developing a strong root system and sitting in wet soil is an invitation for root rot and other soilborne diseases. When you water, do not wet the plant leaves.