Heat and low moisture can cause the edges of the tomato leaves to die back, then twist and curl. Hot dry weather may also cause a symptom called physiological leaf roll. This is a self- defense response, where leaves and leaflets curl slightly to prevent further water loss (Fig.
Add a 2-inch layer of mulch around tomato plants to limit soil moisture evaporation. Tomato leaves curling brought on by harsh growing conditions usually resolves when the conditions improve. Don't expect long-term effects. A short battle with leaf curl "does not significantly reduce plant growth or yield," says Nair.
Inadequate watering, over-watering, unstable temperatures, and hormone weed killers are among the main causes of leaf curl. Here we take a look at some of the reasons why your tomato leaves don't look quite as lush and healthy as you'd like.
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.
Overwatering causes the leaves to curl up at the tips and edges, as seen here.
Leaf curl can usually be controlled satisfactorily by a spray of a suitable registered fungicide at any stage of dormancy. Most effective control is achieved by spraying when the buds are swelling but before they have opened. It's not possible to control the fungus once it's entered the leaf.
Water correctly: Do not overwater. The first week tomato plants are in the ground, they need water every day, but back off watering after the first week, slowly weaning the plants down to 1 to 1.5 inches of water per week.
Weak Stems
Since tomato leaves are thin, they don't retain much moisture and can wilt quickly. Stems hold much more water, transporting it to parts of the plant that need it. When these thick structures droop and weaken, your tomato is seriously dehydrated.
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.
Bacterial wilt disease is most commonly found on tomatoes, although other solanaceous plants such as potato, pepper, and eggplant also may be infected. The first symptom is a sudden and permanent wilting of the leaves, even when there is adequate soil moisture (Figure 18).
Knowing when and how often to water your plants can sometimes feel more like an art than a science, perhaps no more so than for tomatoes. Overwatering tomatoes can lead to yellow and spotted leaves, while underwatering results in wilt and diseased fruit.
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.
You could be applying too much water, the soil might be poorly drained, or there could be a combination of the two factors. Within a few days of the soil drying out a bit, the leaves should uncurl. At that point, begin to monitor how much water you apply to the soil.
One sign of overwatered tomato plants is drooping stems and foliage. Wilting occurs when the soil holds more moisture than the roots can take up but it can also mean the soil is too dry and the plants need water.
Plants may wilt badly when soils are dry, but will revive rapidly when they are watered. A thorough watering once a week during hot, dry weather should be sufficient. Apply water directly to the soil around the base of the plants with a garden or soaker hose.
As the days increase in length and temperatures rise through the season, they flourish. However, come mid-summer, they tire out. “Some of the signs that a tomato plant is dying are browning or yellow leaves that curl up, reduction in flowering and fruit set, and slow development of new vegetation.
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.
Wilting Leaves: This is a common sign of underwatering. Tomato leaves are thin and can wilt quickly when dehydrated. If leaves appear droopy or limp, it's a signal that the plant needs water. Weak Stems: Tomato stems can become weak and droop due to lack of water.
Leaf curl disease shows up in spring, does the damage, and then disappears (until next spring). If your trees were infected last spring, they should have completely recovered by mid to late summer. They usually grow lots of healthy new leaves (like the photo below).
Phosphorus deficiency commonly causes older leaves to curl, distort, and remain smaller than normal. Unusually purple leaf veins and tip dieback from phosphorus deficiency. Purpling of leaf undersides due to phosphorus deficiency.