Consequences of Over Watering Tomato Plants

Tomatoes are among the most commonly cultivated garden vegetables in the United States. These versatile plants produce fruit for eating fresh, cooking and preserving. Most tomato varieties are relatively easy to care for. In fact, according to Colorado State University, they need less water than many other vegetables. Many gardeners overwater their tomato plants, resulting in fungal diseases and other problems.

Blossom end rot is a dark, sunken spot at the bottom end of the tomato fruit. This condition occurs both in greenhouse and garden tomatoes, usually because of irregular watering. If your tomatoes are subjected to drought during the early part of fruit development, they tend to develop rotting areas where the tomato blossom originally grew. Some tomatoes also suffer from blossom end rot after unusually heavy rainfall or excessive watering by gardeners. Calcium deficiency can contribute to this problem. Gardeners can't control blossom end rot once it sets in.

Tomatoes don't do well with very wet roots. Excessive water, especially in soils with poor drainage, can encourage fungal infection and damage to the roots. This problem is difficult to control once established, so prevention is the best option. Tomato plants with root rot may show wilting, poor growth and leaves with "burnt" or brown areas around the tips. These problems occur because the damaged roots aren't providing proper nutrition to the leaves.

Sometimes, the edges of tomato leaves roll up just before fruit set, especially in staked or pruned plants. This problem is largely cosmetic and doesn't affect plant growth or fruit yield, but often happens when the soil stays wet for prolonged periods. Both overwatering and excessive rainfall can contribute to leaf curl. Plants in clay soils may be more likely to suffer from this problem. Leaf curl doesn't hurt the plant, but may indicate that you should reduce irrigation. However, according to Texas A&M University, a few tomato varieties always have curled leaves. This is a trait of the variety and doesn't indicate a problem.

Wet conditions, especially when the weather is warm and humid, can encourage fungal diseases in tomato leaves, fruit and stems. Overwatering your tomatoes in the evening increases the chance of the plants developing wilts, leaf spot conditions and blight. Provide irrigation in the morning whenever possible and use a drip system to prevent water from collecting on the leaves or stems of the plant.