Tomatoes, those kings of the summer vegetable garden, thrive during the hot, dry periods when supplemental irrigation is a must. Yet too much water results in poorly producing plants, disease or early death. Balancing the water needs of the plants requires keeping a sharp eye out for the first signs of tomato distress from too much irrigation.
Several leaf conditions occur from overwatering. Leaf roll results in older leaves on the tomato plant rolling upward while becoming brittle. High soil moisture in conjunction with direct sunlight causes this condition, which is counteracted by providing some afternoon shade to the plant and reducing moisture levels in the soil. Young and old leaves alike may also turn yellow or drop from the plant prematurely because of overwatering.
Although technically caused by a fungal infection, root rot occurs almost exclusively in overly wet soils. This is because the fungi require a wet environment to thrive. The upper portion of the plant may begin to die, usually seen first as dropped leaves and blossoms as well as slowed growth. The lower portion of the stem typically feels soft and mushy as root rot progresses. Reduce watering to prevent the rot from becoming worse. In less severe cases, the tomato plant may bounce back.
Tomatoes that crack, either at the blossom or stem end, are a result of improper watering. The condition is called cat facing and results in ugly fruits that may not reach their full size. Generally, high soil moisture and high temperatures during a period of fast growth result in the condition. Reduce watering to eliminate the problem on the next round of fruit set by the plant. Puffy fruits with hollow insides also result from too much soil moisture in conjunction with high nitrogen levels in the soil. Overly hot or cool temperatures can also result in hollow tomatoes.
Blossom End Rot
Blossom end rot also occurs on the fruit, but it is caused by both underwatering and overwatering. Dark, wet-looking spots develop on the blossom end of the fruit. These spots then become nearly black and may develop into open lesions or rotten spots. Periods of overly dry soil followed by a period of overwatering is the primary cause, in conjunction with a calcium deficiency in the soil. Use mulches to maintain steady soil moisture and don’t allow the soil to dry out completely between waterings.
Proper watering depends on the amount of rainfall versus irrigation and the quality of the soil. Planting in well-drained soil that doesn’t develop puddles during rainy weather helps minimize over watering issues, but this soil may require more frequent irrigation during dry periods. Tomatoes require between 1 and 2 inches of moisture weekly. Generally, if the top inch of soil feels moist, the plants don’t need water.Stick a twig into the soil. If it comes out dry, water the plants. If it comes out with soil clumps sticking to it, the soil may be too wet and needs to dry some before the next watering. Applying mulch over the soil helps maintain constant soil moisture, which prevents issues like cat-facing and blossom end rot.