The Leaves on My Tomatoes Are Spotted, Yellow & Dying

Watering

• Tomato leaves may turn yellow with too little or too much water. Overwatering may be especially problematic since standing water makes it difficult for roots to function properly. If left uncorrected, the roots die and leaves begin to yellow. Under watering may trigger stress, which frequently turns leaves yellow. If conditions are not improved, fruit production diminishes, new growth is smaller and overall health deteriorates. All tomato varieties require regular watering upon planting until they are able to establish a root system. Water if temperatures are high and rain is scarce. The soil should be nutrient rich and well drained to prevent standing water. A good rule of thumb is to keep soil moist, but not wet. If soil is poor draining, amend it with some well-decomposed compost. This creates a healthier, lighter soil that will move excess water away from the plant.

Pests and Disease

• Tomatoes may fall victim to a number of bacterial and fungal infections, many of which may present with spotting, yellowing leaves or a combination of the two. Root rot is among the most common, and is particularly widespread during periods of heavy rain. The disease is caused by pathogenic bacteria in the roots, turning them to a useless mush. An early symptom is leaf yellowing, but the disease is often untreatable even if caught at an early stage. Prevention of infection is key, and includes regular treatment with a bactericide or fungicide, as well as removing dead or fallen debris as soon as possible. Nematodes, caterpillars, aphids and spider mites are all common pests of the tomato and, in large population may be responsible for leaf discoloration and yellowing.

Nutrient Deficiency

• Iron and nitrogen are key elements of chlorophyll production. Chlorophyll is the material that gives leaves their green color. Without chlorophyll, leaves become spotty and turn yellow, and over time will grow in smaller and in fewer numbers. Iron deficiency is indicated by yellowing leaves. Aerating the soil and applying an iron chelate should fix the problem. Nitrogen shortage presents with an all over, even discoloration of leaves. Mixing a bit of decomposed compost into the soil should fix this problem.

Stress

• There are a large variety of conditions, problems or events that may cause stress in a plant. Transplantation, even if done correctly, is likely to cause stress in most tomato varieties and often causes severe foliage problems. Excessive periods of sun or hot weather, drought, pests and soil problems are also causes of plant stress. Liquid chemical fertilizers will cause severe root burn if applied incorrectly. This burning will result in yellow leaves, and may be present on parts of the tomato plant or all over, depending on the severity of damage. Keeping the soil well mixed with compost will greatly reduce the need for such fertilizers, and will help plants recover from stress.