Common problems with tomato plants include early blight, cracks in fruit caused by uneven watering and wilting foliage caused by a lack of moisture. Fruitworms, hornworms and other pests are also a common problem that may damage plants. Soils that lack calcium and droughts can also result in a condition known as blossom-end rot.
While many types of insects are beneficial to the growth of tomato plants, others may harm or even kill plants. Pests like aphids, flea beetles and cutworms can all cause damage to plants. Attempt to identify the species of any insects found on or near plants before taking steps to eliminate them. Even the presence of a single potentially harmful pest may not always warrant extermination efforts. Space tomato plants evenly during planting and clear away weeds and other debris from the base of tomato plants during winter.
Use row covers to ensure that younger plants are well protected from pests. Provide plants with quality nutrient-rich soils and rotate tomato plants with other crops to reduce the risk of the most common and damaging diseases. Avoid watering plant foliage as damp conditions are favored by many disease-causing organisms and refrain from planting tomatoes near tobacco plants as close proximity may allow for transmission of the tobacco mosaic virus.