Keeping your tomato plants healthy: Managing common pests and diseases of homegrown tomatoes

Early blight, Alternaria solani

Symptoms: Early blight causes dark, concentric rings on older leaves, beginning at the base of the plant. This disease leads to yellowing and leaf drop.

Management: Remove infected leaves, apply mulch to prevent soil splash, stake plants to improve airflow, and remove or incorporate plant debris at the end of the season.

Septoria leaf spot, Septoria lycopersici

Symptoms: Septoria leaf spot produces dozens of small, circular spots with gray centers, typically on lower leaves. The disease does not affect fruit.

Management: Prune to improve airflow, mulch soil surface, remove or incorporate plant debris at the end of the season, and avoid overhead watering.

Southern blight, Sclerotium rolfsii

Symptoms: Southern blight causes sudden wilting and collapse. Look for white fungal growth and small, round, tan to reddish-brown fungal structures, called sclerotia, at the stem base.

Management: Remove the entire plant and surrounding soil. Rotate crops and avoid planting tomatoes in the same area for two to three years.

Tomato spotted wilt virus, TSWV

Symptoms: Tomato spotted wilt virus is spread by tiny insects called thrips. The disease leads to bronze or dark streaks on leaves and stems, concentric rings on fruit, and stunted, wilted plants.

Management: Resistant varieties (e.g., 'Amelia,' 'Crista') are by far the best management strategy for this virus. Gardeners may also use reflective mulch, control thrips, and remove infected plants to prevent secondary spread of the virus.

Fusarium wilt, Fusarium oxysporum sp . lycopersici

Symptoms: Fusarium wilt begins with yellowing and wilting on one side of the plant. Discoloration of vascular tissue is visible when stems are cut. Plants may rapidly decline in warm soil.

Management: Select resistant varieties (labeled with "F"), rotate crops, and avoid planting tomatoes and other solanaceous crops in the same bed annually.

Bacterial spot, Xanthomonas spp.

Symptoms: Bacterial spot causes small, dark brown, angular spots on leaves, stems and fruit. The disease can lead to leaf yellowing, drop, and raised, scabby fruit lesions.

Management: Use certified disease-free transplants, avoid wetting leaves by using drip irrigation, rotate crops, and sanitize tools between uses.