Tomatoes are susceptible to several soil borne fungal diseases including early blight and late blight, Septoria leaf spot, and anthracnose. Using good cultural practices can help prevent the spread of fungal spores among plants. Nitzsche and Wyenandt of Rutgers University Extension provide a good explanation in this bulletin:
Simply, fungi live and obtain their nourishment from infected host tissue. Fungi reproduce by spores, tiny microscopic bodies, which are spread by wind, water, or other mechanical means to a new host. On the host, spores germinate and infect healthy plant tissue causing symptoms including leaf spots, rots, and wilts that lead to premature defoliation and reduced tomato yields. Development and spread of fungi in the home garden is determined by rainfall, relative humidity, free moisture, and temperature. -
- Remove dead plant tissue from the area, especially if it was previously infected with a fungal pathogen or in the tomato family.
- Do not plant tomatoes in the same place that tomatoes, peppers, potatoes, or eggplants (nightshades) were grown within the last three years.
- Fungi thrive in humid conditions, and water drops from rain or irrigation can spread spored between plants. Water in the morning so plants will quickly dry, or use drip irrigation or soaker hoses.
- Use mulch, and stake and prune the plants to reduce the risk of fruit coming into contact with the soil. Mulch will also reduce disease pressure and conserve water.
Tomato disorders related to nutrient deficiency:
- Early in the season when the weather is still cool tomatoes may show sighs of phosphorus deficiency - leaves and veins with a purple tint. They problem will typically correct itself as the soil warms.
- Tan lesions on the blossom end of the fruit (blossom end rot) caused by calcium deficiency during fruit formation. Soils in this region are not typically limiting in calcium but plant uptake during blossom set can be hindered by fluctuations in temperature and moisture in the soil. Proper irrigation water management will minimize your risk of blossom end rot.
Further resources on tomato diseases and disorders
More blog posts on Curly Top Virus in Tomatoes.