White Tips on Tomato Plants

Causes

• Late blight is also called "Phytophthora infestans." Late blight is a water mold infection, because it produces spores when the growing conditions have a lot of excess moisture. Late blight prefers cool, wet weather, so when growing conditions for tomatoes are not optimal, there is a greater chance of late-blight development.

Symptoms

• Late blight forms watery lesions as freestanding water is how the pathogen infects tomato plants. Late-blight lesions begin along the tip or outer edges of a tomato plant leaf. As the large watersoaked areas dry out, they turn brown and papery. Eventually, the blight symptoms and infection appear on the stem and fruit of the plant. In these cases, large green-brown or black lesions present themselves as watery lesions that eventually dry out and turn brown and brittle.

Spreading

• Late-blight spores are spread through water and touch. For the most part, the spores travel through water, and infect a garden through windblown rain or in water runoff or splashes from infected plants. In some cases, even running ground water can carry the spores to uninfected plants. The spores only survive mild winters, and heavy frosts and cold temperatures kill the spores.

Control

• There are no blight-resistant breeds of plants. However, growing your tomatoes in areas that have not been previously infected with blight reduces the likelihood of infection. As well, growing your tomatoes in well-draining soil in a sunny area helps keep your tomato plants healthy and less susceptible to blight infection. Consider using drip irrigation rather than watering your plants with a hose to reduce the possibility of a blight infection, as there will be less water left clinging to the leaves of your plant.