How To Save A Tomato Plant Suffering From Septoria Leaf Spot

It's easy to see why tomatoes are a popular choice among home gardeners. They're relatively easy to grow, come in a range of cultivars, and produce plenty of delicious, vitamin-rich fruits. Before your tomatoes are ready to harvest and eat, you'll need to be on the lookout for pests and diseases, which can spread quickly and affect your plant's yield if you don't address them properly. One such disease to watch out for is Septoria leaf spot, caused by the fungus Septoria lycopersici.

Symptoms of Septoria leaf spot first appear on the lower leaves and stem of the plant. You might notice small, dark, water-soaked lesions that later develop light tan or gray centers. The lesions will merge as they spread, causing your tomato plants' leaves to yellow, wither, and eventually fall off. Septoria leaf spot spreads more rapidly during warm, humid, or rainy conditions that don't allow leaves to dry out.

The best way to respond to Septoria leaf spot is to immediately prune infected foliage and optimize growing conditions to stop the spread. You can also resort to fungicides labeled as safe for vegetables if the disease is still in its early stages. If you want to minimize your chances of dealing with this fungus in the first place, you can get ahead of the problem by selecting a disease-resistant tomato variety for your garden.

Preventing Septoria leaf spot involves smart site preparation and gardening practices. An integrated approach is your best bet, as this fungus can survive between seasons in diseased plant debris. To prevent this, rotate your crops and don't grow tomatoes and other solanaceous plants in the same spot every year. Another secret to ridding fungus from your plants is keeping the area dry. Water will spread the spores, and fungus loves growing in moist places. 

Make sure to select a spot with well-drained soil and correctly space your garden veggie plants for good airflow. Tomato plants grow best when spaced 2 to 3 feet apart. Mulching around the base of your tomato plants is another good strategy, since it ensures that spores of Septoria leaf spot in the soil won't splash upward during rainfall or watering your plants. For maximum prevention, try to buy disease-free seeds or transplants each season. There are plenty of varieties that are resistant to Septoria leaf spot, like Iron Lady, Juliet, and Brandywise tomatoes.

Sometimes, no matter what you do to create a flourishing vegetable garden, Septoria leaf spot finds a way in. Though it rarely affects the fruit directly, severe lesions can still impact your tomato plant's yield or even kill plants, so you'll need to find a way to fight it off. The first thing to do as soon as you spot signs of infection is to remove affected foliage. Avoid composting spore-infected leaves, and instead dispose of them. Make sure that you disinfect your tools when pruning and moving between plants to avoid spreading the fungus. 

Once done with pruning, follow up with a fungicide recommended for tomatoes. It won't treat the existing lesions on the leaves, but will prevent the infection from advancing further. Ultimately, an integrated approach that includes preventative measures, crop rotation, and fungicide treatment is your best bet for keeping tomato plants healthy and reducing the risk of reinfection.