Save Your Plants From Disease

You are out checking on your garden and looking for tasty veggies to harvest when it happens. You spot a weird looking leaf. Did it look like that the last time you were out in your garden? What’s going on? Are your plants falling victim to a disease? It could be nothing, or it could be the first sign of serious garden trouble. Nothing strikes fear into the heart of a gardener like unexpected damage to your plants. But don’t worry! In this post we’ll cover five common plant diseases, how to identify them, and what to do to save your plants from disease.

Powdery Mildew

This is a fungal disease that is pretty easy to spot. You will see a powdery white coating on the leaves of your plant. Different species of this fungus can affect peas, beans, cucumbers, squash, some melons, and pumpkins. It spreads easily in hot weather, but doesn’t necessarily spread through contact with wet leaves (like many other plant diseases) as the spores can drift through the air. The spores can overwinter on fallen leaves or buds.

You can manage powdery mildew by choosing varieties that are resistant. Also, removing any infected leaves from your beds at the end of the season can help prevent overwintering. There are also fungicides that are specifically for powdery mildew on squash family plants. However, most infections start on older leaves when plants are already mature, so even if you spot this disease in your garden, it may not cause significant damage to your plants.

Anthracnose Disease

Here is another fungal disease that is also pretty distinctive. There are at least a dozen different species of this fungus that can attack peppers, peas, beans, eggplants, tomatoes, cucumbers, melons, pumpkins, and even spinach. It can also affect fruit trees and ornamental trees and shrubs. The name means “ulcer-like sore”. In wet, humid conditions, your plants’ fruits will develop sunken black lesions covered with light pink spores. It can overwinter in the soil or in seeds or dead leaves. It is not related to anthrax and it will not make you sick.

The best way to save your plants from this disease is to prevent any spores in the soil from getting splashed up onto a new plant the next season. You can cover the soil with mulch, keep fruits off of the ground, and avoid overhead watering on humid, cloudy days. Make sure to remove any infected plant material at the end of the growing season and hot compost it or throw it away. Some fungicides can be effective against anthracnose, including copper spray. The disease generally causes cosmetic damage to your veggies, and if advanced enough, it can ruin the whole fruit. Harvest early and often to minimize any damage.

Tomato Wilt Diseases

Nobody likes to see a wilting tomato in their garden. It could be due to heat, uneven watering, or other stress. But it also could be one of the tomato wilt diseases. One of the most common is fusarium wilt. You will see yellowing and browning of the leaves and stems around the time that the fruit starts to mature. It typically starts at the bottom of the plant and moves up. The fungus can live in the soil for years and does not spread from leaf to leaf, but instead infects the plant through the roots.

Other tomato wilt diseases include verticillium wilt and bacterial wilt. Verticillium wilt generally starts with yellowing and curling of leaf tips, but you don’t usually see the whole plant wilt. It can affect other plants in the tomato/pepper/eggplant family as well as strawberries and brambles. Bacterial wilt, on the other hand is a bacteria spread by the cucumber beetle and affects mostly plants in the squash family. The plants will suddenly wilt and die within a week or so.

The best defense against wilt diseases is to plant varieties that are resistant to them. Discarding any infected plants and sterilizing your containers and tools can help prevent the spread if you have a small outbreak. Also, rotate your tomato plants and keep them in well drained soil or use raised beds or containers if necessary.

Early Tomato Blight

This fungal disease shows up as brown spots on older tomato or eggplant leaves that can develop a yellow halo around the spots. It is a common disease that can overwinter in the soil and can also spread to the fruits with dark lesions. The lesions grow and can kill the leaves and affect your plants’ yield. The fungus is usually splashed up onto the lower leaves by rain or watering, but the spores can also spread in the wind. It is particularly bad in wet, humid growing years.

You can save your plants from this disease by maintaining good airflow between your plants. Use mulch and avoid overhead watering to minimize splashing soil onto the leaves. You can also prune the bottom branches once the plants start to set fruit to limit opportunities for infection. There are also copper-based fungicides that can effectively treat your plants if needed. Remove and hot compost or discard any infected plants to reduce the spread of the disease.

Pepper Bacterial Leaf Spot

The last disease we’ll talk about is bacterial leaf spot. This bacteria can also affect tomato plants, but is most common in peppers. The spots originally appear on the upper leaf surfaces as little pimples that eventually develop grey to tan centers with dark borders. The spots can also form on stems and fruits. The bacteria can be spread by splashing up onto leaves or touching wet leaves on different plants. The leaves will eventually die and fall off and it thrives in humid weather.

One of the best ways to save your plants from this disease is to plant resistant varieties. Mulch the soil and avoid overhead watering during humid conditions. Rotating your crops can reduce the severity of the infection. You can also use a fixed copper fungicide to help slow the spread of the disease. The spots on the fruit generally are only cosmetic damage and do not affect the quality of the fruit, but severe leaf damage can affect the overall yield.

So, there you have it. Five different diseases and how to spot them. Plus ideas for how to save your plants from disease and keep them healthy and strong all the way to harvest.

If you are seeing damage in your garden but it doesn’t look like a disease, maybe you should be on the lookout for garden pests instead. Check out my blog post on How to Solve Garden Insect Problems for more!