how to prevent tomato blight

If you have ever encountered early or late blight on your tomato plants, you know how frustrating it can be to lose fruit, plants, or an entire season’s work to these diseases. To help you avoid this problem, I put together a list of the top 10 blight resistant tomatoes. I also have a list of steps you can take to prevent tomato blight in your garden. Top 10 Blight Resistant Tomatoes Here is my list of the top 10 blight resistant tomato varieties. (Note that the first 7 are “double resistant”, meaning that they resist both early blight and late blight. Number 8 is only resistant to late blight, the more dangerous of the two types of blight. Numbers 9 and 10 are only resistant to early blight.) Mountain Magic Hybrid Tomato – this tomato variety is resistant to both early and late blight. The plants are indeterminate, with a spread of 48 to 52 inches. The fruit weighs 2 to 3 ounces, maturing in 70 to 80 days. For more information, check out the Mountain Magic Hybrid Tomato on the Burpee website.Plum Regal Hybrid Tomato – this tomato variety is resistant to both early and late blight. The plants are determinate. The fruit weighs 4 ounces, maturing in 75 days. For more information, check out the Plum Regal Hybrid Tomato on the Johnny’s Selected Seeds website.Defiant PhR Hybrid Tomato – this tomato variety is resistant to both early and late blight. The plants are determinate. The fruit weighs 6 to 8 ounces, maturing in 67 days. For more information, check out the Defiant PhR Hybrid Tomato on the Johnny’s Selected Seeds website.Jasper Hybrid Tomato – this tomato variety is resistant to both early and late blight. The plants are indeterminate. The fruit weighs 7 to 10 grams (less than 1 ounce), maturing in 60 days. For more information, check out the Jasper Hybrid Tomato on the Johnny’s Selected Seeds website.Matt’s Wild Cherry Tomato – this tomato variety is resistant to both early and late blight. The plants are indeterminate. The fruit weighs 5 grams (less than 1 ounce), maturing in 60 days. For more information, check out Matt’s Wild Cherry Tomato on the Johnny’s Selected Seeds website.Juliet Hybrid Tomato – this tomato variety is resistant to both early and late blight. The plants are indeterminate. The fruit weighs 1.5 to 2 ounces, maturing in 60 days. For more information, check out the Juliet Hybrid Tomato on the Johnny’s Selected Seeds website.Nectar Hybrid Tomato – this tomato variety is resistant to both early and late blight. The plants are indeterminate, with a spread of 24 inches. The fruit is small and red, maturing in 65 days. For more information, check out the Nectar Hybrid Tomato on the Park Seed website.Red Pearl Hybrid Tomato – this tomato variety is resistant to late blight. The plants are indeterminate. The fruit weighs 15 to 20 grams (less than 1 ounce), maturing in 58 days. For more information, check out the Red Pearl Hybrid Tomato on the Johnny’s Selected Seeds website.Verona Hybrid Tomato – this tomato variety is resistant to early blight. The plants are indeterminate. The fruit weighs 2.5 ounces, maturing in 69 days. For more information, check out the Verona Hybrid Tomato on the Johnny’s Selected Seeds website.Valentine Hybrid Tomato – this tomato variety is resistant to early blight. The plants are indeterminate. The fruit is small, red, and oval-shaped, maturing in 55 days. For more information, check out the Valentine Hybrid Tomato on the Harris Seeds website. You might also want to look into grafting tomato plants to provide them with more disease resistance. How To Prevent Tomato Blight Now that we have a list of blight-resistant tomato varieties to choose from, let’s review some other steps you can take to avoid this dread tomato disease. First, it is important to keep in mind the two types of blight that can affect tomatoes: early blight and late blight, both caused by different types of fungus. Early blight (caused by one of the two fungi Alternaria tomatophila or Alternaria solani) can weaken tomato plants and affect your harvest. It spreads more rapidly in damp, humid conditions. Here we can see signs of early blight on tomato leaves. Late blight (caused by the fungus Phytophthora infestans) can kill a tomato plant within a few days of infection. Left unchecked, a late blight outbreak can destroy your entire tomato crop. It spreads more rapidly in cool, wet conditions. Here we can see signs of late blight on a tomato stem. Late blight is the more deadly of the two blights for tomato plants. Even worse, early and late blight can also affect potatoes, posing a threat to your potato crop as well. In fact, late blight was responsible for the Irish Potato Famine in the 1840’s. Here we see a potato affected by late blight. For more information on blight resistant tomatoes, check out this article from the Cooperative Extension (eorganic.org) on late blight management. You can also check out this article on early blight from the University of Minnesota Extension. If you want more information on how tomato plants get blight in the first place, check out my article on how tomato plants get blight. Now let’s get to the ways you can prevent blight in the first place, whether you plant blight-resistant tomato varieties or not. Leave Enough Space Between Your Tomato Plants If you put your tomato plants too close together, their leaves will touch. This makes it easier for early and late blight to spread between plants. Putting plants too close together also increases the chance that splashing rain will cover the leaves of multiple plants with infected soil. Fortunately, there is an easy way to prevent these problems. If you put your tomato plants too close together, the spread of diseases such as blight is more likely. When ordering tomato seeds or seedlings from a catalog or online, check the width (spread) of the variety you choose. If the catalog doesn’t list the information, call or email to ask about it. You should leave a little more space between each plant than the width indicates. For example, if the catalog lists a tomato variety as having a width of 24 inches, you might want to leave 27 to 30 inches between plants, just to be safe. Leave even more space between rows, to give you room to water, fertilize, harvest, pull weeds, and prune your tomato leaves and vines. Use Crop Rotation In Your Garden Early blight can survive in the soil on its own over the winter. Late blight cannot survive on its own, but it can survive inside of infected plant matter, such as potato tubers. This means that you should use crop rotation in your garden to prevent the spread of blight. Crop rotation means that you do not plant the same crop in the same part of your garden two years in a row. In fact, the ideal crop rotation schedule has a 3 or 4 year rotation cycle. For example, in a given area, plant tomatoes in year 1, onions in year 2, beans in year 3, and lettuce in year 4. Be sure to practice crop rotation to prevent the spread of blight. Do not plant tomatoes in the same spot in your garden two years in a row! After that, start back at the beginning and start the rotation over again. This allows more time for any plant diseases (such as blight) to die off from the soil. As mentioned earlier, early and late blight can affect both tomatoes and potatoes, so these two crops should not be planted near each other. They also should not be planted in the same area two years in a row (that is, do not plant tomatoes in an area the first year and then potatoes in the same area the 2nd year). You can learn more about good crops to rotate with tomatoes in my article here. Support Your Tomato Plants As mentioned earlier, when tomato plants touch each other, diseases like blight will spread more easily. Your plants are likely to touch if they grow along the ground, as unsupported tomatoes will do. Growing tomato plants along the ground also means that the stems and leaves are in contact with wet soil. This also increases the chances of disease spreading in your garden. To prevent this, support your tomato plants with trellises, stakes, or tomato cages. For shorter determinate varieties, cages are a good choice. For taller indeterminate varieties, a stake or trellis is the better choice. For shorter, determinate tomato varieties, a tomato cage is a good choice for support. Supporting your tomato plants will help to prevent disease, and also prevents you from bending over to harvest tomatoes from the ground. For taller, indeterminate tomato varieties, stakes (shown here) or trellises are a better choice for support. For more information, check out my article on tomato cages, my article on trellises, and my article on supporting tomatoes. Inspect Your Tomato Plants For Disease Don’t leave anything to chance! Even if you choose blight-resistant tomato varieties and take the other steps on this list, you should still check your tomato plants for disease. If you see any tomato plants with signs of early or late blight, remove them from the garden immediately to prevent the spread of the disease. The sooner you find tomato plants infected with blight, the sooner you can pull them out, destroy them, and prevent the spread of the disease. Some folks recommend composting infected plants, but I recommend against it. The main reason is that the compost pile may not get hot enough to kill diseases, and many diseases can survive the winter in a compost pile. Prune The Lower Leaves And Branches Of Your Tomato Plants The lower leaves and branches of your tomato plants are more likely to get wet, due to splashing from rain or watering. They are also more likely to stay wet, since less sunlight will reach them to dry them off. The lower leaves and branches are also more likely to hang down and touch the soil, where they can pick up diseases. Pruning the lower leaves and branches off of your tomato plants helps to prevent the spread of diseases, such as early and late blight. To prevent this problem, your best bet is to prune off low-hanging leaves and branches from your tomato plants. It can be hard to do this to a healthy branch or leaf, but if it prevents the spread of blight, then it is worthwhile to save your plant (or your entire tomato harvest!) While you're at it, you can also "top" tomato plants by pruning off the tops of tall indeterminate varieties. This will keep them from falling over due to their weight. For more information, check out my article on tall tomato plants and how to prune them. Water Your Tomato Plants From Below Watering tomato plants from below will keep the upper and lower leaves from getting wet. Keeping the leaves dry is an important step in preventing the spread of both early and late blight. Water your plants carefully from below, using a hose or watering can, to prevent the leaves from getting wet. Instead of using a sprinkler, use a garden hose or a watering can to control the amount and location of the water you give your plants. Sanitize Your Garden Tools Since early blight can survive in soil on its own, it is a good idea to sanitize garden tools after using them. For example, have a bucket of soapy water or a rag with alcohol to clean off pruning shears after you finish pruning each plant. Otherwise, if the first plant has blight, you can potentially infect every other tomato plant in your garden. Conclusion Now you have a solid list of 10 blight-resistant tomato varieties to choose from. You also have some actionable advice about how to avoid the disease. Bacterial wilt of tomatoes is often mistaken for blight. You can learn more about bacterial wilt of tomato in my article here. You can also learn about other causes of curled leaves on tomatoes in my article here. I hope you found this article helpful – if so, please share it with someone else who can use the information. If you want to read some of my most popular posts, check out the “Best of GreenUpSide” page here. Enjoy! ~Jonathon