Tips for Preventing and Treating Tomato Blights

You have worked hard on growing your tomatoes this season – youTomato Leaf Blight prepared the prefect soil, carefully tending the tomato seedlings, and planted them with supreme care.

Now it’s time to start thinking about all the different uses for those delicious tomatoes from your garden. Then one day you go out to the garden and notice that some brown spots are forming on the bottom leaves of a particular tomato plant.

Crikey! It’s early blight!

What do I do now?

Here are some tips to help prevent early and late blight in tomatoes:

Preventing Early and Late Blights

  • Inspect transplants and purchase healthy plants. Select wilt and nematode resistant varieties. Look for the capital letters V, F, and N following the cultivar name.
  • Choose a range of varieties that mature at different times. The earlier the tomato variety matures, the more susceptible it is to early blight.
  • Practice crop rotation by planting tomatoes and related vegetables in a different spot in the garden every year. Do not plant tomatoes and potatoes next to each other since they both are susceptible to early and late blight.
  • Allow adequate spacing between plants.
  • Water only at the base of the plant and early in the day. Long periods of moisture on foliage encourage blight.
  • Use a tomato staking system and remove suckers to increase air movement through the plant and to reduce moisture on the foliage. Staking also improves fruit quality and helps prevent root rot.
  • Mulch to keep plants evenly moist and to reduce watering, weeding, cultivation and blossom end rot.
  • Remove the bottom branches of the tomato plant, especially if they come in contact with the soil. Cut the bottom branches with a pair of scissors or garden shears. Trim the branches right at the plant stem, but do not cut into the stem.
  • Monitor the leaves, especially lower ones, for the first symptoms of tomato early blight and Septoria leaf spot. Remove infected leaves and begin application of a labeled fungicide. Tomato late blight can strike suddenly, often attacking the upper stems and foliage first, and then rapidly cause fruit infection. New, more aggressive fungus strains now exist, so early warning and prevention is critical. It is essential that vegetable gardeners monitor information from cooperative extension offices to know if late blight has been found in their region on either tomato or potato.
  • Remove all plant debris from the garden in the fall. Many tomato blight organisms overwinter on dried plant tissues.

If you discover blights in your vegetable garden (whether it’s found on tomatoes, potatoes, eggplant, or other plants) ALWAYS remove the infected plant and dispose of it. You can either burn the plant, or place it in a garbage bag and throw it in the trash.

NEVER place plants that are infected with blight in a compost pile.

This is a very important step in preventing the blight from spreading to other plants in the garden.

Also, make sure to thoroughly wash your hands after touching blight-infected plants. You could accidentally spread the disease to other plants if the blight spores are on your hands.

Treating Early and Late Blights

You have done everything you possibly can to try and prevent blight from forming on your tomatoes. You go out to the garden and Drat! It has begun to form regardless of your measures. Now what? Here are some ways to treat tomato blights:

  • Use a copper or sulphur based fungicidal spray to treat the tomato plants. Spray the leaves until they are dripping wet. It is best to use this spray when it is cloudy or first thing in the morning. Avoid using it in full sun when it’s very hot outside. You could inadvertently burn the leaves when any fungicide is applied in full sun.
  • Use a baking soda spray. These sprays are good for killing fungi such as blight and are a bit more environment-friendly.

    Grow Fantastic Tomatoes

23 Comments on Tips for Preventing and Treating Tomato Blights

  1. Probably worth noting that any plants that have had tomato blight should be disposed of properly i.e. either burn them or bag them and bin them. Never put a plant that has had blight on the compost pile.


  2. Good tips.
    in the book 1493 there is a discussion of one of the causes of the Irish potato famine, based on failure to follow the techniques of the Americans. If potatos have less blight if planted in mounds, should not this same technique help tomatos? If the blight gets on the plants from splashes on the ground, this may be helpful prevention.

  3. I noted very curly leaves at the top of my beefmaster, (horrors) and I sprayed spectracide…no noticable results…I pinched them off, and can only hope to curtail the problem….I live in a townhouse, not enough sun in the back area…does that make the difference? thank you for a reply.

    • Hi Michelle!

      If it’s curly top virus, then it could be caused by the beet leafhopper. It’s a tiny little bug that bites the leaves to suck on the plant juices. It spreads a virus to the plant while doing so.

      I wouldn’t recommend using spectracide because it’s a broad spectrum pesticide which can cause more harm than good. The best defense would be to cover the plant with an insect barrier cloth to keep the bugs away.

      Tomato plants need at least 6 – 8 hours of full sun each day. If you plant is receiving less than that then it will not thrive as it should. Try moving it to another location where it will receive more light, or supplement the light with a fluorescent bulb.

  4. I purchased potassium bicarbonate to prevent and treat tomato blight. It worked better than baking soda because it doesn’t have sodium. Last year I had no blight until the last of the tomatoes were harvested. Three products you can purchase are Greencure 8 ounces for $17.53, GreenSense 1 pound for $11.85, Garden-Ville 1 pound for $8.69.

  5. I lost half of my greenhouse tomato plants due to blight, but was able to save the rest with hydrogen peroxide. I mixed two ounces of 35% food grade hydrogen peroxide into one gallon distilled water and sprayed every 3 to 5 days.

  6. I listened. to a youtub account of a lady putting a 18 gauge bare copper wire though the plant stem near the base. What do you think?

    • did anyone ever try this? My husband has access to copper piping and we wondered if using it to stake the tomato plants would make any difference in blight. We do all the preventions that can be done and we still end up with blight every year. Even if we plant in sterile soil in a container!! I think some of the spores must be airborn.

      • I have found that I have to be sure not to water close to the evening. Never pick when the plants are wet. When I do pick them, I wear gloves. It is important not to plant them to close together, in order to let air circulation in. I do not water for above. For some reason rain water is just different than the water for below. I also make sure they have enough nutrients. Just as a person, when the nutrients on a plant is down it is more apt to catch or end up with a disease. When another plant has an issue with the blight and you are taking something off to prevent its spread do not place it in the garden, also do not touch another plant until washing your gloves. Hopefully some of this helps in the prevention of the blight. Enjoy your garden we do.

    • tried it this year and it does not work.

  7. Zucchini:
    My organic zucchini plants produce fruits that stop growing when the tips become yellowish, and the yellow progresses down the fruit. I also had blight in my tomato plants. The zucchini plants themselves are rotting at the stem, but I am not over watering them. What can be the zucchini problem? Should I try the

    • I had the same problem and I had vine squash borer. It is a white wormy looking thing with a little black dot head. Your plant is not going to survive. You can see if this is them by cutting into the stem length wise and you will find them or you can tell if you have them by looking at the stem and if you see what looks like sawdust then you have them. They are eating the plant from the inside out by burrowing holes to get throughout the plant. I have even found them in the zucchini. If that is what you have get rid of the plant immediately by throwing them away do not compost them. they can survive through the winter so catch them before they leave the plant and go under ground.I found a lot of my info on youtube. They say you can try to remove the borers from the plant by cutting them out but it doesnt work. I hope this helps. I lost all of my zucchini so I am going to definitely going to prepare for them next year.

  8. I have had early and late tomato blight for three years now. this year I put ground cover/weed barrier down, made lovely mounds, mulched with cut grass and fertilized. I did use an over head water method and that might have sparked it again so next year I will use soaker hoses. In the meantime, for fall garden closure I know to bag the plants and rotate the garden next year but is there a soil treatment I can use fall and spring to kill whatever is in my soil? I live in NH and the season is so short here that I have to start early to get anything by August.

    • What can be done to treat the soil if I have to use the same spot to plant the tomatoes? Do I have to replace the soil to plant in the same spot in the spring?

  9. Hi there.
    A week ago I realized all of my tomato plants have early blight.

    I have followed above advice. I mulched, I picked off leaves and sprayed with baking soda solution.
    Then I saw one plant has many leaves with tiny spots (looks like a rash) as shown in the last pic.
    I sprayed again last night and this morning many more plants have the tiny spots. Now I am thinking these tiny spots may not be blight but instead a reaction from the spray.
    What do you think?


    • yes what happens is the bakeing sode solution will collect and pool up on certian parts of the leave and put burn marks on them you need to alternate your sprays with garlic and milk combination ,then go to 1 tablespoon applecider vinegar, then ise bakeing soda use them maybe every 3 to 5 days if conditions are bad be sure to alternate the differant sprays and you should avoid those burn marks from to muck bakeing sode pooling up and congrgating on parts of ther the leaves

  10. I first scater regular cornmeal around whole tomato bed and more thickly 12″ circle around the plant it fights off bad stuff in the soil and benifits the plants also after doing that I take powdered milk a dust that all around the plant aswell 12″ from stem out this is also very helpful also fluctuate the differant foliage sprays so no bacteria or fungus adapts and grows strong against useing only one type and since I had a severe problem and 100% saved all my plants I alternated all my foliage sprays cause some are acid some are alkalide so you will not over dose the soil or damage the plant so I use the diluted apple cider vinegar then next powdered milk mixed with water spray next baking soda next garlic solution spray that I puree garlic in blender with water strain dilute with water and spray plant you can mix milk solution with this and do not forget this works great to grind 1 350 Mg aspirin disolve and shake in very hot water and add to any and or all these solutions before you do your foliage spray and I also add 1 to 3 tablspoons of molasses it not only helps it stick to the plant very good but it feeds the friendly bacteria in the soil that will eat up the bad bacteria and the aspirin is naturally in the plant anyway that helps it fight against stressfull conditions

    • I had a bad problem with worms and stink bugs on my tomatos . found out that if you put tomato leaves and sucker shoots in the blender strain and spray it worked. why ?

  11. I did have a serious problem this year 2013 in Stafford Ct. due to all the rain plus living by a swamp plus anyway they say the northeast USA has more of this problem anyway!!!!But I corrected it 100% due to all my research ,then applied my discoveries with great success!!I will give you a summary but please look up these items yourself in depth!Puree garlic cloves in almost hot water about 1 to 2 quarts then thru regular strainer sceen to catch bulk of pulp into an old old yogurt fine screen this is your concentrated stock solution for folige spray that you can store in frig,you can dilute this with a milk solution when ready to spray plant use either one seperate or in combination,also can use apple cider vinegar 1+ tablespoon per gallon water and sray the plants,also you can use bakeing soda I think 1 tablespoon per gallon of water and spray plant foliage upper and lower of leaves when you use any of these sprays,to help it adhere and feed the plant you can add 1 to 3 tablespoons of molasses per gallon with fish kelp solution and (1) 325 Mg aspirin to each gallon that help fight off stressful conditions and deseases,be sure to alternate these differant sprays at differant times to the same plants so bad fungi or bad bacteria won’t build up resistance plus some sprays are a little acid and some sprays are a little alkilide so you will keep a balance Ph.also take regular cornmeal and powdered milk and sat and pepper it all over the top of the soil around the stem of the plant and the whole bed it fights off bad infection in the soil and feeds the plant aswell and cornmeal is noted for building up the immune system of the plant and feeding the friendly fungi or bacteria that eat the nasty diseased ones there is more but they covered alot of it in the above articles and be sure to keep atleast 6 to 12 inches of all leaves and growth off the bottom of the tomato plant cause blighht is soil born and splashes up when it rains on plant and you need good air circulation to prevent it and keep it in check

  12. Hi I am growing Tomatoes in my new aquaponics system but plants leaves are affected by some sort of white zigzag lines same happened with eggplant trees So please help me to solve this problem.

    • Leaf Miners! I just pull the leaves off and discard them when I see them. Put the leaves in a ziplock bag with a tablespoon of bleach and a little water and seal it up and toss it in the garbage.

  13. Love all the tips. I don’t like using fungicides on my garden. Thank you.

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  1. Tips For Preventing and Treating Tomato Blights Veggie Gardener | Toe Nail Fungus
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