Steps to prevent and manage tomato leaf spot diseases

We wait what seems like a long time before the first garden tomatoes start to ripen. This is especially true if you grew them indoors first from seed to transplant stage. Invariably, our tomato plants will face seasonal challenges, such as excessive heat and drought, stink bugs, stakes and supports that fail to hold up. The one problem we can always count on are the twin torments of all tomato gardeners – Septoria leaf spot and early blight.

Septoria leaf spot appears as small distinct lesions with dark borders and tan centers

These two fungal leaf spot diseases begin their devastation by infecting lower leaves. The disease moves up the plant, spreading rapidly during hot, humid, wet weather. The two diseases often co-occur and are managed the same way:


  1. Provide adequate spacing to increase air circulation and remove all suckers that emerge from the plant base
  2. Monitor transplants carefully for signs of this disease.
  3. Keep plants well mulched to minimize soil splashing.
  4. Water plants at their base. Avoid wetting the foliage.
  5. Prune off the lowest 3-4 leaf branches once plants are well-established and starting to develop fruits. This increases air circulation and slows down infections.
  6. Remove infected leaves during the growing season and remove all infected plant parts at the end of the season.
  7. Apply a synthetic fungicide or an organic fungicide (fixed copper) according to label directions, early in the season, when symptoms appear to slow the spread of the disease. This may be helpful where the disease causes severe blighting each year leading to reduced yields.
  8. Diseased plant parts can be shredded and composted if “hot composting” techniques reused (pile temperatures should exceed 120° F throughout and piles should be turned two to three times).


Before pruning: Typical tomato leaves grow at ground level where fungal spores from the two diseases can begin an infection.


After pruning: Lower branches removed with pruners to improve air circulation around leaves and stems.

Article By: Jon Traunfeld
Home and Garden Information Center Director

5 thoughts on “Steps to prevent and manage tomato leaf spot diseases

  1. Christa July 21, 2017 / 2:43 pm

    I don’t have any of these spots on my tomatoes this season — at least not yet. I was diligent about my spacing, pruning, and watering at the base. So far, things look good! A bigger problem has been the stems bending over from my stakes failing to hold up with the heavy tomatoes. What do you use for staking? I have been enjoying my ‘Purple Cherokees’ already. Yum!

    • jontraunfeld September 7, 2017 / 10:28 am

      I tried something new this year. I have a supply of bamboo and cut the culms into 8 ft. lengths. I drove them in the ground with a stake driver- one per plant. I lashed short cross-pieces 2 ft. apart to each bamboo stake. I cut pieces of jute twine and tied the main stems to the cross pieces. The weight caused the cross pieces to dip because the lashing wasn’t strong enough to hold them at a 90 degree angle to the stakes. But, it worked out for the most part. The vines all stayed upright through the season.

  2. M Monat June 10, 2020 / 7:25 pm

    My tomato plant leaves have tiny holes in them. What is this and How can I get ride it this?

  3. Vicki July 5, 2022 / 2:26 pm

    So my plant leaves are really spotting. I clipped off lower leaves, but it moved up the plants to the mid levels leaves and I clipped those off. My plants have fruit but now it is mostly vine and fruit mid level and good leaves and flowers at the top level. Newer branches are forming below where normally they would be plucked off. I pray the plants which are 5 feet tall will survive! I have used neem oil, water with peroxide trying to aerate soil as recent and fertilizer.

    • jontraunfeld July 6, 2022 / 10:43 am

      Neem oil is not effective against foliar lea spot in tomato. Copper would probably be the most effective organic choice. There is no need to aerate the soil. It could injure the root system of your tomato plants. Dealing with these diseases is challenging. Good luck. I hope you have a decent harvest.

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