{"id":4601,"date":"2026-10-06T17:49:49","date_gmt":"2026-10-06T17:49:49","guid":{"rendered":"https:\/\/www.tomat-pomidor.com\/en\/?p=4601"},"modified":"2026-10-10T20:03:59","modified_gmt":"2026-10-10T20:03:59","slug":"why-dont-my-tomatoes-have-leaf-mold","status":"publish","type":"post","link":"https:\/\/www.tomat-pomidor.com\/en\/why-dont-my-tomatoes-have-leaf-mold\/","title":{"rendered":"Why Don’t My Tomatoes Have Leaf Mold? (A Greenhouse Mystery)"},"content":{"rendered":"\n\n
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\ud83d\udccc Quick Diary Summary: The Leaf Mold Mystery<\/h3>\n
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  • \ud83c\udf44 The Cladosporium Puzzle:<\/strong> Leaf Mold (Cladosporium) often infects tomatoes early in the spring when seedlings are trapped under plastic covers with high humidity. But sometimes, it mysteriously skips a season.<\/li>\n
  • \ud83d\udca8 Elevation and Condensation:<\/strong> A major factor in avoiding fungal diseases is the location of the greenhouse. High, raised ground away from water bodies allows the soil to drain and dry faster. If you only water in the morning, the greenhouse will be dry by evening, preventing deadly nighttime condensation.<\/li>\n
  • \ud83c\udf49 Mixed Greenhouses & Pruning:<\/strong> You can successfully grow tomatoes side-by-side with peppers, eggplants, cucumbers, and melons! Also, be careful when pruning watermelons: if you pinch off early fruit sets hoping for bigger ones later, the plant might simply refuse to set fruit again.<\/li>\n<\/ul>\n<\/div>\n
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    Mariya Suvorova \u2b50 Legend (10,548 posts)<\/span><\/div>\n
    \ud83d\udccd Tver Region (USDA Zone 4a) | \ud83d\udcc5 July 22, 2021<\/div>\n<\/div>\n<\/div>\n
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    Aleksan9ra wrote:<\/strong>
    \nLeaf Mold (Cladosporium) infection actually happens back in the seedling stage, right in April when we bring the seedlings out to the greenhouse and cover them with spunbond and plastic. The plants are crowded, the humidity is sky-high, and the temperature swings are massive. That is exactly when preventative treatments are needed, which we never do.<\/p><\/blockquote>\n

    Luda, I also plant my tomatoes out in the greenhouse in April, and I cover them with both spunbond and plastic… yet I still don’t have any Leaf Mold this year! It is very strange. Usually, it hits me early every single year, but so far, nothing. I wish I knew exactly *why* I don’t have it this year, so I could just repeat the process every year! \ud83d\ude02<\/p>\n<\/div>\n<\/div>\n

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    Lelik ph (Olga) \u2b50 VIP User (23,956 posts)<\/span><\/div>\n
    \ud83d\udccd Ramenskoye, Moscow Reg. (USDA Zone 4b) | \ud83d\udcc5 July 22, 2021<\/div>\n<\/div>\n<\/div>\n
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    Mariya Suvorova wrote:<\/strong>
    \n…yet I still don’t have any Leaf Mold this year! It is very strange. Usually, it hits me early every single year…<\/p><\/blockquote>\n

    Mariya, this summer is very hot. Maybe the Leaf Mold didn’t appear because it’s so dry.<\/p>\n<\/div>\n<\/div>\n

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    Valtwelve (Valeriy) \u2b50 Pro Grower (1,847 posts)<\/span><\/div>\n
    \ud83d\udccd Between Samara and Ufa (USDA Zone 4a) | \ud83d\udcc5 July 23, 2021<\/div>\n<\/div>\n<\/div>\n
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    Mariya Suvorova wrote:<\/strong>
    \nI wish I knew exactly *why* I don’t have it this year, so I could just repeat the process every year!<\/p><\/blockquote>\n

    Did you dig chicken deep litter into the soil last year? A lot of it? How much? Have you done that before? Do your tomatoes currently have any yellow leaves or brown crispy edges?<\/p>\n<\/div>\n<\/div>\n

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    Aleksan9ra (Ludmila) \u2b50 Expert \/ Author (15,056 posts)<\/span><\/div>\n
    \ud83d\udccd Moscow Region (USDA Zone 4b) | \ud83d\udcc5 July 23, 2021<\/div>\n<\/div>\n<\/div>\n
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    Mariya Suvorova wrote:<\/strong>
    \n…yet I still don’t have any Leaf Mold this year! It is very strange. Usually, it hits me early every single year…<\/p><\/blockquote>\n

    Masha, did you provide any extra heat when the nights were cold, or when you finally transplanted them into the ground permanently during the frosts? Also, is your property in a low-lying area? Is there a body of water nearby, and do you get fog often? Do you see condensation forming on the greenhouse walls and the fruits immediately after the sun goes down in the evening?<\/p>\n

    I actually don’t have any Leaf Mold in my second greenhouse either, where the early Pink Bush<\/em> is growing. But over there, I water both morning and evening, I water from above and below, and I have cucumbers sprawling on the ground right next to the tomatoes, completely wrapping around them. It made me wonder – maybe it’s actually a good thing when everything grows tangled together?<\/p>\n<\/div>\n<\/div>\n

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    Mariya Suvorova \u2b50 Legend (10,548 posts)<\/span><\/div>\n
    \ud83d\udccd Tver Region (USDA Zone 4a) | \ud83d\udcc5 July 23, 2021<\/div>\n<\/div>\n<\/div>\n
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    Valtwelve wrote:<\/strong>
    \nDid you dig chicken deep litter into the soil last year? A lot of it? How much? Have you done that before? Do your tomatoes currently have any yellow leaves or brown crispy edges?<\/p><\/blockquote>\n

    I *always* (every year) dig chicken deep litter into the beds, yes, about 5 sacks per greenhouse. Plus, my chickens and ducks actually roamed around inside the second greenhouse all winter until April.
    \nThe tomato leaves are surprisingly clean right now; usually, they would be completely covered in Leaf Mold by this time of year. Last year, we changed the polycarbonate on both greenhouses and painted the metal frames, so I thought maybe I’d get a break from the disease for at least a year – nope, it started very early last year. So this year’s delay must just be the weather!<\/p>\n

    The tomatoes are incredibly productive this year (knock on wood). Yesterday, we even sold 17.6 lbs (8 kg) of our biggest ones (my husband’s coworkers practically begged him for them).<\/p>\n

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    Mariya Suvorova \u2b50 Legend (10,548 posts)<\/span><\/div>\n
    \ud83d\udccd Tver Region (USDA Zone 4a) | \ud83d\udcc5 July 23, 2021<\/div>\n<\/div>\n<\/div>\n
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    Aleksan9ra wrote:<\/strong>
    \nMasha, did you provide any extra heat when the nights were cold… Is there a body of water nearby, and do you get fog often? Do you see condensation forming on the greenhouse walls…<\/p><\/blockquote>\n

    Luda, answering your questions: No, I didn’t heat the tomatoes at all in April (I simply have nothing to heat them with). They were just covered with spunbond and plastic, and I put 5-liter (1-gallon) water jugs inside the tunnels (I filled them with hot water *once*, but then my enthusiasm faded because they are very heavy to carry around!).<\/p>\n

    Our property is actually on high ground, and the greenhouses are raised up on a foundation – so everything dries out very quickly… We don’t have any ponds nearby, but we do get fog, yes. There is condensation in the greenhouses – in the morning everything is wet, but by the evening the condensation seems to be gone; by 11 PM it is definitely dry. I only water the greenhouses in the morning (I have no energy left in the evenings!).<\/p>\n

    In one greenhouse, everything grows together: tomatoes, eggplants, peppers, and cucumbers. In the other one, I have tomatoes on one side, and watermelons and melons on the other. Plus, I have grow-bags and jugs filled with extra cucumbers and peppers lining the walls! They all live together like in a crowded college dormitory – tight on space, but no one is offended!<\/p>\n

    Here are some photos of my melons, they are growing slowly. There are a lot of tiny female flowers, I’m not sure if they will actually grow.
    \nAs for the watermelons, I only have two fruits so far. Out of 6 grafted plants, only 4 survived (I accidentally snapped one at the graft joint myself, and something chewed through another one). This year, I decided to pinch off the early fruit sets hoping the vines would grow larger watermelons later. Well, they got “offended” at me and now two of the plants aren’t setting any fruit at all!!!<\/p>\n

    And a photo of the grapes!<\/p>\n

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    Aleksan9ra (Ludmila) \u2b50 Expert \/ Author (15,056 posts)<\/span><\/div>\n
    \ud83d\udccd Moscow Region (USDA Zone 4b) | \ud83d\udcc5 July 23, 2021<\/div>\n<\/div>\n<\/div>\n
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    Mariya Suvorova wrote:<\/strong>
    \n…Our property is actually on high ground, and the greenhouses are raised up on a foundation – so everything dries out very quickly…<\/p><\/blockquote>\n

    Masha, thank you! So there is nothing highly unusual going on, everything is standard. Except that your lot is not in a lowland, but on high ground.<\/p>\n

    What a gorgeous melon patch you have! And so many different kinds of melons. I used to plant all sorts of different ones too, but gradually all the late-maturing varieties weeded themselves out on their own.<\/p>\n<\/div>\n<\/div>\n","protected":false},"excerpt":{"rendered":"

    \ud83d\udccc Quick Diary Summary: The Leaf Mold Mystery \ud83c\udf44 The Cladosporium Puzzle: Leaf Mold (Cladosporium) often infects tomatoes early in the spring when seedlings are trapped under plastic covers with high humidity. But sometimes, it mysteriously skips a season. \ud83d\udca8 Elevation and Condensation: A major factor in avoiding fungal diseases is the location of the … Read more<\/a><\/p>\n","protected":false},"author":1,"featured_media":4601,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[529],"tags":[],"class_list":["post-4601","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-growing-tomatoes"],"_links":{"self":[{"href":"https:\/\/www.tomat-pomidor.com\/en\/wp-json\/wp\/v2\/posts\/4601","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.tomat-pomidor.com\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.tomat-pomidor.com\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.tomat-pomidor.com\/en\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.tomat-pomidor.com\/en\/wp-json\/wp\/v2\/comments?post=4601"}],"version-history":[{"count":4,"href":"https:\/\/www.tomat-pomidor.com\/en\/wp-json\/wp\/v2\/posts\/4601\/revisions"}],"predecessor-version":[{"id":5037,"href":"https:\/\/www.tomat-pomidor.com\/en\/wp-json\/wp\/v2\/posts\/4601\/revisions\/5037"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.tomat-pomidor.com\/en\/wp-json\/wp\/v2\/posts\/4601"}],"wp:attachment":[{"href":"https:\/\/www.tomat-pomidor.com\/en\/wp-json\/wp\/v2\/media?parent=4601"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.tomat-pomidor.com\/en\/wp-json\/wp\/v2\/categories?post=4601"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.tomat-pomidor.com\/en\/wp-json\/wp\/v2\/tags?post=4601"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}