{"id":1465,"date":"2026-08-31T19:02:04","date_gmt":"2026-08-31T19:02:04","guid":{"rendered":"https:\/\/www.tomat-pomidor.com\/en\/?p=1465"},"modified":"2026-08-31T19:28:16","modified_gmt":"2026-08-31T19:28:16","slug":"late-blight-prevention","status":"publish","type":"post","link":"https:\/\/www.tomat-pomidor.com\/en\/late-blight-prevention\/","title":{"rendered":"Late Blight (Phytophthora) Prevention: Systemic Fungicides vs. Folk Remedies"},"content":{"rendered":"\n\n<div class=\"kk-star-ratings kksr-auto kksr-align-left kksr-valign-top\"\n    data-payload='{&quot;align&quot;:&quot;left&quot;,&quot;id&quot;:&quot;1465&quot;,&quot;slug&quot;:&quot;default&quot;,&quot;valign&quot;:&quot;top&quot;,&quot;ignore&quot;:&quot;&quot;,&quot;reference&quot;:&quot;auto&quot;,&quot;class&quot;:&quot;&quot;,&quot;count&quot;:&quot;0&quot;,&quot;legendonly&quot;:&quot;&quot;,&quot;readonly&quot;:&quot;&quot;,&quot;score&quot;:&quot;0&quot;,&quot;starsonly&quot;:&quot;&quot;,&quot;best&quot;:&quot;5&quot;,&quot;gap&quot;:&quot;5&quot;,&quot;greet&quot;:&quot;Rate this&quot;,&quot;legend&quot;:&quot;0\\\/5 - (0 votes)&quot;,&quot;size&quot;:&quot;24&quot;,&quot;title&quot;:&quot;Late Blight (Phytophthora) Prevention: Systemic Fungicides vs. Folk Remedies&quot;,&quot;width&quot;:&quot;0&quot;,&quot;_legend&quot;:&quot;{score}\\\/{best} - ({count} {votes})&quot;,&quot;font_factor&quot;:&quot;1.25&quot;}'>\n            \n<div class=\"kksr-stars\">\n    \n<div class=\"kksr-stars-inactive\">\n            <div class=\"kksr-star\" data-star=\"1\" style=\"padding-right: 5px\">\n            \n\n<div class=\"kksr-icon\" style=\"width: 24px; height: 24px;\"><\/div>\n        <\/div>\n            <div class=\"kksr-star\" data-star=\"2\" style=\"padding-right: 5px\">\n            \n\n<div class=\"kksr-icon\" style=\"width: 24px; height: 24px;\"><\/div>\n        <\/div>\n            <div class=\"kksr-star\" data-star=\"3\" style=\"padding-right: 5px\">\n            \n\n<div class=\"kksr-icon\" style=\"width: 24px; height: 24px;\"><\/div>\n        <\/div>\n            <div class=\"kksr-star\" data-star=\"4\" style=\"padding-right: 5px\">\n            \n\n<div class=\"kksr-icon\" style=\"width: 24px; height: 24px;\"><\/div>\n        <\/div>\n            <div class=\"kksr-star\" data-star=\"5\" style=\"padding-right: 5px\">\n            \n\n<div class=\"kksr-icon\" style=\"width: 24px; height: 24px;\"><\/div>\n        <\/div>\n    <\/div>\n    \n<div class=\"kksr-stars-active\" style=\"width: 0px;\">\n            <div class=\"kksr-star\" style=\"padding-right: 5px\">\n            \n\n<div class=\"kksr-icon\" style=\"width: 24px; height: 24px;\"><\/div>\n        <\/div>\n            <div class=\"kksr-star\" style=\"padding-right: 5px\">\n            \n\n<div class=\"kksr-icon\" style=\"width: 24px; height: 24px;\"><\/div>\n        <\/div>\n            <div class=\"kksr-star\" style=\"padding-right: 5px\">\n            \n\n<div class=\"kksr-icon\" style=\"width: 24px; height: 24px;\"><\/div>\n        <\/div>\n            <div class=\"kksr-star\" style=\"padding-right: 5px\">\n            \n\n<div class=\"kksr-icon\" style=\"width: 24px; height: 24px;\"><\/div>\n        <\/div>\n            <div class=\"kksr-star\" style=\"padding-right: 5px\">\n            \n\n<div class=\"kksr-icon\" style=\"width: 24px; height: 24px;\"><\/div>\n        <\/div>\n    <\/div>\n<\/div>\n                \n\n<div class=\"kksr-legend\" style=\"font-size: 19.2px;\">\n            <span class=\"kksr-muted\">Rate this<\/span>\n    <\/div>\n    <\/div>\n<h2>Quick Summary: Defeating Late Blight in Cold, Rainy Climates<\/h2>\n<ul>\n<li>\ud83c\udf0d <strong>The Problem:<\/strong> Late Blight (Phytophthora infestans) is the ultimate tomato killer, especially in cool, rainy regions with heavy morning dew (like USDA Zones 3-5). Many growers harvest green tomatoes thinking they are safe, only to watch them rot indoors.<\/li>\n<li>\ud83e\uddea <strong>Folk Remedies vs. Science:<\/strong> Experienced growers agree: in bad weather, folk remedies fail. Relying on &#8220;natural selection&#8221; or greenhouse protection isn&#8217;t enough. You need modern preventative fungicides.<\/li>\n<li>\ud83d\udcc5 <strong>The Calendar Strategy:<\/strong> The key to success is a strict spray schedule. Treatments must begin <em>before<\/em> the rains and disease hit (sometimes as early as June). Keeping a calendar ensures you respect the PHI (Pre-Harvest Interval) for each chemical.<\/li>\n<li>\ud83d\udd04 <strong>Rotate Active Ingredients:<\/strong> To prevent resistance, you must rotate fungicides. Popular choices include Previcur Energy (Propamocarb), Revus (Mandipropamid), Quadris (Azoxystrobin), and Copper-based sprays.<\/li>\n<\/ul>\n<div class=\"add-review-cta\" style=\"margin: 20px 0; padding: 15px; background: #f9f9f9; border-left: 4px solid #4CAF50; border-radius: 4px;\"><strong>\ud83d\udee1\ufe0f How do you fight Late Blight?<\/strong> <a href=\"#wpdcom\">Share your spray schedule and tips in the comments below!<\/a><\/div>\n<article class=\"forum-article\">\n<h1>Tomato Late Blight: Why Green Tomatoes Rot &amp; How to Stop It<\/h1>\n<div class=\"forum-post\">\n<div class=\"author-header\">\n<div class=\"forum-avatar\">O<\/div>\n<div class=\"author-meta\">\n<div class=\"author-name\">sova86 (Oksana) <span class=\"author-stats\">\u2b50 Beginner (23 posts)<\/span><\/div>\n<div class=\"author-geo\">\ud83d\udccd Pskov, Russia (USDA Zone 4b\/5a)<\/div>\n<\/div>\n<\/div>\n<div class=\"post-content\">\n<p>Hello everyone&#8230;<\/p>\n<p>Oh, I rejoiced too early that I managed to pick my green tomatoes. They sat for 2 weeks and started to spoil very rapidly. Spots appeared, and then rot&#8230; my heart bleeds, and honestly, I just want to give up.<\/p>\n<p>I need to rethink my possible mistakes in agrotechnology, understand what kind of infection this is, and whether I need to treat the soil. I don&#8217;t know if I&#8217;ll ever find common ground with tomatoes\u2014apparently, they do not forgive mistakes.<\/p>\n<\/div>\n<\/div>\n<div class=\"forum-post\">\n<div class=\"author-header\">\n<div class=\"forum-avatar\">I<\/div>\n<div class=\"author-meta\">\n<div class=\"author-name\">Inna5867 (Inna) <span class=\"author-stats\">\u2b50 Pro Grower (3,051 posts)<\/span><\/div>\n<div class=\"author-geo\">\ud83d\udccd Saratov Region (USDA Zone 4b)<\/div>\n<\/div>\n<\/div>\n<div class=\"post-content\">\n<blockquote><p><strong>sova86 said:<\/strong><br \/>\nThey sat for 2 weeks and started to spoil very rapidly&#8230;<\/p><\/blockquote>\n<p>It&#8217;s convenient to keep records if you know what variety it is. I try not to repeat the capricious ones; natural selection hasn&#8217;t been canceled! For some people, a variety might perform great, but for me, I&#8217;d have to dance with a tambourine and sing songs to it\u2014fine if the variety is worth it, but otherwise, I just play with it once and move on. How to balance everything\u2014soil, weather, fertilizers\u2014who the heck knows, I can&#8217;t even bother worrying about it, I have too many other chores and varieties to try. \ud83d\udc4b<\/p>\n<\/div>\n<\/div>\n<div class=\"forum-post\">\n<div class=\"author-header\">\n<div class=\"forum-avatar\">O<\/div>\n<div class=\"author-meta\">\n<div class=\"author-name\">sova86 (Oksana) <span class=\"author-stats\">\u2b50 Beginner (23 posts)<\/span><\/div>\n<div class=\"author-geo\">\ud83d\udccd Pskov, Russia (USDA Zone 4b\/5a)<\/div>\n<\/div>\n<\/div>\n<div class=\"post-content\">\n<p>That&#8217;s true, I immediately started a spreadsheet on my computer (it&#8217;s more convenient and easier for me) and started keeping records of when I sowed which varieties.<\/p>\n<p>But right now, of course, in this pile of harvested tomatoes, you can&#8217;t figure anything out. Next year, I&#8217;ll probably rely mostly on disease-resistant F1 hybrids and earlier varieties.<\/p>\n<\/div>\n<\/div>\n<div class=\"forum-post\">\n<div class=\"author-header\">\n<div class=\"forum-avatar\">I<\/div>\n<div class=\"author-meta\">\n<div class=\"author-name\">Inna5867 (Inna) <span class=\"author-stats\">\u2b50 Pro Grower (3,051 posts)<\/span><\/div>\n<div class=\"author-geo\">\ud83d\udccd Saratov Region (USDA Zone 4b)<\/div>\n<\/div>\n<\/div>\n<div class=\"post-content\">\n<blockquote><p><strong>sova86 said:<\/strong><br \/>\nNext year, I&#8217;ll probably rely mostly on disease-resistant F1 hybrids and earlier varieties.<\/p><\/blockquote>\n<p>&#8230;I went through that phase too. But I returned to open-pollinated (heirloom) indeterminates. In the open ground (outdoors), only they and Dwarf Tomato Project varieties truly survive for me.<\/p>\n<\/div>\n<\/div>\n<div class=\"forum-post\">\n<div class=\"author-header\">\n<div class=\"forum-avatar\">S<\/div>\n<div class=\"author-meta\">\n<div class=\"author-name\">Svetlana66 (Svetlana) <span class=\"author-stats\">\u2b50 Member (353 posts)<\/span><\/div>\n<div class=\"author-geo\">\ud83d\udccd Eastern Moscow Region (USDA Zone 4a)<\/div>\n<\/div>\n<\/div>\n<div class=\"post-content\">\n<blockquote><p><strong>sova86 said:<\/strong><br \/>\nI need to rethink my possible mistakes in agrotechnology, understand what kind of infection this is, and whether I need to treat the soil&#8230;<\/p><\/blockquote>\n<p>In my opinion, you absolutely must do preventative sprayings, and <strong>not with folk remedies, but with good modern fungicides<\/strong>. Especially since your climate is quite difficult\u2014it&#8217;s not hot, and it&#8217;s rainy. No greenhouse will save you from diseases. For many growers around here, Late Blight (Phytophthora) wiped out their tomatoes a long time ago, while mine are still standing outdoors in the open ground right up until the frosts.<\/p>\n<\/div>\n<\/div>\n<div class=\"forum-post\">\n<div class=\"author-header\">\n<div class=\"forum-avatar\">S<\/div>\n<div class=\"author-meta\">\n<div class=\"author-name\">Svetikk <span class=\"author-stats\">\u2b50 Pro Grower (29,351 posts)<\/span><\/div>\n<div class=\"author-geo\">\ud83d\udccd South Moscow Region (USDA Zone 4a)<\/div>\n<\/div>\n<\/div>\n<div class=\"post-content\">\n<blockquote><p><strong>Svetlana66 said:<\/strong><br \/>\nIn my opinion, you absolutely must do preventative sprayings, and not with folk remedies, but with good modern fungicides&#8230;<\/p><\/blockquote>\n<p>I completely agree. ONLY preventative sprayings of tomatoes and potatoes against Late Blight and Cladosporium (Leaf Mold in the greenhouse) with modern systemic and systemic-contact fungicides will help save the harvest. You don&#8217;t need to treat the soil, and variety selection doesn&#8217;t play a massive role either.<\/p>\n<p>I have a large 3-month block calendar hanging on my wall where I record all my sprayings. This allows me to track the <strong>PHI (Pre-Harvest Interval)<\/strong> before picking, and to know exactly when to do the next spray if the weather gets dangerous. I&#8217;ve already been through all those stages in the past: when Late Blight strikes suddenly in a couple of days, when seemingly clean green fruits spoil while ripening indoors, and when I sprayed too late\u2014at the first signs of disease rather than preventatively.<\/p>\n<p>Now I&#8217;ve developed a &#8220;sixth sense.&#8221; In the summer, I analyze the weather, especially in the mornings. Our nights are often cold, with heavy morning dew. If rain is also in the forecast\u2014spraying is mandatory. Sometimes I have to start as early as June.<\/p>\n<\/div>\n<\/div>\n<div class=\"forum-post\">\n<div class=\"author-header\">\n<div class=\"forum-avatar\">N<\/div>\n<div class=\"author-meta\">\n<div class=\"author-name\">NataliaG (Natalia) <span class=\"author-stats\">\u2b50 Pro Grower (8,470 posts)<\/span><\/div>\n<div class=\"author-geo\">\ud83d\udccd Kursk, Russia (USDA Zone 5a)<\/div>\n<\/div>\n<\/div>\n<div class=\"post-content\">\n<blockquote><p><strong>Svetikk said:<\/strong><br \/>\nNow I&#8217;ve developed a &#8220;sixth sense.&#8221; In the summer, I analyze the weather&#8230; If rain is also in the forecast\u2014spraying is mandatory.<\/p><\/blockquote>\n<p>I spray before <em>every<\/em> heavy rain starting from the end of June. And if there are cold nights and heavy dew, I do it then too. I leave 7, 10, or 12 days between treatments, and <strong>I always rotate the fungicides<\/strong>. This year, Phytophthora devoured the tomatoes for many people here (no surprise, June and July were completely rainy), not letting them taste a single tomato. Meanwhile, mine are thriving in the open ground.<\/p>\n<p>Generally speaking, despite the horrible weather, the tomatoes this year are gorgeous in taste\u2014all sweet, almost no bland or watery ones. What&#8217;s strange is that even though June and July were very cold and wet, the tomatoes that started ripening in mid-July were delicious, just with thicker skins. Now the skins have returned to normal.<\/p>\n<\/div>\n<\/div>\n<div class=\"forum-post\">\n<div class=\"author-header\">\n<div class=\"forum-avatar\">O<\/div>\n<div class=\"author-meta\">\n<div class=\"author-name\">sova86 (Oksana) <span class=\"author-stats\">\u2b50 Beginner (23 posts)<\/span><\/div>\n<div class=\"author-geo\">\ud83d\udccd Pskov, Russia (USDA Zone 4b\/5a)<\/div>\n<\/div>\n<\/div>\n<div class=\"post-content\">\n<p>Girls, thank you all for the answers and advice. I will try to grow tomatoes again next year.<\/p>\n<p>Before the new season, I need to find out from you what you spray with and when, to make a written action plan for myself. Because when the gardening chores are in full swing, there&#8217;s no time for writing&#8230;<\/p>\n<p>I sprayed them with <em>Profit Gold<\/em> (Cymoxanil + Famoxadone), but apparently it was too late. As I understand it now, I need to spray with different chemicals throughout the entire period.<\/p>\n<\/div>\n<\/div>\n<div class=\"forum-post\">\n<div class=\"author-header\">\n<div class=\"forum-avatar\">D<\/div>\n<div class=\"author-meta\">\n<div class=\"author-name\">DRYGAN (Vadim) <span class=\"author-stats\">\u2b50 Pro Grower (2,694 posts)<\/span><\/div>\n<div class=\"author-geo\">\ud83d\udccd Minsk, Belarus (USDA Zone 5a)<\/div>\n<\/div>\n<\/div>\n<div class=\"post-content\">\n<p>Oksana! It&#8217;s a pity for your hard work, of course. So many people right here on the forum have had problems with Late Blight (Phytophthora) on their tomatoes.<\/p>\n<p>But this disease has been studied far and wide by now. Protection schemes have been developed, and there is a choice of fungicides against it. Yet, many people still comfort themselves with illusions that it won&#8217;t affect their tomatoes. You just have to take a protection scheme as a guide and execute it. Of course, depending on your region and local climate, the scheme might be adjusted.<\/p>\n<\/div>\n<\/div>\n<div class=\"forum-post\">\n<div class=\"author-header\">\n<div class=\"forum-avatar\">S<\/div>\n<div class=\"author-meta\">\n<div class=\"author-name\">Svetlana66 (Svetlana) <span class=\"author-stats\">\u2b50 Member (353 posts)<\/span><\/div>\n<div class=\"author-geo\">\ud83d\udccd Eastern Moscow Region (USDA Zone 4a)<\/div>\n<\/div>\n<\/div>\n<div class=\"post-content\">\n<blockquote><p><strong>sova86 said:<\/strong><br \/>\nI sprayed them with Profit Gold, but apparently it was too late. As I understand it now, I need to spray with different chemicals throughout the entire period.<\/p><\/blockquote>\n<p>Yes, you must have different fungicides with different active ingredients so the fungus doesn&#8217;t build resistance. <em>Profit Gold<\/em> (Cymoxanil + Famoxadone, similar to US brands like <strong>Tanos<\/strong>) is a good product, but applying it once, and too late, is not enough.<\/p>\n<p>I start right from sowing the seeds with <strong>Previcur Energy<\/strong> (Propamocarb + Fosetyl-Al; available in the US under the same name or as <strong>Aliette<\/strong>). Then throughout the season I use many others: <strong>Luna Experience<\/strong> (Fluopyram + Tebuconazole; available to US home gardeners in products like <strong>BioAdvanced Disease Control<\/strong>), <strong>Ordan<\/strong> (Cymoxanil + Copper oxychloride; similar to mixing <strong>Curzate<\/strong> with a standard <strong>Liquid Copper Fungicide<\/strong>), <strong>Revus<\/strong> (Mandipropamid), <strong>Quadris<\/strong> (Azoxystrobin; widely sold to US home growers as <strong>Scott&#8217;s DiseaseEx<\/strong> or <strong>Heritage<\/strong>), etc.<\/p>\n<\/div>\n<\/div>\n<div class=\"forum-post\">\n<div class=\"author-header\">\n<div class=\"forum-avatar\">S<\/div>\n<div class=\"author-meta\">\n<div class=\"author-name\">Svetikk <span class=\"author-stats\">\u2b50 Pro Grower (29,352 posts)<\/span><\/div>\n<div class=\"author-geo\">\ud83d\udccd South Moscow Region (USDA Zone 4a)<\/div>\n<\/div>\n<\/div>\n<div class=\"post-content\">\n<blockquote><p><strong>Svetlana66 said:<\/strong><br \/>\nYes, you must have different fungicides with different active ingredients so the fungus doesn&#8217;t build resistance&#8230; I start right from sowing the seeds with Previcur Energy, then throughout the season I use many others: Luna Experience, Ordan, Revus, Quadris and..<\/p><\/blockquote>\n<p>I completely agree! I will add to the list: <strong>Oxyhom<\/strong> (Oxadixyl + Copper oxychloride), <strong>Infinito<\/strong> (Fluopicolide + Propamocarb), and <strong>Consento<\/strong> (Fenamidone + Propamocarb).<\/p>\n<p>Also, <strong>HOM<\/strong> (Copper oxychloride, widely sold in the US as standard <strong>Liquid Copper Fungicide<\/strong>). It is a contact fungicide with the shortest pre-harvest interval (PHI)\u2014but keep in mind that it washes off with rain.<\/p>\n<p>It is better to buy them in advance and from verified sources. There is a high risk of buying fake products on general marketplaces (like Amazon\/eBay). I buy mine through our forum&#8217;s joint co-op purchases, on the Onprofi website, and at Lemana Pro <em>[Editor&#8217;s note: trusted agricultural and home improvement suppliers in Russia]<\/em>.<\/p>\n<\/div>\n<\/div>\n<\/article>\n","protected":false},"excerpt":{"rendered":"<p>Quick Summary: Defeating Late Blight in Cold, Rainy Climates \ud83c\udf0d The Problem: Late Blight (Phytophthora infestans) is the ultimate tomato killer, especially in cool, rainy regions with heavy morning dew (like USDA Zones 3-5). Many growers harvest green tomatoes thinking they are safe, only to watch them rot indoors. \ud83e\uddea Folk Remedies vs. Science: Experienced &#8230; <a title=\"Late Blight (Phytophthora) Prevention: Systemic Fungicides vs. Folk Remedies\" class=\"read-more\" href=\"https:\/\/www.tomat-pomidor.com\/en\/late-blight-prevention\/\" aria-label=\"Read more about Late Blight (Phytophthora) Prevention: Systemic Fungicides vs. Folk Remedies\">Read more<\/a><\/p>\n","protected":false},"author":1,"featured_media":1465,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[472],"tags":[541,182,49,539,540],"class_list":["post-1465","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-diseases-weeds","tag-fungicide-schedule","tag-late-blight","tag-open-ground","tag-phytophthora","tag-tomato-disease"],"_links":{"self":[{"href":"https:\/\/www.tomat-pomidor.com\/en\/wp-json\/wp\/v2\/posts\/1465","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=1465"}],"version-history":[{"count":4,"href":"https:\/\/www.tomat-pomidor.com\/en\/wp-json\/wp\/v2\/posts\/1465\/revisions"}],"predecessor-version":[{"id":1469,"href":"https:\/\/www.tomat-pomidor.com\/en\/wp-json\/wp\/v2\/posts\/1465\/revisions\/1469"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.tomat-pomidor.com\/en\/wp-json\/wp\/v2\/posts\/1465"}],"wp:attachment":[{"href":"https:\/\/www.tomat-pomidor.com\/en\/wp-json\/wp\/v2\/media?parent=1465"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.tomat-pomidor.com\/en\/wp-json\/wp\/v2\/categories?post=1465"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.tomat-pomidor.com\/en\/wp-json\/wp\/v2\/tags?post=1465"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}