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--- garden:about:plants:tomatoes:blight [2014/09/24 10:23] – created davidbac
+++ garden:about:plants:tomatoes:blight [2015/09/30 11:47] (current) – davidbac
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+===== Late season tomato blight =====
+I attended a webinar about late season blight. It is caused by a fungus that can affect both tomatoes and potatoes. The presenters at the webinar, all agricultural researchers, agreed on several statements:
+  * The several fungi active in the U.S. cannot survive cold winter weather unless they inhabit an over-wintering potato. As the potato sprouts it can release thousands of spores to infect the area.
+  * Once blight has begun there is no rescuing the crop - blight rules.
+  * A couple of fungicides can reduce blight but only if applied regularly **before spores are present**.
+==== Factors ====
+  * Spores from specific fungi in the air (often over-winter with potatoes)
+  * Moisture on the leaves
+  * Fungal spores traveling on the wind from another blighted garden
+Agricultural scientists who conducted a webinar I attended said that the most likely way for spread of the fungal spores is via over-wintering potatoes who had blight the previous season. I believe it is also possible for spores to travel on the breezes from one blight-stricken garden to another.
+==== Managing ====
+{{ :garden:about:plants:tomatoes:blight:img_0293.jpg?200|No hope for these tomatoes}}Agriculture scientists say not much can be done after blight appears. However, if it is late enough and fruit is getting close to ripe enough to take inside, I do the following:
+  * Never spray water directly on tomato leaves. In some situations it may help to protect plants with a cover.
+  * Trim off any leaf or non-essential stem (and put in yard waste, not a compost pile)
+  * Remove any fruit that has a blighted (dark gray to brown to black)
+  * Cross your fingers and hope for warm sunny weather
+In our experience, once the blight gets to the trunk and stems of a tomato plant the game is over. Soon any fruit will be blighted also and even heroic efforts to save the fruit will have minimal effects. I have attempted heroic measures with very little success.\\
+<note tip>
+Some fruit such as tomatoes, melons and pumpkins can ripen even after leaves have been removed.
+</note>
+==== Nice try ====
+{{:garden:about:plants:tomatoes:blight:img_0313.jpg?250 |Protecting from rain with plastic}}This wasn't a bad idea - it just didn't help. The extended cool and cloudy weather in late August took out all of the tomatoes with blight in a really ugly fashion.\\
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+==== Saved this one ====
+{{ :garden:about:plants:tomatoes:blight:img_0387dw.jpg?200|Denuded tomato plant}}In this case I managed to ripen this tomato on the vine. This particular plant resisted blight longer than any other so I wanted to have this last fruit fully ripened for seeds. This tomato did ripen on the vine and I saved its seeds along with those from a couple of other tomatoes.