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Sep 2, 2010 10:21 AM

avoiding blight for next year

Hello all. Long time chowhound, intermediate gardener, but first time poster on the chowhound gardening board.

I was just out cleaning up in the garden, and as is usual where I live, late blight has started to hit the tomato plants. I removed the most severely diseased plant, removed diseased sections of the other 3, and disposed of in the trash - not compost.

So, my question is this. Is there anything I can or should be doing this winter to my soil to destroy the fungal spores? It seems that despite the limited amount of crop rotation I can do in my small space, I am setting myself up for a worsening fungal problem year after year. Of course, this years hot, dry summer was nothing in comparison to last year. However, we still seem to get this by late August no matter what we have done - water from the bottom, plenty of space for air circulation, etc. I also seemed to get diseases on my eggplant and yellow squash, but not sure what it was, perhaps it was insect damage instead.

Any ideas to lessen problems for next year?


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  1. Late Blight is an "obligate pathogen," meaning it needs living plant tissue to survive, meaning it cannot overwinter in the soil per se but only in plant tissue that hasn't been killed by frost. If you live in the U.S. north of Florida, that means potatoes left in the ground or buried deep in a compost pile are the only way LB can remain in your garden over the winter.

    You almost certainly are not suffering from LB from your description, which overwhelms tomato plants completely within a couple of days.

    There are various other fungal diseases that affect tomatoes that aren't so immediately fatal and can overwinter in the soil-- Early Blight is one, Septoria Leaf Spot is another, and there are various others. Go look up something called the Tomato Problem Solver on the Web for help in diagnosing which disease is affecting your tomatoes.

    Almost everybody gets either EB or SLP or both by the end of summer, no matter what precautions you take, but most years it shows up late enough that it doesn't severely affect the harvest. Removing affected branches daily helps slow these things down somewhat, and your planting and watering habits are good ones. You might add to that keeping the bottom branches trimmed off rather drastically because that's where these diseases usually start since those parts of the plant get the least air circulation.

    You can also spray the darn things every few days with a copper spray or one of the non-organic fungicides starting as soon as you put the plants in the ground and all the way through summer, but even that won't guarantee protection but it will help if you do the spraying religiously.

    Eggplant is a member of the same family as tomatoes and potatoes, so they may be suffering from the same problems. I don't grow them, so can't offer advice on that. Summer and winter squash and melons are very susceptible to powdery mildew. If you go Google it, you'll find various formulas for a baking powder spray that will help to keep PM under control.

    1. remove all traces of stems, leaders, foliage, etc, or in my case, I build a little brush fire in my beds. Nice way to spend a fall afternoon, depending where you live

        1. I believe gyfalcon must be right, based on morwen's links - I don't actually have "late blight". Perhaps early blight is what I've got, dead foliage that starts with the dark spots, then yellow leaves. For the most part, the fruit is spared.

          I believe it is in my soil because it always starts on lower leaves, despite my attempts to trim away lower branches early in the season. I read about "solarizing", but I live in the NE, and it sounds as if it is more successful in the south. Does anyone know about this method for killing fungal spores, or better yet, has anyone had any success with it?

          Yes, every year I throw away as much of any infected plant as I can. And I don't add it to compost. I plan on getting a soaker hose for next year to make watering from the bottom even easier.

          1 Reply
          1. re: centralpadiner

            Every year we get leaf spot and early blight to some degree no matter what we do, and while it's frustrating and unsightly we still get a good harvest. I think how badly we get it depends a lot on what the summer's weather conditions are. This year we had a little blossom end rot and some cat facing due to the dry conditions but those only affect individual fruits and don't spread from plant to plant. We use soaker hoses under the mulch for our gardens. At first because it just made life easier where watering is concerned and then because we discovered that watering from below is better for the plants and conserves water better. Air flow around the plants is a big help when it comes to controlling pests and diseases. I clip off and remove vegetation when it begins to have symptoms of leaf spot and early blight. Right now my tomato vines look more like tomato trees - a stout central stem devoid of leaves or branches about 2 1/2' up with a canopy full of leaves and ripening tomatoes. Our tomato harvest peaked the first 2 weeks of August so what we're still harvesting I consider pure "profit". Just yesterday I noticed the beginnings of late blight symptoms so in the next day or so I'll harvest the rest of the tomatoes in whatever stage they're in and pull and bag the plants for complete removal.

            If you decide to use copper in your garden, use it judiciously and sparingly because it does accumulate over time and can present a whole 'nother set of problems.