Bobberman
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With all this rain how to prevent tomato blight?

My tomatoes are really nice but its raining way too much. All night tonight and very heavy. Wet plants all night is bad especially since we had a blight two years in a row in Pa. Will mulch help or What can?

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Lindsaylew82
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Mulch will definitely help. Thick Wheat straw is my go to. We couldn't get wheat straw this year, though. I used pine straw! But you want to prevent the soil from splashing up on the plants. Removing lower leaves that are showing signs of yellowing or browning helps. Bag them and trash them. No composting them. Use sharp shears and spray them with rubbing alcohol between plants. I also use neem (4 tablespoons/gallon) every week as a prophylactic measure. I spray at dusk. I fight for the right to grow tomatoes!

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hendi_alex
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Grow a steady stream of replacements. Disease will most always win out in the south, no matter what you do. Combining high disease resistance with a spray routine gives the best chance. I read of one extensive field trial from an ag agency. The trials showed spraying had near zero effect on any except disease resistant plants. Spraying was moderately helpful on the DR ones.

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Lindsaylew82
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It especially has no effect if you spray and then it pours all night.....
It never pours until I treat.

Maybe I have resistant cultivars. IDK, but but I have 15 or so different tomato cultivars currently in my garden. Mostly heirlooms, but I have a couple hybrids. IME, I have noticed a difference in longevity of plant life. I HAVE noticed that if fungal infections are taking over, there is no treatment. Here (in the south), I agree with you, demise is inevitable, but IME, it can be delayed with neem and getting rid of the parts that are showing signs of progression.
In the fall, I've notice a lot of my plants rejuvenate and I usually get a small fall crop if I can keep the bugs off. I have seeds from a very tasty yellow (the tag fell off the first year I planted it) heirloom tomato that gives a heavy fall crop every year. Even on previously blighted vines, the new growth is vigorous and healthy, maybe it adapts, maybe it's more resistant, maybe its the neem.

If blight weren't so bad here, and I didn't adore tomatoes, I'd be interested in doing a trial of my own. Maybe I'll till up a new spot next year (far away from my big garden) and test it. Maybe 2 resistant cultivars and 2 nonresistant cultivars in each of 2 beds. Only difference in treatment would be neem....

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feldon30
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There are few tomatoes tolerant (and none truly resistant) to the kind of fungal foliar diseases seen so often after torrential downpours. I'm talking Early Blight (Alternaria) as well as Anthracnose which is a fruit rot.

I grow whatever tomato varieties I like and then provide a thick layer of mulch such as wheat straw or pine bark. Then, I spray plants weekly with Daconil (chlorothalonil) or Serenade (if you prefer organic).

There is a new kid on the block which is the first ever systemic fungicide approved for vegetable crops and it is organic to boot -- Exel LG. It is a soil drench which is effective against these diseases.. << this turned out to be not organic >>
Last edited by applestar on Thu Aug 14, 2014 7:38 am, edited 1 time in total.
Reason: Correction made about Exel LG being NOT organic per OP's request

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lakngulf
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I agree that the Early Blight, some BER and other tomato "leaf getters" are a part of the territory of growing tomatoes in the south. But Oh! the reward of the juicy red fruit that makes it through the hot, humid conditions. As most know, I grow a lot of tomatoes down near the lake. And, we get so many downpours in some years. My "lake pier" tomatoes start off so well, put on lots of fruit, but those bottom leaves succumb to early blight. This year I tried to give more space for the tomatoes, planting low growers like squash next to tomatoes, but I have had to clip off a lot of bottom leaves.

I do have one batch of tomatoes behind my house, in a spot that gets good sun from 10 to 3, and the plants have plenty of air space on each side. They are also in pots with fresh, rich top soil from the farm. Also, I put newspapers to help control weeds, maintain moisture. I have not clipped any leaves from these plants yet, and this is a picture from this morning.

Image

As founding member of PETC (Plants Everything Too Close) it is hard for me to give plants space, but these models may help with my rehabilitation.

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Lindsaylew82
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I'm a recovering member of PETC. (I still crowd the junk out of some okra!)
Blight is so bad here, that I have been forced to abide by a strict 3 foot rule with tomatoes. That was haaaaaaaaaaaaaard to do. I used to cram them 1 foot apart and string them between 2 rebar posts. Not no mo... I WILL plant smaller herbs around them, but not too close, never too close... I am a notoriously heavy mulcher, and I cover each year with either news paper, or packaging paper. Exercise in futility indeed. But it does help!

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hendi_alex
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Over the past few years I've come to a better understanding of typical tomato disease in my garden areas. First, rotating the planting area is of no help. The spores are everywhere. Planting in sterile soil is of only modest help. The spores move throughout the yard when conditions are favorable. When temperatures are in the 90's for highs and 70's for lows, most mature plants are going to die. I have found that young, rapidly growing plants in morning sun only locations are pretty immune to the leaf and stem diseases even when very hot and humid.

My response: grow lots of replacements started at approximate three week intervals. I don't pay any attention to planting site or contaminated soil. If conditions are good for the disease, the plants will die. When temperatures drop into highs in the 80's and lows in the 60's, the tomatoes will thrive. So now I plant in the same pot with the same soil or plant in the same spot in which a diseased plant died. In cooler temperature the plant does just fine and makes a good crop. I also plant a wide variety of tomatoes with multiple plants each. For some reason a sprinkling of plants tend to be only modestly affected.

With this method we usually get a huge harvest in May and June. There is a slowdown mid July through the end of August as most plants die. Our late planting goes into the ground when temperatures moderate in September. That usually results in a good harvest early October until frost in late November.



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