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Joined: Mon Aug 09, 2010 7:34 am
Location: massachusetts

late tomato blight

I have the begining of tomato blight on my plants, should I remove the fruit to prevent rotting?

Super Green Thumb
Posts: 2097
Joined: Fri Jul 25, 2008 7:27 pm
Location: Mid Ohio

You can pick anytime after the fruit has started to blush/turn color.

Senior Member
Posts: 161
Joined: Wed Mar 24, 2010 7:17 pm
Location: Pittsburgh, 6A

I was under the impression that once late blight is spotted, you need to pull the plant. Otherwise it can spread around the community and affect your neighbors' plants.

I'm *completely* new at this and that very well may be bad info!

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Super Green Thumb
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Joined: Sun Feb 15, 2009 6:04 pm
Location: TN/GA 7b

Pulling and disposing of it is the safest thing. If I had a bunch of tomato/ potato plants (potatoes are also susceptible) that's what I would do.

However, I'm a backyard gardener with 5 plants. If I noticed blight beginning on one, rather than losing a fifth of my crop, I would try to save it first.

Trying to save it involves:

1) spray all the other tomato/ potato plants with an organic fungicide first to help prevent spread. Organic fungicides include copper sulphate (considered organic, but I don't use it), milk solution, baking soda solution, things with bacillus subtilis (e.g. Serenade), 3% hydrogen peroxide sprayed straight from the bottle. All of these are fungicidal treatments, but all work best used preventatively or at the first signs of infection.

2) remove and dispose of every affected leaf (don't put in compost pile).

3) trim the plants back enough to be sure you have good air circulation

4) water the soil only, in the AM, don't get the leaves wet

5) once the affected leaves are removed spray the rest of the affected plant with one of the above.

Do them in this order, I.e protect the unaffected ones first so you don't risk spreading it around my your touch, tools, sprays, etc. Remove the infected leaves next so you don't risk spreading it with the spray....

You will need to repeat the sprays at least every couple weeks, more if its been raining. It helps to rotate them, use one one time and a different one the next time.

If none of these are working and your plant is getting progressively worse, THEN pull it.

Super Green Thumb
Posts: 2097
Joined: Fri Jul 25, 2008 7:27 pm
Location: Mid Ohio

Commercial growers want you to pull the plants as soon as you see them because they don't want to lose their crop because of backyard gardeners, but tomato and especially potato farmers deal with low level late blight every year and rely on spraying.

Late blight often acts quickly and completely so pulling plants as soon as you see that they are a lost cause is a good practice, but sometimes with spraying, removing infected tissue and good weather you can prolong the inevitable for a couple of weeks and get additional fruit to ripen. I think that this is what many people do.

Senior Member
Posts: 141
Joined: Sun Nov 08, 2009 8:03 am
Location: 4a-Vermont

An extension agent from the University of Vermont has officially identified LB in Vermont. Unfortunately, we've had several powerful thunderstorms over the past two days so it's quite likely those darn spores are being widely dispersed. I have 50 tomato plants and am watching for any early signs of the disease. The tomatoes are just now ripening in sufficient number to allow me to make my salsa, relish, etc. so I'm hoping for the best.

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Super Green Thumb
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Joined: Mon Mar 23, 2009 1:59 pm
Location: TN. 50 years of gardening experience.

Baking soda is good for early blight but not good for late blight.

If one of your plants has blight it exposes all the other plants. It is like having one of your family memebers get sick with the flu by the time you realize they have the flu everyone else in the family is already exposed. It never seems to help to pull up the plant that has blight because all the other plants get blight anyway. It is best to spray and water the plants with copper sulfate before the plants become infected. Copper sulfate is like getting a flu shot it keeps you from getting the flu but if you wait until you already have the flu it is too late to get the flu shot.

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