Have Late Blight...Spray Now or Give Up?

Jimche · August 4, 2009

Hi All.

We have the dreaded LB and our tomto garden is over 600 plants, 53 varieties. It started as a glorious year, our first in the market gardening hobby-business. You can see how enthusiatic we have been about this whole venture on our website www.solanagardens.com so this is a real heart-breaker. There are huge numbers of large, beautiful tomatoes on the plants, not yet ripe. But there is LB suddenly here, infecting perhaps 1/3 or more of the plants to one degree or another. Do we have a shot at salvaging the crop by culling out the infected leaves or plants? Doing so would be a huge effort which we'd prefer to avoid if it is futile at this point. And if we spray with chlorothalonil now, will it reverse the existing infection? Likewise, would dry and sunny weather prevent further infection?

As always, any help will be much appreciated!

Jimche and Galinche

bcday · August 4, 2009

I would say it's worth a shot -- after all, 400 of your plants still look healthy, right? I've defeated LB and got ripe unblemished fruit before, and only lost a few plants that were all determinate varieties.

If you check the current updates online by Cornell, UCONN and other extension services, you'll see that they are now getting reports that spraying is succeeding in saving fields that had infected plants. If you're a market gardener and not organic, you have access to much stronger fungicides than a home gardener could use, and those will give you very good results.

It does help if the weather cooperates though. Warm, dry and sunny is what we need.

Edit -- spraying chlorothalonil now will help the healthy plants stay healthy. And copper spray such as Kocide is said to be able to kill spores before they get too far along. Neither of those will heal foliage that is already infected, and you need to remove all of that and seal it up in plastic bags so that it doesn't continue releasing spores onto your healthy plants. Don't go into the field to prune infected leaves when the foliage is wet, wait until it dries out.

I ordered Kocide from Johnny's and it arrived two days later. It's not too late to order supplies you don't have yet.

Jimche · August 4, 2009

Thanks, BC. It is good news that spraying after the infection may knock it back. We don't have a pesticide license, but a farmer friend who does suggested he could help us out with some Bravo. Hate to do it, but the alternative is worse.

It is funny. I had been all excited to use the drip irrigation system we set up this year for the first time. It was turned on only once, and we find ourselves praying for no rain, to keep the LB in check. If we are lucky, we will need to use it in the coming weeks.

bcday · August 4, 2009

Quote:

Originally Posted by Jimche

a farmer friend who does suggested he could help us out with some Bravo.

That will be a big help. Try to prune off as much infected foliage as possible before he sprays the Bravo, so that the spraying doesn't spread spores around.

But even getting the spray on before you get the diseased leaves off is better than not spraying. You're probably somewhat subject to his schedule, as in he can get there when he can get there, so again while avoiding wet foliage as much as possible, just do as much as you can before he gets there.

August 4, 2009	#1
Jimche Tomatovillian™ Join Date: Feb 2009 Location: New Jersey, USA Posts: 58	Have Late Blight...Spray Now or Give Up? Hi All. We have the dreaded LB and our tomto garden is over 600 plants, 53 varieties. It started as a glorious year, our first in the market gardening hobby-business. You can see how enthusiatic we have been about this whole venture on our website www.solanagardens.com so this is a real heart-breaker. There are huge numbers of large, beautiful tomatoes on the plants, not yet ripe. But there is LB suddenly here, infecting perhaps 1/3 or more of the plants to one degree or another. Do we have a shot at salvaging the crop by culling out the infected leaves or plants? Doing so would be a huge effort which we'd prefer to avoid if it is futile at this point. And if we spray with chlorothalonil now, will it reverse the existing infection? Likewise, would dry and sunny weather prevent further infection? As always, any help will be much appreciated! Jimche and Galinche

August 4, 2009	#2
bcday Tomatovillian™ Join Date: Jan 2006 Location: NY z5 Posts: 1,205	I would say it's worth a shot -- after all, 400 of your plants still look healthy, right? I've defeated LB and got ripe unblemished fruit before, and only lost a few plants that were all determinate varieties. If you check the current updates online by Cornell, UCONN and other extension services, you'll see that they are now getting reports that spraying is succeeding in saving fields that had infected plants. If you're a market gardener and not organic, you have access to much stronger fungicides than a home gardener could use, and those will give you very good results. It does help if the weather cooperates though. Warm, dry and sunny is what we need. Edit -- spraying chlorothalonil now will help the healthy plants stay healthy. And copper spray such as Kocide is said to be able to kill spores before they get too far along. Neither of those will heal foliage that is already infected, and you need to remove all of that and seal it up in plastic bags so that it doesn't continue releasing spores onto your healthy plants. Don't go into the field to prune infected leaves when the foliage is wet, wait until it dries out. I ordered Kocide from Johnny's and it arrived two days later. It's not too late to order supplies you don't have yet.