Southern Blight

Fusion_power · July 2, 2015

I've had two customers report heavy damage from Southern Blight this year. This disease usually expresses as lesions on the stem near the soil line, sometimes a white powdery residue outside the stem, with rapid plant death a few days after symptoms are observed. There is no good organic way to control this disease once it gets started. It is soilborne and can infest dozens of different plant species. Corn and other grasses are non-hosts so can be grown for a couple of years to reduce innoculum in the soil. As an emergency treatment, Strobilurin compounds can help control Southern Blight. Quadris is a combination fungicide with azoxystrobin, Abound is dilute azoxystrobin. Both have been shown effective at preventing Southern Blight though they may not be effective after plants are infected. These are systemic fungicides. Note that the seedlings I provided were not the likely source of infection. If they had been, many more people would have had a problem and I would be seeing it in my own garden. This is mostly a soilborne disease so contaminated soil must be avoided. Genetic tolerance is currently unavailable.

b54red · July 2, 2015

I had that hit a few plants many years ago but haven't seen it since. I lost one plant very quickly and sprayed the bases with a Clorox solution a good bit stronger than I use for foliage diseases. I went around and sprayed the stems of all my tomatoes from about a foot above the ground down to the ground. If I remember correctly I don't think I lost any other plants nor have I seen it since. I don't know if the bleach worked or what because I really didn't know what I was dealing with until much later when I read about it.

If you know someone who is currently having that problem they might want to try it and see if it helps. The solution I used back then was 10% mix of the old Clorox formula and water with a good dose of liquid dish washing soap added in so it would wet the stem well. The new Ultra Clorox would have to be adjusted some to get it to that strength so it would probably take somewhere between 7 and 8 oz added to a gallon of water. They would have to be careful not to overdo it and not to spray any foliage with that high concentration.

Bill

ginger2778 · July 2, 2015

Soil born, thank goodness. This would be so scary if I wasn't a container gardener. I never heard of it before this thread.

July 2, 2015	#1
Fusion_power Tomatovillian™ Join Date: Feb 2006 Location: Alabama Posts: 2,250	Southern Blight I've had two customers report heavy damage from Southern Blight this year. This disease usually expresses as lesions on the stem near the soil line, sometimes a white powdery residue outside the stem, with rapid plant death a few days after symptoms are observed. There is no good organic way to control this disease once it gets started. It is soilborne and can infest dozens of different plant species. Corn and other grasses are non-hosts so can be grown for a couple of years to reduce innoculum in the soil. As an emergency treatment, Strobilurin compounds can help control Southern Blight. Quadris is a combination fungicide with azoxystrobin, Abound is dilute azoxystrobin. Both have been shown effective at preventing Southern Blight though they may not be effective after plants are infected. These are systemic fungicides. Note that the seedlings I provided were not the likely source of infection. If they had been, many more people would have had a problem and I would be seeing it in my own garden. This is mostly a soilborne disease so contaminated soil must be avoided. Genetic tolerance is currently unavailable.

July 2, 2015	#2
b54red Tomatovillian™ Join Date: Sep 2009 Location: Alabama Posts: 7,068	I had that hit a few plants many years ago but haven't seen it since. I lost one plant very quickly and sprayed the bases with a Clorox solution a good bit stronger than I use for foliage diseases. I went around and sprayed the stems of all my tomatoes from about a foot above the ground down to the ground. If I remember correctly I don't think I lost any other plants nor have I seen it since. I don't know if the bleach worked or what because I really didn't know what I was dealing with until much later when I read about it. If you know someone who is currently having that problem they might want to try it and see if it helps. The solution I used back then was 10% mix of the old Clorox formula and water with a good dose of liquid dish washing soap added in so it would wet the stem well. The new Ultra Clorox would have to be adjusted some to get it to that strength so it would probably take somewhere between 7 and 8 oz added to a gallon of water. They would have to be careful not to overdo it and not to spray any foliage with that high concentration. Bill

July 2, 2015	#3
ginger2778 Tomatovillian™ Join Date: Aug 2011 Location: Plantation, Florida zone 10 Posts: 9,283	Soil born, thank goodness. This would be so scary if I wasn't a container gardener. I never heard of it before this thread.