What is in this article?:
- Fungicide-resistant Rhizoctonia solani found in Louisiana
- Hybrid selection extremely important
- Soil-borne Rhizoctonia solani fungus found to be resistant to strobilurin fungicides.
- Fungus causes sheath blight in rice and aerial blight in soybeans.
- So far, only in a small area of southern Louisiana.
Hybrid selection extremely important
“Hybrid selection will be extremely important. We’ll need to plant the hybrids and varieties with the most tolerance to Rhizoctonia solani.
“Seed treatments will be a major player, as well. Whether it’s rice, corn or soybeans, you want every advantage in your favor to get a crop out of the ground and growing faster.
“Don’t under- or over-fertilize -- doing that can actually” promote the fungus.
“As for plant populations, we suggest folks plant on the low side. That’s true whether it’s rice, soybeans, corn, grain sorghum, whatever.
“But we really must focus on cleaning equipment. We must start cleaning debris from equipment when it’s moved from field to field or farm to farm.”
On further research…
“Syngenta will continue testing in 2012 to extend our understanding and knowledge base of actually where and how widespread (the disease) is.
“Right now, the map is based only on the samples we were able to pull late-season last year. We pulled approximately 40 samples and were able to plate 400 isolates from those. Some samples simply didn’t have Rhizoc on them.
“We will continue investing in research and development. We’ll be (in the affected area) in 2012 testing a lot of our old chemistries as well as our new ones to see if there’s anything that may have been missed with fungicide opportunities. We want to provide the farmers with help with this disease.”
Did the discovery of this answer questions about problems that might have occurred in previous seasons?
“We did have some eyebrows raised in a couple of fields in 2010.
“We looked at a couple of (odd situations) but those could be explained away through misapplications, equipment issues, too much rainfall immediately after a (fungicide) application and things along those lines.
“This really developed last year in five or six fields.”
What about flooding?
“That’s one of the BMPs. We’ll promote some rather non-conventional BMPs and flooding will be one of them.
“Rhizoc does have the potential to move in water – but that isn’t likely to be the main avenue it will take. Plant and crop debris along with soil are the major concerns.
“For those who continue to grow rice in that area, we’ll suggest burning fields. How much that will help is yet to be determined but you’ll remove some organic matter and destroy crop debris.
“We’ll promote increased disking at the end of the growing season.
“We’ll also promote the elimination of a ratoon crop. That won’t be popular, but the practice will escalate the disease incidence long-term.
“We’ll suggest pulling levees and holding water over the fall and winter and fallow ground.
“However, I can’t stress cleaning equipment enough.”
On strobilurins and soybeans…
“This will not just impact rice.
“Rhizoctonia solanibasically develops two diseases: sheath blight in rice and aerial blight in soybeans. Aerial blight is the Number Two disease in southwest Louisiana soybeans -- second only to cercospera.
“With the (fungus) being cross-resistant to the strobilurin class, other competitor products won’t have any control. Producers will be looking for alternatives.”