Outwardly, it looks like it takes a medical degree to discuss innovations in the fight against powdery mildew, particularly the concept of RNA interference, or spray-induced gene silencing.
Only the concept creates more of a “Huh?” as a “Wow!”
University of California, Berkeley plant biologist Mary Wildermuth, who is studying how to turn off the infection mode of grape powdery mildew, says the breakthrough technology will allow growers to control powdery mildew with less reliance on FRAC 3 fungicides .
“Compared to traditional chemicals, mold is less likely to develop resistance to this technology, reducing the need for fungicide applications,” she said. For grapevines, which are typically treated up to a dozen times during a growing season, and with 90% of grapevine pesticide use treating powdery mildew, this is good news.
Essentially, SIGS (Spray-Induced Gene Silencing) are RNAi molecules that target powdery mildew genes, which are essential for the development and growth of infections.
“Our results suggest that SIGS treatment could be used as a replacement for systemic fungicides in the middle of the growing season because it has no effects on canopy, berry development, or berry chemistry,” she said, after about 20 years had studied the interaction of powdery mildew and host plants for years.
“This technology solves a need and adds a novel mode of action to the grower’s toolbox. Topical RNAi should be an effective method of controlling powdery mildew,” she added. Project scientist Jyoti Taneja estimates that the field technology could be available to growers within three years.
What are the scientists so excited about?
“Every organism has DNA, the blueprint, which is translated into protein via converted RNA messengers, and we can now spray a small piece of RNA that is complementary to the powdery mildew messenger RNA. It is very specific to only recognize powdery mildew,” says Wildermuth.
“We designed things to be very specific to the target, stick to it, and not harm other beneficial insects or microbes, just the target gene that we’re trying to kill.” RNA is a natural part of the environment and is easily degraded.
“We are still in the process of deciding on the final formulation to be launched,” Taneja said, noting that the registration process with the EPA will require further large-scale testing in a variety of environmental conditions. Tests have already been conducted in vineyards in Fresno and Yolo counties.
Because it is organic technology, it is beneficial to the environment. From a cost perspective, “right now it’s similar to chemical fungicides that are applied every 10 to 14 days, but we expect costs to continue to come down while allowing longer intervals between applications,” Wildermuth said.
“I suspect growers would start with a few rounds of copper sulphate combos before relying more heavily on this technology. I see our process as complementary to other technologies, although there is potential for a full replacement for the way things are done today, possibly a full biological replacement for chemicals as double-stranded RNA is a naturally organic sustainable product. ”
Which would lead to the question of whether or not this technology could kill powdery mildew? “It will definitely control it, but biologically, the end of something is hard to predict,” she said. “Our field testing has shown that it is definitely an effective form of control.”