This article appears in the September 2017 issue of Potato Grower.
Brian Zens fully expected to have a Texas-sized, late blight rumble on his hands during the 2016 potato-growing season. Instead, armed with Syngenta’s Orondis Opti fungicide, his advance preparation led to 100 percent prevention.
“Given the weather patterns we saw in 2016, I would’ve bet money that we would’ve picked up late blight,” says Zens, who is the director of agronomy for CSS Farms and helps oversee 4,000 acres of chip potatoes near Dalhart, Texas. “But we stuck to our program and relied on Orondis Opti. We never saw late blight in the field.”
Dynamic Duo
New to the retail market in 2016, Orondis Opti combines two fungicides, Orondis and Bravo, into a double-barreled disease fighter that beats back late blight in potatoes and downy mildew in cucurbit vegetables. Offered as a multipack during its first year of use, Orondis Opti is now available as a pre-mix formulation, starting with the 2017 season.
“It combines the best of both in one mixture,” says Kiran Shetty, technical development lead at Syngenta, North America. The latest active ingredient from Syngenta, Orondis’ oxathiapiprolin, makes for a dynamic pairing with Bravo’s chlorothalonil, a trusted performer. “Orondis fits into an already established program.”
Oxathiapiprolin has a novel, single-site mode of action and is the only fungicide active ingredient in Fungicide Resistance Action Committee (FRAC) Group 49. Chlorothalonil is a multi-site inhibitor with low resistance risk.
“They work extremely well in concert,” Shetty says.
A Step Ahead
Although he battles a host of diseases at farms in different states, Zens had never encountered late blight in his Dalhart fields. CSS Farms had grown potatoes in the area for about 15 years and, due to the fields’ relative isolation, had managed to avoid late blight the entire time. That environment began to change in recent years, as newer farms set up shop nearby.
In 2015, a neighboring potato farm attracted seed-borne late blight. The disease also brushed the CSS crop, so Zens figured he would need additional protection in 2016. As the season rolled into production, Zens decided to trust Orondis Opti.
“We did two applications of Orondis at the lower recommended rate,” Zens says, as part of a broader late-blight program. “We never picked up any disease in-season, despite heavy pressure.”
Wilson Faircloth, a Syngenta agronomic service representative based in Leesburg, Ga., credits much of the product’s success to oxathiapiprolin’s mode of action. He likens the concept to a human who takes the same antibiotics over and over again. Eventually, without new ways to tackle the problem, the medicine will become ineffective.
“New modes of action are critically important when fighting diseases,” says Faircloth, who works with growers who depend on healthy crops of cucumbers, peppers and squash to make a living. “It was obvious from the start how powerful Orondis was.”
The Perfect Fit
Orondis Opti is designed for use in no more than one-third of the total applications in an overall spray program. For potatoes, applications may begin when the plants are 12 to 15 inches tall. Subsequent sprays can be made at row closure and again several weeks prior to harvest.
With cucurbits, sprays can begin 10 to 14 days after transplant. In direct-seeded plants, Orondis Opti may be applied when two true leaves appear. Additional applications can be made one to two weeks later.
Orondis Opti fits into a broad-based program of other products for tackling late blight, including Bravo Weather Stik, Revus Top and Omega fungicides.
“Last year, our first line of defense was Orondis Opti,” Zens says. “We were so impressed that we’re going with the same program in 2017.”