Spraying wheat could pay off. Texas A&M-Commerce researchers monitoring relationships between fungicides, increased disease pressure, and doubled crop yields say studies support judicious use of fungicides.
“If a fungicide is properly timed and the disease is a present threat, a $2.50 return on every dollar spent is likely,” says Jim Swart, Extension integrated pest management specialist at Texas A&M-Commerce.
Swart has been working with wheat disease for more than 20 years.
In 1984, Swart and Don Reid, professor of agronomy, began doing applied research with foliar fungicides.
Swart says, “The two main diseases limiting high yields in wheat crops are leaf rust and stripe rust.”
Stripe rust was a particularly prominent threat in Northeast Texas this year. Some crops treated actually doubled in yield. Leaf rust posed less of a threat this season but, with fungicide applications, yield increase was still substantial, up 30 percent to 40 percent, says Swart.
Alton Norman, Howe, Texas, wheat producer, says the last two years fungicides increased yields, improved test weights, and strengthened wheat straw.
Norman sprays a split application of Quilt — 7 ounces early in the growing season and 7 ounces six weeks later — on susceptible varieties, Pioneer 25R78 and 2549, which tend to rust earlier than 2557. “One 14-ounce application of Quilt is adequate for 2557,” he says.
Larger spray tips
Norman recommends changing to larger spray tips and removing some strainers when applying Quilt. “We had a little difficulty with stopped-up tips and screens,” he says.
Timing also affects fungicide efficiency.
“You want to spray ahead of the disease, but if you're too early the material will not be around to protect the flag leaf during the critical grain filling period,” says Swart. He advises applying the treatment as late as possible in the growing season because a single fungicide application will only offer 25 days of leaf protection.
He and Reid have been experimenting with split applications of fungicides at reduced rates with good success. The fungicides studied in recent years include Quilt, Stratego, Headline, propiconazole (Tilt, Propimax), and Folicur. All these materials have provided good to excellent disease control and, except for Folicur, are labeled for wheat.
Fungicides appear to be a good investment. Swart says spending $14 per acre for fungicides to control leaf rust could increase returns as much as $35. Even greater returns are possible when fungicides are used to protect the crop from an early stripe rust infection.
“It's a judgment call on whether to use fungicides or not, but it looks like we'll have to spray every year now to help with quality,” says Norman.