Incredibly effective against sheath blight, Quadris has “fundamentally changed” the way fungicides are used on Arkansas rice, says Rick Cartwright.
“Quadris has become the standard for sheath blight fungicides in the South. Every company that comes up with a new product has to compare them to Quadris,” says Cartwright, Arkansas Extension plant pathologist.
Quadris also has good staying power. It's a product that producers can count on to suppress sheath blight for a set period of time.
“It's different from the fungicides that preceded it for that reason. You can use a lower rate of it without affecting control — control will still be achieved, just for a shorter time period. That means we've been able to use it as a prescription product.”
Cartwright says using Quadris is kind of like visiting the doctor's office.
“You go in and, depending on your symptoms, get a dose of medicine. We can do that with a sheath blight-affected field. By knowing the field's history and checking how bad the disease is, you can make a Quadris prescription. Knowing how effective it is — a rate range — and how long the product will last out in the field means Quadris use can be tailored to specific circumstances. That eliminates waste and expense. Prior to Quadris, when using the old fungicides, we used a one-rate-fits-all approach.”
In Arkansas, producers tend to use 9 ounces per acre as an average. In more severely affected fields, they'll use 10 to 12 ounces.
“Nine ounces fits the crop normally grown in the state — taller varieties and well-managed Cocodrie (which isn't as susceptible as some of the other semidwarfs).
“With the 9-ounce rate we like to wait to treat until the rice is in the boot stage. That's another difference from the old days. We wait a little longer because sheath blight isn't quite as aggressive in these fields. We try and keep the upper foliage clean instead of going with a more preventative approach.”
Some growers, on their better fields, shoot for maximum yields and so, at a certain growth stage, they treat automatically with Quadris. That might happen on 10 percent of the state's acreage.
Another group of farmers — perhaps 20 percent — scout heavily and use more of an IPM (Integrated Pest Management) approach, says Cartwright.
“They make decisions to treat based on what's out there. So, we're probably treating at least 30 percent of our rice (that equates to about 400,000 to 450,000 acres) with Quadris or a related compound.”
Research ears ago by Cartwright and colleagues showed how Quadris “holds on.” Twelve ounces will work for 28 to 35 days. Nine ounces will hold for 21 to 24 days. And 6 to 7 ounces will hold for 14 to 17 days. Producers now know the rates and corresponding “hold” dates and act accordingly.
“For instance, if it's getting late in the season, they may not need 28 days of control, so they'll go with 6 ounces. Quadris is a product that you can get comfortable with fairly quickly.”
In terms of ranking this product for the rice crop, there's little doubt Quadris is the most important fungicide producers have at their disposal, says Cartwright. The newer products, while effective, don't hold the same level of comfort in farmers' collective psyche as Quadris.
“Blast is another disease we treat with Quadris — mostly as a preventative. Quadris and Gem, another product, are becoming more important as more of the new rice varieties — Wells, Francis — are proving to be blast-susceptible.”
Quadris has weaknesses, though. “It isn't very effective on the smuts and those have become more persistently problematic in the northeast and north-central parts of Arkansas.
“The most popular tank mix of fungicides in the state has become 9 ounces of Quadris and 4 to 6 ounces of Tilt. If that is sprayed at the booting stage, you not only get sheath blight control but also kernel smut prevention.” The new rice varieties — Cocodrie, Francis, and some of the Clearfield varieties — are “pretty susceptible” to smut, so putting Quadris and Tilt out is a common practice. That combination is especially popular among seed growers.
“There's also a new product, Stratego, that mixes sheath blight material with Tilt. Some producers are giving that a shot,” says Cartwright.