Start clean, stay clean Regardless of the rice type grown, Feist said it’s always best to start clean and stay clean by applying a preplant residual herbicide, such as clomazone or pendimethalin. Because Highcard is a grass herbicide, he said growers will need to incorporate broadleaf products into their weed control program. The Highcard label allows for up to 15.5 fluid ounces per application and no more than 31 fluid ounces per season. Feist said researchers compared three 10-ounce applications to two 15-ounce applications and found two at the higher rates provided nearly complete control of grasses, including weedy rice. “We don’t want the red rice to escape and cross pollinate with the crop,” he said. The label also restricts use to two applications
spaced at least 10 days apart. As part of weed resistance management, Feist recommended against cutting Highcard rates, noting Max-Ace rice can withstand the higher labeled rates without crop response because of its strong genetic tolerance. Herbicide application timings The first Highcard application should be made when the rice is at the two- to three-leaf stage, with a second application made at least 10 days later and before panicle initiation. The actual timing depends on weed pressure. For best results, applications should be made on warm, sunny days when both the rice and weeds are actively growing. And weather for the preceding days is much more important than for the following days, Feist said. Application during cloudy or overcast days should be avoided when possible. As part of Max-Ace stewardship, growers must agree to make two Highcard applications. The stewardship agreement also recommends growers rotate to conventional rice, a different herbicide-traited rice — or better yet, a different crop entirely — the year following Max-Ace rice. Because Highcard does not carry over in the soil, growers are able to plant non-ACCase-tolerant rice varieties or hybrids the following year. Adama researchers continue to test the tankmix compatibility of Highcard and broadleaf herbicides. So far, quinclorac and Loyant appear to be suitable tankmix partners, he said. “I think we’re going to see a lot of quinclorac-type mixes be very popular. It’s going to have a good fit,” Feist said. “The others we’re still exploring. They’re not perfect mix partners, let’s put it that way.” Among the more antagonistic are phenoxies, which are rarely used on rice any more, and propanil, he said. PHOTO COURTESY ADAMA
blast resistance and comparable production to the highest yielding varieties on the market. “The Max-Ace Rice Cropping Solution is in high demand for its outstanding grass weed control with Highcard herbicide in rice, and RiceTec is doing all that we can to provide seed for our growers,” Pasqualli said. “Max-Ace will give an additional herbicide rotation partner to steward weed resistance in herbicide tolerant rice solutions.” RiceTec recommends planting RTv7231 MA at 800,000 to 900,000 seeds per acre, since it is a variety. The company recommends planting RT7331 MA at its standard hybrid seeding rate of 450,000 seeds per acre. With the early maturity of RTv7231 MA, it will be important to ensure harvesting at the optimal 18% to 20% grain moisture, which could be easily overlooked, he said. In field trials so far, the Max-Ace system has provided excellent yield performance, good disease resistance, and strong weed control and crop tolerance when paired with Highcard herbicide, Pasqualli said.
Postscript label changes Label changes to Postscript herbicide this year will offer greater rotational flexibility if growers want to plant MaxAce rice the season following FullPage rice, said Dave Feist, Adama product strategy manager for rice. In the past, labels for Preface and Postscript — Adama’s imidazolinone herbicides labeled exclusively for use on FullPage rice — contained 18-month plant-back restrictions for non-IMI rice cultivars. Concerns about herbicide carryover in the soil prompted the warning. But research has found the Postscript formulation does not pose the same risk. With the new label language, growers who use Postscript for both applications on FullPage rice one season can plant a non-IMI rice the following year. The label for Preface, which contains the active ingredient imazethapyr, still carries the 18-month plant-back restrictions for non-IMI rice. TWITTER: @RICEFARMING
With new label language, growers who use Postscript herbicide for both applications on FullPage rice one season can plant a nonIMI rice the following year. VICKY BOYD
MAY 2021
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RICE FARMING
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