BURLEY, Idaho (AP)—Weeds, bugs and diseases were on the minds of sugarbeet growers, as they gathered for the annual University of Idaho Snake River Sugarbeet Conference. But rather than thinking solely about eliminating those pests, growers are increasingly looking for more sustainable alternatives for control.
This move toward sustainability is being driven by several factors. One is that major agricultural companies, along with manufacturers and retailers, have pledged to reach company-specific sustainability goals by 2020, largely in response to consumer demand.
Sugarbeet growers are also looking for ways to reduce costs and stretch out the effectiveness of key pesticides.
SUSTAINABILITY IN PEST CONTROL
Roundup Ready sugarbeet seed allowed growers to cheaply and effectively control weeds when the technology was first introduced in 2008. But the technology was so effective that growers quickly adopted it, and now they are starting to see the ramifications.
University of Idaho weed specialists, along with their counterparts in Oregon and Montana, confirmed glyphosate-resistant kochia in Canyon County and Malheur County, Oregon, in July. Glyphosate is the chemical name of the active ingredient in Roundup.
Don Morishita, a U of I extension weed specialist at Kimberly, said glyphosate-resistant Russian thistle is also suspected in Canyon County, and there are reports of glyphosate-resistant lambsquarters in Lincoln County. Testing of suspect plants is required before a weed species is confirmed resistant.
Morishita has warned growers to be careful about overreliance on glyphosate for several years, as the list of resistant weeds in the Midwest continued to grow. At least 14 weeds in 28 states have confirmed glyphosate resistance, and that was before glyphosate-resistant kochia was found in Idaho.
Herbicide resistance is nothing new; it was first documented in the U.S. in a Hawaiian sugarcane field in the late 1950s. But it is a particular concern for sugar beet growers because of the limited number of herbicide options available to them.
Herbicide companies develop products primarily for the corn and soybean market, along with rice and wheat, and then determine if the products can be used in minor crops like sugar beets. For every one herbicide available for use in beets, there are 10 options for corn growers.
No new herbicide chemistry has been developed for the last 20 years, and although companies are gearing up research in that area, Morishita doesn’t expect to see new products with new modes of action for sugarbeets for many years. If growers aren’t careful, they will be back to hoeing beet fields, and it was the scarcity of hoeing crews that helped push them toward Roundup Ready beets in the first place.
He recommended that growers save Roundup for their sugarbeet crop and use other herbicides on the remaining crops in their rotation. Growers also need to scout their fields for weeds that are not controlled by herbicides, and to mechanically remove those plants so they don’t set seed.
Morishita recommends contacting a fieldman or U of I extension educator to collect plant samples if herbicide resistance is suspected.
Cultural control is also critical for controlling several insect pests, including sugar beet root aphids and wireworm. Stretching out the crop rotation to at least four years will help reduce many potential insect and disease problems. Planting oil seed radish as a cover crop before beets may also help reduce nematode populations and boost soil organic matter.
U of I researchers are studying the interactions of tillage, irrigation management and fertilizer on sugar beet production.
One study evaluated three different tillage systems—conventional, strip till and direct seed—overlaid by three different irrigation management strategies—50, 100 and 150 percent of crop water use—and four different nitrogen fertilizer rates—50, 75, 100 and 125 percent of U of I recommended rates. Production, weeds and insects were all monitored in the two-year study.
Researchers found that tillage costs were highest in the conventional tillage system at $136 per acre, compared to $71 per acre for strip till and $33 per acre for direct seed.
While the conventional and strip tillage plots yielded higher than the direct seed in 2013—largely due to better stand counts—the differences between the three tillage methods was minimal in 2014. U of I used a Monosem planter for conservation systems and Yetter trash managers for the direct seed plots.
“That’s kind of comforting,” said Howard Neibling, a U of I extension irrigation specialist at Kimberly. “You’re not giving up a lot with strip till and maybe just a little with direct seed if you want to manage towards sustainability.”
Kelli Belmont, a research assistant who worked on the project, said weed counts in 2013 indicated that the best weed control was achieved when plots were fertilized at 100 percent of the recommended nitrogen rate regardless of what irrigation management strategy was used. Overall, the conventional tillage plots had more weeds and also more leafminer eggs and larvae than either of the reduced tillage treatments.
“It doesn’t seem to take much special irrigation or weed or fertility management to make strip till or direct seed work,” Neibling said.
Source: www.heraldandnews.com/