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Carrot Weed Control 2007

Carrot Country
Summer 2007

What kinds of herbicide products can be used effectively to control weeds in carrot?

Bernard Zandstra, a professor and weed specialist with the Department of Horticulture at Michigan State University (MSU), updated growers Feb. 15 during the Empire State Fruit and Vegetable Expo carrot session.

“Lorox is effective preemergence and postemergence on carrot for most grasses and broadleaves,” the researcher said. “Other herbicides labeled for carrot include Dual Magnum and Trefl an preemergence and Sencor postemergence. The postemergence grass herbicides Fusilade, Poast, Select and Roundup also are registered.”

Other Herbicides Coming
Several additional herbicides are in process of being registered for use in carrot fields, Zandstra said. Oxyfl uorfen (Goal) has fair to good selectivity postemergence on carrot and would improve control of common purslane, herbicide resistant pigweeds, common groundsel, marestail and ragweed.

“The new formulation of oxyfl uorfen (GoalTender) should improve crop safety for use on carrot,” he said. “Goal for carrot is an IR4 project, and we are waiting for company (Dow) approval to proceed with residue trials.”

Nortron recently received a carrot tolerance and will be registered for use on carrot in Washington and Oregon, he said, expressing hope that the label will be expanded in the near future to include the eastern United States. Nortron has postemergence activity on yellow nutsedge, common chickweed, mustards and

Another product coming down the pike is Caparol (prometryn), being registered on carrot through IR4; a label is expected in 2007. Caparol is similar in activity to Lorox and has the same mode of action (photosystem II inhibitor). It causes slightly more crop stunting than Lorox when applied pre or postemergence, Zandstra
explained. Its primary use will be as a substitute for linuron, where its use is restricted, or if an additional postemergence application is needed. On the down side, weeds resistant to linuron also are usually resistant to Caparol.

Command and Prowl herbicides are also being considered for use in carrot. Command 3ME has been submitted to IR4, Zandstra said. Canada is working on a registration. Its use would be for PRE control of annual grasses and some broadleaves. One concern is its moderate phytotoxicity under some conditions; however, carrots grow out of it. If this product moves forward, FMC will have to support the label, he said.

Prowl H2O 3.8 CS has tolerance and could be labeled in 2007, the researcher predicted. It is used for PRE control of annual grasses and prostrate spurge. It could be a substitute for Lorox PRE. One drawback is that it provides no control of ragweed.

“The Dual Magnum Section 24c (SLN) label for New York has been expanded to include carrot,” the speaker said. “Growers need to indemnify the company from any liability resulting from this use. To agree to the indemnification language and obtain a copy of the label, growers need to access the Syngenta website at www.farmassist.com.

After registering and signing in, click on PRODUCTS, then SPECIAL LABELS, then INDEMNIFIED LABELS. Then you will be able to select the state and print the Dual Magnum label.” Dual Magnum may be used on carrots on any soil type, Zandstra pointed out. Previously, its use was limited to high organic soils.

Muck Soil Recommendations
The following are the researcher’s recommendations for carrot weed control on muck soil:
1. Plant barley one week before planting carrots.
2. Lorox 0.5-1 lb product + Dual magnum 1.3 pt. PRE 1-2 weeks after seeding carrots.
3. Kill barley with Fusilade or Poast at 4-5 inches.
4. Lorox, 1-2 lb product, to kill emerged weeds at carrot 2-4 leaf stage.
5. Sencor 0.3 lb product, if needed, at 5-6 leaf stage
6. Poast, Fusilade or Select Max to kill emerged grasses.

Mineral Soil Recommendations
Zandstra’s recommendations for carrot weed control on mineral soil:
1. Plant barley one week before carrot.
2. Lorox 0.5 lb product + Dual Magnum 0.5 pt 1-2 weeks after seeding carrot.
3. Fusilade or Poast to kill barley at 4-5 inches.
4. Lorox 0.5 lb at carrot 2-3 leaf stage.
5. Sencor 0.3 lb at 5-6 leaf stage.
6. Poast, Fusilade or Select Max, as needed, for grass control.

© 2007 Columbia Publishing