Weed Control in Carrots1
Although carrots may be grown on mineral soils, production in Florida is almost exclusively on the organic soils of central and south Florida. The practice of seeding the crop in six lines per bed enhances total yield that may be harvested per acre, but almost eliminates the use of mechanical cultivation for weed control.
Control of weeds is extremely important in several aspects. Weeds reduce yields of carrots by reducing the size of carrot roots by direct competition for nutrients, space, and water. Weeds also cause carrot roots to be deformed and therefore unmarketable. Weeds late in the season may also cause severe harvesting problems.
Weed control is critical early in the season for the formation of good straight roots, but is important for the above reasons throughout the growing season.
At the present time only linuron is labeled for preemergence (both carrots and weeds) application on muck soils and linuron and trifluralin on mineral soils.
Linuron, and metribuzin may be applied over the top of carrots to control small broadleaf weeds. Great care should be taken to apply these herbicides at the correct rate and at the correct growth stage of the crop and weeds (see Table 1). Carefully read the labels for these directions.
Fusilade DX, Poast and Select are labeled for the control of emerged grass weeds. They may be applied several times during the growing season up until 45 days of harvest for Fusilade and 30 days of harvest for Poast and Select.
Read and follow all label directions for each herbicide used.
Tables
Chemical Weed controls: Carrots.
Herbicide |
Labeled crops |
Time of application to crops |
Rate (lbs. AI./Acre) |
|
Mineral |
Muck |
|||
Carfentrazone (Aim) |
Carrots |
Preplant Directed-hooded Row-middles |
0.031 |
0.031 |
Remarks: Aim may be applied as a preplant burndown treatment and/or as a post-directed hooded application to row middles for the burndown of emerged broadleaf weeds. May be tank mixed with other registered herbicides. May be applied at up to 2 oz (0.031 lb ai). Use a quality spray adjuvant such as crop oil concentrate (coc) or non-ionic surfactant at recommended rates. |
||||
Clethodim (Select) (Arrow) |
Carrot |
Postemergence |
0.1-0.125 |
---- |
Remarks: Use Select for the control of annual and perennial grasses. Use a crop-oil concentrate at 1% v/v in the finished spray volume. Do not apply more than 8 fl. oz. product/A per application. Do not apply within 30 days of harvest. |
||||
Fluazifop (Fusilade DX) |
Carrots |
Postemergence |
0.188 |
0.188 |
Remarks: Controls actively growing emerged annual and perennial grasses. Check the label for specified rates per grass species. Use a crop oil or non-ionic surfactant. Do not apply if rainfall is expected within 1 hour. Do not apply more than 0.75 lb ai/A per crop. Do not harvest carrots within 45 days of application. Withhold field flooding 45 to 60 days following application. In Palm Beach and Hendry counties a 60 day interval must be observed for flooding. |
||||
Glyphosate (Roundup, Durango, Touchdown, Glyphomax) |
Carrots |
Chemical fallow Preplant, pre emergence, Pre transplant |
0.3 - 1.0 |
---- |
Remarks: Roundup, Glyphomax and Touchdown have several formulations. Check the label of each for specific labeling directions. |
||||
Linuron (Lorox DF) |
Carrots |
Preemergence |
0.5 |
0.5 - 1.5 |
Remarks: Make a single application after planting but before carrots emerge. Plant seed at least 2 inches deep. Subsequent postemergence treatments may be made provided total does not exceed 4 pts./4lbs. material per acre per season. |
||||
Linuron (Lorox DF) |
Carrots |
Postemergence |
0.75 |
0.75 - 1.5 |
Remarks: Apply after carrots are at least 3 inches tall. Apply before annual grasses exceed 2 inches in height and before broadleaf weeds exceed 6 inches in height. Repeat applications may be made but do not exceed 4 pts./4 lbs. material per acre. Can be applied following Stoddard's Solvent provided that the applications are at least one day apart. Do not tank mix with Stoddard's Solvent, surfactants, nitrogen or fertilizer solutions. Do not apply when temperatures exceed 85°F as crop injury may result. |
||||
Metribuzin (Sencore DF) (Sencore 4) |
Carrots |
Postemergence |
0.25 |
0.25 |
Remarks: Apply as a broadcast spray over the tops of carrot plants. Application should be made after carrots have formed 5 to 6 true leaves but before weeds are 1 inch in height. If needed, a second application may be made after an interval of at least 3 weeks. Application may be made up to 60 days of harvest. Label through I-R-4 program. |
||||
Paraquat (Gramoxone Inteon) (Firestorm) |
Carrots |
Preplant; Preemergence |
0.5 - 1.0 |
0.5 - 1.0 |
Remarks: Product is a contact, non-selective, foliar applied herbicide. There is no residual control. May be tank mixed with soil residual compounds. Consult label for rates and other information. |
||||
Sethoxydim (Poast) |
Carrots |
Postemergence |
0.188-0.28 |
0.188-0.47 |
Remarks: Controls actively growing grass weeds. A maximum rate of 2.5 pints product may be made per application. A total of 5 pints product may be applied per season. There is a 30 day PHI (pre harvest interval). Consult label for rates for grass species and growth stages for best control. |
||||
Trifluralin Treflan EC, Treflan HFP, Treflan, Trilin) |
Carrots |
Preplant incorporate |
0.5 |
---- |
Remarks: Apply to mineral soils only. Mineral soils with 2-5% organic matter, apply 0.75 lb ai. |
||||
Footnotes
This document is HS-201, one of a series of the Horticultural Sciences Department, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. Last revision date: October, 2006. Please visit the EDIS Website at http://edis.ifas.ufl.edu.
William M. Stall, professor, Horticultural Sciences Department, Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, 32611.
The use of trade names in this publication is solely for the purpose of providing specific information. It is not a guarantee or warranty of the product named, and does not signify that they are approved to the exclusion of others of suitable composition.7.9.1
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contact your county Cooperative Extension service.
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University of Florida, IFAS, Florida A. & M. University Cooperative
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