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Publication #HS189

Weed Control in Cole or Brassica Leafy Vegetables (Broccoli, Cabbage, Cauliflower, Collard, Mustard, Turnip, Kale)1

Peter J. Dittmar and William M. Stall2

The Brassica leafy vegetables (cole crops) range from major crops such as cabbage to very minor ones, including mustard and rape greens. Optimal production of these crops depends on successful weed control. Weeds reduce yields by direct competition for nutrients, water, and light. Weed control is especially important early in the season when weed competition can substantially reduce vigor, uniformity, and overall yield. In Florida, there are a large number of weeds that are also in the Brassicaceae (mustard) family. These weeds in and around the field can breed and harbor insects and disease pathogens that can invade or spread to the crop soon after planting.

Management Practices

Effective weed control should include a combination of management practices designed to suppress weeds during the entire year. These practices include crop rotation, cover cropping, high planting density, mulching, cultivation, flooding, and herbicide use. The amount and timing of cultivation has been shown to be very important. Cultivating more than one or two times early in the season reduces head quality and yield in cabbage.

The most effective weed management strategies must be made long before the crop is planted.

Planting Dates

Planting dates can have an impact in a given region. Hard-to-control winter or summer annuals may be present in a field, dictating planting the crop when the specific weed or weeds are not growing. Cabbage is much more competitive against weeds when grown under optimal conditions. During the warmer part of the spring and fall seasons, wild radish will not reduce yields of cabbage up to 16 wild radish plants/meter of row. During the cooler part of the season, one wild radish plant will reduce yield significantly.

Perennial weeds such as nutsedge should be controlled during noncrop periods. Detailed weed maps made during several seasons will help with decisions about when to plant and which herbicides are the most effective.

For example, if one is growing cabbage from transplants and wishes to use either Dual or Goal® for specific weed problems, the grower must plan on having at least 5-week-old transplants in 1-inch cells. Use of younger transplants in smaller cells may result in phytotoxicity to the young plants.

Labels and Crop Groups

The labels for Dual on cabbage are third-party registrations by TPR, Inc., Orlando. The label is issued by TPR, Inc. and is valid only when a grower indemnification agreement is signed.

The term "Brassica (cole) leafy vegetables" refers to a crop group set up by the EPA to allow tolerances to be established for the whole crop group. The group is separated into two subgroups: head and stem Brassica and leafy Brassica greens. The head and stem Brassica subgroup includes broccoli, Chinese broccoli, Brussels sprouts, cabbage, Chinese cabbage (napa), Chinese mustard cabbage, cauliflower, cavalo broccoli, and kohlrabi. The leafy Brassica greens subgroup includes broccoli raab, Chinese cabbage (bok choy and chilhilli), collards, kale, mizuna greens, mustard, spinach, rape greens, and turnip greens. If the total crop group is not stated, then the product may only be used for those commodities listed on the label.

If a label states directions for cabbage, then it may only be used on cabbage; if it states cabbage and tight-headed Chinese cabbage, it may also be applied to the napa types of Chinese cabbage. The chilhilli types are classified as loose headed, as is bok choy.

Table 1 lists the herbicides that are suggested for use on the various crops before crop seed emergence or transplanting in Florida. Table 2 includes chemical weed control that can be used after crop seed emergence or after transplanting. Before using an herbicide, read the label carefully and follow all directions and restrictions.

Tables

Table 1. 

Preemergence or pretranslplant chemical weed control in cole crops

Common name

lb. a.i./A

(Trade name)

amount of product/A

Crops

Weeds controlled / remarks

Bensulide

5–6

(Prefar®) 4E

5–6 qt.

Head and stem and leafy Brassica

Annual broadleaf and grass weeds. Fair to poor control of lambsquarter, purslane, and some amaranth. Mechanically incorporate 1–2 in. or irrigate 2–4 in. deep within 36 hours.

Carfentrazone

Up to 0.031

(Aim®) 2 EC

(Aim®) 1.9 EW

Up to 2 fl. oz.

Head and stem and leafy Brassica

Emerged broadleaf weeds. Use as a chemical fallow treatment and preplant burndown application. Include a nonionic surfactant or crop oil concentrate.

DCPA

4.5–10.5

(Dacthal®) 75 WP

6–14 lb.

Broccoli, Brussels sprouts, cauliflower, cabbage, and leafy Brassica vegetables

Annual grass and broadleaf weeds. Can be preplant incorporated. If weeds have emerged, they must be cultivated or weeded before application.

Glyphosate

0.3–1.0

(Various formulations)

Head and stem and leafy Brassica vegetables

Actively growing broadleaf and grass weeds. Use as a preplant burndown.

S-metolachlor

Mineral

0.64–1.91

Muck

1.91

(Dual Magnum®) 7.62 EC

Mineral

0.67–2.0 pt.

Muck

2.0 pt.

Head and stem Brassica

Annual broadleaf and grass control. Apply immediately after planting. Label is a third-party registration by TPR, Inc., and grower must sign an indemnification agreement. Use higher rate on fine-textured soils or soils high in organic matter. Do not apply more than 1.91 lb. a.i./A of Dual Magnum® per crop on sandy soils. Chinese varieties are more sensitive to Dual Magnum® injury. PHI 60 days.

S-metolachlor

Mineral

0.76–1.26

Muck

1.91–3.82

(Dual Magnum®) 7.62 EC

Mineral

0.80–4.0 pt.

Muck

1.82–3.64 pt.

Direct-seeded cabbage

Annual broadleaf and grass weeds. Label is a third-party registration by TPR, Inc., and grower must sign an indemnification agreement. May be applied preemergence or postemergence to direct-seeded tight-headed cabbage. Preemergence application should be made at least 20 days after seeding. Apply once per crop season. At higher rates, anticipate delayed maturity.

Oxyfluorfen

0.25–0.5

(Goal® 2XL) 2 EC

1–2 pt.

(Galigan®) 2 E

1–2 pt.

(GoalTender®, Galigan® H2O) 4 E

0.5–1 pt.

Broccoli, cabbage, cauliflower

Certain annual broadleaf weeds. Transplants less than 5 weeks old or in containers less than 1 inch square may result in more crop injury. Injury occurs as leaf cupping or crinkling. DO NOT apply in fields where acetanilide herbicides (Dual Magnum®, Lasso®, or Ramrod®) have been applied in the same growing season.

Paraquat

0.5–1.0

(Gramoxone® SL) 2.0 SL

2.0–4.0 pt.

(Firestorm®) 3.0 SL

1.3–2.7 pt.

Broccoli, cabbage, cauliflower, cavalo broccoli, Chinese cabbage, turnip

Emerged broadleaf and grass weeds. Use as a preplant burndown. Crop plants that have emerged will be injured.

Pelargonic acid

(Scythe®) 4.2 EC

3%–10% v/v

Broccoli, cabbage, cauliflower, collards, kale, mustard/turnip greens

Emerged broadleaf and grass weeds. Use as a preplant burndown.

Trifluralin

0.5–0.75

(Treflan® HFP, Trifluralin, Trifluralin HF) 4 EC

1.0–1.5 pt.

(Treflan®) 4 L

1.0–1.5 pt.

Broccoli, Brussels sprouts, cabbage, cauliflower

Annual broadleaf and grass weeds. Incorporate or irrigate 4 inches within 8 hours. Results in Florida are erratic on soils with low organic matter and clay content.

Table 2. 

Postemergence or posttransplant chemical weed control in cole crops

Common name

lb. a.i./A

(Trade name)

amount of product/A

Crops

Weeds controlled / remarks

Carfentrazone

Up to 0.031

(Aim®) 2.0 EC

(Aim®) 1.9 EW

Up to 2 fl. oz.

Head and stem and leafy Brassica

Emerged broadleaf weeds. Apply with a hooded sprayer to row middles. Do not exceed 4.1 fl. oz./A in season as a row middle application. PHI 0 days.

Clethodim

0.09–0.13

(Select®) 2 EC

6–8 fl. oz.

(Select Max®) 1 EC

9–16 fl. oz.

Head and stem and leafy Brassica

Emerged grass weeds. Include crop oil concentrate at 1% v/v in finished spray volume. Head and stem Brassica PHI 30 days. Leafy Brassica PHI 14 days.

Clopyralid

0.09–0.19

(Stinger®) 3 EC

0.25–0.5 pt.

Cabbage, Chinese cabbage (bok choy, napa), Chinese mustard cabbage

Broadleaf weeds. Do not apply more than 0.5 pt./A per year. Check plant-back dates. PHI 30 days.

DCPA

4.5–10.5

(Dacthal®) 75 WP

6–14 lb.

Broccoli, Brussels sprouts, cauliflower, cabbage, and Brassica leafy vegetables

Broadleaf and grass weeds. Spray over transplants without injury. If weeds have emerged, they must be cultivated or weeded before application. Can be preplant incorporated.

Glyphosate

0.3–1.0

(Various formulations)

Head and stem and leafy Brassica

Broadleaf and grass weeds. Use a hooded sprayer and direct to row middles only.

Napropamide

2

(Devrinol®) 50 DF

4 lb.

Broccoli, Brussels sprouts, cabbage, cauliflower

Apply to transplanted crops only. Within 24 hours of application, 2–4 inches of irrigation or rainfall are necessary. Do not exceed 4 lb./A per crop cycle.

Paraquat

0.3–0.5

(Gramoxone® SL) 2 SL

1.2–1.9 pt.

Cabbage

Emerged broadleaf and grass weeds. Direct spray solutions to row middles only. Do not allow spray to contact crop as injury or excessive residues may result. Outer leaves should be stripped at the time of harvest. Do not apply where paraquat products have been used as preplant application.

Pelargonic acid

(Scythe®) 4.2 EC

3%–10% v/v

Broccoli, cabbage, cauliflower, collards, kale, mustard/turnip greens

Emerged broadleaf and grass weeds. Apply as hooded spray to row middles only. Include a residual herbicide to broaden spectrum of weed control.

Sethoxydim

0.28

(Poast®) 1.5 EC

1.5 pt.

Broccoli (including Chinese and raab), Brussels sprouts, cabbage (bok choy, Chinese mustard, napa), cauliflower, collards, kale, kohlrabi, mustard / rape greens

Annual and perennial weeds. Include a crop oil concentrate or methylated seed oil in spray solution. Maximum rate or 3.0 pt./A per season. PHI 30 days.

Footnotes

1.

This document is HS189, one of a series of the Horticultural Sciences Department, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. Original publication date October 2000. Revised August 2012. Visit the EDIS website at http://edis.ifas.ufl.edu.

2.

Peter J. Dittmar, assistant professor, and William M. Stall, emeritus professor, Horticultural Sciences Department, Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL 32611.

The use of trade names in this publication is solely for the purpose of providing specific information. UF/IFAS does not guarantee or warranty the products named, and references to them in this publication do not signify our approval to the exclusion of other products of suitable composition. All chemicals should be used in accordance with directions on the manufacturer's label. Use pesticides safely. Read and follow directions on the manufacturer's label.


The Institute of Food and Agricultural Sciences (IFAS) is an Equal Opportunity Institution authorized to provide research, educational information and other services only to individuals and institutions that function with non-discrimination with respect to race, creed, color, religion, age, disability, sex, sexual orientation, marital status, national origin, political opinions or affiliations. For more information on obtaining other UF/IFAS Extension publications, contact your county's UF/IFAS Extension office.

U.S. Department of Agriculture, UF/IFAS Extension Service, University of Florida, IFAS, Florida A & M University Cooperative Extension Program, and Boards of County Commissioners Cooperating. Nick T. Place, dean for UF/IFAS Extension.