Weed Control

NOTE:  For the herbicides listed below, one product trade name and formulation is provided for each active ingredient along with preharvest interval (PHI), restricted entry interval (REI), resistance management group number, and example of rates and special instructions. In many cases, there are other products available with the same active ingredient. However, not all products with the same active ingredient are registered for use in a crop. Always check the product label to be sure that the crop is listed before using. 

Stale Seedbed

See Stale Seedbed Technique in the Weed Management section.

glyphosate (Roundup Power Max): REI 12h, Group 9.

paraquat (Gramoxone SL 2.0*): restricted use. REI 12h, Group 22. Use 2 – 4 pts/A. 

pelargonic acid (Scythe): PHI 1d, REI 12h, Group 17. Use a 3 -10% solution (3 to 10 gallons per 100 gallons).

Garlic is not very competitive, so good weed control is critical. Mulch will control weeds and conserve moisture.  If the mulch is removed, cultivation will likely be needed.  It should be shallow so as not to damage roots. 

Herbicides Used Preemergence to Weeds   

bensulide (Prefar 4E): REI 12h, Group 8.  Apply 5 to 6 qt/A.  Can be preplant incorporated by shallow cultivation (1-2”) or applied preemergence and incorporated by irrigation within 36 hours of application. Grass control only; should be supplemented with cultivation or another registered herbicide for broadleaf control. See label for rotation restrictions.

dimethenamid (Outlook): PHI 30d, REI 12h, Group 15.  This herbicide is a root and shoot growth inhibitor that controls susceptible germinating seedlings before or soon after they emerge from the soil. Do not apply until garlic has reached the 2 true-leaf stage or significant crop injury can occur. May be applied as a single application (up to 21 oz/A) or used in split applications.  For split applications do not exceed a total of 21 oz/A per season. An initial application of 10 to 14 oz/A can be followed by another application of the remaining 7 to 11 oz/A.  Applications must be a minimum of 14 days apart. Application rates are influenced by soil organic matter content. See label for info on application rates depending on soil type and organic matter content. See label for info on tank mixing with other herbicides.

flumioxazin (Chateau SW)REI 12h, Group 14.   Apply up to 6 oz/A with 3 days of planting garlic and before garlic has emerged.  Must be sprinkler or rainfall incorporated (0.5 – 0.75” of water) for preemergence weed control.  Will control many broadleaf weeds and some grass species. 

s-metolachlor (Dual Magnum): REI 12h, Group 15.  MASSACHUSETTS AND NEW HAMPSHIRE ONLY. This is a restricted label available only to those Massachusetts and New Hampshire growers who register through the website www.farmassist.com and agree to a waiver of liability.  Main target weeds for this registration are galinsoga and yellow nutsedge. All label instructions will be supplied after the application for use is completed. Once on the farm assist web site, click products at top left, then indemnified labels.  Create a username and password, select Dual Magnum, and the crop.

pendimethalin (Prowl H2O): PHI 45d, 24 hr REI, Group 3. Apply 1.5 to 3.2 pt/A.  Select rate based on soil texture.  See label for detail.  Can be used preemergence after planting but before crop emergence, after crop emergence when garlic is in the 1 to 5 true leaf stage, or at both timings. Emerged weeds will not be controlled.

Herbicides Used Postemergence to Weeds

carfentrazone (Aim EC): REI 12h, Group 14.  Aim is a burndown herbicide and will injure any foliage it comes into contact with. Apply Aim to row middles of emerged crops with hooded sprayers to control emerged weeds, including crops grown on mulch or plastic.  Prevent any spray from contacting the crop, or injury will occur.  For best results, make application to actively growing weeds up to 4 inches tall and rosettes less than 3 inches across. Good coverage is essential for good control.  Apply up to 2 oz/A per application, and do not exceed a total of 6.1 oz/ per season. 

clethodim (Select Max)PHI 45d, 24hr REI, Group 1.  Will control grass weeds only. Apply to actively growing grasses.  See label for rate selection.  Multiple applications permitted of 9 to 32 oz/A per application, minimum 14-days between applications, not to exceed 64 oz/A per year.  Add 0.25% v:v nonionic surfactant (1 qt per 100 gal of spray).  Can also be used as a spot-spray by mixing 1/3-2/3% (0.44 to 0.85 oz per gallon) Select Max and 0.25% v:v nonionic surfactant (0.33 oz per gallon).  Spray to wet, but do not allow runoff of spray solution.

fluazifop (Fusilade DX): PHI 45d, REI 12h, Group 1.  For grass weed control only. Apply 6 to 16 oz/A.  See label to select rate based on grasses targeted for control. Allow for minimum 14-days between applications, and not to exceed 48 oz/A per year.  Apply to actively growing grasses (see product label for susceptible stage). Add either crop oil concentrate (0.5-1%, 0.5-1 gallon per 100 gallons of spray) or nonionic surfactant (0.25-0.5%, 1-2 qt per 100 gal of spray).

oxyfluorfen (Goal 2 XL): PHI 60d, REI 48h, Group 1. Provides early postemergence and residual control of many broadleaf weed species. For direct seeded garlic, apply 2 to 4 oz/A to garlic that has at least 3 fully developed true leaves. For transplanted garlic, apply 2 to 4 oz/A to garlic transplants as soon as possible after transplanting. Multiple treatments may be applied up to a maximum of 32 fl oz per acre preseason. For optimum postemergence control, apply when susceptible weeds are in the 2 to 4 leaf stage and actively growing. Application to weeds at later than 4 leaf growth stage may result in reduced weed control. Adjust nozzles for minimum spray contact with garlic plants, directing the spray to the soil at the base of garlic plants and adjacent bed top and furrow area.  Do not tank mix or add adjuvants unless directed to do so on Dow supplemental labeling.

pelargonic acid (Scythe):  PHI 1d, REI 12h, Group 17. Use a 3 -10% solution (3 to 10 gallons per 100 gallons). Use a 3 to 5% solution for annual weeds, a 5 to 7% solution for biennial and perennial weeds, and 7 to 10% solution for maximum burndown. Delivery rate for boom applications should be 75 to 200 gals of spray solution per acre; complete coverage of weed foliage is essential. Use a DIRECTED/ SHIELDED SPRAY; contact with crop will cause injury. For hand-held equipment, spray to completely wet all weed foliage but not to the point of runoff. Repeat applications as necessary. Tank mixes are allowed with this product. See label for complete details.

sethoxydim (Poast): PHI 30d, REI 12h, Group 1.  Controls grass weeds only.  Apply to actively growing grasses (see product label for susceptible stage).  Maximum 1.5 pt/A per application, minimum 14-days between applications.  Do not exceed 4.5 pt/A per year. Use with crop oil concentrate (2.0 pt/A) or methylated seed oil (1.5 pt/A).  Note that crop oil can cause injury under hot and humid conditions.  Can also be used as a spot-spray by mixing 1-1.5% (1.3 to 1.9 oz per gallon) Poast and 1% v:v crop oil concentrate (1.3 oz per gallon).  Spray to wet, but do not allow runoff of spray solution.