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. 

See section on Soil Fumigation. Proper use of Vapam can provide control of most weed species.

Stale Seedbed

See Stale Seedbed Technique in the Weed Management section. In place of herbicides, flaming can also be used.

carfentrazone (Aim EC): REI 12h, Group 14. Apply up to 2 oz/A per application, and do not exceed a total of 6.1 oz/ per season. 

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

paraquat (Gramoxone SL 2.0*): restricted use. REI 12h, Group 22. Use 2 – 4 pts/A.  Preplant or stale seedbed application. See Stale Seedbed Technique in the Weed Management section.

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

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. Mainly annual grass control, and should be supplemented with cultivation or another registered herbicide for broadleaf control. See label for rotation restrictions.

pronamide (Kerb SC): PHI 25 to 55d (based on rate used), 24 hr REI, Group 3. Must be applied prior to weed emergence.  Can be applied either pre-plant, post-plant, or postemergence to head or leaf lettuce, endive, escarole or radicchio greens in banded, bed-topped or broadcast applications.  It is necessary to move Kerb into the root zone of germinating weeds to provide effective control (by overhead sprinkler irrigation, by rainfall, or by shallow mechanical incorporation).  See label for rotation restrictions.

The rate required is dependent on soil texture, target weeds, and method of irrigation/incorporation. Read label carefully to select the proper rate based on your farm conditions.  Apply 2.5 to 5.0 pts/A per acre for head lettuce, endive, escarole, and radicchio greens.  Apply 1.25 to 5.0 pts/A per acre for leaf lettuce.  Up to two applications are permitted and must be separated by at least 10 days.  Total product applied must not exceed 5.0 pts/A.

trifluralin (Treflan HFP): REI 12h, Group 3. Endive and escarole only. Apply 1 to 2 pts/A as a soil-incorporated treatment in spring or early summer prior to planting. Rate based on soil texture and crop, see label for details. Must be incorporated into the top 2 to 3 inches of the final seedbed within 24 hours of application.  Disc twice after spraying for satisfactory incorporation. See label for info on incorporation recommendations based on different equipment and single pass incorporation.

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 14d, 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 16 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.

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 head lettuce; PHI 15d for leaf lettuce, escarole, and endive, 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 3 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.