NOTES: 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.
No-Till
Based on work done in New York State, it may be possible to achieve good weed suppression by allowing winter rye to grow to 30", killing it with glyphosate (Roundup), and then seeding the pumpkins or squash with a no-till planter. Remember that if weed suppression is not adequate, cultivation will be very difficult in the rye stubble. Any of the herbicides registered for postemergence control can be used in no-till pumpkins to control weeds not suppressed by the killed cover crop.
Stale Seedbed
Prepare field 10 to 14 days prior to planting. Allow weeds to germinate. After seeding, but prior to crop emergence, then apply herbicides or flaming. See Stale Seedbed Technique for information on the use of these herbicides or flaming.
- carfentrazone (Aim EC): PHI 0d, REI 12h, Group 14.
- glyphosate (Roundup Power Max): PHI 14d, REI 4h, Group 9.
- paraquat (Gramoxone SL 2.0*): restricted use. REI 12h or 24h, Group 22.
- pelargonic acid (Scythe): PHI 1d, REI 12h, Group 0.
Preemergent Herbicides (before weeds germinate)
bensulide (Prefar 4E): REI 12h, Group 0. Summer and winter squash only. Apply 5-6 qt/A per application, only 1 application per year. Can be applied to flat-bedded or bedded crops. Incorporate 1-2” into the soil with shallow cultivation or with water through irrigation or rainfall within 36 hours of application.
clomazone (Command 3ME): REI 12h, Group 13. Apply 10.7-32 fl oz/A per application, only 1 application per year. Can be applied to the soil surface before seeding or transplanting, but be sure to place roots of transplants or seeds below chemical barrier when planting. Apply in a minimum of 10 gal/A of spray. Use the lower rate on sandy soils and the higher rate on silt and clay soils. Has not been tested on all varieties, crop tolerance should be verified before treating the entire field. Do not apply to soil that will be covered with plastic, or on certain pumpkin cultivars, including Jack-o-lantern pumpkins, which will experience unacceptable fruit whitening.
ethalfluralin (Curbit EC): REI 24h, Group 3. Apply 3-4.5 pt/A per application, only 1 application per year. Can be applied after planting but before crop emergence, no later than 2 days after seeding. Can also apply as a banded spray between rows after crop emergence or transplanting. Activate with 0.5” of irrigation within 2 days of application or 0.5” of rainfall within 5 days of application. If no rainfall occurs a shallow cultivation may activate but a deep incorporation or excessive water may cause crop loss. Rate based on soil texture. Use during cold, wet weather can result in crop injury or stunting. Has not been tested on all varieties, crop tolerance should be verified before treating the entire field.
s-metolachlor (Dual Magnum): PHI 30d, REI 12h, Group 15. For Pumpkins only. Apply 1-1.33 pt/A per application, only 1 application per year. Apply as an inter-row or inter-hill application in pumpkin. Leave 1’ of untreated area over the row or 6” to each side of the planted hill (do not apply directly over the planted pumpkin seed or young pumpkin plants). 2. An indemnified label for use over the top of pumpkins available in Massachusetts, Maine, and New Hampshire only.
Indemnified label for Pumpkin available in MASSACHUSETTS, MAINE, and NEW HAMPSHIRE only and for Winter Squash available in MASSACHUSETTS, CONNECTICUT, and NEW HAMPSHIRE only. Make sure the label for your state is available for download before using this product. This is a restricted label available only to growers who apply through the website www.syngenta-us.com/labels/indemnified-label-login and agree to a waiver of liability. Main target weeds for this registration are galinsoga and yellow nutsedge.
Pre- and Postemergent Herbicides
halosulfuron (Sandea): PHI 30d, REI 12h, Group 2. Apply 0.5-0.75 oz/A per application, up to 2 applications allowed per year. Do not exceed 2 oz/A per year. Use teh lower rate on sandy soils and the higher rate on silt and clay soils. Can be applied after planting seeds but prior to soil cracking, or before transplanting crop. Transplant into treated area no sooner than 7 days after application and take care to limit movement of treated soil. Can also be applied over-the-top, directed, or with crop shields, after the crop has 2-5 true leaves (preferably 4-5) but before the 1st female flowers appear. Do not apply sooner than 14 days after transplanting. Can also apply to row middles before or after crop and weeds have germinated. Apply in a minimum of 15 gal/A of spray and settle soil after planting and prior to application with 0.5-0.75” of water through irrigation or rainfall.
Postemergent Herbicides (after weeds germinate)
carfentrazone (Aim EC): PHI 0d, REI 12h, Group 14. Apply 0.5-2 oz/A per application. Do not exceed 6.1 oz/A per season. Can be applied as a preplant burndown no later than 7 days before seeding or immediately before transplanting crop. Can also be applied 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” tall and rosettes less than 3” across.
clethodim (Select Max): PHI 14d, REI 24h, Group 1. Apply 9-16 oz/A per application, up to 4 applications allowed per year, a minimum of 14 days apart. Do not exceed 64 oz/A per year. Apply to actively growing grasses. Add 0.25% v:v nonionic surfactant (1 qt/100 gal of spray). Can also be applied as a spot-spray by mixing 0.33-0.66% (0.44-0.85 oz/gal) Select Max and 0.25% v:v nonionic surfactant (0.33 oz/gal). Spray to wet, but do not allow runoff of spray solution.
glyphosate (Roundup Power Max): PHI 14d, REI 4h, Group 9. Apply 10 oz to 3.1 qts/A per application, multiple applications allowed per year. Do not exceed 5 qts/A per year. Rate based on target weed species. Can be applied during fallow intervals, prior to planting or transplanting, at planting, or before crop has emerged. Allow a minimum of 3 days between application and seeding and do not apply after seeding. Could cause injury when applied prior to transplanting or direct-seeding into plastic mulch. Remove residual product from plastic mulch with a 0.5” of water through irrigation or rainfall prior to planting.
paraquat (Gramoxone SL 2.0*): restricted use. REI 12h or 24h, Group 22. Apply 1.3-2.7 pts/A per application, up to 3 applications allowed per year, a minimum of 14 days apart. Do not exceed 6.6 pts/A per year. Can be applied before, during, or after planting but before emergence. Can also be applied after the crop has emerged with a directed spray. Apply in a minimum of 10 gal/A of spray. May be fatal if swallowed or inhaled. Applicators must complete an EPA-approved paraquat training listed on the following website https://www.epa.gov/pesticide-worker-safety/paraquat-dichloride-training.... The training must be completed a minimum of every three years.
pelargonic acid (Scythe): PHI 1d, REI 12h, Group 0. Apply a 3-10% solution (3-10 gallons per 100 gallons of spray). Apply in 75-200 gal/A of spray. Can use preplant, or as a directed and shielded spray during crop growth. Avoid contact with foliage or crop damage may occur. Spray to wet, but do not allow runoff of spray solution.
sethoxydim (Poast): PHI 20d, REI 12h, Group 1. Apply up to 1.5 pt/A per application, multiple applications allowed per year, a minimum of 14 days apart. Do not exceed 3 pts/A per year. Apply to actively growing grasses. Use with crop oil concentrate (2 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 applied as a spot-spray by mixing 1-1.5% (1.3-1.9 oz/gal) Poast and 1% v:v crop oil concentrate (1.3 oz/gal). Spray to wet, but do not allow runoff of spray solution.