Weed Control

Gourds have recently been added to this section. Of herbicides listed below, only Roundup, Gramoxone Max, Scythe and Prefar are registered for use in gourds.

NOTE:  For the herbicides listed below, one product trade name and formulation is provided for each active ingredient (common name) as an example of rates, days to harvest (dh), REI, and special instructions. In many cases there are other products available with the same active ingredient. Please see Table 17 and Alphabetical Listing by Trade Name for more information on products with the same active ingredients. 

Stale Seedbed and 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.

See page 44 in Weed Information section. Prepare field 10 to 14 days prior to planting. Allow weeds to germinate. After seeding, but prior to crop emergence, apply paraquat (Gramoxone Inteon*2S) at 2.0 to 4.0 pt/A (REI 12h, Group 22). Add a nonionic surfactant at 8 to 32 oz/100 gal spray. Avoid contact between spray and crop cotyledons or foliage. Bensulide (Prefar 6E) may be incorporated at time of field preparation to provide some residual control of annual grasses. Gramoxone Inteon* is a contact herbicide and will control only those annual weeds that have emerged at the time of application.

glyphosate (Roundup 4S): 1 to 5 qt/A (REI 12h, Group 9). See Stale Seedbed Technique.

pelargonic acid (Scythe 4.2): 3 to 10 gal/A (REI 24h, Group 27). See Stale Seedbed Technique.

Preplant Incorporated/Preemergence

bensulide (Prefar 4E): 5 to 6 qt/A (REI 12h, Group 8). Must be thoroughly incorporated to a depth of 2” before planting. Use primarily where grasses are a serious problem. May be applied preemergence if 1” of rainfall or irrigation follows application.

clomazone (Command 3ME): 10 to 32 oz/A (REI 12h, Group 13). Do not exceed 20 ounces in summer squash. NOT LABELED FOR USE IN PUMPKINS. Apply after seeding or prior to transplanting. May also be applied to the soil surface between rows of plastic mulch. Will control many broadleaf weeds including common lambsquarters, velvetleaf, and jimsonweed. Combining with Curbit will also control pigweed species. Some temporary crop injury (partial whitening of leaf or stem tissue) may be visible after crop emergence or after transplanting. Complete recovery will occur from minor early injury without affecting yield or earliness. See label for replanting restrictions.

ethalfluralin (Curbit 3EC): 3 to 4 1/2 pt/A (REI 12h, Group 3). Apply to the soil surface immediately after seeding. Do not incorporate. Irrigation or rainfall within five days of application is needed for good weed control. Do not use under mulches, row covers, or hot caps. May be banded between rows of plastic mulch. Use during cold, wet weather can result in crop injury or stunting. Not registered on gourds.

ethafluralin + clomazone (Strategy 2.1 lb/gal): 2 to 6 pt/A (REI 24h, Groups 3 and 13). Apply after seeding and before crop emergence for cucurbits grown on bare ground. Do not incorporate. May also be applied between plastic for crops grown either from seed or transplants. Set equipment to avoid application over plastic mulch. Irrigation or rainfall is needed within 5 days of application for good weed control. Do not use under mulches, row covers, or hot caps. Use during cold, wet weather, or prior to heavy rains can result in crop injury or stunting. See label for list of weeds and use precautions.

halosulfuron (Sandea 75 WSG): 1/2 to 2/3 oz/A (30 dh, REI 12h, Group 2). PUMPKINS and WINTER SQUASH ONLY. Apply after seeding and before crop emergence. Use the lower rate on lighter textured soils. Heavy rains following application will increase the potential for crop injury. See the label for other precautions and a list of weeds controlled. Consider using Sandea as a supplement to Strategy (ethalfluralin + clomazone) in cases where Strategy has not provided sufficient weed control and when a postemergence application is not practical.

s-metolachlor (Dual Magnum 7.62E) : 0.95-1.27 lb/A. (REI 12 hr, Group 15)  Apply 1 to 1.33 pints of Dual Magnum 7.62E per acre as a directed and shielded spray between the rows of plastic mulch or between bare ground rows in pumpkins to suppress or control annual grasses, yellow nutsdge, and certain annual broadleaf weeds including nightshade species.  Leave 1 foot (12 inches) of untreated area between the spray and any emerged pumpkin foliage. Do NOT apply Dual Magnum under the plastic or spray the plastic mulch.  Tank-mix with other herbicides to improve the number of annual broadleaf weeds controlled.  Dual Magnum will not control emerged weeds.  In CT, ME, and NH, can be tank-mixed with Gamoxone Inteon and applied as a directed shielded spray if weeds have emerged.  Use the lowest recommended rates on coarse-textured sandy soils low in organic matter.  Higher rates should only be used on medium and fine textured soils.  Dual magnum is labeled for use ONLY in pumpkins.  Dual Magnum is NOT labeled on winter squash.  Do NOT use Dual Magnum in winter squash.

Postemergence

carfentrazone (Aim 2EC or Aim 1.9EW):  0.008-0.031 lb/A.  (REI 12 hr, Group 14)  Apply 0.5 to 2 fluid ounces of Aim 2EC or Aim 1.9EW as a banded directed shielded spray between the rows of plastic mulch to suppress or control broadleaf weeds including morninglory species, pigweed species, common lambsquarter, and nightshade species when the crop has 2 to 5 true leaves but has not yet begun to bloom or run. Aim applied postemergence will not control annual or perennial grasses. Add nonionic surfactant to be 0.25 percent of the spray solution (1 quart per 100 gallons of spray solution), or oil concentrate or methylated seed oil to be 1 -2% percent of the spray solution (1-2 gallons per 100 gallons of spray solution).  The shielded (hooded) sprayer must be designed to prevent spray or drift from contacting the stems, leaves, flowers or fruit of the crop, or severe injury may occur.

clethodim (Select 2 EC): 6 to 8 oz/A (14 dh, REI 24h, Group 1). Apply to actively growing grasses. See label for grass height and herbicide rate. Always use a crop oil concentrate at a rate of 1 gal/100 gal spray mix. See both container label and supplemental label available from dealer.

halosulfuron (Sandea 75 WSG): 1/2 to 2/3 oz/A (30 dh, REI 12h, Group 2). PUMPKINS and WINTER SQUASH ONLY. Apply after the crop has reached the 2-5 true leaf stage but before the first female flowers appear for control of nutsedge and many broadleaf weeds. Use the lower rate on lighter textured soils. Heavy rains following application will increase the potential for crop injury. See the label for other precautions and a list of weeds controlled.

halosulfuron (Sandea 75 WSG): 1/2 to 1 oz/A (30 dh, REI 12h, Group 2). Winter squash, summer squash, and pumpkins. Apply between rows of direct seeded and transplanted cucurbit vegetables for control of nutsedge and many broadleaf weeds. Will provide both preemergence and post-emergence control of many weed species. Avoid contact of the herbicide with the planted crop. If plastic is used on the planted row, adjust equipment to keep the herbicide off the plastic. Reduce rate and spray volume in proportion to the area actually sprayed. See the label for other precautions and a list of weeds controlled.

paraquat (Gramoxone Ineon* 2S): 2 pt/A (REI 12h, Group 22). Apply as a directed and shielded spray to emerged weeds between rows of pumpkin or squash. Crop contact by the spray will cause severe injury or death. For use in CT, ME and NH only.

pelargonic acid (Scythe 4.2): 3% to 10% (REI 24h, Group 27). Use a 3-5% solution for annual weeds (4-6 oz/gal water), a 5-7% solution for biennial and perennial weeds (6-9 oz/gal water), and 7-10% solution for maximum burndown (9-13 oz/gal water). Delivery rate for boom applications should be 75 to 200 gal spray solution/A; 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. These include tank mixes with glyphosate (Roundup), sulfosate (Touchdown), and residual herbicides. See label for complete details.

sethoxydim (Poast 1.5L): 1 to 2 pt/A (14 dh, REI 12h, Group 1). Apply with crop oil concentration at 2 pt/A. Apply to actively growing weed grasses (see product label for susceptible stage of growth). Do not cultivate for five days prior or seven days after Poast application. During periods of high temperature and/or high humidity some flowers may be damaged or dislodged and some foliar necrosis may result. Not registered on gourds.