Weed Control

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. 

Seeded Without Plastic

clomazone (Command 3ME): 6 to 16 oz/A (REI 12h, Group 13). Apply after seeding to the soil surface. For melons (muskmelon and watermelons), the maximum rate cannot exceed 10 oz/A. 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. 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 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.

ethalfluralin + 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 cucumbers and melons 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 the 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 1 oz/A (30 dh, REI 12h, Group 2). Cucumbers only. Apply after seeding and before crop emergence. Use the lower rate on lighter textured soil. Heavy rains following applications 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 (ethafluralin + clomazone) in cases where Strategy has not provided sufficient weed control and when a postemergence application is not practical. This treatment may also be used on cantaloupes, honeydew melons, and crenshaw melons (57 dh) but NOT muskmelons.

naptalam (Alanap 2EC): 1 to 1 1/2 gal/A (REI 48h, Group 19). Apply immediately after seeding. Effective only if rainfall occurs or irrigation is applied within 24 to 48 hours of application. Can also be used to improve the broadleaf weed control activity of ethalfluralin (Curbit).

Seeded or Transplanted

bensulide (Prefar 4E): 5 to 6 qt/A); or bensulide (Prefar 4E): 1 1/2 gal/A plus naptalam (Alanap) 1 gal/A preplant incorporated (REI 48h, Groups 8 and 9). Must be thoroughly incorporated to a depth of 1” to 2” before planting. Used primarily where grasses are a serious problem. May be applied preemergence to seeded crops if 1” of rainfall or irrigation follows application.

DCPA (Dacthal W75): 8 to 12 lb/A (REI 24h, Group 3). Apply only when plants have four to five true leaves, are well established, and growing conditions are favorable for good growth. If weeds have emerged, crop should be cultivated and weeded prior to application. May also be banded to weed-free soil between rows of plastic mulch.

Stale Seedbed

Also, see Stale Seedbed Technique on page 45.

Prepare field 10 to 14 days or more prior to planting. Allow weeds to germinate. Prior to transplanting or after seeding apply paraquat (Gramoxone Inteon 2S*) at 2.0 to 4.0 pt/A. Add a nonionic surfactant at 8 to 32 oz/100 gal of spray. Avoid contact between spray and crop cotyledons or foliage. Bensulide (Prefar) may be incorporated at time of field preparation to provide some residual control of annual grasses (see recommendation under Clear Plastic). Gramoxone Inteon 2S* is a contact herbicide and will control only those annual weeds that have emerged at the time of application.

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

Postemergence

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 1 oz/A (30 dh, REI 12h, Group 2). Cucumbers 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. May also be used over transplants on bare ground after the transplants are established and actively growing (at least 14 days). 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. This treatment may also be used on cantaloupes, honeydew melons, and crenshaw melons (57 dh) but NOT muskmelons.

paraquat (Gramoxone Inteon 2S*): 2.0 to 4.0 pt/A (REI 12h, Group 22). Apply as a directed and shielded spray to emerged weeds between rows of cucumbers or melons. 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 1.53EC): 1 to 2 pt/A (14 dh, REI 12h, Group 1). Apply with crop oil concentrate 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.

Between Black Plastic Rows

See Weed Management section.

ethalfluralin + 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 cucumbers and melons 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 five 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 1 oz/A (30 dh cucumbers, 57 dh melons, REI 12h, Group 2). Cucumbers and all melons. Apply between rows of direct seeded and transplanted cucurbit vegetables for control of nutsedge and many broadleaf weeds. Will provide both preemergence and postemergence 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.

naptalam (Alanap, Group 19) and/or ethalfluralin (Curbit, Group 3) can be applied after plastic is laid. Use rates suggested for seeded or transplanted crop. Reduce the rate in proportion to area covered. Spray only the soil area between the plastic strips and avoid any crop contact. Irrigate if rainfall does not occur within 24 hours.

Under Clear Plastic

See Weed Management section.

bensulide (Prefar 4E): 5 to 6 qt/A (REI 12h, Group 8) just prior to laying plastic. Must be thoroughly incorporated to depth of 1” to 2”. One inch of irrigation or rainfall may be substituted for mechanical incorporation prior to laying plastic.