Cucurbit and Vine Crops
Cantaloupe, cucumber, pumpkin, squash, and watermelon
CUCURBIT AND VINE CROPS—Site Preparation, Stale Seedbeds, and Selective Postemergence Applications
See “Site Preparation”, “Labeled ‘L’ Uses for Glyphosate in Vegetable Crops” (table), and “Registered Uses of Carfentrazone (Aim) Herbicide in Food Crops” (table) at the beginning of Section N. Vegetable Crops in this handbook.
CUCURBIT AND VINE CROPS—Preplant Incorporated
bensulide (Prefar 4-E)
Cantaloupe, cucumber, winter and summer squash, and watermelon
Rate 5 to 6.lb ai/A (5 to 6 quarts/A)
Time Apply preplant and incorporate 0.5 to 1 inch deep simultaneously or immediately after application, by cross-disking or using a power take-off rotary tiller.
Remarks Sometimes the first flush of weeds must be controlled with cultivation before the herbicide begins to control grass. Consult label for planting sensitive crops following treatment. Inhibits roots of seedlings. Can be tank mixed with Alanap to improve spectrum of weed control.
Caution Do not apply more than once every 12 months.
Site of action Group 8: lipid synthesis inhibitor but not an ACCase inhibitor
Chemical family Organophosphorus
CUCURBIT AND VINE CROPS—Preplant or Preemergence Surface
bensulide (Prefar 4-E)
Rate 5 to 6 lb ai/A (5 to 6 quarts/A)
Time Apply before crop and weeds emerge, preferably soon after planting; follow with sprinkler irrigation to wet soil 2 to 4 inches deep.
Remarks For furrow irrigation, thoroughly saturate bed top. Germinated or seedling weeds must be cultivated before application. Consult label for planting sensitive crops after treatment.
Caution Do not apply more than once every 12 months.
Site of action Group 8: lipid synthesis inhibitor but not an ACCase inhibitor
Chemical family Organophosphorus
clomazone (Command 3ME)
Preplant surface, pretransplant surface, and postplant surface; Cucumber, winter and summer squash, pumpkin, and watermelon
Rate 0.15 to 0.75 lb ai/A (0.4 to 2 pints/A) depending on crop: cucumbers 0.4 to 1 pint/A; melons 0.4 to 0.67 pint/A; summer squash 0.67 to 1.33 pints/A; winter squash including processing pumpkin 0.67 to 2 pints/A.
Time Apply using a boom mounted on front of incorporation equipment to ensure immediate incorporation at 1 inch.
Remarks See label for crop-rotation restrictions for up to 16 months after treatment. Plant crop seed below treated layer. The new formulation is designed to reduce or minimize drift but requires moisture to activate. Avoid overlaps in spraying and in treating very sandy soils. Inhibits chlorophyll development.
Caution May discolor fruit of some orange varieties. Do not use on NK530, NK580, “Turk’s turban,” “Golden Delicious,” all banana types and all other Cucurbita maxima that have a pink or burnt-orange color at harvest. Do not use on jack-o-lantern pumpkins. Clomazone may inhibit development of orange pigments. Before applying, check adjacent properties and avoid spraying within 300 to 1,200 ft of desirable plants. Sensitive crop and sites include landscapes, orchards, vegetable gardens, berry patches, and property lines. Do not graze cover crops or harvest food or feed within 9 months of applying or allow livestock to graze treated plants.
Site of action Group 13: inhibits DOXP synthase
Chemical family Isoxazolidinone
dimethenamid-P (Outlook)
Winter squash (var. “Golden Delicious”), Oregon and Washington only
Rate 0.56 to 0.84 lb ai/A (12 to 18 fl oz/A)
Time Apply postplant, preemergence, and irrigate with 0.5 inch water to activate herbicide.
Remarks Supplemental label. Preharvest interval is 90 days. Planting at 1.5 inches or below will help to mitigate potential crop injury.
Caution Do not apply more than 21 fl oz/A per year. Replanting winter squash is not recommended if there is a crop failure. Other labeled crops can be planted immediately; cereals can be planted within 4 months of the Outlook application. Excessive rain after planting may temporarily injure crop.
Site of action Group 15: inhibits very long chain fatty acid synthesis
Chemical family Chloroacetamide
ethalfluralin (Curbit EC)
Cucumber, winter and summer squash, pumpkin, and watermelon
Rate 1.13 to 1.69 lb ai/A (3 to 4.5 pints/A)
Time Apply preemergence surface and activate with 0.5 inch of irrigation within 2 to 5 days, or cultivate soil surface above seed. Crop may be injured with excessive rain or irrigation or if seeding is too shallow.
Remarks Adjust rates depending on soil texture and organic matter content.
Caution Do not graze or apply to wet or cloddy soils. Note replanting restrictions for sugar beets and red beets listed on label. (Inhibits mitosis, primarily in shoots.)
Site of action Group 3: microtubule assembly inhibitor
Chemical family Dinitroaniline
ethalfluralin + clomazone (Strategy)
Cucumber, winter and summer squash, pumpkin, and watermelon
Rate 2 to 6 pints/A, depending on soil texture (see label)
Time Apply only as a postplant surface treatment before crop and weeds emerge. Activate with 0.5 inch of irrigation within 2 to 5 days, or cultivate soil surface above seed. Crop may be injured with excessive rain or irrigation or if seeding is too shallow.
Remarks Adjust rates depending on soil texture and organic matter content. Do not preplant-incorporate, as crop will be injured. Inhibits mitosis, primarily in shoots.
Caution Avoid drift onto neighboring plants. Clomazone will make affected plants turn white. Will occasionally “lift” from fields after application and cause adjacent crops to turn white for a short period of time. Use with caution within 300 ft of high value crops. Do not graze or apply to wet or cloddy soils. Note replanting restrictions for sugar beets and red beets listed on label.
Site of action (ethalfluralin) Group 3: microtubule inhibitors; (clomazone) Group 13: inhibits DOXP synthase
Chemical family (ethalfluralin) dinitroaniline; (clomazone) isoxazolidinone
glyphosate (Touchdown HiTech)
Winter squash, Oregon only
Rate 0.39 to 0.78 lb ai/A (10 to 20 fl oz/A)
Time Apply to emerged annual weeds after planting winter squash in spring but before crop emerges. May be mixed with residual herbicides.
Remarks Oregon special local needs label OR-050006 in Benton, Lane, Linn, and Marion counties.
Caution Do not apply if crop seeds are exposed because of poor row closure during planting. Do not apply if the radicle has emerged or if soil covering the seeds is cracking. Do not use on soils with less than 1% organic matter.
Site of action Group 9: inhibits EPSP synthase
Chemical family None generally accepted
halosulfuron-methyl (Sandea)
Rate 0.0157 to 0.0313 lb ai/A (0.5 to 1 oz/A) for cucumbers and other cucurbits approved for directed applications in row-middles. 0.375 to 0.56 oz ai/A (0.5 to 0.75 oz/A) for processing winter squash and pumpkins. Consult label for the diversity of rates recommended depending on crop and method of planting.
Time Apply before emerging crop cracks the soil, before transplanting, or before seeding or transplanting under plastic mulch.
Remarks For control of broadleaf weeds and nutsedge. Adjust rates, depending on soil texture and organic-matter content. Can be applied preemergence surface as a tank-mix with Outlook (dimethenamid-P) in processing squash to enhance control of lambsquarters control. Use the 0.5-oz/A rate to avoid crop stunting if tank mixing with Outlook and if wet, cold soil conditions are expected.
Caution Crop growth may be stunted briefly after emergence. Consult label for rotation crops, soil-applied organophosphate insecticides, and other precautions. Do not exceed 1 oz/A herbicide per year. Preharvest interval is 30 days for squash, cucumbers, and pumpkin, 57 days for melons.
Site of action Group 2: acetolactate synthase (ALS) inhibitor
Chemical family Sulfonylurea
naptalam (Alanap-L)
Cucumber, melons (cantaloupe, musk, honeydew, casaba), and watermelon
Rate 0.5 to 1 lb ai/A (1 to 2 gal/A)
Time Preemergence immediately after planting. Water is needed to incorporate herbicide.
Remarks Registration voluntarily withdrawn but no time limit on selling or using Alanap. Primarily grass control and often used in tank-mixes with Prefar (bensulide, preplant incorporated or post plant surface) and Command (clomazone).
Caution Do not use under adverse conditions in the spring with extended cold and soil temperatures below 60°F.
Site of action Group 19: inhibits indole acetic acid transport
Chemical family Phthalamate
S-metolachlor (Dual Magnum)
Pumpkin (Group 9B; including winter squash), inter-row or inter-hill only
Rate 0.95 to 1.27 lb ai/A (1 to 1.33 pints/A)
Time Apply preemergence or postemergence before weeds germinate or yellow nutsedge emerges.
Remarks Leave 1 ft of untreated area over the row, or 6 inches to each side of the planted hill and/or any emerged pumpkin foliage (inter-row or inter-hill means not directly over the planted seed or young pumpkin plants). Use the lower rate on soils light in texture (loamy sand or lighter) and low in soil organic matter (less than 3%).
Caution Consult label for specific rates, depending on soil texture and especially organic matter, or for restrictions on planting sensitive crops within 4 to 5 mo. Inhibits roots and shoots. Preharvest interval is 30 days.
Site of action Group 15: inhibits very long chain fatty acid synthesis
Chemical family Chloroacetamide
terbacil (Sinbar)
Watermelon only
Rate 0.1 to 0.2 lb ai/A (2 to 4 oz/A, to a maximum of 4 oz/A per year)
Time Apply before transplanting or before crop emerges, if direct-seeding watermelon.
Remarks Supplemental label for watermelon only. Moisture is required to activate the herbicide and should arrive within 2 wk of planting. May be applied preemergence under plastic mulch. Preharvest interval is 70 days.
Caution Do not use on sand or gravel soil types. Use with caution if soil organic matter is less than 1%. Do not replant any crop for 2 years after applying terbacil.
Site of action Group 5: photosystem II inhibitor
Chemical family Uracil
CUCURBIT AND VINE CROPS—Postemergence
clethodim (Prism; Select 2C in Oregon only)
Rate Consult label for rate required to control different grasses.
Time Apply to actively growing grasses at recommended weed heights.
Remarks Add crop oil concentrate as described on label.
Caution Consult labels for maximum rate per application and season. Preharvest interval is 14 days.
Site of action Group 1: acetyl CoA carboxylase (ACCase) inhibitor
Chemical family Cyclohexanedione
halosulfuron-methyl (Sandea)
Broadcast sprays on cucumbers, cantaloupe, processing winter squash, and pumpkins only; selective sprays allowed on other cucurbit crops
Rate 0.023 to 0.046 lb ai/A (0.5 to 1 oz/A) for cucumbers and other cucurbits depending on soil type; 0.023 to 0.035 lb ai/A (0.5 to 0.75 oz/A) for processing winter squash and pumpkins.
Time Apply postemergence to seeded or transplanted crops that are well established and that have two to five leaves (preferably four to five leaves), and before the first female flowers appear.
Remarks Results in the Pacific Northwest indicate potential for crop injury or delayed flowering with broadcast postemergence treatments. Primary use is nutsedge suppression. Applications are allowed for most cucurbit crops if spray is directed to row middles after planting or transplanting, or if applied with shielded sprayers that prevent herbicide contact with the crop. Avoid irrigation or rain within 4 hr after treatment.
Caution Crop growth may be stunted or become yellow briefly after treatment. Consult label for rotation crops, soil-applied organophosphate insecticides, and other precautions. Do not exceed 2 oz/A herbicide per year. Preharvest interval is 30 days for squash, cucumber, and pumpkin, 57 days for melons.
Site of action Group 2: acetolactate synthase (ALS) inhibitor
Chemical family Sulfonylurea
sethoxydim (Poast)
Rate 0.19 to 0.28 lb ai/A (1 to 1.5 pints/A)
Time Apply at optimum growth stage listed on the label.
Remarks Identify susceptible grasses and add 2 pints/A nonphytotoxic crop oil concentrate to improve leaf absorption. Control often is erratic on grasses stunted or stressed from drought, high temperatures, or low fertility. Resistant grasses include annual bluegrass and all fine fescues, but quackgrass can be suppressed. Inhibits fatty acid production, cell membranes, and new growth.
Caution Preharvest interval is 14 days (3 days for cantaloupe). Do not exceed 3 pints/A per season.
Site of action Group 1: acetyl CoA carboxylase (ACCase) inhibitor
Chemical family Cyclohexanedione
CUCURBIT AND VINE CROPS—Postemergence Layby Treatments
DCPA (Dacthal W-75)
Melons (all types) only
Rate 4.5 to 10.5 lb ai/A (6 to14 lbs/A)
Time Apply after plants have four to five true leaves, after cultivation and weeding but before any new weeds become established.
Remarks Performs poorly in western Oregon and Washington. Results improve with rain or overhead irrigation immediately after application. Consult label for restrictions on planting sensitive crops within 8 months. Inhibits mitosis.
Site of action Group 3: microtubule assembly inhibitor
Chemical family Phthalic acid
ethalfluralin (Curbit)
Rate 1.13 to 1.69 lb ai/A (3 to 4.5 pints/A)
Time Apply in bands between rows after planting or transplanting. Activate with 0.5 inch irrigation within 2 to 5 days or cultivate soil 1 to 2 inches deep.
Remarks Adjust rates depending on soil textures and organic matter.
Caution Do not graze or apply to wet cloddy soils. Note replanting restrictions on label for sugar beets and red beets. (Inhibits mitosis, primarily in shoots.)
Site of action Group 3: microtubule assembly inhibitor
Chemical family Dinitroaniline
trifluralin (Treflan 4L or HFP)
Rate 0.5 to 1.0 lb ai/A (1 to 2 pints/A)
Time Apply as a directed spray between rows when crop has three to four true leaves.
Remarks Incorporate 2 to 3 inches deep, using rolling cultivators set to throw soil toward plants in row. Spray only once per year. Consult label for restrictions on planting sensitive crops within 12 months. (Inhibits mitosis, primarily in shoots.)
Site of action Group 3: microtubule assembly inhibitor
Chemical family Dinitroaniline