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Insecticides Commonly Used on Alfalfa

These notes are intended to help producers make preliminary decisions on chemicals to be used on their crops. However, growers and applicators should read pertinent sections of the label before final selection or application.

Alfalfa Insecticide Use Instructions

Insecticide

Special Instructions — These notes are intended to help producers make preliminary decisions on chemicals to be used on their crops. However, growers and applicators should read pertinent sections of the label before final selection or application.

Beta-cyfluthrin* (Baythroid XL)

Signal word on label is WARNING. Extremely hazardous to fish and aquatic invertebrates. Do not apply this product or allow it to drift to blooming crops or weeds on which bees are actively foraging. Minimum application volume (water) 10 GPA ground and 2 GPA aerial application. Chemigation and ULV applications are allowed by label. Maximum of 5.6 fl. oz./ acre (0.044 lb. a.i./acre) per cutting for alfalfa or 2.8 fl. oz./acre (0.022 lb. a.i./acre) per cutting on mixed-stands of alfalfa and intentionally-grown grasses. REI is 12 hours. PHI is 7 days.

Carbaryl (Sevin)

This carbamate insecticide is sold by several companies and in different formulations. Check the product label to make sure it is approved for the intended use. Signal word on label: CAUTION or WARNING depending on formulation. BEE CAUTION: Do not apply or allow to drift to blooming crops or weeds if bees are visiting the treatment area. Carbaryl is extremely hazardous to aquatic invertebrates, so do not apply directly over water. Some phytotoxicity is possible and may cause bleaching of tender alfalfa foliage. Most labels recommend the use of 25 to 40 gallons of water with ground equipment to ensure adequate coverage. Refer to specific product labels for information on chemigation. Apply only once per cutting. REI is 12 hours. Do not apply within 7 days of harvest or grazing.

Chlorpyrifos* (numerous products including Chlorpyrifos, Eraser, Govern, Lorsban, Nufos, Pilot, Warhawk, Whirlwind and Yuma)

Signal word on label is WARNING. Do not apply more than once per cutting or four times per year. For aerial applications use 2 to 5 gallons of water per acre. For best coverage when using ground application, a minimum of 20 gallons of water per acre with hollow cone nozzles is recommended. Chemigation is allowed. See label for more information. To avoid contamination of irrigation tail water, do not flood irrigate within 24 hours following an application of chlorpyrifos. Highly toxic to bees exposed to direct treatment. Some phytotoxic symptoms may be observed on young, tender, rapidly growing alfalfa. REI is 24 hours. Do not cut or graze treated alfalfa within seven days after applications of 0.25 lb. a.i./acre, 14 days after applications of 0.5 lb. a.i./ acre, or within 21 days after application exceeding 0.5 lb a.i./acre.

Chlorpyrifos plus gamma-cyhalothrin* (Cobalt)

The signal word on the label is DANGER. It is highly toxic to bees exposed to direct treatment on alfalfa. Do not flood irrigate for 24 hours following application. Do not cut or graze treated alfalfa within 7 days after application of 7 to 13 fl oz per acre of Cobalt, within 14 days after application of 13 to 26 fl oz per acre, or within 21 days after application of rates above 26 fl oz per acre. Do not make a second application of Cobalt or another product containing chlorpyrifos within 10 days of first application. REI is 24 hr.

Chlorpyrifos plus zeta-cypermethrin (Stallion)

REI is 24 hrs. PHI for cutting or grazing is 7 days.

Cyfluthrin (Tombstone)Signal word on label is WARNING. For control or suppression of many common insect pests. Extended residual activity due to helios technology. REI is 12 hours. PHI is 7 days. See label for directions.

Dimethoate* (Dimate and others, formerly Cygon)

This organophosphate insecticide is available from various suppliers and in various formulations. Signal word on label: WARNING or DANGER, depending on formulation. Highly toxic to bees. Do not apply to alfalfa in bloom. Do not apply directly to water; runoff may be hazardous to aquatic organisms. Chemigation allowed on some labels. Apply only once per cutting. REI is 48 hours. Do not apply within 10 days of harvest or pasturing.

Gamma-cyhalothrin* (Proaxis)

This microencapsulated pyrethroid insecticide is labeled restricted use due to toxicity to fish and aquatic organisms. Signal word on label: CAUTION. Apply in a minimum of 2 gallons per acre by air or 10 gallons per acre by ground. When foliage is dense and/or pest populations are high, 5 to 10 gallons per acre by air or 20 gallons per acre by ground and higher label use rates are recommended. Do not apply more than 0.015 pound active ingredient (0.24 pint) per acre per cutting. Do not apply more than 0.06 pound active ingredient (0.96 pint) per acre per season. Apply only to fields planted to pure stands of alfalfa. Do not apply this product or allow it to drift to blooming crops or weeds if bees are visiting the treatment area. REI is 24 hours. PHI is 1 day for forage and 7 days for hay.

Indoxacarb (Steward 1.25 SC)

This insecticide carries the signal word of CAUTION. Product is highly toxic to bees. It can be applied by air using a minimum of 3 gallons of water per acre or by ground equipment with a minimum of 5 gallons of water per acre. Higher gallonage will provide better coverage and performance. One application per cutting. REI is 12 hours, and PHI is 7 days.

Lambda-cyhalothrin* (numerous products including Warrior II with Zeon Technology, Silencer, Taiga Z, and Lambda T)

This pyrethroid insecticide is labeled restricted use due to toxicity to fish and aquatic organisms. Signal word on label: WARNING. Apply by ground or air using sufficient water to obtain full coverage of foliage. Use a minimum of 2 gallons of water per acre by air. REI is 24 hours. PHI is 1 day for forage or 7 days for hay. Apply only to pure stands of alfalfa.

Lambda-cyhalothrin plus chlorantraniliprole (Voliam Xpress)This product is a combination of 2 insecticides with activity agains both chewing and sucking insects. It is highly toxic to bees exposed to direct treatment or to residues on blooming crops and weeds. PHI is 1 day for forage and 7 days for hay.

Methomyl* (Lannate)

This carbamate insecticide is labeled restricted use due to high acute toxicity to humans. Signal words on label: DANGER–POISON. Toxic to fish and wildlife. Drift and runoff from treated areas may be hazardous to aquatic organisms. Highly toxic to bees. Do not apply or allow to drift to blooming crops or weeds if bees are visiting the treatment area. Do not apply through any type of irrigation system. Do not apply to dormant or semi-dormant alfalfa when minimum daily temperature is less than 50°F. REI is 48 hours. PHI is 7 days. See label for other restrictions.

Methyl Parathion* (Cheminova Methyl 4EC)

This organophosphate insecticide is labeled a restricted use pesticide due to very high acute toxicity to humans and birds, and should be used only by those willing to assume special safety precautions on the label. Signal words on label: DANGER – POISON. Do not apply through irrigation systems. Five-day REI in areas where average rainfall is less than 25 inches per year and four days where rainfall is 25 inches or greater. PHI is 15 days.

Permethrin* (Arctic, Ambush and Pounce)

This pyrethroid insecticide is labeled restricted use due to toxicity to fish and aquatic organisms. Signal word on label CAUTION or WARNING depending on formulation. Use a minimum of 10 gallons of finished spray per acre by ground application and a minimum of 1 gallon of finished spray if applied by air. Can be chemigated; refer to label for details. REI is 12 hours. PHI for 0.1 lb. a.i./acre or less is 0 days. Above 0.1 lb. a.i./acre a 14-day PHI is required. Do not apply more than 0.2 lb. a.i./acre per cutting.

Phosmet* (Imidan)

This organophosphate insecticide car-ries the signal word WARNING on its label. It is highly toxic to bees exposed to direct treatment on blooming crops or weeds. Extremely toxic to fish. Apply in a minimum of 3 gallons of water by air, or 20 to 75 gallons of water with conventional ground equipment. Can be chemigated. Only one application per cutting. REI is 12 hours. PHI is 7 days.

Spinosad (Tracer)

This fermentation-derived insecticide carries the signal word CAUTION on the label. Use on Alfalfa and other legume forages is based on Supplemental labeling that must be in possession of the user at the time of application. This product is toxic to bees exposed to treatment for 3 hours following treatment and toxic to aquatic invertebrates. REI of 4 hours. Chemigation instructions on label. Do not harvest hay or fodder for 3 days after treatment. There is no preharvest interval for forage. Do not allow cattle to graze from treated area until spray has dried. Do not apply more than 6 fl. oz. of Tracer (0.186 lb. a.i. spinosad) per acre per year.

Zeta-cypermethrin* (Mustang MAX EC)

This pyrethroid insecticide is labeled restricted use due to its toxicity to fish and aquatic invertebrates. Signal word on label: CAUTION. Apply in a minimum of 2 gallons of finished spray per acre by aerial equipment or 10 gallons per acre by ground equipment. Can be chemigated. Refer to label for more information. REI of 12 hours. Application may be made up to three days before cutting or grazing or up to seven days for harvesting seed. Maximum use 0.025 lb. a.i./acre per cutting and 0.075 lb. a.i./acre per season. Do not make applications less than 7 days apart.

* Restricted Use Pesticide

Using Insecticides Safely

Read the label carefully. It is a legal document. It tells what, where, how and when the product can be used. It is against the law to use a pesticide in a manner inconsistent with the label. For poison control information contact the Mid-America Poison Control Center. Emergency phone number: 800-222-1222.

From: MF-809, R. Jeff Whitworth, J. P. Michaud and Holly N. Davis. Alfalfa Insect Management, Kansas State University. (Pdf )

This publication was prepared to help producers manage insect populations with the best available methods proven practical under Kansas conditions. Pesticide label directions and restrictions are subject to change, and some may have changed since this publication was written. Kansas State University entomologists assume no responsibility for product performance, personal injury, property damage, or other types of loss resulting from the handling or use of the pesticides listed. Remember, it is illegal to use a pesticide in a manner that is inconsistent with the label. The user bears responsibility for correct use. Always read and follow label directions carefully.