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CHLORDANE

and

TOXAPHENE

for

GRASSHOPPER

CONTROL

PLANT QUARANTINE

AGRICULTURAL RESEARCH ADMINISTRATION

U.S. DEPT. of AGRICULTURE

FEBRUARY 1950

CHLORDANE and TOXAPHENE for

GRASSHOPPER CONTROL

The value of chlordane and toxa- phene in grasshopper control has been demonstrated by their extensive use in many States. On dense, succulent veg- etation these insecticides are particu- larly effective when applied as sprays. Under such conditions they give better initial results and ccntinue to kill longer than sodium fluosilicate bait, which for many years was considered the best weapon for fighting grasshoppers . They may also be applied PS dusts, but sprays give higher initial kills and continue to kill over a longer period.

Baits still have a place in grass- hopper control. In short, sparse, green vegetation and grain stubble they are as effective as sprays and more economi- cal. Indry vegetation which is no longer attractive to grasshoppers as food, and in fall -seeded grain when the plants are only a few inches tall, baits are m.ore effective than sprays or dusts. Baits containing chlordane or toxaphene give quicker and longer killing action than sodium fluosilicate baits. Since they are soluble in common organic solvents, it is possible to spray them onto dry bran, and thus reduce mixing costs and provide a bait suitable for spreading by aircraft.

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Sprays and Dusts

Formulations and Dosages. - -Ready- mixed emulsion concentrates, wettable powders, and dusts containing chlordane or toxaphene in various strengths are available from local dealers. Emulsion concentrates and wettable powders should be diluted with water to suit avail- able spraying equipment.

Whatever the formulation or dilution, the quantity of technical m aterial applied per acre should conform to the following recommendations:

Chlordane Toxaphene

Sprays 1/2 to 1 lb. 1 to 1 1/2 lb. Dusts 3/4 to 1 1/2 lb. 1 1/2 to 2 1/2 lb.

Use the lower dosages for young grasshoppers in short, dense, succulent vegetation and on open stands of taller growth when longKiontinued killing action is not essential.

Use the higher dosages when vege- tation is tall and dense or when long- continued killing action is desired. When it is necessary to control young grass- hoppers before the main hatch is com- pleted, the higher dosages may extend residual action long enough to kill the rest of the hatch and thus save the cost of a second treatment.

Dosages even higher than those listed may be needed for the treatment of bar- rier strips or for late-season use when

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grasshoppers are adult and vegetation is maturing. When vegetation becomes so dry that grasshoppers feed on it only sparingly, failure may be expected re- gardless of the dosages used.

The dosages recomm ended are based on performance in experimental trials and in general use. They were endorsed by the State Leaders' Advisory Commit- tee at its meeting at Denver, Colo. , November 28-30, 1949. These recom- mendations should not be expected to cover all local conditions within the many States where grasshopper control is needed. They are offered as a guide to help individuals solve their own prob- lems. If difficulties are encountered, county agricultural agents and State entomologists should be consulted.

Time and Methods of Application. -~ Chlordane and toxaphene are most ef- fective when applied evenly at the right time and in the right places. They may be applied with ground sprayers or dusters, or by airplane. The equip- ment used should be carefully adjusted so that the rate of application is accu- rately controlled. Too much material is wasteful and increases the danger of harmful residues. Too little insecti- cide also wastes time and materials, because it will not prevent crop losses. Areas treated with less than effective dosages will have to be retreated to obtain control.

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Farmers using these insecticides as sprays or dusts for grasshopper control should proceed as follows:

1. Determine the location of dan- gerous infestations of young grass- hoppers in relation to the fields plant- ed to crops. They may be found on roadsides, canal banks, field mar- gins, or idle lands bordering culti- vated fields, as well as in the fields themselves. Spray or dust these places when the main hatch is com- pleted or when the young grass - hoppers begin to move off the hatch- ing grounds, and thus greatly reduce the acreage that otherwise might have to be treated later. Grass- hoppers that d^-rrage row crops gen- erally hatch in the field margins. Timely spraying or dusting of vege- tation in such margins will destroy grasshoppers before they move into the fields.

2. Prevent grasshoppers from damaging corn by treating margins of cornfields and adjacent infested small-grain fields or weed patches when the small grains begin to ma- ture and before the grasshoppers move into the corn.

3. When an entire alfalfa field is infested with damaging populations of grasshoppers, it is ordinarily most economical to cut the alfalfa and then apply chlordane or toxaphene to protect the next cutting. Spray or

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dust field margins, ditch banks, patches of weeds, or uncut strips of

alfalfa where grasshoppers have con- centrated. Grasshoppers frequently hatch in considerable numbers after the first crop has been harvested. To control these insects, spray or dust the next crop as soon as the new growth is about 6 inches high. This practice protects the new growth and avoids heavy residues at harvest- time.

Precautions. --Chlordane and toxa- phene are poisonous to man and ani- mals, but with care they can be handled safely at strengths recommended for grasshopper control. In concentrated form they may cause acute poisoning when in contact with the skin or if in- haled or swallowed accidentally.

KEEP INSECTICIDES CONTAINING CHLORDANE OR TOXAPHENE OFF THE SKIN AND AWAY FROM THE EYES AND NOSE» BATHE THOR- OUGHLY AND CHANGE TO CLEAN CLOTHING DAILY AFTER SPRAYING OR DUSTING.

If the insecticide is accidentally swallowed, induce vomiting by taking 1 tablespoonful of salt in a glass of warm water. Repeat if necessary. Call a doctor.

DO NOT FEED FORAGE TREATED WITH CHLORDANE OR TOXAPHENE TO DAIRY ANIMALS OR TO ANIMALS BEING FINISHED FOR SLAUGHTER.

I

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These insecticides are known to accumulate in the fatty tissues and to be secreted in the milk of animals fed on forage containing the residues . For- age treated with them at dosages heavier than needed for grasshopper control has been fed to m eat animals continuously for several weeks to the exclusion of all other feed, without visible impairment of their health or development. How- ever, animals fed for long periods on treated forage may accumulate enough of these chemicals in their tissues to make the meat unfit for food. This pos- sibility is greatly reduced if no treated vegetation is fed during the last 2 months before slaughter.

If these chemicals are used on fruits and vegetables, DO NOT APPLY THEM TO THE PARTS OF THE PLANTS THAT WILL BE 3ATEN OR MARKET- ED unless the residues can and will be removed by washing or stripping.

Bees are essential to legume seed production. BECAUSE OF THE DAN- GER OF KILLING BEES, DO NOT AP- PLY THESE INSECTICIDES TO LEG- UMES WHILE IN BLOOM. If grass- hoppers must be controlled during this period to save the seed crop, spray in the early morning or late evening while bees are inactive. Sprays are lesSj harmful than dusts. \

Baits \

Wet Baits. - -Chlordane or toxaphene in the form of emulsion concentrates or wettable powders can be substituted for

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sodium fluosilicate in any wet-bait for- mula containing bran and sawdust. Ei- ther one kills more quickly and for a longer period than sodium fluosilicate. Chlordane at 1/2 pound and toxaphene at 1 pound have consistently given at least as good kill as 6 pounds of sodium fluo- silicate per 100 pounds of dry bran and sawdust.

Stir the emulsion concentrate or wet- table powder into the quantity of water required for wet baits and apply to the bran-sawdust mixture in a single mix- ing operation. They are obtainable at various strengths, but, whatever their strength, use enough to provide the amount of insecticide indicated in the following formula:

Mill-run bran 25 lb.

Sawdust, three times the

volume of bran ..3 1/2 bu.

Chlordane 1/2 lb.

or

Toxaphene o .... 1 lb.

or

Sodium fluosilicate 6 lb.

Water to make a moist,

crumbly mash 10-12 gal.

Spread wet bait uniformly at the rate of 20 pounds per acre.

Dry Baits. --Dry baits made by im- pregnating coarse bran with an oil solu- tion of chlordane or toxaphene have been used very successfully in controlling grasshoppers on range land.

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I

Use 1/2 pound of chlordane or 1 pound of toxaphene in each 1/2 gallon of solu- tion. Kerosene and fuel oil have been used as solvents. Apply the oil solution as a finely divided spray at the rate of 1/2 gallon to 100 pounds of coarse, dry ik bran containing no flourlike materia]. M Power bait-mixing machines may be equipped with spraying devices for this purpose. In mixing dry bait every effort should be made to obtain uniform distri- bution of the small quantity of solution throughout the dry bran.

Dry bait can be applied by airplane and single-outlet dusters, but wet-bait broadcasting machines are not equipped to apply such a small quantity uniformly. |

The dosage recommended, 5 to 10 ! pounds of dry bait per acre, is equiv- alent to 20 to 40 pounds of wet bait in terms of bran content. This is an ad- vantage, particularly when bait is ap- plied by airplane, because the plane can i operate four times as long without re- i loading. Dry bait may be prepared in ' advance and stored until needed.

Precautions. - -Baits containing chlordane or toxaphene are very toxic if eaten by livestock. When baits are spread uniformly at recommended dos- ages, the animals cannot pick up enough flakes to affect their health, but if they ^ have access to baits stored in sacks or piles or to heavy accumulations on the I ground^their health and lives are endan- gered.

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STORE BAIT WHERE LIVESTOCK CANNOT REACH IT AND AVOID GROUND ACCUMULATIONS.

KEEP LIVESTOCK OFF AIR STRIPS WHERE PLANES ARE BEING LOADED.

LOAD PLANES WITH AS LITTLE SPILLING OF BAIT AS POSSIBLE, AND CLEAN UP ALL SPILLED BAIT ON THE AIR STRIPS OR IN SUR- ROUNDING GRASS, WEEDS, OR BRUSH.

Community Action Needed for Successful Control

Regardless of the method used, grasshopper control is most effective when all property owners in a com- munity cooperate in destroying threat- ening infestations of grasshoppers wher^ ever they are found.

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This publication was prepared by Claude Wakeland, Division of Grass- hopper Control, and J. R. Parker, Division of Cereal and Forage Insect Investigations. It supersedes EC-7, Grasshopper Control Improved by New Insecticides, issued in February 1949.