TATE PLANT BOAWO E-478 June 1939 United States Department of Agriculture Bureau of Entomology and Plant Quarantine RECOMMENDATIONS FOR THE CONTROL OF CERTAIN INSECTS ATTACKING VEGETABLES, STRAWBERRIES. AND RASPBERRIES By W. H. White, in Charge, Division of Truck Crop and Garden Insect Investigations Contents Page Introduction 2 Location of work 2 Materials tested 2 Principal insects involved 2 Recommendations for control 2 Cabbage caterpillars on cabbage 3 Materials for dusts 3 Materials for sprays 3 Relative effectiveness of dusts to specific cabbage insects 4 Derris 4 Pyre thrum 5 Pyrethrum-derris extracts in combination 5 Paris green dusts 6 Cryolite (sodium fluoaluminate) dusts 6 Calcium arsenate dusts 6 Cabbage caterpillars on cauliflower, broccoli, kale, and collards 6 Cutworms and corn earworms on cabbage 7 Cabbage webworms on cabbage 7 Celery insects 7 Celery leaf tier 7 Celery looper 7 Cutworms 8 Cultural practice 8 Lettuce and spinach insects 8 Melonworm and pickleworm 8 Pepper weevil 9 Vegetable weevil 10 Mexican bean beetle 10 Sprays 10 Dusts 10 Strawberry weevil 11 Raspberry fruitworm 12 Clean-up measures as an aid to control 13 Where to obtain insecticides 13 Quantities of insecticides or ingredients to be used in preparing sprays 13 -2- INTRODUCTION This supersedes raultigraphed circular E-376, Recommendations for the Control of Insects Attacking Certain Vegetables, Small Fruits, and To- bacco, which was issued in April 1936 and revised in March 1937. The de- velopments during 1937 and 1938 at the various laboratories of this Bureau have made desirable certain changes in the information and recommendations previously issued. LOCATION OF WORK This Bureau's researches on methods of control of certain insects, having for their object the elimination of harmful insecticidal residues from the vegetable products, are being conducted at the following field laboratories: Alhambra, Calif., Baton Rouge, La., Chadbourn, N. C, Charles- ton, S. C, Columbus, Ohio, Sanford, Fla., and Phoenix, Ariz. MATERIALS TESTED The recommendations included in this circular are based principally upon tests with the following insecticides: Dusts: Commercially prepared or home-mixed derris or cube root powder, pyrethrum powder, and cryolite (nat- ural and synthetic), used with various diluents, paris green diluted with hydrated lime, and commercial calcium arsenate in the undiluted form and diluted with sulfur. Sprays: Derris or cube root powder in water, com- mercially prepared extracts of derris and of pyrethrum and combinations of these materials, and cryolite (natural and synthetic). PRINCIPAL INSECTS INVOLVED The principal pests involved in these experiments are several kinds of lepidopterous larvae attacking cabbage and including the imported cabbage worm, the cabbage looper, the diamondback moth, the cabbage webworm, the corn earworra, and cutworms. Also the celery leaf tier, the Mexican bean beetle, the pepper weevil, the vegetable weevil, the melonworm, the pickleworm, the strawberry weevil, and the raspberry fruitworm. RECOMMENDATIONS FOR CONTROL The following recommendations are applicable only to certain crops on which harmful insecticidal residues may occur on the marketed product and are the best methods available that can be utilized and at the same time insure against harmful residues remaining on the product consumed by man. Lead arsenate is not recommended for the control of insects attacking any vegetable crop considered in this circular. The use of other arsenicals and cryolite is suggested as a control for certain insects on several of the crops under consideration. This suggestion is made with the provision that the £0 ison should not be used after the appearance on the plant of fruit or foliage which will be sent to market or consumed , except in cases where it is definitely known that washing or strip- ping will remove all spray residues . -3- Everyone handling or using insecticides should be warned of the poi- sonous nature of arsenicals and similar materials and should take special precautions to be certain that such materials do not remain on the marketed product. From the evidence at hand, the compounds of derris, cube, and pyre- thrum, when applied at the dosages recommended herein, should not leave harm- ful residues on the market product. The active principles of these materials are rendered inert within a comparatively short time through the action of sunlight and exposure to the air, especially when spread thinly over the plants . CABBAGE CATERPILLARS ON CABBAGE As a general recommendation for the control of the imported cabbage worm, the cabbage looper, and the diamondback moth on cabbage, the following materials (as dusts) are recommended in the order listed, at the dosages detailed later in this circular. Materials for dusts (1) Derris, (2) Pyrethrum, (3) Paris green, cryolite, calcium arsenate. The dusts containing these materials should be applied in such a man- ner as to cov.r all infested portions of the plant, care being taken to reach the insects whenever possible. The rate of application may vary according to the size of the plants. Applications of 15 to 20 pounds per acre, per application, of the dust mixtures discussed later have given satisfactory results. Applications should be made in accordance with the more specific recommendations that follow; they should begin when the caterpillars first appear and be repeated as often as necessary to protect the crop. It is essential that the insecticides be applied when the caterpillars are small, as the larger ones, especially the cabbage looper. are usually more difficult to kill, r'urthermore , it is essential that the caterpillars be killed before they have caused appreciable injury to the plants. NOTE: Paris green, cryolite, and calcium arsenate should not be used on any portion of the cabbage plant that is to be marketed. This means that cabbage intended for marketing as U. S. grade No. 1 (which allows four loose outer leaves) should not be poisoned with these materials after the head be- gins to form. If the marketed product is to bear a greater number of loose outer leaves than those allowed in the above grade, these materials should not be used after the plants have been thinned or transplanted. Materials for sprays In general, dusts have given better results than sprays in cabbage caterpillar control. If desirable to use a spray, the following materials are recommended. Experiments to date have not indicated any special prefer- MBR^Vabd. -4- ence for either of these spray materials on the basis of their effectiveness. (1) Derris root powder in water. (2) Pyrethrum extract, or pyrethrum-derris extract combined. Relative effectiveness of dusts to specific cabbage insects Based upon the relative efficiency, at the dosages recommended herein, of each of the insecticides tested, against each of the principal species of cabbage caterpillars present, experiments indicate: (1) That as a control for the imported cabbage worm, derris is more effective than pyrethrum, paris green, cryolite, or calcium arsenate; (2) that derris and cryolite are approximately equal in effectiveness in controlling the cabbage looper, and that both materials are more effective than paris green, pyrethrum, or cal- cium arsenate; (3) that derris and calcium arsenate are approximately equal in effectiveness in controlling the larvae of the diamondback moth, while pyrethrum, cryolite, and paris green are relatively less effective for this species. Derris Derris dusts. — Derris dusts containing 0.5 to 1.0 percent of rotenone have given very promising results in four sections of the Central, Eastern, and Southern States. Satisfactory diluents for the derris root powder are such nonalkaline materials as finely ground tobacco dust, finely ground inert clay, talc, diatomaceous earth, infusorial earth, wheat flour, dusting gyp- sura, kaolin (china clay), and finely ground dusting sulphur. Some of these diluents have the advantage of being more economical in cost and more readily available in some sections of the country than in others. Indications are that derris retains its insecticidal value for a period of only approximately 1 week in the field, under favorable weather conditions. The rotenone content of derris root varies, and purchases should be made on the basis of rotenone content, total extractives, and degree of fine- ness. For example, a derris root powder containing 4 percent rotenone should contain not less than 14 percent total carbon-tetrachloride or ether extrac- tives. In general, the total extract (either by carbon tetrachloride or ether) should average approximately three and one-half times the rotenone content. The derris root powder should be of such degree of fineness that not less than 90 percent of it will pass through a sieve having 200 meshes per linear inch, and all of the material (100 percent) should pass through a sieve having 80 meshes per linear inch. The rotenone content of the finished mixed dust depends, of course, on the quantity of diluent used as well as on the percentage of rotenone in the original material. Insecticide companies now sell high-grade, finely ground derris powder of specified rotenone content made by blending the var- ious analyzed batches. -5- To prepare a dust containing 1 percent of rotenone, use the following formula: Derris powder (4 percent rotenone) 25 lbs. (1 part by weight) Diluent 75 lbs. (3 parts by weight) To prepare a dust containing 0.5 percent of rotenone, use the follow- ing formula: Derris powder (4 percent rotenone) 12^ lbs. (1 part by weight) Diluent 87j lbs. (7 parts by weight) If the rotenone content of the derris powder is greater or less than 4 percent, the proportions of inert diluent must be varied accordingly. For example, a derris powder containing 5 percent of rotenone should be mixed with 4 parts of the diluent by weight, that is. 20 pounds of the derris pow- der containing 5 percent of rotenone and 80 pounds of the diluent, to obtain a 1-percent rotenone dust. Derris dusts have also given an indication that they may aid in the control of certain aphids, as well as flea beetles which infest cabbage and related crops. Derris sprays . — Good control has been obtained with derris root pow- der (containing 4 percent of rotenone) in water at the rate of 2 to 2-^ pounds per 50 gallons of water, giving a rotenone content in the spray rang- ing from 0.02 to 0.025 percent. If the rotenone content of the derris pow- der is greater or less than 4 percent, the amount of the powder used should be varied accordingly in order to give the above indicated strengths of 0.02 to 0.025 percent rotenone content in the spray. For example, if the derris root powder contains 5.5 percent rotenone, 1-| pounds of the powder should be used to give the desired content in the spray. Under some conditions it may be necessary to add a nonalkaline spreader or sticker to the spray, such as high-grade liquid or powdered neutral coconut oil soap, miscible pine oil, or one of the sulphonated oils. Pyrethrum Pyre thrum dusts . — Pure fresh pyrethrum dust, containing approximately 0.9 percent total pyrethrins, diluted with 2 to 3 parts of the same diluents, by weight , as recommended for use with derris dust , have shown promising results . Pyrethrum sprays. — Fairly satisfactory results have been obtained by the use of commercial pyrethrum extracts. These extracts vary as to their pyrethrin content. The directions given by the manufacturer should be used as a basis for the dilution of these materials. Pyrethrum-derris extracts in combination Fairly satisfactory results have been obtained with commercially pre- pared extracts of pyrethrum and derris in combination. The directions given by the manufacturer should be used as a basis for the dilutioon of these materials. -6- Paris green dusts Results indicate that paris green is more effective as a dust than as a spray when used at a dilution of 1 pound to 9 pounds of hydrated lime, ap- plied at a rate of 20 pounds per acre, per application, until the plant be- gins to head, provided the headed cabbage is stripped to four loose outer or wrapper leaves when being prepared for market. If the marketed product is to bear a greater number of loose outer leaves than those allowed in the above grade, paris green should not be used after the plants have been thinned or transplanted. Cryolite (sodium fluoaluminate) dusts Both synthetic and natural cryolite prepared for insecticidal purposes have given favorable results when mixed with from 1 to 2 parts of the dilu- ents mentioned for derris dusts. The same care should be exercised to avoid harmful residues from cryolite, as has been prescribed for arsenicals. Calcium arsenate dusts Results with commercial calcium arsenate, for cabbage caterpillar control, have shown a variation in the toxicity of various brands of this arsenical. Calcium arsenate, in the undiluted form, gave fairly satisfactory results when applied at the rate of 15 to 20 pounds per acre per application. On account of the harmful residue hazard, this material is subject to the same limitations mentioned for paris green and cryolite. CABBAGE CATERPILLARS ON CAULIFLOWER, BROCCOLI, KALE, AND COLLARDS The Bureau has not yet had an opportunity to conduct any extensive ex- periments on the control of cabbage caterpillars on cauliflower, broccoli, kale, or collards. In general, it is believed that the derris and pyrethrum compounds should give the same results on these crops as when used on cab- bage, provided a good coverage of the affected parts of the plant can be obtained. Preliminary experiments in California have shown that derris, or cube, or pyrethrum dust mixtures, at the same dilutions as have been mentioned for cabbage, gave as satisfactory results in the control of the three more common species of cabbage caterpillars on cauliflower as they did on cabbage. It was found to be especially important . however, to start the treatments early in the development of the cauliflower, while the plants were small , since it was not possible to obtain a good coverage of the insecticides over the heavy foliage of nearly mature cauliflower plants . Good results were also obtained against cabbage caterpillars on cauliflower with sprays of derris root powder containing from 0.02 to 0.025 percent of rotenone (viz., 2 to 2j pounds of derris root powder containing 4 percent of rotenone per 50 gallons of water) , The experiments of 1934 on collards indicate that each of the three more common species of cabbage caterpillars may be controlled satisfactorily with a derris dust mixture containing 0.5 percent of rotenone. Less satis- factory results were obtained with pyrethrum powder containing 0.9 percent -7- total pyrethrins, diluted with 5 parts of the same materials as mentioned for derris dust. It should be emphasized that arsenicals are not recommend- ed for cabbage caterpillar control on these crops, owing to the poisonous residues likely to remain on the edible portion, and because less satisfactory results were obtained with arsenicals. CUTWORMS AND CORN EARWORMS ON CABBAGE In certain sections of th'i country, especially during the fall season, several species of cutworms and the corn earworm are sometimes more abundant and cause more damage to the foliage of cabbage than do the usually more prevalent species of "green" cabbage caterpillars. Neither derris nor pyrethrum, at the dilutions tested, has been effective in combating cutworms or the corn earworm on cabbage. When such cutworm infestations are ex- pected, a standard cutworm poisoned bait should be used before the crop is set in the field, or, in cases where seed is planted, the treatments should be made before the plants appear above the ground. The early treatments can be followed by later treatments, care being exercised to prevent the bait from lodging on any portion of the plants that are to be marketed. When the corn earworm is present in destructive abundance on cabbage, dust applications of paris green, calcium arsenate, or cryolite should be made, at the strengths recommended in this circular, before the plants begin to head. CABBAGE WEBWORMS ON CABBAGE Recent experiments indicate that the cabbage webworm can be controlled by applications of dust containing 0.75 percent of rotenone, or undiluted cal- cium arsenate, provided applications are made during the early stages in the growth of the insects and of the plants. In these treatments, the young cabbage plants should be covered thoroughly with the dust. CELERY INSECTS Celery leaf tier The celery leaf tier is the major pest of celery in the Florida pro- ducing area, and also periodically becomes troublesome in the North and in California. This pest can be controlled by careful treatments with pyre- thrum dust, the dust being mixed with an equal quantity by volume of tobacco dust. The treatment consists of making two applications within a period of one-half hour. The object of making the second treatment within such a period is to kill those caterpillars which have moved from the web as a result of the first treatment. Approximately 25 pounds of the mixture per acre are necessary for each application. Except under unusual conditions in the Florida area, one treatment, that is, two applications at a half-hour interval, is sufficient to protect any one given area of celery. Arsenicals are not satisfactory as a control for this pest. Celery looper Several species of loopers attack celery. In Florida these pests are usually held in check by a bacterial disease, and observations so far would indicate that ordinarily no artificial control measures are necessary. These -8- pests succumb readily to treatments of pyrethrum powder as recommended for the celery leaf tier, and arsenical applications are not necessary. Cutworms The use of a poisoned bait is the only practicable means for the con- trol of the majority of the species of cutworms attacking celery. The risk from poison residue can be eliminated by distributing the bait between the rows, provided care is taken to keep the bait from falling on the plants. In the Florida celery district the southern armyworm is usually con- sidered as a cutworm, inasmuch as it exhibits similar habits in the late stages of its development. The successful control of this species, however, depends on the prompt application of an arsenical at the time the eggs are hatching. Paris green added to the regular bordeaux mixture and applied when the presence of the young caterpillars is first detected may be used, pro- vided no applications are made on plants which will be harvested within a period of less than 6 weeks. From 1 to 2 pounds of paris green per 100 gallons of bordeaux mixture have been used successfully. Cultural practice Under Florida conditions, the cleaning up of the crop refuse during harvest is valuable in pest control, particularly of the celery leaf tier. LETTUCE AND SPINACH INSECTS There are several leaf-feeding forms which may attack lettuce and spinach, and on occasion cause considerable damage. Pyrethrum or derris is recommended as a substitute for the arsenicals in the control of these pests, using the same dosages as given for cabbage caterpillars. MELONWORM AND PICKLEWORM The indications are that the melonworm and the pickleworm may be con- trolled satisfactorily on squash in the coastal areas of North Carolina and South Carolina, and probably elsewhere when the returns from the crop will justify the expense involved, by dusting with a derris-sulfur mixture con- taining from 1 to 1.5 percent of rotenone. In instances of light to moder- ate infestation the 1-percent or even 0.5-percent strength rotenone dust should be sufficient if it is applied early and regularly. Where the in- festation is heavy the 1.5-percent dust should be used. While finely ground dusting sulfur seems to be the most effective diluent for derris powder for use in melonworm and pickleworm control on squash, this material may cause slight injury to the foliage of this crop. The addition of from 10 to 25 percent of tobacco dust, clay, or talc to the derris-sulfur mixture will im- prove its dusting qualities. The treatments should be begun when the caterpillars first appear on the leaf buds of the squash plant, which may be within a week or 10 days af- ter the plants appear above ground, and continued at 7-day intervals as long as the caterpillars are present or the crop is being harvested. The rate of -9- application will depend upon the size of the plants and should range from 15 to 25 pounds per acre. Extreme care should be exercised to see that the growing tips of the plants are well covered with the dust, as the caterpil- lars feed extensively on the young leaf buds before tunneling into the fruit, stem, and vines. Pyrethrum powder has also proved of some value in the control of these pests. The pyrethrum powder should be used in a mixture with clay or talc and dusting sulfur, equal parts of the pyrethrum and the diluent being used, Cryolite, mixed with clay and finely ground dusting sulfur in the ratio of 1 pound of cryolite to 1 pound of clay and 2 pounds of sulfur, may be used to advantage in early treatments. In order to avoid danger of poisonous residues on the market product, tretment with this material should not be made after the fruit has begun to set. Calcium arsenate has not proved satisfactory as a poison for the melonworm or pickleworm. A bellows-type duster is more satisfactory for the treatment of the squash crop than a duster of the rotary type because of the method of plant- ing and the necessity of applying the material directly to the growing tips of the plant. In the case of crops producing extensive vines, a duster of the rotary type may be more satisfactory. PEPPER WEEVIL While the pepper weevil can be controlled by treating the crop at regular intervals with undiluted calcium arsenate, or with equal parts of calcium arsenate and hydrated lime, this method is not to be recommended unless the residue can be adequately removed by washing. Excessive appli- cations of calcium arsenate may result in heavy infestations of plant lice which are capable of causing more crop loss than pepper weevil infestations. Such aphid infestations may be controlled with nicotine dust applied alone, or mixed with the calcium arsenate. CAUTION:- It is emphasized that all peppers treated with calcium arsenate or other arsenical must be washed before they are marketed or proc- essed. For conditions which obtain in California, cultural control is recom- mended. This involves complete destruction of pepper plants after harvest, and also the clean-up of nightshade plants and eggplants in the vicinity of pepper fields, the nightshade being a favorite winter host of the pepper weevil. The pepper fields should be plowed at least by January 1, and all nightshade plants destroyed by the 10th of January. This gives a period be- tween the destruction of the winter host plants and the planting of the seed bed in excess of the time that pepper weevils are able to live on other than their normal host plants. No experiments have been conducted on the control of the pepper weevil in New Mexico or Texas, and no recommendations are made for the control of this pest in these two areas. -10- VEGETABLE WEEVIL The vegetable weevil is a pest of vegetable crops in certain sections of Alabama, Arkansas, California, Florida, Georgia, Louisiana, Mississippi, and Texas. It is also known to occur in Tennessee and South Carolina. The following methods are recommended for its control: (1) Experiments have shown that early applications of derris or cube dust mixtures containing 1.0 percent of rotenone, with any of the diluents mentioned for use against cabbage caterpillars, or of dust mixtures con- taining equal parts of pure fresh pyrethrum dust and talc, or similar dilu- ent, will control the vegetable weevil if applied at intervals of approxi- mately one week at the time when the young weevil grubs are feeding on the plants. (2) The treatment of seed beds, such as tomato and cabbage, or young field-set plants, and crop remnants after harvest, with arsenicals or fluo- rine compounds is advocated. Arsenicals or fluorine compounds should not be applied to turnips, mustard, or similar crops, the leaves of which are in- tended for food. (3) Field sanitation. All rubbish and weeds where the insect may find shelter during inactive periods should be cleaned up. MEXICAN BEAN BEETLE Finely ground derris or cube root, as well as cryolite, are recom- mended for the control of the Mexican bean beetle. Sprays Ground derris or cube having a rotenone content of 4 percent should be used at a dosage of 1-g- pounds in 50 gallons of water or at a rate of ly oun- ces in 3 gallons. This gives a rotenone content of approximately 0.015 percent. Derris or cube of different rotenone content may be used in the proper proportion so as to make the finished spray of a content of 0.015 percent rotenone, If the ground root contains a higher percentage of rotenone than 4 percent, decrease the dosage proportionately. For instance, if a 5 percent rotenone-content derris or cube powder is on hand, use only four- fifths as much, namely, approximately 1^ pounds to 50 gallons or 1^ ounces to 3 gallons. Extensive tests indicate that no spreader or sticker is necessary with derris or cube in water for use on beans. Cryolite, either natural or synthetic, may be used at a dosage of 3 pounds in 50 gallons of water, or 3 ounces in 3 gallons. When cryolite is used, treatments with this material should stop when pods begin to form. Dusts Growers who prefer to dust or are not equipped to spray will obtair fairly satisfactory results rith any of the following dust mixtures' -11- Derris powder or cube powder may be mixed with one of the following diluents or carriers and used in dust form: Talc, finely ground dusting sul- fur, inert clay, tobacco dust, kaolin (china clay), or other inert, finely gound material. The finished dust should contain 0.5 percent of rotenone, that is, 12-|- pounds of 4-percent derris or cube and 87-g- pounds of carrier or ciluent. Finely ground sulfur is of value against the common red spider, the potato leafhopper on bean, powdery mildew, and the Mexican bean beetle and is to be preferred when any of these are present in injurious numbers. It is likely to flow too freely from many dusting machines, and care should be taken not to apply unnecessarily heavy dosages with consequent higher costs. Twenty to 25 pounds to the acre per application is the recommended dosage. The use of hoods or trailers, constructed from bamboo poles and barrel hoops and covered with muslin, 10 feet long, used one to the row be- hind power or traction dusters, makes possible a considerable saving in the dosage. Commercial rotenone-bearing dusts usually contain 0.5 percent to 0.75 percent of rotenone and are prepared to be used as dusts. These mixtures should not be used for spraying, unless the label on the package indicates that a diluent has been used which will mix readily with water. Except in semi-arid regions, plant injury often results from the use of calcium arsenate mixtures on beans. Lead arsenate should never be used on bean foliage because serious injury and reductions in yields often result from its use, even when combined with bordeaux mixture. The beans should be sprayed or dusted when adults are found in the field or when egg masses become numerous on the underside of the leaves. One to three, sometimes four, applications are required, depending on the abundance of the insect. The beans must be treated on the underside of the leaves, and care should be taken that the spraying or dusting is done thoroughly. Cultural control . — The destruction of crop remnants after harvest is as important as thorough spraying or dusting. Plow under all plant remnants at least 6 inches deep. STRAWBERRY WEEVIL Fairly satisfactory control of the strawberry weevil may be obtained by dusting with a mixture consisting of 1 pound of calcium arsenate and 5 pounds of finely ground dusting sulfur. The first application should be made as soon as the weevil appears in the field. The rate of application will range from 10 to 30 pounds per acre per application, depending upon the den- sity of the strawberry planting. Ordinarily two applications are sufficient to protect the early fruit. All applications of poison dusts should be discontinued at least 3 weeks prior to the ripening of the first berries, because, where a long bearing season obtains, the treatment with an arsenical poison after this period may result in harmful residues on the ripened berries. The hibernation habits of the strawberry weevil in some sections, par- ticularly in North Carolina, are such that the destruction of the weevil by burning over its hibernating areas is an aid in reducing losses from attacks -12- of this pest. This burning is necessary only in a strip approximately 100 feet wide along the edges of the strawberry field, because experiments have shown that approximately 97 percent of the strawberry weevils hibernate within 100 feet of the cultivated areas. CAUTION: The burning should be carried on in the winter and in the spring and every precaution should be taken to prevent the fire from getting into the woods. RASPBERRY FRUITWORM The raspberry fruitworm is one of the most important pests of rasp- berries in the northern part of the United States. Damage by this insect has been recorded from Washington, Idaho, Montana, North Dakota, Minnesota, Iowa, Wisconsin, Michigan, Indiana, Ohio, New York, New Jersey, Massachusetts and Connecticut. In addition to raspberries, this pest often damages logan- berries, youngberries, blackberries, and boysanberries. Application of either ground derris or cube root will give satis- factory control of the raspberry fruitworm, if the work is done properly, whether such applications are made in the form of a spray or as a dust. In general, however, sprays have given better results than dusts in the control of this pest. Three applications of sprays containing finely ground derris or cube root powder, diluted in such a manner as to contain 0.01 percent of rotenone in the finished spray, are necessary for the best results. The first spray should be applied 10 days after blossoming begins, the second 7 days after the first, and the third 7 days after the second. If only two sprays are used, the first spray should be applied 15 days after blossoming begins and the second 10 days later. The last spray, if applied later than recommended, may leave an unsightly residue on the harvested fruit, particularly if derris or cube root low in rotenone is used, thus making it necessary to use a large quantity of the material. The derris or cube powder should be made into a paste with a small quantity of water before being added to the water in the spray tank. It is important to spray thoroughly on both sides of each row, and better results will be obtained if little or no breeze is blowing during the spraying operation. Since a few warm days will cause rapid development of the blossom buds, the grower should obtain his insecticides in advance and be prepared to apply them on short notice. Dust mixtures for use against the raspberry fruitworm should contain one-half of 1 percent (0.5 percent) of rotenone. There does not appear to be any advantage in using a mixture containing a higher percentage of roten- one. Very finely ground talc, bentonite clay, and tobacco dust are suitable for use as carriers. Lime should not be used for this purpose, since lime reduces greatly the effectiveness of these insecticides. Apply the dust mixtures early in the morning or late in the evening when there is little or no wind blowing. Do not point the nozzle of the dust gun directly at the plants but direct the dust down the between-row space near the plants and allow it to drift into them. Dust both sides of each row. Particular care should be taken in the last application to avoid covering the berries with an excessive quantity of dust, since this may leave an unsightly residue on the harvested fruit. -13- CAUTION: Under no circumstances should lead arsenate or any other arsenical be applied as a dust or a spray for the control of the raspberry fruitworm after the blossoms have opened. Treatments made after this period may leave dangerous quantities of poisonous residues on the harvested ber- ries. Derris or cube sprays or dusts have the advantage of not leaving poisonous residues on the marketed product. CLEAN-UP MEASURES AS AN AID TO CONTROL Emphasis should be placed on the thorough cleaning up of crop remnants after harvest. It has been observed, in the southern producing areas partic- ularly, that fields of harvested cabbage and similar crops serve as a source of infestation to new plantings. 'WHERE TO OBTAIN INSECTICIDES Information regarding the purchase of the insecticide materials men- tioned in this circular may be obtained usually through local dealers in agri- cultural supplies, seedsmen, general stores, and drug stores, or through the county agricultural agent. State agricultural experiment station. State department of agriculture, or Bureau of Entomology and Plant Quarantine. U. S. Department of Agriculture. QUANTITIES OF INSECTICIDES OR INGREDIENTS TO BE USED IN PREPARING SPRAYS The following table gives the quantities of insecticides or in- gredients that should be used with 1,3, or 50 gallons of water in making up some of the sprays used commonly in combating insects which attack vege- tables and berries. When slightly different strengths of the sprays are required for certain insects, a corresponding change can be made in the quantities used. Quantities of ingredients to be used — Materials With 1 gallon With 3 gallons With 50 gallons DERRIS OR CUBE ROOT POWDERl/ 5-percent rotenone 4-percent rotenone 3-percent rotenone 0.75-percent rotenone 0.5-percent rotenone of water 1 ounce 1 ounce 1^ ounces 4^ ounces 7 ounces of water 2 ounces 2^ ounces 3i ounces 13^ ounces 1-j pounds of water 2 pounds 2 2/3 pounds 3|- pounds 14 pounds 21 pounds CRYOLITE Cryolite 1 ounce 3 ounces 3 pounds 1/ These dilutions give a rotenone content of approximately 0.025 percent in the completed spray. UNIVERSITY OF FLORIDA -14- 3 1262 09236 6730 Materials PARIS GREEN-LIME MIXTURE With 1 of water Quantities of ingredients used — _ gallon With 3 gallons With 50 gallons of water of water •iL Paris green Lime 2 level tea- spoonfuls 2 level table- spoonfuls 6 level tea- spoonfuls 2 ounces ■g- pound 2 pounds CALCIUM ARSENATE-LIME MIXTURE Calcium arsenate Lime 10 level tea- spoonfuls 10 level table- spoonfuls 2 ounces 8 ounces 2 pounds 8 pounds NICOTINE SULFATE-SOAP MIXTURE Nicotine sulfated/ Cake soap (Or soap flakes) 1 level tea- spoonful 1-inch cube 2 level table- spoonfuls 3 level tea- spoonfuls 4 ounces 2 ounces 6 fluid ounces 4 pounds 2 pounds 2/ A solution containing 40 percent of nicotine by v/eight. The derris or cube powder should be wet thoroughly in a small quantity of water before it is added to the bulk of the water in the spray tank. The results to date indicate that no sticker or spreader is necessary when derris or cube root powder in water is used on beans. Under some condi- tions, however, it may be found necessary to add to the spray a nonalkaline spreader or sticker, such as high-grade liquid or powdered neutral coconut- oil soap, miscible pine oil, or one of the sulfonated oils.