,TATE PLANT I February 19-+2 ' " . £-560 United States Department ..of Agriculture ; Bureau of Entomology and Plant Quarantine SUGGESTED REDUCTIONS IN ROTENOInIE CONTENT ., OF INSECTICIDE. DUST MIXTURES APPLIED TO VEGETABLES Prepared by the Division of Truck' "Crop""" and' Garden Insect Investigations . In view of the probable shortage of rotenone whi<:h hag been im- posed by war' concitions, with the consequent necessity of conserving available supplies of this niiaterial, it seems possible, that , v;ithout a marked loss in effectiveness, slight reductions can be made in the rotenone content of insecticides recomraende,d by this Burea-ii for use in the control of certain of the mdre important insects v/hfcH attack. veg- etables, ■■ Such reductions, however, make it necessary that extreme care, be takea to make certain that "the rotenone content is not lower than that' shown in the revised recom-nendations given below. These re- ductipiis crlso require that there' be no decreases .in_ the .recommended dosages .or rates of application per acre, that, equipment b,e used that will ensure a thorough coverage of the treated plants, and that the insecticide applications Ibe made at the proper time. As a further measure in conserving the supplies of rotenone, emphasis is placed upon the desirability of using, whenever possible, and with the restrictions mentioned Itelow, .certain .substitutes for in- :secticides Containing rotenone* ' • Cabbago Caterpillars on Cabbage . Present ■reeommendationt For mixed populations of cabbage c-^ttr- pillars 1/ attacking cabbage the present recommendations specify (l) the use of dust mixtures containing 1.0 percent of rotenone applied at the rat-e of 15 to 25 pounds per. acre, depending upon the size of the plants, or- .(2) t'he use. of pyrethrum dust mixtures containing ,appro:jcimately 0,3 percent. :of total pyrethrins, at the same rate as in (l). Revised recommendation t (l) It is believed that reasonably satis- factory control of cabba&c Co^terpillars on .cabbage can be achieved by applying a" dust mixture containing 0,75 percent "of " rottnonw at the rate of application mentioned previously, with the provision .that if one appli- cation is not ciff active "a second applicoition bo given.. (2) .It is recommend- ed that whonevor. possible pyrethrum dust mixtures containing 0,3 percent of total pyrethrina, or impregnated pyretlv"um dusts co^itaining 0,j percent of totfetl pyrothrins, "bo used insteaci of/thvi dUst mixtures or dusts con- taining rotenone, ' ' 1/ Imported cabbage "worm, cabbage looper, and ■-iamdnt.back moth. •2- Note: Ihi'st- ci'xtures or dusta containing the "dilutions of rotenone or pyrethrum teentidhed i'n this -circular "rKiy be used -for the purpose in- dicated L.t any tLn:e during the gro-./th of the crop without incurring the hc^rroful residue -hazard. Substitutes recomiTiended; The following insecticides nuy be ap- plied prior to tOle' heltding- of the- CGtb-igc pla'nts ," although in gcncr'il they are less effeotive in controlling' cabbage caterpillars than dust mixtures contc^ining the recommended dilutions of rotenone or pyrethrura. (1) Paris green (l pouhd) and hydrated limie (9 pounds) (2') Cryolite'(l pound) and' talc or clay (2- pounds ) ^:^ (3) Calcium arsenate j undiluted ■ '-■' -^" *' '"' ■■■ '• '■• Caution: Paris grfeen, cryolite, and calcium'arsehate should not be used on- any portion of the cabbage plant that is to be marketed. This means' thut cabbage intended for m^'ifkctihg as U. ' S. gradg No.'l (which allows four loose outer* leaves) should hot lie poisoned with.tliese materials -after the heads begin to' form. If the marketed product is to bear a greater number of loose outer leaves than thoje allowed in tho "above grade, these-'materiala should not Be used after the plants have been thinned or transplanted, • ' '• Cabbage Caterpillars on C.culif lov/er, Broccoli, Kale, a'rtd'Cillards The derris or pyrothrum dust mixfure 'recoianended for the control of cabbage caterpillars on cabb..go should also be u-sed f or the control of these caterpillars on cauliflower, broccoli, kale, collards, and similar crops. Special care- ^sho^uld- be taken to get ^ complete coverage of the affected parts of the plant \;ith the insecticide. It should bo emphasized that arsonicds, cryolite, or other " inorganic' insecticides are' hot recomm ended fo'r cabb-gc caterpillar, con- trol on these crops at" any t-imc after thinning or transplanting ov/ing to tJ^G poisonous rociduos likely to remain 'on the edible "portion. Pea Aphid Present recommendation t Specifies (l)-.the use of a dust mixture containing 1,0 percent of rotenone, applied' at 'the rate of 3.5. to ;4Q pounds per acrai,- or (2) the use of. a dust mixture containing 4 percent of nicotine, applied at the safti© rate per acre as in (l). Revised rctommcndatiohi (l) As a revised recommendation it is suggested that during the emergency the rotenone content of the dust mixture be reduced to 0.75 percent, with the provision that the appli- -outions bo made carlyin-the stage" of the " pea aphid' infestation and that the dust mixture bo applied thoroughly to' the plants at tho aam« rate mentioned previously. In applying this dust mixture the boom on .-3- the duster should be .enclosed completely, and a trailer 25 feet or more in length should be used. The insecticide is jnosi effective when there is little or no wind.. movement. Fields receiving the reduced rotenone- content dust mixture should be watched carefully and a' second appl-^ca- tion made it. such is found to be necessa.ry in order to b.chieve control. (2) It is re commended that v/henever possible a dust mixture containing 4 percent of nicotine be substituted for one containing rotenonc for use against the pea aphid. The nicotine dust mixture may be made up accord- ing to the follov/ing formula: Hydrated lime ^_-_-- - -; -40 pounds l.'onqhydrated copper sulfate - - 3 to 5 pounds • -;0,^ 'nicotine sulfate ------ 5 pounds (2 quarts) It is emphasized that for satisfactory results against the pea aphid with the ni'cotine 'dust mixture it is necessary to use a trailer at -least ■fO feet in length and that this dust mixture should be applied when the air temperature is above 65° F. and when the vines are dry. Mexican Bean 'Beetle .... Present recom^endat ion r Specifies (l) the use of a dust mixture containing 0,5 percent of rotenone, applied at the rate of 20 to 25 pounds per acre per application against the Mexican bean beetle, or (2) the use of a dust mixture, applied at the same rate per acre as in (l), made up according to tiie following formula: Cryolite ------------- 60 pounds ' ' " ^ Finely ground talc. or sulfur - -"- 40 pounds Caution: To avoid the harmful residue hazard, cryolite should not be applied to beans intended for harvest as green or snap beans after the pods. begin to 'form. ' ' "; Revised recommendation: As a revised recommendation for the control of the Mexican bean beetle durin.g the present emergency, it is suggested: (1) That no change be made in'th'o present recommended dilution of the dust mixture containing rotenone but that as a means of conserving supplies of rot.enone materials every effort b«i' made to use efficient equipment for applying this dust mixture and that the recommended rate of application per acre bo- not exceeded. (2) That ■.vhenevct possible the cryolite dust mixture be used, as a substitute for the rotenone dust mixture, with the provision that this material ^be" not" used after the pods begin to form on b-ia'ns intended for harvest' c;."s gre^-n or snap beans, in order to avoid the harmful residue hazard. It should be understood also that in some instances the cryolite dust mixture has not been' so efficient as the rotenone dust mixture^ in killing the Mexican- bean beetle. Substitutes recommended: It is recommended for the duration of the present emergency that vhcnever possible dust mixtures containing approximately 0,5 percent of total pyrethrins, or impregnated pyrethrum dusts containing approximately 0,3 percent of- total pyrethrins, be substituted for the dust mixtures containing rt>tenone or cryolite, against the Mexic-n bean beetle. P-ea Weevil Present recommendation: Specifies that a dust mixture containing not less than 0,75 percent of rotenohc, applied at the rate of" 20 to 25 pounds per acre, be used for the control of the pea weevil. Dust mix- tures containing 1 percent of rotehonc are also recommended. In apply- ing this dust mixture the boom on the duster should be enclosed complete- ly, and a trailer 25 feet or more in length should be used. Effective applications can not be made if the wind velocity exceeds 12 miles per hour. Revised recommendation: As a revised recommendation for the con- trol of the pea weevil during the present emergency it is suggested that dust mixtures containing 0,75 percent of rotenone be used for the control of the pea' weevil at the same recommended rate and method of application as at present, with emphasis upon the same precautions as" have been mentioned for' the pea aphid. ' '■ ' Turnip' Aphid Present recommendation: Specifies the use of a dust mixture con- taining 1.0 percent of rotenone or a dust mixture containing 3 percent of nicotine. Revised recommendation: (l) As a revised recommendation; for the control of the turnip aphid during the present bTnergency it is suggested that the rotenone content of the rotenone dust mixture be reduced to 0.75 percent, with emphasis upon the s^.m'o- precautions as ha.vo been men- tioned in the instance of the pea :.phid", except th>..t it is not essential to use ::. boom or trailer on the duster, (2) It is- recommended that when- ever possible -. dust mixture cont..ining 3' pc-rcent of nicotine bo sub- stituted for one containing rotenone. Such a nicotine dust mixture can be made up according to the' follov/ing formula: Hydratcd lime -------------- 92^ pounds 40 percent nicotine sulfate ------ ']2 pounds (3 quarts) This dust mixture should be applied at the rate of 15' to 30 pounds per :.cre per applic>.tion, depending on the size of the plants. It should not be applied 'when the temperature is bolo"\y ^^5^ ^t or when the vinua arc wet. ■5- GL-IIERAL The suggestions in the preceding discussion, insof:ir -s rotcnone compounds ;ire concerned, may be suimr.urizod us follows: (l) That in tho instances whore a 1,0 percent rotonone dust mixture hr.s been used a,^ inst c^^bbage ciiterpillurs, tho pea r.phid, ..nd the turnip aphid :i 0.75-percont rotcnone dust mixture be substituted, provided that special eraph-sis be placed upon the thoroughness ^nd tiraclinuss of applic-tion of a dust mixture containing the recomraended strength, 'tith a dosage v/hich does, not exceed jO pounds per .-ere. (2) That pyrethruni en be substituted for rotenone in the instance of cabbage caterpill-^rs and the Mexican bean beetle. (3) That nicotine dust can be substituted in the in3t:.nce of the pea aphid and the turnip aphid, (4) That the present recommenda- tion for -V dust mixture containing 0.5 P'TCcnt of rotenone for the Mexican bean beetle should be continutd. In addition it is recommended that for the control of fle^ beetles, stripea cucumber beetles, lettuce .nd celery loopers, pot:.to aphids, and asp...rugus beetles .. dust mixture containing 0.75 percent of rotenone be substituted for the present practice of using a dust mixture containing 1.0 percent of rotenone. The ^.bove recommendations -re iii..do ,;ith the full knowledge that the results of some experimental -.vork indic-vto that strengths lower than 0.75 percent of rotenone c^n be used in some instances, but, considering the limited evidence available, and that the chances of failure to control the insect are incre^-sed with tho lower strength dust and the minor s_.v- ing involved, the recommendation of a dust of lower strength is not warranted for general purposes. UNIVERSITY OF FLORIDA llllllllllliliililiillllllllllilll 3 1262 09230 3782