>AKl' October 1948 E-759 United States Department of Agriculture Agricultural Research Administration Bureau of Entomology and Plant Quarantine PAMTHION IN AEROSOLS FOR THE CONTROL OF PESTS ON GREENHOUSE ORNAMENTALS By Floyd F. Smith and P. H. Lung, Division of Truck Crop and Garden Insect Investigations, and R. A, Fulton, Division of Insecticide Investigations Parathion in aerosols has proved to be highly toxic to a wide range of greenhouse insects and other pests in experiments conducted during the past year at Beltsville, Md., and in commercial greenhouses nearby .■» In these experiments studies have been made to determine the dosage and fre- quency of application required to kill various pests, the fumigating and contact action of the chemical, the optimum temperature and moisture con- ditions for applying aerosols, and the tolerance of greenhouse plants to the chemical; also to gain experience with regard to safety precautions for the protection of greenhouse workers. The following information, which is based on experiments (Smith et al . 6) and observations, is presented for the use of formulators of parathion aerosols and for florists using them. Formulations The following formula (No. 151) has been used in most of our experi- ments. All percentages are by weight. Percent Parathion (technical 0,0-diethyl 0-£-nitrophenyl thiophosphate) 10 Acetone. 10 Methyl chloride • • 30 The acetone and parathion are mixed before they are introduced into the bomb. Tests have also been made with another formula (No. 168) containing 10 percent of technical parathion and 90 percent of methyl chloride. Some lots of parathion as received from the manufacturers are totally soluble in methyl chloride and perform satisfactorily in aerosols (Blauvelt and Hoff- man 1, 2). Other lots contain insoluble material, especially on cooling to about 40° F. or on long standing. When an equal quantity of acetone is added to parathion, a clear solution is obtained in methyl chloride, and the , 1/ Numerous commercial-scale treatments have also been conducted in Pennsylvania, in cooperation with C. A. Thomas, Pennsylvania Agricultural Experiment Station, the results of which are intended for separate publi- cation. - 2 - aerosol performs satisfactorily without clogging of nozzles. For this reason it is suggested that acetone be added to all lots of parathion. The health hazards in the handling of parathion are similar to those for tetraethyl pyrophosphate. Precautions and other details to be followed in applying this insecticide and in filling the cylinders are given in pre- vious articles (Smith et al . ^,£) • The possible hazard due to the pro- longed fumigation effect of parathion must also be considered. Pests Controlled Our findings on the pests controlled with parathion aerosols are in general agreement with those of Blauvelt and Hoffman QL, 2) • The green- house pests included in our experiments are listed below, together with a suggested treating schedule. Insect Number of applications Days between applications Rose leaf rollers, Platynota flavedana (Clem.) and P. stultana (Wlsm. ) 2 Red-bandea leaf roller, Argyrotaenia velutinana (Wlkr.) 2 Greenhouse leaf tier, Phlyctaenia rubigalis (Guen. ) 2 Tussock moth, Hemerocampa leucostigma (A. and S.) 1 Acalea leaf miner, Gracilaria azaleella Brants 2 Fuller rose beetle, Pantomorus godmani (Crotch) 1 Japanese beetle, Popillia~japonica Newm. 1 Strawberry root worm, Paria cane 11a (F. ) 1 American cockroach, Periplaneta americana (L. ) 1 Surinam roaoh, Pycnoscelus surinaxiensis (L. ) 1 European hearth cricket, Gryllodes sigTllatus Walk. 1 Field cricket, Acheta asslmiXls ft. 1 Greenhouse stone cricket, Tachycines asynamorus Adel. 1 Ring-legged earwig, Euborellia annul ipes (Lucas) 1 Greenhouse whitefly, Trialeurodes vaporariorum (Westw. ) 3 Mexican mealybug, Phenacoccus gossypii T. and C. Citrus mealybug, Pseudococous "oitri (Risso) 2 Grape mealybug, P. maritimus (Ehrh. ) 2 Greenhouse thrips", HeliothrTps haemorrhoidal is (Bouche) 2 Banded greenhouse thrips, Hercinothrips femoral is (Reut.) 2 Onion thrips, Thrips tabaci Lind. 2 Chrysanthemum thrips, T. nigropiiosus Uzel 2 Two-spotted spider mite" (red spider), Tetranychus bimaculatus Harvey 2 Cyclamen mite, Tarsonemus pallidus Banks 3 10 10 10 10 10 10 10 10 - 3 - Insect Number of applications Days between applications Broad mite, Hemitarsonemus latus (Banks) Sowbug, Armadillidiuro nasatum B.L. Pavement ant f Tetramorium cae'spitum (L. ) Pharaoh ant, Monomorium pharaoni s ^L. ) Black carpenter ant, Camponofaus herculeanus pennsylvanicus (Deg. ) Leaf-curling plum aphid, Anuraphis helichrysi (Kltb. ) Bean aphid, Aphis fabae Scop» Melon aphid, A. gossypii Glov. Corn leaf aphTd, A. maidis Fitoh Spirea aphid, A. spiraecola Patch Chrysanthemum aphid, Macro's iphonie 11a sanborni (Gill.) Potato aphid, Macrosiphum solanif olii (Ashm. ) Cre s cent-marked lily aphid, Myzus circumflexus (Buck. ) Foxglove aphid, M. convolvuli (Kltb. ) Carnation aphid,~M. dianthi (Schr. ) Green peach aphid"7 Myzus persicae (Sulz.) Gr e e n c hr y s ant hemum aphid, Rhopalo s iphum ruf omaculatum (Wilson) Spiders, including black widow spider, Latrodectus mactans (F. ) Climbing snailT Zonoitoides arboreus (Say), species of slugs nto5 but not several 10 Effect of Aerosols on plants In extensive tests in Maryland, Ohio, and Pennsylvania, where a dosage of 1 gram of parathion to 1,000 cubic feet of air space was used, no injury to floral crops and conservatory plants was noted except in the presence of sulfur. Where sulfur had been applied to heating pipes and volatilized for mildew control, or where sulfur-containing dusts had been applied to roses concurrently with, or shortly before, applica- tions of parathion, severe yellowing and dropping of old foliage has occurred. Present indications are that sulfur oan be applied about 7 days after the parathion aerosol without injuring plants. It has not been determined how soon after a sulfur application it is safe to use para- thion, because the volatilization of sulfur varies with greenhouse con- ditions. Based on the persistant odor of sulfur in treated greenhouses, it appears that at least 1 week should elapse before the parathion is applied. It may be advisable to use malachite green (McClellan 3) instead of sulfur, if there is need for mildew control at the time par- athion is being used. - 4 - No information is available as to the results that might be experi- enced if parathion is used with other fungicides or insecticides, with the exception of one report received that in the presence of selenium plant injury may follow. Therefore, in cases where sulfur and selenium are liable to cause complications when parathion is used, it would be advisable to use tetraethyl pyrophosphate or DDT and to apply parathion aerosols only against insect pests that are resistant to these materials, such as rose leaf rollers and the Surinam roach. Time of Treatment The parathion aerosol may be applied at any time that the greenhouse ventilators can be left closed for at least 2 hours, and preferably 4 hours, without endangering the crop from high temperatures. Treatments can therefore be made for the required period in early morning or on cloudy days, or with an overnight exposure if applied late in the after- noon. Killing Effect Parathion has a contact killing effect on insects and mites. It also has a toxic fumigating action, which persists in the greenhouse for 3 to 7 days after application of the recommended dosage and will kill some pests during this period if the ventilators are closed for 4 hours or longer each night. A 2-hour period at warm temperatures also appears to be effective. Against certain pests, such as the Surinam roach, the residue on the soil is effective for more than 7 days. Dosage The recommended dosage of 10-percent parathion aerosol is 10 grams per 1^00 cubic feet^ or 1 pound per 50,000 cubic feet* of greenhouse space. With an oil-burner nozzle of 5-gallons-per-hour- capacity on the standard applicator, the treating time is about 4 seconds per 1,000 cubic feet of space when the temperature is 75° F. This dosage is effective against the pests listed in this paper, and its residual contact and fumigating action lasts 3 to 7 days. Preparation of Greenhouse for Treatment Before parathion aerosol is applied, weeds in the greenhouse should be pulled and where possible leaves touching the ground should be removed if they harbor the pests. Weeds in outside areas adjacent to the green- house should be destroyed, and crops in nearby outside frames should be sprayed or dusted with appropriate insecticides to destroy sources of greenhouse re infestation. Doors, windows, and ventilators should be closed. All places of entrance should be locked or barricaded except the doors to be used by the operator. After the operator leaves the house, the doors should be locked and warning signs should be placed on the doors, - 5 - The blooms and foliage should be dry. The temperature inside the greenhouse should be between 70° and 85° F. The fumigating action of the material is reduced by temperatures below 70°. Application The volume of greenhouse space should be determined and the required dosage calculated on the basis of 1 pound of aerosol per 50,000 cubic feet or a treating time of 4 seconds per 1,000 cubic feet. The particle size of the aerosol is approximately the same, when discharged at temperatures of 60° to 100° F», but the discharge rate greatly increases at the higher temperatures. To avoid an overdosage, therefore, the cylinders of aerosol should be placed under shade in the greenhouse for about 2 hours before use, to adjust their temperatures to that of the greenhouse. This procedure will give a uniform discharge rate and proper dosage, particularly if the aerosol is applied on a time basis. To apply the aerosol, the cylinder should be inverted, with valve down and opened one full turn. The operator should walk down the aisle, directing the aerosol to his right and left well above the plants, not on the foliage or flowers. At least 10 feet on each side of the pathway will be covered in this way« If the operator has walked too rapidly through the house and insuf- ficient aerosol has been applied, the central aisle can 1$ re-treated. The amount of aerosol applied can be determined by weighing the cylinder be- fore and after the application,and appropriate adjustments made in succeed- ing treatments. It is advisable to have one man equipped with a bomb and a mask for each pathway to be treated, and to have the men keep abreast as they walk through the house while making the application. An additional man to check the speed of application and to obtain uniform distribution through- out the house is desirable until treating crews have become experienced. By this procedure the exposure of any one operator to the aerosol is kept at a minimum, and a house can be treated more rapidly. Ventilation after Application The ventilators should be opened after the 2- to 4-hour or overnight treatments to parathion. Workers should not return to the treated green- house until it has been thoroughly ventilated, which will be after 1 hour or more according to atmospheric conditions. At any time within several days after treatment that ventilators are closed as suggested for the control of certain insects, the greenhouse should again be aerated before workers are allowed to return. Repetition of Treatments Because of the residual action of parathion, a single application has given almost complete control of a number of pests. Some insects, how- ever, require more than one treatment, as follows: - 6 - Against aphids in the growing tips of chrysanthemums and lilies, two or three applications at 10-day intervals have been required to bring infestations under control. Against rose leaf rollers two applications 10 days apart have been successful during winter and summer months, the venti- lators on treated houses being kept closed for 2 hours each evening for 1 week after each application to obtain the fumiga- ting action of the residue* Infestations of spider mites have been destroyed by single applications, but two applications a week apart have sometimes been necessary* Mealybugs appear to require two to three applications at 10-day intervals, although the investigations on this group of insects are incomplete and the timing of applications is sub- ject to revision. After the original clean-up program, regular treatments at 1- to 2- month intervals are advised for control of reinfestations. Labeling of Cylinders The aerosol cylinders used should be Interstate Commerce Commission container No. 3-B-300, or acceptable equivalent, and should be distinctly labeled with the words "Poison" and "Parathion." Aerosols produced for sale should be clearly labeled "For greenhouse use only" and should meet other requirements stipulated in connection with the license agreement. They should also fully meet the labeling requirements of Federal and State Acts and regulations dealing with insecticides. Employees who may be handling the aerosol containers should be instructed as to the nature of the contents and the precautions for use. Care of Equipment The aerosol cylinders should be stored in a clean, well-ventilated place, where the temperatures will not be excessive. The applicator hose rod and nozzle should be kept dry and free from dirt. Any foreign matter from the cylinders or other sources will find its way to the nozzle screen. It is not advisable to flush out the hose and rod between applications unless they can be thoroughly dried afterward. However, the nozzle tip and screen should be removed, taken apart, cleaned in kerosene, alcohol, or hot water, dried, and reassembled after each opera- tion. It is important to keep the screen and grooves in the inner tip of the nozzle clean at all times for proper atomization of the aerosol. After each operation the mask should be sponged off with soap and water, dried thoroughly, and replaced with the canister in its carrying case. The case should be stored in an upright position to prevent settling of can- ister contents to one side and thereby reducing its period of usefulness. - 7 - Hazard to the Operator The operator should avoid getting any parathion on his skin, espe- cially when he is handling the concentrated mater ial or if valve, connection, or hose should leak. Rubber-covered gloves should be worn. His shirt should be buttoned at the neck and his sleeves rolled down and buttoned at the wrist. A protective head covering, such as a cap with a visor to the back, should be worn and also a serviceable coverall, smock, or coat of rubberized cloth, which can be easily removed and washed after each exposure to the aerosol. To avoid inhalation the operator should wear a tight -fitting, full- face gas mask equipped with a canister specified for use in handling organic vapors, acid gases, and dusts. (Example": Mine Safety All Vision Industrial Gas Mask with GMC-1 canister or equivalent. ) The canister should be replaced with a new one after use, according to the recommenda- tions of the manufacturer. After each application he should thoroughly wash his hands and face with soap and water. Any aerosol solution that is spilled on the skin should also be washed off without delay. Any persons developing symptoms of headache, nausea, impaired vision, or tightness of the chest when using parathion should go or be removed immediately to fresh air. If parathion has been ingested, an emetic, such as mustard or warm soapy water, should be given immediately and a doctor called. Atropine sulfate is an antidote for parathion, but it should be administered only by a physician. Special Rote For the present, parathion aerosols should not be used on greenhouse fruits or vegetables, including such crops as tomatoes, cucumbers, rad- ishes, lettuce, and mushrooms. License for Manufacture The manufacture of parathion aerosol for use or sale is covered by a patent assigned to the Secretary of Agriculture. Several companies have been licensed and authorized to produce parathion aerosols for sale. No license is required to use these products. Licenses have also been issued for the manufacture of parathion aerosols for use but not for sale. Inquiries about licenses should be addressed to the Bureau of Entomology and Plant Quarantine, Washington, 25, D. C. Literature Cited (1) Blauvelt, W. E., and Hoffman, J. R. 1948. Parathion aerosol for greenhouse pest control. N. Y. State Flower Growers Bui. 29: 1-6. UNIVERSITY OF FLORIDA IIIIIIIIIIIIIIIIII 3 1262 09239 1928 (2) Blauvelt, W. E. , and Hoffman, J. R. 1948. Parathion controls greenhouse pests. Farm Res, (N. Y. State Sta.) H(3): 1. (3) McClellan, W. D. 1947. Rose mildew is more severe where HETP and azobenzene are used. Florists' Rev. 109 (15): 14. (4) Smith, Floyd F. , Fulton, R. A., Lung, P. H., and Brierley, Philip. 1947. Potent new insecticide and new method undergo thorough trial. (Hexaethyl tetraphosphate in aerosols for control of certain greenhouse pests.) Florists' Rev. 99 (2569) l 31-35. (5) Smith, Floyd F., Fulton, R. A., and Brierley, Philip. 1947-194-8. Use of DDT and H.E.T.P. as aerosols in greenhouses. Agr. Chem. 2(12) j 28-31, 61; 3(1) * 37,39,77. (6) Smith, Floyd F. , Fulton, R. A., and Lung, P. H. 1948. Recent developments in the control of greenhouse pests by liquefied-gas aerosols. Jour. Econ. Ent. (In press) Additional Precautions The precautions necessary for safeguarding persons applying parathion aero- sols or working in greenhouses where these aerosols have been applied cannot be too strongly emphasized. Three cases of illness following improper use of parathion aerosols have come to the attention of the writers. In one case the aerosol was applied in the greenhouse in accordance with recommended procedures, but the unused material in the cylinder was applied in the packing shed, where the ventilation was inade- quate. In the second case a surplus war mask and canister, of a type not suitable for protection against vapors of parathion or methyl chloride, was worn by the operator. In both cases the operators developed symptoms of severe headache, . tightness of chest, nausea, and vomiting. The headache and tightness of chest persisted for 2 or 3 days. In the third case the operator went outside the green- house to clean the nozzle on his applicator and inadvertently sprayed some of the solution into his gas mask, which was suspended around his neck. He merely wiped out the visible solution, instead of washing the mask thoroughly, put on his mask, and continued with the treatment. He later developed headache and tightness of the chest but no nausea. No illness has been experienced by the writers or reported by commercial florists in extensive use of this aerosol when the approved gas mask, canister, and suitable clothing have been properly used and ventilation has been adequate. The greenhouse man should realize that he is using a highly toxic material and that deviation from strict observance of precautionary measures , in either equipment or practice, may have serious consequences.