o U.S. DEPARTMENT OF AGRICULTURE, BUREAU OF ENTUMOLOGY CIRCULAR No. 168. L. O HOWARD. F-nlomologui and Chi^f of Bureau. SPRAYING FOR WHITE PLIES IN FLORIDA. BY \Y. w. MOTHERS, Entomological Assistant. ... •WaHTOH iwnioin >«,»T|»« OTFKJ f the cloud] \% i mri-tl white fly is thin and membranous and collapses after the emergence of the adult, while thai of the citrus white flj retains its shape indefinitely. The adults are easily distinguished; the cloudy winged white fly has dark markings <«n it- wings, while the wings of the citrus white fly are pure white. The broods of the cloudy-winged white fly appear about a month later than those <<( the citrus white fly. INJURY FROM WHITE FLIES. The injury caused by the citrus and cloudy winged while flic- i- much greater than is generally supposed. Tin- damage occasioned by tin' loss of sap is considerable anil 1- a serious 'train mi the tree, hut i- of secondary importance to the damage caused by the sooty mold which follows the white fly. The sooty mold affects both the fruit ami leaves, blackening the former ami covering the upper surface of the latter with a dark- brown coating which excludes the sunlight anil clogs ami checks the growth. The reduction in yield from tin' white Hie- ami sooty mold is variously estimated to he from 25 to 50 per cent. If the sooty moli I form- a coating on the upper half of the orange, the rind underneath it may remain green indefinitely, while the lower half of the fruit becomes well colored. The retardation of ripening, delaying as it does in some cases the time when the fruit i- market- able anil materially increasing the percentage of culls, causes further loss, which i- very conservatively estimated to range from 2 to ."> per rent of the value of the crop. It is customary to dean fruit noticeably affected with sooty mold. The process of cleaning causes many mechanical injuries which afford entrance to the -pore- of the blue mold with its resulting decay. SPRAYING. White Hies may he controlled in two ways: (\) By subjecting the infested plant- to the fume- of hydrocyanic-acid gas, or (2) by spraying with a contact insecticide. The latter method only i- con- sidered in this paper and has the advantage of being comparatively inexpensive and adapted to grove conditions in Florida. ait\i; \ i OS FOB -I'K O i\>.. Tn spraying, an extension rod, varying from s to 10 feet in length, should be supplied with each line of hose, the length depending upon the heighl of the tree-. This roil ma\ be an ordinary bamboo pole or a -mall <:as pipe. The former i- more suitable for this work in that it i- lighter ami more easily handled after becoming wet. 4 SPRAYING FOR WHITE FLIES IN FLORIDA. * A cut-off should always be inserted between the extension rod and the hose. This will enable the operator to cut off the spray at any time, either when going from tree to tree or in order to clean out the nozzle should it become clogged. If a power sprayer is used it is also necessary to insert a cut-off between the hose and pump, which would relieve the pressure on the hose in case of a break. A cut-off inserted at this point also makes it possible for a machine to be fitted with any number of leads of hose which the work may require. The hose should be from three-eighths to one-half inch in diameter, of the very finest quality, and able to withstand such pressure as the methods of application may require. If a power sprayer is used the hose should be a good quality 7-ply; with reasonable care this will stand up for a season under 150 or 170 pounds pressure. If a barrel pump is used, 4-ply will be sufficient, but even for this the 7-ply is to l)c preferred and will be found cheaper in the long run. In our ex- perimental work leads of hose 50 feet in length have been found more satisfactory than shorter ones. With long hose both mules and machine may be kept out of range of the spray. Then, too, when using two leads of hose it will be possible, if the hose is long, to progress uninterruptedly on both sides even though there may be a tree missing in one row or the other. In spraying the larger trees long hose is essential in order that the sides of the trees away from the machine may be reached. To secure satisfactory results the application should be thorough and with sufficient force to break up the liquid into a fine mist. The kind of pump to be used should be governed by the size of the grove and other conditions. A barrel pump will serve every purpose if the trees are low and only a small amount of spraying is required. For larger operations a gasoline-power outfit will give better satisfaction. For Florida such an outfit should be light in weight, with 6-inch tires and an engine of not less than two and one-half horsepower. To keep the machinery free from sand the engine should be provided with canvas curtains. To obtain satisfactory results it is necessary to have the proper equijunent for applying the insecticide. Much of the prejudice against spraying for the control of white flies arises from the ineffi- cient results due to improper equipment. Since the insects congregate on the underside of the leaves the spray should always be directed upward. To accomplish this one should use a straight nozzle attached to an elbow which makes an angle of approximately 45 degrees or. better still, an angle nozzle which will not get entangled in the foliage and branches. A nozzle which emits the spray in the form of a cone haying an angle of about 90 degrees has been found to be very efficient, whereas a flat or solid stream will not give satisfactory results. BPRAYING FOB w 1 1 III I I 1 1 B in PLOBIDA. i> I n i \\ PO M'l'i v i in BPB \ V. Tn spraying for control of white flies the method of application is the same when using either ;i barrel pump or :i power outfit. In applying the spray the operator should begin on the far side dt" the tree and work around to the point nearest the machine I he second half of the tree should be handled in like manner, If two operators are at work on the same tree they should l><>ih l»'L r m :ii t- 1 » < * point farthest from the machine and proceed until they meet. Tin' spray should be applied in tin' tree in a systematic way. The operator should begin at the base ami work (<> the top, inserting the rod among the branches bo a- to spray the center of the tree. Tin' entire tree may be thus sprayed in sections, tin' operators proceeding alternately from the bottom t<> the tup and from the top t<> the bot- lom. 'In prevent kinks from appearing in tin- hose tl perator, in moving from tree i<> tree, should never make a complete turn. In case kinks appear thej should be immediately taken out by turning tin 1 -pray rod ami qoI by pulling the hose. BPB \ V M i\ n KB. It i- important thai tin- insecticide used should kill all the inserts hit by the spray. Emulsions of various heavy mineral oils have been found to give the | M .-t satisfaction. While petroleum fuel oil, or "crude oil." and distillate, or <;a> oil. will give good results, yet the paraffin oil-, known also a- lubricating oils, having a specific gravity of from 24 to 28 Baume* have been found to possess cer- tain qualities which make them superior as base- for an insecticide against the white Hie-. The following formula ha- given highly satisfactory results : Foumi i s No. 1. Whale-oil soap 8 pounds, or] pallon. Paraffin oil. 24" or 28 Baume 2 gallons. Water 1 gallon. DIIU' nonS I oi! PR] PARATIl Tn preparing the stock mixture the soap should be put into a re- ceptacle of about 5 gallons' capacity and the oil should then !><• added very slowly while the mixture i- being vigorously stirred. It is important that the oil he added in -mall quantities at first and also that the stirring he sufficient to keep the oil and soap in the form of an emulsion after each addition of oil. Thus at first about a pint of oil should he added to the -oap and the mixture stirred until no free oil appears. As the amount of oil i- increased it should always he stirred or mixed thoroughly before the next addition is b SPRAYING FOB WHITE FLIES IN FLORIDA. made. After the required amount of oil has been added and after free oil has ceased to appear on top of the soap, the water is slowly poured in, about a quart at a time. To determine whether the mix- ture will form a perfect emulsion add a little of it to soft water, and if no oil floats, the mixture is perfect and may be used for spraying. The presence of floating oil indicates an imperfect mixture and results from adding the oil too suddenly or from insufficient stir- ring. This condition may be remedied by the addition of more soap, which is preferable to throwing away the entire mixture. For spraying orange trees u.se 1 gallon of the stock mixture pre- pared as just described to 50 gallons of water, or use the entire amount to make 200 gallons of spray material. This dilution con- tains approximately 1 per cent of oil, which is the maximum strength required for white flies and the purple scale. For three-fourths of 1 per cent of oil add 1 gallon of the stock mixture to 66 gallons of water, and to obtain one-half of 1 per cent add 1 gallon of the stock mixture to 100 gallons of water. Many alterations may be made in the foregoing formula. The quantity of soap will depend largely upon the time consumed in adding the oil and the amount of stirring accompanying this process. The amount of soap is lessened if the stirring is uniform and if ample time is taken in the preparation. Petroleum fuel oil, or "crude oil," and distillate, or gas oil, may be used instead of the paraffin oil, but in these casas a mixture of about twice the strength will be needed to kill the insects. The amount of water is unim- portant, since the emulsion should be perfect if either 1 or 4 quarts be added. The only thing to be remembered is that the diluted spray should contain the required percentage of oil. The following formula from Farmers' Bulletin Xo. 172, page 17, has also been found satisfactory : Formula Xo. 2. Water ( boiling) gallons.. 5 Distillate.' 28° Baunie do 5 Whale-oil soap pounds.. 1J DIRECTIONS FOR PREPARATION. Dissolve the soap in hot water and add the distillate, thoroughly emulsifying by means of a pump until a rather heavy creamy- yellowish emulsion is produced. For use against "die white fly dilute 1 part of the stock emulsion with 25 parts of water. This dilution will contain about 2 per cent of the oil. 1 Tin' term " distillate " ia commonly given in California to a form of petroleum widely ased for spraying purposes. BPRAYING FOR whim iiiis i\ FLORIDA- 7 PBOPRIS1 w:v I NSW i i< IDH, There are Beveral articles on the market under the bead of miscible oils which when properly applied will give satisfactory results. These, however, should not contain sulphuric Bcid, rosin oil, or carbolic acid. WHIN TO BPB \Y. - far as the effed of various insecticides on the trees and fruit is concerned it is safe to spray at any season "f the year except dur- ing the blooming period. It" the application is made during the winter, it will be found much more convenient t<> Bpray after the removal of the fruit. The insecticide will do no injury to the fruit itself, hut its presence <>n unwashed fruit may prose objectionable to the consumer. It can also be applied during the summer or rainy >ii, l>ut spring, early fall, or winter applications are preferable in that the benefice] parasitic fungi are not affected by the inseoti- i ide during these seasons. So far as the effect on the various stages of the insects i- con- cerned spraying may be done at any tune. The white fly is in the tendered larval stages about two week- after the disappearance of the adults of the first brood, ami if spraying is done at this period the insecticide can be used at about one half or three-fourths the usual strength. The grower should aim to keep the white fly below the point whore it will do serious damage, and the number of treatments will depend upon the thoroughness of the work and the abundance of the bisects in the grove at the time of spraying. One thorough spray- ing is much more effective than two or three carelessly applied. The application of the insect icide should be SO timed as to be effec- tive in killing the rust mite (Eriophyes oleivorus Ashm.) and scale insects as well as the white flies. Experience has shown that two sprayings are sufficient to control the white (lies. One of these can be given in the spring, following it by an early fall application, or one can he given during midsummer and the second during the winter month-. The spring and summer sprays are also beneficial in killing the rust mite. Sale insects frequently gain such a foot- hold as to demand winter treatment, hut in some instances one spray- ing a year has produced clean fruit. SPRAYING W \m iv-n n \M> Tin- BUBT KITE. The paraffin-oil emulsion spray when used with 1 per cent of oil will kill the rust mite and its eir^s and also the purple scale {Lipidosapfus beckii Newm.). It is also effective when used S SPRAYING FOR WHITE FLIES IK FLORIDA. against the young of the Florida red or "nail-head" scale (Chry- somphalus aonidum L.). EFFECT OF THE OH SPRAYS ON BENEFICIAL FUNGI. The experiments so far conducted indicate that the oil sprays do not possess any fungicidal properties, nor do they affect the bene- ficial parasitic fungi in the least. These fungi develop during the rainy season, while the scale insects, rust mite, and white flies do their greatest damage from September 1 to June 1. The fact that these sprays are applied during seasons when the fungi are inactive is evidence in favor of such remedies in that the increase of the fungi is not directly affected. Approved : James Wilson, Secretary of Agriculture. Washington, D. C, January IS, 1913. ADDITIONAL COPIES of this publication it may be procured from the Superintend- ent of Documents, Government Printing .Office, Washington, D. C, at 5 cents per copy UNIVERSITY OF FLORIDA 3 1262 09216 6064