PENTAGONA (Targ.) stead, in providing assistance and plants for. The white peach scale was first mentioned

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1 376 FLORIDA STATE HORTICULTURAL SOCIETY, 1967 Acknowledgment The help of Mr. EL M. Landrum of Home stead, in providing assistance and plants for the photographs, is acknowledged. LITERATURE CITED 1. Popenoe, Wilson. Manual of tropical and subtropical fruits. The Macmillan Company, New York Ruehle, Geo. D. The sapodilla in Florida. Circular S-34. Univ. of Fla. Agric. Exp. Sta OBSERVATIONS ON THE BIOLOGY BIONOMICS AND CONTROL OF WHITE PEACH SCALE, PSEUDAULACASPIS PENTAGONA (Targ.) L. C. KUITERT Distribution Entomology Department I FAS University of Florida Gainesville Introduction Peach production in Florida was extensive from about 1870 to The white peach scale destroyed many peach orchards in the early 1900's including one of 10,000 trees in South Georgia (5). Snapp, 1928, reported that the white peach scale is as injurious as the San Jose scale (8). After 1930, production and marketing problems could not be overcome and the peach industry in Florida faded away. Re newed interest in peach production occurred in the early 1950's with the introduction of nematode resistant rootstocks and early bearing vari eties. Commercial peach growing is almost certain to become a more important industry in Florida than it is at present, however, some orchards have been abandoned in spite of distinctive Florida varieties including the nematode resis tant ones. One of the factors retarding this development is the necessity for controlling white peach scale. Control of the scale with chemicals is effective but programs have been inadequate. The white peach scale, Pseudaulacaspis pentagona (Targioni) was first described as Diaspis pentagona by Targioni in It was described by Tyron in Australia as D. amygdali in 1889, as D. lanatus in 1892 by Morgan and Cockerell in the U. S. and as D. patelleformis by Sasakin in Japan in Ferris (4) desig nated P. pentagona (Targioni) as the correct name for this species. The white peach scale was first mentioned by Targioni in 1886 as a pest of Mulberry, Morus sp. in Como province of Northern Italy. By 1912 the insect was threatening the then prosperous silk industry throughout Italy. The spread of P. pentagona was so extensive that the Italian government passed a law against the Diaspis, compelling tree owners to fight the 4 insect by mechanical means (scraping the trunk and the infested branches, pruning, sterilizing by fire) and by insecticidal solutions (6). Gossard (5) first reported the scale from Florida on peach in It is now found throughout the state and has become an indi vidual problem for every orchardist and home owner interested in peach culture. Description op Injury Heavy infestations of white peach scale have been obsereved on chinaberry, persimmon, mul berry, privet and black walnut without any evidence of serious damage present on the host. Peach is the only host observed which is highly susceptible to the feeding of this scale. Usually only a few branches or twigs are killed, how ever unattended trees usually die within two to three years. The larger branches often die following development of blossoms and new fol iage. Heavily infested trees which survive often, have small fruits and these drop from the trees when the tree encounters periods of stress such as drought. The writer is of the opinion that the pruning requirements of peach upsets the natural control factors; however, infested trees which are not pruned show the same suscepti bility.

2 KUITERT: WHITE PEACH SCALE 377 Description Eggs and oviposition: Eggs vary from a light creamy yellow to light red with some falling into an intermediate category. Bennett and Brown (1) reported the eggs and crawlers of P. pentagona as being sexually dimorphic by virtue of a difference in color. Eggs containing reddish embryos are females while the pinkish white eggs are males. The various colored eggs are observed under the same female. Females appear to deposit the entire complement of eggs over an 8 to 15 day period although this may vary somewhat in the first generation. Eggs hatch within 2 to 5 days after being laid. Crawler: The crawlers continue to show dichromism. The male crawlers locate in clusters on the older and lower portions of the tree. The female crawlers tend to move out over the plant; however, they are seldom observed on the terminal green wood and when present are found at the buds. As the new growth matures and turns brown from the base outward the female crawlers begin to settle on the brown wood. Apparently, the brown wood has tiny cracks and crevices in the bark which the crawler requires for support when inserting its mouthparts. Adult 2 armor: The armor is 2 to 2.5 mm or.08 to.10 inches in diameter, quite convex and usually grayish white. The scales are often rather inconspicuous because they are covered with a thin layer of the skin of the outer bark. The armor is semi-circular although the shape varies considerably with the density of the scales. The exuvia is subcentral and usually reddish-brown although it is orange-yellow in some specimens. The armor usually is firmly cemented to the host plant and apparently is water tight. Removing the scale or armor ex poses the usually creamy-white to reddishorange insect (Fig. 2). Male: The pre-adult male scale armor is pure white. The exuvia is a light yellow color. The dorsal median carina or ridge is poorly de veloped. The length is usually 1.5 mm. The males cluster together in dense patches and are usually found on the lower branches and trunk (Fig. 1). The adult male is a tiny, fragile, two-winged insect and is rarely observed. Host Plants Ferris (4) states that P. pentagona can live on all plants with the possible exception of the Fig. 1. Pre-adult male scales. The crawlers settle in cracks and crevices of the bark. conifers. Dekle (3) lists 97 hosts for Florida. Some of the more common hosts in addition to peach, Prunus persica Batsch, include French mulberry, (C. americana L.), chinaberry (Melia), persimmon (Diospyros virginiana L.), holly, plum and privet. The list includes such diverse plants as geraniums and tung oil tree. Life History At Gainesville there are four generations or broods per year. The scale apparently passes the winter in this area as a fertilized female. Egg laying by the overwintering female is initiated early in February. At this time less than 1% of the adult females have deposited eggs and almost all males have emerged. Exam inations of female scales made early in Febru ary indicated 84.7% live scales on the twigs and 91.7% live scales on the older bark. No crawl ers were present at this time. Egg deposition continues over an extended period for the first generation. On March 30, 95% of the females had oviposited and it was estimated that 35-40% of the eggs had hatched. Crawlers were

3 378 FLORIDA STATE HORTICULTURAL SOCIETY, 1967 scales overwinter; however, gravid females are not observed until January. A period of about 50 days are required for development from egg hatch to peak egg laying. Parasites and Predators Fig. 2. Female scale with armor turned back. Many females are partially covered with a thin layer of bark. numerous at this time; however, none were ob served on the new growth. Counts made of first stage larvae showed as many as 1000 per square inch of bark. Examinations made April 11, showed that 95% of the eggs had hatched and that females die following oviposition. The total number of eggs deposited varied from 107 to 144 per female and averaged 131 per female. This figure varies somewhat be tween generations. The egg laying process extends over a period of 5 to 7 weeks for each generation and may be extended some in the first generation. Adults of the first generation begin appear ing in late April and begin depositing eggs for the second generation early in May. Scales of the second generation reach maturity in late June and begin laying eggs for the third genera tion in mid-july. Scales for the 3rd generation reach maturity in late August and September and oviposition begins around late September and early October. Adults of this generation reach maturity in early November. As the scales mature, mating takes place and these Natural enemies of the white peach scale have been reported from many areas of the world (la). There are few published records of the natural enemies of white peach scale in Florida. Gossard (5) reported that the twicestabbed lady beetle, Chilocorus stigma (Say) apparently consumed large numbers but failed to exert sufficient pressure to subdue it. Hughes (7) investigated and collected the parasites and predators extensively in Alachua County. He reported two hymenopterous parasites, Prospaltella berlesei (Howard) and Aspidiotiphagus Citrinus (Crawford), along with the coccinellid predators Chilocorus stigma (Say), Lindorus lophanthae (Blaisdell) and Exochomus childreni Mulsant as attacking P. pentagona. He also reported Thysanus flavopalliatus (Ashmead) as being a hyperparasite attacking the primary parasite, P.berlesei. The author has observed the above parasites and predators along with a mite, Belbidae sp. and a species of thrips. The author is of the opinion that the natural enemies do not exert adequate pressure to control this scale. Control Several factors make control of white peach scale difficult. The armor of the adult female provides considerable protection from sprays. Eggs which are deposited beneath the armor appear to survive most spray treatments. Some times crawlers will remain beneath the armor and develop to maturity thus making some heavy infestations consist of layers of the scales. The crawlers prefer to insert their stylets at some crack or declivity in the bark and many females often have a thin layer of bark covering them. The scale is active year round and goes through four generations making it essential that spray applications be timed to coincide with peak crawler and immature scale activity. Insecticidal treatments were applied with a John Bean 30 gallon power garden sprayer using a 75 foot lead of hose equipped with a small John Bean hand gun. The treatments were applied at p.s.i. The gun was adjusted

4 KUITERT: WHITE PEACH SCALE 379 F M A M J J A S O N D ADU LTS niiiimiir! E^vS II8BSSIIIIIIIIIII TABLE 1. Seasonal History of P. pentagona Adults and Eggs at Gainesville TABLE 2: Post treatment No. 1, November 22, 1963 TREATMENT LIVE DEAD PERCENT LIVE Sevin Bayer Ethion

5 380 FLORIDA STATE HORTICULTURAL SOCIETY, 1967 TABLE 3: Bost treatment No. 2, December 18, 1963 TREATMENT LIVE DEAD PERCENT LIVE Ethion Bayer Sevin provided good initial control. At seven we.eks all treatments provided considerable control although none gave economic control. to deliver a mist spray. Sprays were mixed in Mortality was determined by obtaining samthe spray tank by running the spray into the pies of infested twigs and bark and determintank for several minutes before application. ing the per cent of live female scales before Each tree was sprayed from four sides to the and following treatments. Scales were placed point of run off. Sprays were directed toward in the dead category when they were brown the inner and older parts of the tree. and dry. Only adult female scales were exam- TABLE 4: Post treatment Counts of treatments applied April 13, 1966, TREATMENT RATE/100 GALS. LIVE DEAD PERCENT LIVE 1 1/2 pt Diazinon 1 1/2 pt Diazinon 1 pt TH /2 pt

6 KUITERT: WHITE PEACH SCALE 381 TABLE 5: Post treatment Counts of treatments applied October 27, 1966 TREATMENT RATE/100 GALSc LIVE DEAD PERCENT LIVE 1 qt Ethion + Superior Oil 3 qts Diazinon 1 qt TH pt ined since immature scales and pre-adult males were usually controlled very easily. The pretreatment counts were made 1 to 5 days before application and the post treatment counts 3 weeks following application. Usually 100 to 150 scales were examined from each tree used in the treatment. Control tests were undertaken in 1964, 1966, and TESTS Four treatments were evaluated in replicated tests in a commercial orchard at Hawthorn, Florida. The materials, formulations and rates at which they were used per 100 gallons were: (1) dimethoate 2E, 1 qt., (2) Sevin 50W, 2 lbs., (3) Bayer Experimental E, 1 pt. and (4) ethion 4E, 1 pt. Treat ments were applied on October 29, Results of the post treatment counts are given in Tables 2 and TESTS Four materials were evaluated in replicated tests at Gainesville. Three of the treatments were used at two concentrations. The materials, formulations and concentrations at which they were applied per 100 gallons were: (1) dimethoate 267E, 1V2 pt. and 1 qt.; (2) diazinon Ag 500, 1 pt. and 1 qt.; (3) Thompson- Hayward 346-1, Vz and 1 pt., and (4) ethion 0.67 plus Superior 60 oil, 3 qts. Results of the post treatment counts are given in Tables 4 and 5. DISCUSSION Spray treatments should be directed toward the control of crawlers and im mature scales. Diazinon and the ethion plus superior oil combination gave excellent control of white peach scale when the application was timed to coincide with peak crawler and imma ture scale activity. In addition, infestations of peach tree borers and bark beetles failed to develop in these treatments. pro vided excellent control; however, it provided little or no control of the borers. The TH experimental insecticide also provided good scale control but it is not commercially available. LITERATURE CITED 1. Bennett, F. D. and S. W. Brown, Life History and Sex Determination in the Diaspine Scale, Pseudaulacasis pentagona (Targ.) (Coccoidae) Can. Ent. XC, p la. Bennett, F. D., Some Parasites and Predators of Pseudaulacaspi pentagona (Targ.) in Trinidad B.W.I. Can. Ent., 88: DeBach, P., Thysanus flavopalliatus (Ashm.) Parasitic on Comperiella bifasciata, How. in California Red Scale. Jour. Econ. Ent. 46: Dekle, G. W., Florida Armored Scale Insects. Arthropods of Florida and Neighboring Land Areas. Fla. Dept. of Agr. 3:265 pp. 4. Ferris, G. F., Atlas of the Scale Insects of North America. Series 1, Calif.: Stanford Univ. Press. 5. Gossard, H. A., Two Peach Scales. Fla. Agr. Exp. Sta. Bui. 61, Howard, L. O., The Activity of Prospaltella Berlesei Howard Against Diaspis pentagona Targ. in Italy. Jour. Econ. Ent., 5: Hughes, I. W., Some Natural Enemies of the White Peach Scale, Pseudaulacaspis pentagona (Targ.) (Homoptera: Coccoidea) in Florida. Fla. Entomologist. 43: Snapp, O. I., Insects Attacking The Peach in the South. Farmers' Bui. 1557, p. 34.