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1 Crop Protetion 29 (2010) 860e866 Contents lists ville t SieneDiret Crop Protetion journl homepge: Dormnt seson folir sprys of rod-spetrum insetiides: An effetive omponent of integrted mngement for Diphorin itri (Hemipter: Psyllide) in itrus orhrds Jwwd A. Qureshi *, Philip A. Stnsly Deprtment of Entomology nd Nemtology, University of Florid/IFAS, Southwest Florid Reserh nd Edution Center, 2685 SR 29N, Immoklee, FL 34142, USA rtile info strt Artile history: Reeived 19 Otoer 2009 Reeived in revised form 9 April 2010 Aepted 12 April 2010 Keywords: Asin itrus psyllid Biologil ontrol Chemil ontrol Citrus sinensis Hunglonging Citrus greening Integrted pest mngement Diphorin itri Kuwym (Hemipter: Psyllide), is glol pest of itrus nd vetor of Cndidtus Lieriter, teri tht uses hunglonging or greening, devstting disese of itrus. Mture itrus trees re dormnt in winter nd produe most new shoots in spring, followed y spordi nopy growth in summer nd fll. Young shoots re required for oviposition nd nymphl development, ut dults n survive nd overwinter on hrdened leves. Surviving dults reprodue in spring shoots nd their progeny re proly responsile for lrge portion of disese spred s they disperse to serh for food. Therefore, folir sprys of rod-spetrum insetiides pplied to mture trees in winter were evluted in ommeril itrus orhrd s tti to redue pest popultions nd insetiide use in spring nd summer when enefiil insets re most tive. A single spry of hlorpyrifos (2.8 kg.i. h 1 ) in Jnury 2007 redued dult psyllids n verge of 10-fold over six months ompred to untreted trees. The following yer, differenes with the untreted ontrol verged 15-fold for over five months following single spry of hlorpyrifos, fenpropthrin (0.34 kg.i. h 1 ), or oxmyl (1.12 kg. i. h 1 ) pplied in Jnury. Spiders, lewings nd ldyeetles were eqully undnt during the growing seson in oth treted nd untreted trees oth yers (P ¼ 0.05). Thus folir sprys of rod-spetrum insetiides efore spring growth suppressed D. itri for five to six months, with no detetile impt on key nturl enemies. This tti hs een widely dopted to ontrol the psyllid in Florid, in some ses re-wide. Additionl sprys during the growing seson should e sed on souting nd trgeted t dults efore ntiipted new flush. Ó 2010 Elsevier Ltd. All rights reserved. 1. Introdution Diphorin itri Kuwym (Hemipter: Psyllide), lso known s the Asin itrus psyllid (ACP), is n eonomilly importnt inset pest in mny itrus-growing regions of the world (Hlert nd Mnjunth, 2004). A different speies, Trioz erytree (Del Guerio), is present in South Afri nd some neighoring ountries with only the Mediterrnen nd Austrli still psyllid free mong mjor itrus-growing regions. Feeding y D. itri nymphs nd dults on young itrus shoots uses redued nd distorted lef development. Of muh greter onern is the ility of the pest to trnsmit phloem-limited teri of genus Cndidtus Lieriter, the usl orgnism of hunglonging (HLB) lso known s itrus greening disese (Grnier et l., 2000; Hlert nd Mnjunth, 2004; Bové, 2006). HLB is one of the world s most devstting * Corresponding uthor. Tel.: þ ; fx: þ E-mil ddress: jwwdq@ufl.edu (J.A. Qureshi). diseses of itrus, responsile for the deline of most trees in the disese infeted regions (Roisther, 1996; Hlert nd Mnjunth, 2004; Bové, 2006). In the United Sttes, D. itri ws first disovered in Plm Beh County, Florid on hedges of ornge jsmine, Murry pniult (L.) Jk. (Rutee) in 1998 (Hlert, 1998). The psyllid is now well estlished in itrus produing regions of the stte (Mihud, 2002; Tsi et l., 2002; Hlert nd Mnjunth, 2004; Qureshi et l., 2009) nd is lso present in Texs, Louisin, Mississippi, Georgi, South Crolin, Hwii nd southern Cliforni (Frenh et l., 2001; FDQO-CG-ACP, 2008). First identifition in the USA of the Asin form of itrus greening disese used y the terium Cndidtus Lieriter sitius, ws in south Mimi Dde during August 2005 (Hlert, 2005). The disese now ours throughout the stte with highest inidene in the est ost nd southwest regions nd thretens itrus industry vlued t $1.3 illion in diret sles lone (Anonymous, 2008; FDACS-DPI, 2008). HLB ws lso identified from Louisin in 2008 nd from South Crolin nd Georgi in 2009 ( /$ e see front mtter Ó 2010 Elsevier Ltd. All rights reserved. doi: /j.ropro

2 J.A. Qureshi, P.A. Stnsly / Crop Protetion 29 (2010) 860e itrus_greening/index.shtml, Septemer 12, 2009). Other thn plnt movement y people, D. itri is the primry use of the spred of the itrus greening disese (Hlert nd Mnjunth, 2004); therefore, effetive nd sustinle pest nd disese mngement strtegies re required to redue spred. Insetiidl ontrol of the vetor long with removl of HLB infeted trees re the ttis eing employed to slow the spred of HLB in Florid itrus orhrds (Qureshi nd Stnsly, 2007, 2008; Rogers et l., 2008; Brlnsky et l., 2009). However, iologil ontrol hs lwys een n importnt omponent of itrus inset pest mngement in Florid (MCoy, 1985) inluding D. itri. Ldyeetles, lewings nd spiders re ll well-known predtors of itrus psyllids (Vn den Berg et l., 1992; Shivnkr et l., 2000; Mihud, 2002, 2004; Qureshi nd Stnsly, 2008, 2009). These nd other predtors were oserved to inflit 80e100% mortlity to D. itri immtures nd were undnt during spring nd summer, though lrgely sent during winter in onert with itrus growth ptterns nd psyllid undne (Mihud, 2004; Qureshi nd Stnsly, 2007, 2009). Tmrixi rdit (Wterston) (Hymenopter: Eulophide), speies-speifi eto-prsitoid of D. itri tht ws imported from Tiwn nd southern Vietnm, is well estlished in Florid. However, prsitism rtes in Florid re vrile nd pper to e generlly low ompred to other regions where intentionl or identl introdution of the prsitoid ourred (Étienne nd Auert, 1980; Étienne et l., 2001; Pluke et l., 2008; Qureshi et l., 2009). While ugmenttion of nturl enemy popultions remins n option for the future, iologil ontrol lone hs not een suffiient to hlt the spred of greening in Florid. Nevertheless, nturl enemies provide signifint mortlity to psyllid popultions nd wrrnt onservtion (Qureshi nd Stnsly, 2009). The dvent of HLB hs gretly intensified insetiide use in Florid itrus (Rogers, 2008; Rogers et l., 2008). The systemi insetiides, thimethoxm nd imidloprid re llowed in Florid itrus ut re sujet to rte restritions tht limit their use to young trees. Aldir is lso leled for use in Florid itrus during the dry seson from 15th Novemer through April, ut effetiveness is sometimes ompromised y lk of rin required for tivtion of the insetiide (Qureshi nd Stnsly, 2008). Therefore, folir insetiides re required to suppress D. itri in most Florid itrus. The inility of folir sprys to provide nything ut shortterm ontrol of psyllid when direted ginst immture stges on new shoots is mply doumented (Qureshi nd Stnsly, 2007; Stnsly et l., 2008,,d). This is proly due to the protetion fforded to eggs nd young nymphs y the tightly ppressed emergent leves of young shoots (¼ flush) whih re nevertheless ttrtive to diverse nd effetive fun of nturl enemies of the psyllid (Qureshi nd Stnsly, 2007, 2008, 2009). Therefore, pplition to flushing trees is generlly ontrindited. Reprodution of D. itri is totlly dependent on vilility of young shoots ontining fether stge to reently expnded tender leves. Femle psyllids must feed on tender shoots to mture eggs nd prefer opening uds nd shoots for oviposition. During the following 2e3 weeks, shoot nd lef tissues re still tender nd re utilized y nymphs nd newly emerged dults respetively to omplete development nd mture eggs. Adults n lso feed nd survive on the fully developed leves for severl months (Tsi et l., 2002; Qureshi nd Stnsly, 2008). Flush prodution is influened y wether, plnt ge nd vriety (Knpp et l., 1995). However, the typil pttern of shoot prodution in mture itrus trees in Florid is omprised of growing seson strting with mjor flush in lte winter nd erly spring, reltively smll flush in the erly summer nd some minor flushes during lte summer nd fll, followed y dormnt winter seson in lte fll nd erly winter with little or no new folige growth (Hll nd Alrigo, 2007; Qureshi et l., 2009). Over-wintering psyllid dults survive y feeding on mture leves until the pperne of spring flush to ommene oviposition. There is little or no flush or suitle host to ttrt psyllid nturl enemies in winter nd most prsitoids re proteted inside their hosts. However, if llowed to enter the spring flush without insetiidl intervention, survivl of the first genertions of D. itri is high due to undne of flush tht not only provides unlimited food ut lso over from nturl enemies (Qureshi nd Stnsly, 2009). Highest numers of D. itri dults testing positive for C. Lieriter sitius were ught in sution trps in April soon fter spring flush (Mnjunth et l., 2008). Therefore, overwintering popultions of D. itri should e suppressed to redue the spred of psyllid nd itrus greening in the spring nd fterwrd. Mny of the inset nd mite pests found in Florid itrus groves re under iologil ontrol where they merely o-exist with other onsistently injurious speies (MCoy, 1985; MCoy et l., 2009). Therefore, repeted sprys of rod-spetrum insetiides during spring nd summer (Rogers, 2008) when most pests nd enefiil insets re ommon will likely selet for resistne nd result in seondry pest outreks. Therefore, it would e enefiil to onfine rod-spetrum insetiides to the dormnt winter seson s muh s possile. In this two yer study, the impt of folir sprys of some urrently reommended rod spetrum insetiides pplied to itrus trees during the dormnt winter period ws evluted y monitoring the popultions of D. itri nd its nturl enemies during the following spring nd summer. Our ojetive ws to provide proof of onept for the dormnt spry tti to ontrol ACP, not to ompre the effiy of urrently ville insetiides per se, whih hs een well doumented elsewhere (Qureshi nd Stnsly, 2007; Stnsly et l., 2008,,,d). 2. Mterils nd methods Experiments in oth yers were onduted in ommeril itrus grove of Brron Collier Compny in Immoklee, FL in two equl size djent loks of 27 h eh plnted in 1982 with Hmlin ornge trees originlly on sour ornge rootstok t density of 373 trees h 1 on doule-row rised eds. Trees susequently lost to itrus tristez disese hd een repled y the sme vriety grfted to Crrizo itrnge rootstok Eh of the two 27 h loks of itrus ws onsidered replite. Within eh lok, two side y side 6.1 h plots, were rndomly ssigned to either the spry pplition tretment or the untreted ontrol. Tretment plots were spryed on 15th Jnury with hlorpyrifos 2.8 kg.i. h 1 (Lorsn 4 E, Dow AgroSienes LLC, Indinpolis, IN) using trtor mounted Air-O-Fn ir lst spryer operting t pressure of 1241 kp with 8 Aluz, lue nozzles per side delivering medium qulity spry t 936 L h 1.No other insetiides were pplied nywhere in the loks through August. Applitions of rodst fertilizer were mde in Jnury, Mrh nd Otoer. Stndrd ulturl prties were followed uniformly throughout the grove. Flush density nd popultions of D. itri nd generlist predtors were monitored on 22nd Jnury, 8th nd 29th Mrh, 12th nd 25th April, 29th My, 22nd June, 24th July nd 27th August. Bedsides of the four trees t eh of eight non-systemtilly seleted lotions in treted nd untreted plots were smpled. Shoot density ws estimted y using qudrt frme mde from PVC pipe to smple volume of 39 dm 3 ( m) of tree nopy (Qureshi et l., 2009). The frme ws pled t nonsystemtilly hosen lotion in the outer tree nopy out 1e2 m ove ground nd shoots ontining fether stge to

3 862 J.A. Qureshi, P.A. Stnsly / Crop Protetion 29 (2010) 860e866 reently expnded leves were ounted to depth of 30 m. Density of D. itri dults nd predtors ws estimted from tp smple mde y ounting the numer flling on m lminted white sheet held on lipord horizontlly under non-systemtilly seleted rnhes whih were tpped three times y hnd (Qureshi nd Stnsly, 2007). Depending upon vilility, 10 or fewer non-systemtilly seleted shoots were exmined per tree nd the numer infested with eggs or nymphs of D. itri ws reorded to estimte infesttion rtes. Eight to 10 shoots tree 1 were exmined on verge, exept on 12th April when shoot density ws estimted t only one per frme. Shoots were even srer on 27th August nd not smpled. On other dtes, one of the infested shoots from eh tree ws olleted nd exmined in the lortory under stereosopi mirosope to ount the eggs nd nymphs of D. itri The totl re of 54 h ws divided into 24 plots of 2e3 h, eh ontining seven-eds nd 14 tree rows. Plots were ssigned rndomly to five tretments nd n untreted ontrol using rndomized omplete lok design with 4 replitions. The dditionl tretments were inluded to determine whether rodspetrum insetiides in 3 different hemil lsses (orgnophosphte, rmte nd pyrethroid) ould e used s dormnt sprys nd lso whether two dormnt sprys were more effetive thn single spry. Proedures for spry pplitions were the sme s desried ove. Sprys pplied in designted plots on 16e17th Jnury inluded tretments of the rmte oxmyl t 0.56 nd 1.12 kg.i. h 1 (Vydte 2 L, DuPont Compny, Dupont Crop Protetion, Newrk, DE), the orgno-phosphte hlorpyrifos t 2.8 kg.i. h 1 (Lorsn 4 E, Dow AgroSienes LLC, Indinpolis, IN) nd the pyrethroid fenpropthrin t 0.34 kg.i h 1 (Dnitol 2.4 EC, Vlent USA Corportion, Wlnut Creek, CA). Fenpropthrin ws pplied to two plots in eh replite, one of whih reeived seond pplition of hlorpyrifos t 2.8 kg.i. h 1 on 12th Ferury. No other insetiides were pplied nywhere in the loks through July. Applitions of rodst fertilizer were mde in Jnury, April nd Otoer. Stndrd ulturl prties were followed uniformly throughout the grove. Flush nd D. itri popultions were monitored on 7th Ferury, 10th Mrh, 10th April, 11th My, 4th June nd 1st July. Three entrl eds per plot were used nd four trees smpled t eh of the two non-systemtilly seleted lotions per ed for totl of 24 trees plot 1. The sme proedure ws used s in the 2007 experiment exept tht nymphl density ws rted in the field on sle of 0e5: 0 ¼ none, 1 ¼1e10, 2 ¼ 11e20, 3 ¼ 21e30, 4 ¼ 31e40 nd 5 ¼ 41þ nymphs per shoot. An verge of 6 (10th Mrh), 6 (10th April), 5 (11th My), 9 (4th June) nd 7 (1st July) shoots per tree were exmined to estimte infesttion rtes. Shoots were very sre nd not smpled on 7th Ferury. In ddition to the designed experiments t the ommeril grove, severl loks of different itrus vrieties were monitored tht hd een treted in Jnury of 2007 nd 2008 t the experimentl orhrd of the Southwest Florid Reserh nd Edution Center (SWFREC), Immoklee, FL (Tle 1). The ojetive ws to ontrol psyllids nd not to ondut replited tril, lthough one lok ws left untreted to ompre with dormnt seson treted loks for psyllid popultions. These loks ontined 12e13 yr old trees plnted t density of 373 per hetre on doule-row rised eds. Bloks, re, vrieties nd pplition rtes of insetiides re given in Tle 1. Folir pplitions were mde using trtor mounted Durnd Wylnd 3P-10C-32 ir lst spryer (Qureshi nd Stnsly, 2007). Aldir (Temik 15 G, Byer CropSiene LP, Reserh Tringle Prk, NC) systemi insetiide ws pplied in the soil using modified Gndy grnulr pplitor (Qureshi nd Stnsly, 2008). Applitions of rodst fertilizer nd KeyPlex 445 formultion of mironutrients were mde in April nd June, respetively. Although, treted nd untreted loks were monitored monthly over two-yer period, dt re presented only through My due to susequent insetiide pplitions mde in some loks for vrious resons. Stndrd ulturl prties were followed uniformly throughout the grove. Four trees were smpled t eh of the eight non-systemtilly seleted lotions per lok. Proedures were similr to the ones desried for the ommeril grove experiment 2007 exept tht tp smples were inresed from one to four per tree, one eh on the north, south, est nd west sides etween Deemer 2007 nd Deemer 2008 due to the low popultions of D. itri. Only dult dt re presented Sttistil nlysis Estimtes of dults per tp smple nd nymphs per 39 dm 3 nopy volume were nlyzed. Nymphs per 39 dm 3 were otined y multiplying men shoot density per smple y the proportion of shoots infested nd the numer of nymphs per shoot (Hll et l., 2008; Pluke et l., 2008). Averge nymphl density per shoot represented y eh rting sle ws used for 2008 dt. There were only two ses when nymphl density ws rted 5 for whih no rnge ws speified so n ritrry vlue of 50 ws used. The Shprio Wilk W test (P ¼ 0.05) nd normlity plots were used to test dt for ssumptions for prmetri nlysis using the univrite proedure (Shpiro nd Wilk, 1965; Shpiro et l., 1968; SAS Institute, 2004). Dt did not onform to these ssumptions despite pproprite trnsformtions used to redue heterogeneity of vrine. Therefore, the nonprmetri KruskleWllis test ws used to nlyze tretment effets, followed y pirwise tretment omprisons mde with the MnneWhitney U-test t signifine level of 0.05 (Hollnder nd Wolfe, 1973; SPSS, 2004). Atul mens nd their stndrd error (SE) re presented for ll dt. No sttistil nlysis ws onduted of dt from SWFREC whih ws unreplited. 3. Results 3.1. Designed experiments The single spry of hlorpyrifos mde to itrus trees in Jnury resulted in signifintly fewer D. itri dults in the treted trees thn untreted trees on ll smpling dtes through July with overll mens of 0.1 (SE ¼ 0.02) nd 1 (SE ¼ 0.07) per tp smple, respetively (H ¼ 144, df ¼ 1, P < , Fig.1A). No dults were oserved in the tp smples onduted in the treted trees ompred to men of 0.3 (SE ¼ 0.1) per tp smple in the untreted trees through 12th April (22nd Jnury: H ¼ 4.1, df ¼ 1, P ¼ 0.043; 8th Mrh: H ¼ 8.5, df ¼ 1, P ¼ 0.004; 29th Mrh: H ¼ 13.1, df ¼ 1, P ¼ ; 12th April: H ¼ 28.9, df ¼ 1, P < ; Fig. 1A). On 25th April, 46-fold fewer dults were oserved in treted trees ompred to untreted trees (H ¼ 40.4, df ¼ 1, P < ). Adult density peked t 3.06 per tp smple in untreted trees on 29th My, 11-fold more thn treted trees (H ¼ 48.6, df ¼ 1, P < ). Numers delined onsistently fter tht in oth treted nd untreted trees. However, signifint differene of 8 nd 3-fold in dult numers ws still oserved etween treted nd untreted trees on 22 June (H ¼ 38.4, df ¼ 1, P < ) nd 24 July (H ¼ 13.9, df ¼ 1, P ¼ ), respetively. Adults verged <1 per tp smple on 27th August nd did not differ etween treted nd untreted trees (H ¼ 0.527, df ¼ 1, P ¼ 0.468).

4 J.A. Qureshi, P.A. Stnsly / Crop Protetion 29 (2010) 860e Tle 1 Men (SEM) numer of Diphorin itri dults per tp smple on dormnt seson treted nd untreted itrus trees t SWFREC grove, Immoklee, FL 2007e2008. Bloks (No.) Are (h) Vrieties Dormnt Seson Tretments Jn. (07e08) Rte (Kg/h) Applition method Diphorin itri dults per tp smple Mrh April My Mrh April My 1 2 Vleni Untreted None 0.19 (0.11) 0.28 (0.10) 1.94 (0.30) 0.45 (0.09) 0.13 (0.04) 0.16 (0.07) Vleni Fenpropthrin 0.34 Spry 0.00 (0.00) 0.00 (0.00) 0.03 (0.03) 0.00 (0.00) 0.05 (0.02) 0.04 (0.03) 2 2 Vleni þ Grpefruit Fenpropthrin þ Aldir 0.34 þ 5.6 Spry þ Soil 0.00 (0.00) 0.00 (0.00) 0.02 (0.02) 0.00 (0.00) 0.00 (0.00) 0.04 (0.01) Hmlin þ Vleni Chlorpyrifos þ Aldir 2.8 þ 5.6 Spry þ Soil 0.00 (0.00) 0.00 (0.00) 0.02 (0.02) 0.00 (0.00) 0.01 (0.00) 0.02 (0.01) þ Grpefruit Grpefruit þ Nvel Aldir 5.6 Soil 0.00 (0.00) 0.00 (0.00) 0.05 (0.03) 0.00 (0.00) 0.02 (0.01) 0.00 (0.00) Vrieties plnted in seprte loks. Overll nymphl density ws lower on the treted trees ompred to untreted trees, verging 20 (SE ¼ 3) nd 67 (SE ¼ 9) nymphs per 39 dm 3, respetively (H ¼ 39.58, df ¼ 1, P < , Fig. 1B). Nymphl density differed etween treted nd untreted trees on four smplings onduted in spring (8th Mrh: H ¼ 13.5, df ¼ 1, P ¼ ; 29th Mrh: H ¼ 24.1, df ¼ 1, P < ; 12th April: H ¼ 28.9, df ¼ 1, P < ; 25th April: H ¼ 25.4, df ¼ 1, P < ; Fig. 1B) nd verged only 0.1 (SE ¼ 0.1) nymphs per 39 dm 3 in treted trees ompred to 39 (SE ¼ 23) per 39 dm 3 in untreted trees. The gretest redution, 335-fold, ws seen on 25th April. Most nymphs were seen on 24th July when they verged 67 (SE ¼ 12) nd 212 (SE ¼ 45) per 39 dm 3 in treted nd untreted trees, respetively, still signifintly different etween the two tretments (H ¼ 11.8, df ¼ 1, P ¼ ). Differenes were not signifint on 29th My nd 22nd June (H ¼ 1.9, df ¼ 1, P ¼ nd H ¼ 1.9, df ¼ 1, P ¼ 0.163, respetively), nor on 22nd Jnury (H ¼ 0.1, df ¼ 1, P ¼ 0.820) one week fter tretment. Ldyeetles [Oll v-nigrum (Mulsnt), Curinus oeruleus (Mulsnt), Hrmoni xyridis (Plls) nd Cyloned snguine (L.)] nd lewings (Cereohrys sp. nd Chrysoperl sp.) were eqully undnt in treted nd untreted trees over ll smple dtes (H ¼ 1.86, df ¼ 1, P ¼ 0.17 nd H ¼ 0.17, df ¼ 1, P ¼ 0.68, respetively) nd on respetive dtes [H 3, df ¼ 1, P > 0.05 for ldyeetles omprisons etween treted nd untreted trees on individul dtes (Fig. 2A); H 2, df ¼ 1, P > 0.05 for lewings omprisons etween treted nd untreted trees on individul dtes (Fig. 2C)]. Spiders were more undnt in untreted trees on Jnury 22nd Fig. 1. Men (SEM) numer of Diphorin itri dults per tp smple (A) nd nymphs per 39 dm 3 of tree nopy (B) in Hmlin ornge trees untreted nd treted with folir spry of hlorpyrifos on 15th Jnury 2007 t ommeril grove in Immoklee, FL. No other insetiides were used in the experimentl loks through August. Shoots were sre nd not smpled on 27th August to estimte nymphl density. Treted nd untreted trees represented y olumns with sme letter were not signifintly different (KruskleWllis test, P > 0.05). Fig. 2. Men (SEM) numer of ldyeetles (A), spiders (B) nd lewings (C) per tp smple in Hmlin ornge trees untreted nd treted with folir spry of hlorpyrifos on 15th Jnury 2007 t ommeril grove in Immoklee, FL. No other insetiides were used in the experimentl loks through August. Treted nd untreted trees did not differ for ny of the three predtory groups (KruskleWllis test, P > 0.05), exept spiders on Jnury 22nd (* ¼ signifintly different, P < 0.05).

5 864 J.A. Qureshi, P.A. Stnsly / Crop Protetion 29 (2010) 860e866 soon fter tretment (H ¼ 21.52, df ¼ 1, P < ) ut were eqully undnt in the treted nd untreted trees fterwrd [H 3, df ¼ 1, P > 0.05 for omprison etween treted nd untreted trees on individul dtes (Fig. 2B)]. Averges over ll smple dtes of 0.05 (SE ¼ 0.01), 0.09 (SE ¼ 0.01) nd 0.02 (SE ¼ 0.005) per tp smple were otined for ldyeetles, spiders nd lewings, respetively Dormnt seson sprys mde in Jnury were gin effetive in suppressing D. itri popultions well into the growing seson, resulting in signifintly fewer dults in ll treted trees ompred to untreted trees over ll smplings through June 4 (H ¼ , df ¼ 5, P < , Fig. 3A). Adults per tp smple verged 1.34 (SE ¼ 0.08) in untreted trees ompred to 0.03 (SE ¼ 0.01), 0.04 (SE ¼ 0.01) nd 0.06 (SE ¼ 0.01) in trees treted with fenpropthrin followed y hlorpyrifos, fenpropthrin lone nd the high rte of oxmyl, the three most effetive tretments. No more thn 0.01 (SE ¼ 0.01) dults were oserved per tp smple in Ferury (H ¼ 43.37, df ¼ 5, P < ) nd Mrh (H ¼ , df ¼ 5, P < ) on trees reeiving these tretments ompred to 0.92 (SE ¼ 0.12) in the untreted trees, redution of 92e100-fold (Fig. 3A). On 10th April, dults were redued y 19, 34 nd 103-fold in the trees treted with the high rte oxmyl, fenpropthrin nd fenpropthrin þ hlorpyrifos, respetively (H ¼ , df ¼ 5, P < ). Signifint redution of 16e40-fold ws still oserved in these tretments during My (H ¼ , df ¼ 5, P < ) nd June (H ¼ , df ¼ 5, P < ). Tretments signifintly redued nymphs over ll smplings through 1st July (H ¼ , df ¼ 5, P < ) exept the low rte oxmyl tht did not differ from the untreted hek (Fig. 3B). The sme 3 tretments were most effetive with respet to nymphs, A Adults per tp smple Nymphs per 39 dm 3 B Untreted oxmyl (0.56 kg/h) oxmyl (1.12 kg/h) hlorpyrifos (2.8 kg/h) fenpropthrin (0.34 kg/h) fenpropthrin (0.34 kg/h) + hlorpyrifos (2.8 kg/h) d de e 2/7 3/10 4/10 5/11 6/4 7/ d d d Fig. 3. Men (SEM) numer of Diphorin itri dults per tp smple (A) nd nymphs per 39 dm 3 of tree nopy (B) in Hmlin ornge trees untreted nd treted with sprys of oxmyl, hlorpyrifos nd fenpropthrin on 16e17th Jnury Fenpropthrin ws pplied in two plots in eh replite, one of whih reeived seond pplition of hlorpyrifos on 12th Ferury to evlute the effet of two dormnt sprys. No other insetiides were used in the experimentl loks through July. Shoots were sre nd not smpled on 7th Ferury to estimte nymphl density. Treted nd untreted trees represented y olumns with sme letter were not signifintly different (KruskleWllis test followed y MnneWhitney U-test for pirwise tretment omprisons, P > 0.05). verging 35.9 (SE ¼ 6.4) in untreted trees ompred to 2.2 (SE ¼ 0.5), 2.3 (SE ¼ 0.5) nd 6.1 (SE ¼ 1.1), per 39 dm 3 for fenpropthrin þ hlorpyrifos, fenpropthrin lone nd the high rte of oxmyl, respetively (Fig. 3B). However, fenpropthrin lone or followed y hlorpyrifos provided 16e17-fold redution in nymphs, ompred to 6-fold redution with the high rte of oxmyl (U ¼ ; n ¼ 83, 79; P ¼ nd U ¼ ; n ¼ 89, 79; P ¼ 0.001, respetively). Gretest redution (14e23-fold) ws seen in April nd June with fenpropthrin tretments followed y the high rte oxmyl. On 1st July, ll treted trees exept those reeiving the low rte oxmyl hd signifintly fewer nymphs thn untreted trees with gretest redution (11e17-fold) seen following either fenpropthrin tretment (H ¼ 52.15, df ¼ 5, P < ). Ldyeetles, lewings nd spiders verged 0.02 (SE ¼ 0.004), 0.03 (SE ¼ 0.003) nd 0.09 (SE ¼ 0.003) per tp smple, respetively, over ll smple dtes (Fig. 4). No differenes etween treted nd untreted trees were seen in numers of lewings (H ¼ 1.48, df ¼ 5, P ¼ 0.92). However, ldyeetle numers were lower thn the untreted hek in the trees treted with the high rte of oxmyl nd fenpropthrin lone (H ¼ 11.94, df ¼ 5, P ¼ 0.04) nd spiders were low in oth fenpropthrin tretments (H ¼ 13.31, df ¼ 5, P ¼ 0.02) SWFREC grove Dt from this grove provided n dditionl exmple of how dormnt sprys funtioned under different onditions. Suppression of D. itri ws indited y low dult numers oserved through My during oth yers in loks treted during the dormnt seson ompred to the untreted lok supported the results otined from designed experiments (Tle 1). No dults were oserved in tp smples onduted in the treted trees in Mrh nd April of 2007 nd Mrh 2008 nd verged etween 0 nd 0.05 per tp smple in treted trees in April 2008 ompred to verges of 0.19e0.28 nd 0.13e0.45 dults per tp smple in untreted trees in Mrh nd April of 2007 nd 2008, respetively. In My, dult density ws still very low in treted trees nd verged etween 0 nd 0.05 per tp smple ompred to 0.16e1.94 per tp smple in untreted trees. Psyllid popultions were reltively low in 2008 ompred to An inrese of 10-fold nd derese of 3-fold ws oserved in the dult numers in untreted trees from Mrh to My in 2007 nd 2008, respetively. No. per tp smple Untreted oxmyl (0.56 kg/h) oxmyl (1.12 kg/h) hlorpyrifos (2.8 kg/h) fenpropthrin (0.34 kg/h) fenpropthrin (0.34 kg/h) + hlorpyrifos (2.8 kg/h) Ldyeetles Lewings Spiders Predtors Fig. 4. Men (SEM) numer of ldyeetles, lewings nd spiders per tp smple over ll smple dtes in Hmlin ornge trees untreted nd treted with sprys of oxmyl, hlorpyrifos nd fenpropthrin on 16e17th Jnury Fenpropthrin ws pplied in two plots in eh replite, one of whih reeived seond pplition of hlorpyrifos on 12th Ferury to evlute the effet of two dormnt sprys. No other insetiides were used in the experimentl loks through July. Treted nd untreted trees represented y olumns with sme letter were not signifintly different (KruskleWllis test followed y MnneWhitney U-test for pirwise tretment omprisons, P > 0.05).

6 J.A. Qureshi, P.A. Stnsly / Crop Protetion 29 (2010) 860e Disussion Suppression of D. itri dults overwintering during the dormnt winter seson efore ud rek nd prior to ntiipted flush is imed t reduing reprodution in the spring nd lter into the growing seson. A single spry of rod-spetrum insetiide in winter onsistently redued psyllid popultions for five to six months into the growing seson. Effets were similr, irrespetive of insetiide lss nd most pronouned on dults, whih re the prime ontrol trget euse they re diretly responsile for the spred of the greening pthogen from disesed trees. By killing over-wintering dults, dormnt sprys llowed fewer psyllids to enter into the spring flush, resulting in signifintly lower popultions throughout spring nd into erly summer in treted trees ompred to untreted trees. Reprodution in D. itri is ssoited with new shoot growth. Net reprodutive rte verged 379 t 25 C for D. itri developing on flushing grpefruit, Citrus prdisi Mfdyen, under lortory onditions (Tsi nd Liu, 2000). Thus, high nymphl densities re expeted under optiml field onditions. Fewer nymphs were present during spring nd summer in trees reeiving effetive winter tretments followed presumly y predtion from nturl enemies tht were generlly in omprle numers in oth treted nd untreted trees. Bioti mortlity ws estimted to redue net reprodutive rte of psyllids from 5 to 27-fold during 2006e2007 in ohorts exposed to generlist predtors nd speilist prsitoids tht ttk psyllid immtures (Qureshi nd Stnsly, 2009). Therefore, infesttion rtes ould e expeted to e higher in the sene of predtors, prtiulrly ldyeetles, lewings nd spiders. Dormnt sprys mde prior to spring flush ppered to hve little effet on density of predtor insets migrting lter into the orhrds in serh of phids nd other prey. Susequent preying upon psyllids my explin, t lest in prt, why effets of these sprys ontinued to e oserved well into the growing seson. The effetiveness of dormnt sprys in suppressing psyllids ppered to e greter in 2007, possily due to the impt on psyllid predtors from inresed insetiide use in 2008 s growers eme more wre of the HLB thret. A similr trend of deresed tivity mong psyllid predtors in 2007 ompred to spring 2006 ws lso ttriuted to inresed insetiide use in the re (Qureshi nd Stnsly, 2009). Another ftor my hve een smller plot size in 2008 so tht psyllid migrtion etween plots tended to oliterte differenes more quikly. Effets of dormnt seson tretments on D. itri onsistently oserved in this study provide strong evidene for the effetiveness of this tti in reduing psyllid popultions. Signifint redution of vetor popultions should ultimtely ontriute to redution in the rte of HLB spred. Over-wintering psyllid dults re vulnerle during tree dormny euse of nturl ttrition of the popultion, reltively thin nopy nd lk of over, nd prolonged exposure to insetiides. Furthermore, movement of psyllid dults for thermoregultion within the tree nopy is proly greter during ool wether, inresing ontt with toxi residues. These ftors together with the reltive sene of nturl enemies mke the dormnt winter period the est time to employ rod-spetrum insetiides ginst ACP in Florid itrus. No signifint dvntge ws oserved with two dormnt sprys, proly due to the short intervl etween pplitions in the one instne when this prtie ws evluted. However, spry in Novemer or Deemer followed y seond spry t the end of Jnury or erly Ferury might e more effetive thn single dormnt spry. This prtie hs een generlly dopted in southwest Florid, with pyrethroids the usul winter hoie, due to their effetiveness t tht time nd short (1 dy) pre-hrvest intervl (Stnsly et l., 2009). Additionl sprys during the growing seson should e sed on souting nd pplied prior to ntiipted flush. Seletive mterils inluding hortiulturl oils my e etter suited to post-loom pplitions due to reltively fewer negtive impts on enefiil insets. Orgno-phosphtes nd rmtes ould e resorted to lter in the growing seson when enefiil insets re not s prevlent s in spring nd erly summer (Qureshi nd Stnsly, 2009; Stnsly et l., 2009). The dormnt spry tti is now prt of n re-wide mngement progrm to redue the inidene of Asin itrus psyllid nd spred of itrus greening disese eing dopted in southwest Florid (Stnsly et l., 2009). Aerilly pplied dormnt sprys oordinted through Gulf Citrus Growers Assoition nd monitored y Florid Deprtment of Agriulture over 80,000 res of itrus redued psyllid popultions y 71e88% ompred to unspryed groves in spring Thus, dormnt sprys hve lredy eome key mngement omponent eing dpted re-wide to ontrol Asi itrus psyllid in Florid. 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