Comparative Study of Dutch and Hungarian Environmentally-friendly Apple Orchards on Potential Ascospore Dose of Apple Scab

Transcription

1 Comprtive Study of Dutch nd Hungrin Environmentlly-friendly Apple Orchrds on Potentil Ascospore Dose of Apple Sc Imre Hol 1 Brt Heijne 2 1 University of Derecen, Centre of Agriculturl Sciences, Fculty of Agriculturl Sciences, Deprtment of Plnt Protection, Derecen 2 Wgeningen University nd Reserch Centre, Applied Plnt Reserch, Zetten-The Netherlnds SUMMARY In 2-yer study, Dutch nd Hungrin environmentllyfriendly pple orchrds were compred s regrds the mount of pple sc primry inoculum. The PAD (potentil scospore dose) method ws used to quntify the potentil mount of primry inoculum (scospores) per m 2 orchrd floor. Applying this method, the numer of lesions per m 2 of lef in the utumn (LD), the proportion of the orchrd floor covered y lef litter t ud rek (LLD) nd potentil scospore dose (PAD) were determined. In utumn, LD vlues rnged etween 2.2 nd 13. in the integrted orchrds, while in the orgnic orchrds the vlues were etween 42. nd 16.2, with especilly high vlues in the Dutch orgnic orchrd. LLD vlues rnged etween 24 nd 43% t ud rek in oth countries. PAD vlues were 1-6 times higher thn those of the integrted orchrds. The PAD vlues were etween 673 nd 427 scospore/m 2 orchrd floor in the integrted orchrds, while in the orgnic orchrds these vlues were 3712 nd 239 scospore/m 2 orchrd floor, respectively. On the sis of the recorded primry inoculum quntity, the Dutch integrted pple orchrd is considered to e excellently protected, while the Hungrin orchrd hs medium level of protection. However, oth countries orgnic orchrds cn e regrded overll s eing very poorly protected. Accordingly, in the integrted orchrds the predicted epidemic risk is low or medium, while in the orgnic orchrds it is very high on the sis of PAD vlues. INTRODUCTION The pple sc, cused y Venturi inequlis (Cooke) G. Wint., overwinters s pseudotheci in the infected pple lef litter. The overwintered pseudotheci egin to develop from the end of Ferury. After few weeks in erly spring, pseudothecium mtures nd produces scospores. Ascospores egin to dischrge from pseudotheci when they re moistened y rin or hevy dew. Ascospores re dispersed minly y wind to susceptile young green tissues of the tree where infection occurs. Infection is highly influenced y the susceptiility of the cultivr, wether conditions nd the quntity of primry inoculum (scospore). How these fctors interct with scospore production, dischrge nd infection under the locl conditions of n orchrd is criticl to know in order to mke proper plnt protection decisions. The most frequently detected phse of pple sc life cycle in Hungry is the time when infection occurs ccording to Mills infection criteri (Mills nd LPlnte, 191). Less energy nd time re devoted in domestic orchrds specifying the time when scospores dischrge, lthough the methods for identifying the mturity of pseudotheci (Surján, 1974) nd using smll suction spore collectors (Slli, 198) re widely known. Unfortuntely, in Hungry, the quntittive ssessment of sc scospores is rrely used, lthough it is proved tht there exists strong correltion etween the mount of scospores nd the length s well s the intensity of the primry infection period (McHrdy, 1996). In mny countries, severl methods re used for mesuring nd ssessing the quntity of ccumulted scospores in orchrds. Such methods re the different spore trps operted in the primry infection period (Hirst, 192; Gdoury nd McHrdy, 1983) or the so-clled dy-degree models (Gdoury nd McHrdy, 1982; Rossi et l., 2) nd the method for determining the potentil scospore dose (PAD) (Gdoury nd McHrdy, 1986). In the lst decdes, more emphsis hs een lin on the dy-degree models y incorporting them into sc wrning simultion models (Seem, 1986) nd on the PAD in order to integrte control mesures for the mngement of primry pple sc (McHrdy nd Jeger, 1983; McHrdy et l., 1993). Presently, the PAD technique is the most frequently used method in Western countries for ssessing nd compring the ctul scospore dose of pple sc in pple orchrds in order to predict the dnger of epidemic in erly spring (Scheer vn der, 1993; McHrdy nd Sutton, 1997; Stensvnd nd Amundsen, 1997). The ims of this pper were: (i) to determine potentil scospore dose in domestic nd Dutch environmentlly-friendly (integrted nd orgnic) pple orchrds (ii) to compre the orchrds of two countries on the sis of the PAD method nd dt of wether oservtions. MATERIALS AND METHODS Orchrd site nd sprying In Hungry, experiments were crried out in 1 h pple orchrd with 4 cultivrs t Derecen Fruit Experimentl Sttion, University of Derecen. The orchrd ws estlished in the spring of 1997, using grfted on M26 rootstocks t spcing of 4 x 1. m. Cultivrs were plnted in plots. Ech plot consisted of 7 trees per cultivr. Plots were plced in rndomised lock design with 6 replictes. From the

2 first yer on, one hlf of the orchrd hs een treted ccording to the Integrted Fruit Production guidelines (Anonymous, 199), nd the other hlf ccording to the Orgnic Fruit Production guidelines (Anonymous, 1997). The cultivrs re: resistnt: Resi, Remo, Retin, Rewen, Rend, Releik, Reglindis, Renor, Relind, Rek, Fw-7262 nd Lierty; tolernt: Pilot, Pinov nd Piros; current: Jongold, Jonic, Elstr, Red Elstr, Idred, Royl Gl, Mutsu nd Grnny Smith; trditionl: Red Astrchn, Egri piros, Nyári fontos, Winter Gold Permin, Winter Bnn, Clville Blnc d Hiver, Téli piros pogács, Fertődi téli, Húsvéti rozmring, Mosolygós tul, Btul, Drusóvári, Grvenstein, Frnci renet, Prker s Pippin nd London Pippin. In the Netherlnds, exmintions were crried out t Rndwijk in two experimentl orchrds of Wgeningen University, Institute of Applied Plnt Reserch. Orchrd one hs een treted ccording to the principles of the Dutch Integrted Fruit Production (Mt) nd orchrd two ccording to the principles of the Dutch Orgnic Fruit Production (SKAL). Regultions of disese nd pest control hve een renewed nnully in oth production systems. Spry schedules hve een pplied since 1996 (yer of settlement), in oth experimentl orchrds. The two orchrds re seprted y 6 m wide itumin rod nd 2 rows of Alnus cordt hedge. Both orchrds consisted of 32 rows. Two rows of cultivr Jongold lternted with two rows of cultivr Schone vn Boskoop in the orgnic field, nd with two rows of cultivr Elstr in the integrted field. All trees were plnted t spcing of 3 x 1.2 nd grfted on M9 rootstocks. In oth orgnic orchrds t Rndwijk nd t Derecen, disese control ws sed on the regulr use of copper nd sulphur gent pproved in orgnic production. In the integrted orchrds, ll the pplied chemicls were contct or systemic fungicides from the green nd the yellow list. Disese spryings were pplied in ccordnce with the criteri of Mills nd LPlnte (191). Survey on the role of wether The role of wether in the development of epidemics nd in the chnges of PAD vlues were evluted y determining the Mills infection periods from 1 April until 1 Octoer. For this, HP 1 (G. Lufft Mess- und Regeltechnik Gmh, Germny) disese wrning system ws used in Hungry from In the Netherlnds, the durtion of lef wetness ws registered with n Omnidt ES 46 (Techno Co. Ltd. Apfeldoorn, the Netherlnds) in 1999 nd 2. Afterwrds, the Mety 2. sc wrning system ws utilised to determine the Mills infection periods. Quntity of primry inoculum The ssessment nd clcultion of the potentil quntity of primry inoculum in the experimentl orchrds ws sed on the PAD method developed y Gdoury nd McHrdy (1986). Accordingly, we pplied the next PAD formul dpted to the locl conditions of the survey: PAD = LD x LLD x PD x AD x n PAD = potencil scospore dose (estimted production of scospores per m 2 orchrd floor); LD = lesion density (numer of lesions per m 2 of lef t lef fll); LLD = lef litter density (the proportion of the orchrd floor covered y lef litter t ud rek); PD = pseudothecil density (numer of pseudotheci per visile lesion), this normlly hs to e multiplied y lesion fertility fctor (f); AD = Ascl density (numer of sci per pseudothecium); n = numer of scospores per scus. At the end of Octoer in 1997, 1998 nd 1999 t Derecen nd in 1998 nd 1999 t Rndwijk we recorded the numer of sc lesions per m 2 of lef t lef fll (LD). At ud rek lef litter density (LLD) ws determined in 1998, 1999 nd 2 t Derecen- Pllg nd in 1999 nd 2 in Rndwijk. Oservtions were crried out in 4 replictes y exmining 2 rndomly chosen leves per replicte. The proportion of fertile lesions vries with the numer of lesions per lef, therefore, it ws djusted ccording to the mesurements of Gdoury nd McHrdy (1986). For PAD clcultion the fertility index (f), pseudothecil density (PD) nd scl density (AD) were set to.2-.4, 23.4 nd 122.8, respectively in the integrted orchrds. In the sme order f, PD, nd AD were.2-.4, 46. nd in orgnic orchrds. PAD nd the five density fctors were clculted s the verge of ll cultivrs in Hungry, nd s the verge of cv. Jongold nd cv. Schone vn Boscoop in the Dutch orgnic nd of cv. Jongold nd cv. Elstr in the Dutch integrted orchrd. After clculting PAD, the orchrds were clssified into three groups: well-mnged, modertely-mnged nd poorly-mnged ccording to McHrdy nd Sutton (1997). The ctegories for the effectiveness of disese mngements were: PAD<6; 1- nd >, respectively. In ccordnce with these, the dnger of epidemic ws considered smll in the well-mnged, medium in the modertely-mnged nd high in the poorly-mnged orchrd. Sttisticl nlysis All dt were sujected to nlysis of vrince (ANOVA) t P<. using the Genstt Relese 4.1 sttisticl pckge. The significnt differences etween the two production systems nd within the two production systems were evluted for the density fctors of LD, LLD nd PAD. 2

3 RESULTS Wether conditions Derecen-Pllg A totl of 39 nd 4 infection periods were recorded from 1 April 1 Octoer in 1998 nd 1999, respectively. The Mills infection periods were hevy in 14 nd 19 instnces, moderte in 16 nd 1 instnces nd low in 9 nd 6 instnces in 1998 nd 1999, respectively (Figure 1). Wether in 1998 nd 1999 ws fvourle for the sc epidemic in Hungry. Figure 1: The numer of Mills infection periods nd distriution of infection y intensity (light, moderte nd severe) etween 1 April nd 1 Octoer t Derecen Numer of Mills' infection periods light moderte severe Rndwijk A totl of 9 nd 8 infection periods were recorded from 1 April 1 Octoer in 1998 nd In 1998, the Mills infection periods indicted possiility of hevy infection in 16 instnces, of moderte infection in 23 instnces nd of low infection in 2 instnces (Figure 2). In 1999, the numers were 33, 8 nd 17, respectively (Figure 2). On the sis of these figures, wether conditions were very fvorle for the development of hevy sc epidemic in oth yers. Figure 2: The numer of Mills infection periods nd distriution of infection y intensity (light, moderte nd severe) etween 1 April nd 1 Octoer t Rndwijk Numer of Mills' infection periods light moderte severe Quntity of primry inoculum Derecen-Pllg In the orgnic orchrd, the lesion density (LD) ws 42. nd 4.7 lesions/m 2 of lef re in the end of Octoer in 1998 nd 1999, resp. In the integrted orchrd these vlues were 11. nd 13. lesions/m 2 of lef re, respectively (Figure 3). At ud rek, lef litter density vlues (LLD) in % were pproximtely equl (41-43%) in oth production systems t Derecen-Pllg (Figure 4). At Derecen-Pllg, the PAD vlues were 362 scospores/m 2 in 1999, nd 427 in 2 in the integrted orchrd. The estimted production of scospores per m 2 orchrd floor ws 1 times higher in the orgnic orchrd in ech yer t Derecen- Pllg (Figure ). Rndwijk The lesion density (LD) ws 2.2 nd 2.3 lesions/m 2 of lef re in the integrted orchrd nd ws 79.4 nd 97. lesion/m 2 of lef re in the orgnic system in the utumn of 1998 nd 1999, respectively. The reltively low lesion density in the Dutch integrted orchrd nd the very high lesion density in the Dutch orgnic orchrd showed significnt differences compred to the Hungrin integrted nd orgnic orchrd, respectively (Figure 3). The lef litter density vlues (LLD) in % rnged etween 24 nd 36% t ud rek in the Dutch orchrds (Figure 4). In the integrted orchrd, the rtio of overwintered leves ws 32-36%, while in the orgnic orchrd this ws 24-26%. The vlues of the orgnic orchrd were significntly lower thn those mesured in the Hungrin orgnic orchrd. The estimted production of scospores per m 2 orchrd floor (PAD) in erly spring ws the lowest in the Dutch integrted orchrd (under 9 scospores/m 2 in oth yers). On the other hnd, PAD vlues were out -6 times higher in the Dutch orgnic orchrd compred to the Dutch integrted orchrd (Figure ). Orchrd clssifiction The numer of scospores per m 2 soil surfce (PAD) ws significntly lower in the integrted orchrd thn in the orgnic one in oth countries. When compring the two systems, PAD vlues were often 1-6 times higher in the orgnic systems thn in the integrted orchrds. The comprison of PAD vlues ccording to criteri of McHrdy nd Sutton (1997) indicted tht the Dutch integrted orchrd is well-mnged, while the Hungrin one is modertely-mnged. However, oth counries orgnic orchrds were considered very poorly-mnged in the investigted yers. In complince with these, the predicted risk of epidemic ws low nd medium in the integrted orchrds, while it ws very high in the orgnic orchrds on the sis of PAD. 3

4 Figure 3: Lesion density (the numer of sc lesions per m 2 of lef t lef fll) in the integrted nd orgnic pple orchrds in 1998 nd Lesion density D 1998 D 1999 R 1998 R 1999 Orgnic Integrted The old letters on the columns sign the significnt differences within the given plnt protection system t P<.. D = Derecen, Hungry; R= Rndwijk, The Netherlnds. Figure 4: Lef litter density (the proportion of the orchrd floor covered y lef litter t ud rek) in % in integrted nd orgnic pple orchrds in 1998 nd Lef litter density % Integrted D 1999 D 2 R 1999 R 2 Orgnic The old letters on the columns sign the significnt differences within the given plnt protection system t P<.. D = Derecen, Hungry; R= Rndwijk, The Netherlnds. Figure : Potentil scospore dose (estimted production of scospores per m 2 orchrd floor) in integrted nd orgnic pple orchrds in 1998 nd 1999 t ud rek Potentil scospore dose D 1999 D 2 R 1999 R 2 Orgnic Integrted The old letters on the columns sign the significnt differences within the given plnt protection system t P<.. D = Derecen, Hungry; R= Rndwijk, The Netherlnds. 4

5 DISCUSSION Determintion of potencil scospore dose showed tht primry inoculum ccumulted in high mounts in the orgnic orchrds. According to literture dt, PAD vlues cn rnge etween nd 1 scopores/m 2 in the orchrd floor ut the vlues re highly dependent upon the efficiency of the previous yer s plnt protection (Gdoury nd McHrdy, 1986; Scheer vn der, 1993; McHrdy, 1996; Stensvnd nd Amundsen, 1997). In this study, PAD vlues of the integrted orchrd t Derecen-Pllg were medium in 1999 nd 2 (362 nd 427 scospores/m 2 ) nd low t Rndwijk orchrd (842 nd 673 scospores/m 2 ). The reltively high PAD vlues in Hungry were due to the fct tht the two orchrds (orgnic nd integrted) were close to ech other. Moreover, fungicide spryings in oth yers were finished y the middle of August. This hs lso contriuted to the increse of inoculum ccumultion, which cused slight utumn epidemic. This lte epidemic incresed the LD vlues, which were higher compred to the Dutch integrted orchrd. PAD vlues in the Dutch integrted orchrd were remrkly low, in spite of the fvourle wether conditions. The possile explntion for this is tht orchrds were seprted y 6 m wide itumin rod nd 2 rows of Alnus cordt hedge. In ddition, spryings were performed y precision techniques nd pplictions were not finished until the end of Septemer. Proly, these were the min resons for the low PAD vlues, lthough wether conditions were fvourle. In the orgnic orchrds PAD vlues were remrkly high in oth countries. PAD vlues of Dutch orgnic orchrds were similr to those of in Hungry, lthough conditions were different in the two countries. The effect of different conditions cn e seen in the differences of LD nd LLD vlues. Lesion density (LD) ws pproximtely twice higher in the Dutch orgnic orchrd thn in the Hungrin one (Figure 3). The reson for this ws proly the fct tht t Derecen-Pllg 6% of the cultivrs were resistnt or tolernt ginst pple sc, while in the Netherlnds modertely (Schone vn Boscoop) nd highly susceptile cultivr (Jongold) served s the ses of clcultion. At the sme time, Dutch LLD vlues in the orgnic orchrd were just the hlf of those in the orgnic orchrd of Derecen. This ws proly due to the etter minerlistion conditions (winter nd erly spring re more mild nd riny in the middle prts of the Netherlnds thn in Estern- Hungry). Summing up, Dutch LD vlues re two times higher, while Dutch LLD vlues re two times smller thn those of Hungry. As consequence, PAD vlues re pproximtely equl, despite the different growing nd ecologicl conditions of the two countries. It cn e stted tht the PAD method demonstrtes the lrge differences etween the integrted nd orgnic orchrds s regrds the mount of primry inoculum. The integrted wy of disese control is effective nd ensures low level of fruit dmge. In greement with McHrdy et l. (1993), omitting spryings t the eginning of the seson might e good strtegy for sving cost in integrted orchrds if PAD vlues re lower thn 6 scospores/m 2. However, results hve verified tht the ccumultion of primry sc inoculum is extremely high in the orgnic orchrds. This result ws verified y the disese mngement evlution method of McHrdy nd Sutton (1997). As consequence, these orchrds re very much exposed to high disese pressure ecuse of the limited tools of protection ginst pple sc. All this indictes tht the reduction of primry inoculum sources could hve decisive role in the improvement of pple sc protection s effectiveness. Acknowledgements Thnks re due to the stff of University of Derecen, Centre of Agriculturl Sciences, Deprtment of Horticulture nd the stff of the Wgeningen University, Institute of Applied Plnt Reserch for their finncil support of the work crried out. REFERENCES Anonymous (199): Az integrált gyümölcstermesztés nemzeti irányelvei In: Inántsy F. (eds.): Az integrált lmtermesztés gykorlti kézikönyve. Gyümölcs- és Dísznövénytermesztési Kuttó Fejlesztõ Intézeti Rt. Állomás, Újfehértó Anonymous (1997): Biotermékek előállításánk és minősítésének feltételrendszere. Biokultúr Egyesület, Budpest Gdoury, D. M.-McHrdy, W. E. (1982): Preprtion nd interprettion of sqush mounts of pseudotheci of Venturi inequlis. Phytopthology, Gdoury, D. M.-McHrdy, W. E. (1983): A 7-dy recording volumetric spore trp. Phytopthology, Gdoury, D. M.-McHrdy, W. E. (1986): Forecsting scospore dose of Venturi inequlis in commercil pple orchrds. Phytopthology, Hirst, J. M. (192): An utomtic volumetric spore trp. Annls of Applied Biology, McHrdy, W. E. (1996): Apple sc, iology, epidemiology nd mngement. APS Press, St. Pul, Minnesot, USA McHrdy, W. E.-Gdoury, D. M.-Rosenerger, D. A. (1993): Delying the onset of fungicide progrms for control of pple sc in orchrds of low potentil scospore dose of Venturi inequlis. Plnt disese, McHrdy, W. E.-Jeger, M. J. (1983): Integrting control mesures for the mngement of primry pple sc, Venturi inequlis (Cke.) Wint. Protection Ecology, McHrdy, W. E.-Sutton, D. K. (1997): Autumn sc development: crucil ut poorly understood phse of pple sc epidemiology. Proceedings of 4 th workshop on integrted control of pome fruit diseses, August 1996, Croydon, Englnd. IOBC/WPRS Bulletin, Bulletin OILB/SROP

6 Mills, W. D.-LPlnte, A. A. (191): Diseses nd insects in the orchrd. Cornell Univ. Ext. Bull., Rossi, V.-Ponti, I.-Mrinelli, M.-Giosuè, S.-Bugini, R. (2): A new model estimting the sesonl pttern of ir-orne scospore of Venturi inequlis in reltion to wether condition. Journl of Plnt Pthology, Slli, P. (198): Kiegészítések mgyr kidáshoz: Az Ellenőrző műszerek és z előrejelzés c. fejezethez In: Oerhofer, H. (eds.): Der Apfelshorf Leensweise und Bekämpfung (Az lmfvrsodás iológiáj és védekezés). A dél-tiroli gyümölcs- és szőlőtermesztési tnácsdókör, Len, Budpest Scheer, vn der H. A. Th. (1993): forecsting scospore dose of Venturi inequlis s n id to control of primry sc in commercil orchrds. Act Horticulture, Seem, R. C. (1986): Methodologicl comprison of three pple sc simultors. Act Horticulture, Stensvnd, A.-Amundsen, T. (1997): Investigtions on the potentil scospore dose of Venturi inequlis in Norwegin pple orchrds. Proceedings of 4 th workshop on integrted control of pome fruit diseses, August 1996, Croydon, Englnd. IOBC/WPRS Bulletin, Bulletin OILB/SROP Surján, J. (1974): Az lmf-vrsodás In: Benedek, P.- Surján, J.-Fésűs, I. (eds.): Növényvédelmi előrejelzés. Mezõgzdsági Kidó, Budpest 6