Abstract
The effect of autumn application of urea on the activity and composition of saprotrophic fungi associated with sour cherry (Prunus cerasus) leaf litter infected with the leaf spot pathogen, Blumeriella jaapii, was studied under orchard conditions from the time of leaf fall to the release of ascospores, the following spring. The ability of treatment of infected leaves post leaf fall with urea or with inoculum of selected fungal strains to reduce primary inoculum (ascospores and winter conidia) of B. jaapii in spring was evaluated. Fungal activity was measured enzymatically by quantifying β-N-acetylgly-cosaminidase and fungal composition and frequency were evaluated following isolation at low temperature of mycelia embedded in leaf particles. Activity of the general fungal flora increased in both the urea and water treatments throughout the experimental period and a significantly higher level of activity was detected in urea-treated leaves up to 79 days after treatment. Most of the 2,146 fungal isolates recovered from the leaf litter during November-May could be placed in the following six groups: Phoma macrostoma (52.7%), other Pho-ma spp. (12.3%), Cladosporium spp. (13.8%), Alternaria and Ulocladium spp. (5.4%), Epicoccum purpurascens (2.9%) and Fusarium spp. (1.6%). These groups were isolated from the leaf litter throughout the experimental period and the effect of urea on fungal composition in the litter was very limited. Of these groups only the frequency of recovery of E. purpurascens was higher from urea than from water-treated leaves and this significant difference was maintained throughout the 115 days of the experimental period. Phoma macrostoma var. macrostoma, Cladosporium sp., Ulocladium chatarum, Epicoccum purpurascens and Fusarium lateritium var. lateritium were evaluated and compared with urea to reduce primary inoculum of B. jaapii. Urea reduced primary inoculum of B. jaapii in the spring by 77% and of the fungal strains, especially Cladosporium strain MB167 was found to be equally effective.
Zusammenfassung
Der Einfluss einer Harnstoffbehandlung im Herbst auf Aktivität und Artenspektrum saprophytischer Pilze auf abgeworfenem Laub der Sauerkirsche (Prunus cerasus), das mit dem Erreger der Sprühfleckenkrankheit, Blumeriella jaapii, infiziert war, wurde unter Plantagenbedingungen zwischen dem Laubfall und und dem Beginn des Ascosporenfluges im folgenden Frühjahr untersucht. Im Einzelnen wurde der Einfluss einer Laubbehandlung mit Harnstoff oder ausgewählten Pilzisolaten auf das Primärinokulum (Ascosporen und Winter-konidien) von B. Jaapii im Frühjahr untersucht. Die biologische Aktivität der Pilze wurde über eine Messung der Enzymaktivität der ß-N-Acetylglucosaminidase bestimmt und Artenspektrum und -häufigkeit wurden nach der Isolierung von Pilzmycel aus Blattfragmenten bei niedrigen Temperaturen diagnostiziert. Die Aktivität der Pilze nahm sowohl in den Harnstoff- als auch in den Wasservarianten während des Untersuchungszeitraums zu und eine signifikant erhöhte Aktivität konnte in den mit Harnstoff behandelten Blättern bis zu 79 Tage nach Beginn der Behandlung festgestellt werden. Die meisten der 2.146 zwischen November und Mai aus dem Laub isolierten Pilze konnten den folgenden sechs Gruppen zugeordnet werden: Phoma macrostoma (52,7%), andere Phoma spp. (12,3%), Cladosporium spp. (13,8%), Alternaria und Ulocladium spp. (5,4%), Epicoccum purpurascens (2,9%) und Fusarium spp. (1,6%). Diese Gruppen wurden während des Untersuchungszeitraums durchgängig aus dem abgeworfenen Laub isoliert und der Einfluss der Harnstoffbehandlung auf das Artenspektrum war äußerst gering. Als einzige Art wurde E. Purpurascens häufiger aus Harnstoff- als aus Was-ser-behandeltem Laub isoliert und der Unterschied war während des gesamten 115tägigen Versuchszeitraums signifikant. Phoma macrostoma var. macrostoma, Cladosporium sp., Ulo-cladium chatarum, Epicoccum purpurascens und Fusarium lateritium var. lateritium wurden zusammen mit der Harnstoffvariante hinsichtlich ihres Potenzials zur Reduzierung des Primärinokulums von B. jaapii getestet. Harnstoff reduzierte das Primärinokulum im Frühjahr um 77% und von den untersuchten Pilzstämmen zeigte Cladosporium strain MB167 einen vergleichbaren Effekt.
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Literature
Andrews, J.H., C.M. Kenerley, 1979: The effects of a pesticide program on microbial populations from apple leaf litter. Can. J. Microbiol. 25, 1331–1344.
Bengtsson, M., 2001: Biological control of the overwintering stages of cherry leaf spot (Blumeriella jaapii) and apple scab (Venturia inaequalis). Ph.D. thesis, The Royal Veterinary and Agricultural University, Copenhagen, Denmark.
Bernier J., O. Carisse, T.C. Paulitz, 1996: Fungal communities isolated from dead apple leaves from orchards in Quebec. Phytoprotection 77, 129–134.
Bills, G.F., J.D. Polishook, 1994: Abundance and diversity of microfungi in leaf litter of a lowland rain forest in Costa Rica. Mycologia 86, 187–198.
Burchill, R.T., R.T.A. Cook, 1971: The interaction of urea and micro-organisms in suppressing the development of perithecia of Venturia inaequalis (Cke.) Wint. In: Preece, T.F., C.H. Dickinson (eds.): Ecology of leaf surface micro-organisms, pp. 471–483. Academic Press, New York.
Carreiro, M., R.E. Koske, 1992: Room temperature isolations can bias against selection of low temperature microfungi in temperate forest soils. Mycologia 84, 886–900.
Cirano, J.O., J.F. Peberdy, 1993: Effect of carbon source on chitobiase production by Trichoderma harzianum. Mycol. Res. 97, 45–48.
Crosse, J.E., C.M.E. Garett, R.T. Burchill, 1969: Changes in the microbial population of apple leaves associated with the inhibition of the perfect stage of Venturia inaeqalis after urea treatment. Ann. Appl. Biol. 61, 203–216.
Dickinson, C.H., 1975: Fungi on the aerial surfaces of higher plants. In: Dickinson, C.F., T.F. Preece (eds.): Microbiology of aerial plant surfaces, pp. 293–324. Academic Press, New York.
Freeman, C., G. Liska, S.E. Jones, M.A. Lock, 1995: The use of fluorogenic substrates for measuring enzyme activity in peat lands. Plant Soil 17 5, 147–152.
Hering, T.F., 1965: Succession of fungi in the litter of a Lake District oakwood. Trans. Brit. Mycol. Soc. 48, 391–408.
Hogg, B.M., H.J. Hudson, 1966: Micro-fungi on leaves of Fagus sylvatica. I. The micro-fungal succession. Trans. Brit. Mycol. Soc. 49, 185–192.
Hudson, H.J., 1971: The development of the saprophytic fungal flora as leaves senesce and fall. In: Preece, T.F, C.H. Dickinson (eds.): Ecology of leaf surface micro-organisms, pp. 447–455. Academic Press, New York.
Jacobsen, H., K. Jørgensen, 1986: Cherry leaf spot disease. Danish investigations of perennation state and primary infection in sour cherries. Tidsskr. Planteav 90, 161–175.
Jones, A.L., 1995: Cherry Leaf Spot. In: Ogawa, J.M., E.I. Zehr, G.W. Bird, D.F. Ritchie, K. Uriu, J.K. Uyemoto (eds.): Compendium of Stone Fruit Diseases, pp. 21–22. APS Press, St. Paul, MN, USA.
Kollar, A., 1995: A simple method to forecast the ascospore discharge of Venturia inaequalis. Z. Pflanzenkrankh. Pflan-zensch. 105, 489–495.
Kuter, G.A., 1986: Microfungal populations associated with the decomposition of sugar maple leaf litter. Mycologia 78, 114–126.
Machardy, W.E., 1996: Apple Scab. Biology, Epidemiology, and Management. APS Press, St. Paul, MN, USA.
Miller, M., A. Palojärvi, A. Rangger, M. Reeslev, A. Kjøller, 1998: The use of fluorogenic substrates to measure fungal presence and activity in soil. Appl. Environ. Microbiol. 64, 613–617.
Pedersen, H.L., J. Hockenhull, 1996: Effects of urea on the formation of apothecia and winter conidia of Blumeriella jaapii (cherry leaf spot) and associated microfungi on overwintered cherry leaves. Gartenbauwissenschaft 61, 257–261.
Rast, D.M., M. Horsch, R. Furter, G.W. Gooday, 1991: A complex chitinolytic system in exponentially growing mycelium of Mucor rowxii: properties and function. J. Gen. Microbiol. 137, 2797–2810.
Ross, R.G., R.T. Burchill, 1968: Experiments using sterilized apple-leaf discs to study the mode of action of urea in suppressing perithecia of Venturia inaequalis. Ann. Appl. Biol. 62, 289–296.
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Bengtsson, M., Green, H., Leroul, N. et al. Effect of autumn application of urea on saprotrophic fungi in off-season leaf litter of sour cherry and evaluation of fungal isolates to reduce primary inoculum of Blumeriella jaapii. J Plant Dis Prot 113, 107–112 (2006). https://doi.org/10.1007/BF03356166
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DOI: https://doi.org/10.1007/BF03356166