Anthracnose of Caused by Glomerella cingulata in Florida

C. M. HOWARD, Professor of Plant Pathology, and E. E. ALBREGTS, Professor of Soil Science, University of Florida, Agricultural Research Center, Dover 33527

A few drops of the conidial suspensions ABSTRACT that were prepared as inocula were used Howard, C. M., and Albregts, E. E. 1984. Anthracnose of strawberry fruit caused by Glomerella to measure five groups of 25 conidia of cingulata in Florida. Plant Disease 68: 824-825. each isolate. Measurements for each were averaged to obtain ranges of group sizes for each isolate. anthracnose lesions on strawberry . Lesions caused by average conidial Glomerella cingulata was isolated from also made of one inoculated fruits Were indistinguishable from those caused by Measurements were G.cingulata on fruits in the field and than Conidia of G. cingulata were slightly shorter but larger in diameter Colletotrichumfragariae. of the G. cingulata those reported for C. fragariae. group of 25 isolate. Additional key words: gloeosporioides, FragariaX ananassa RESULTS Seven days after inoculation of fruits, sites and Since 1972(2), Colletotrichumfragariae MATERIALS AND METHODS lesions had developed at 15 of 20 cingulata Brooks has been recognized as causing a The isolates used in this study were 13 of 20 sites inoculated with G. Lesions serious fruit rot of strawberry (FragariaX obtained from crowns of strawberry and C. fragariae, respectively. appeared ananassa Duch.) in Florida. Several plants that were wilting from the crown caused by either isolate to lesions species of fungi cause anthracnoselike rot phase of anthracnose. The G. identical. They were similar diseases of strawberry fruit. A cingulata isolate was obtained from a shown by Howard (2) and by Maas (4) Gloeosporium sp., later named C. plant that had been grown in a nursery in and typical of those that occur in the field, acutatum Simmonds (7), caused serious Nova Scotia, Canada, and transplanted except there was more aerial mycelium on losses in Queensland, Australia (9,10). A into a fruit production field in Florida. experimentally infected fruit. The similar disease caused by a Gloeosporium The plant was apparently infected in the increased aerial mycelium was probably sp. was found in fruit shipped from nursery (3). This isolate was identified by due to the high humidity in the tightly Louisiana to Chicago (12). C. dematium J. E. M. Mordue at the Commonwealth closed jars used in this trial. Reisolations (Pers. ex Fr.) Grove was reported to Mycological Institute, Kew, Surrey, from fruit lesions yielded only the species cause fruit rot in Michigan (1). England, where it is on deposit as IMI with which the particular fruit was Strawberry fruit rots caused by C. 259098. The C. fragariae isolate was inoculated. Lesions did not develop on fragariae or Colletotrichum spp. have obtained from a plant grown in Florida. control fruits. This trial was repeated been reported in Argentina (6), India (8), The isolates were grown for 7 days on with similar results. and Mexico (5). Maas (4) reported potato-dextrose agar (PDA, Difco) in The ranges of average measure- 13.7-16.1 anthracnose of strawberry fruit in petri dishes. The cultures were flooded ments for the two isolates were for Maryland caused by a species of with sterilized distilled water and the X6.9-7.1 and 16.9-17.7X6.3-6.8um Gloeosporium that was similar to C. resulting spore suspensions were used to G. cingulataand C.fragariae,respectively. were gloeosporioides (anamorph of inoculate strawberry fruits. There were Thus, the G. cingulata in diameter G. cingulata). 10,000 and 3,250 spores per milliliter slightly shorter but larger isolate C.fragariaewas the only Colletotrichum from the G. cingulata and C. fragariae than spores of the C. fragariae used in sp. isolated from anthracnose lesions on isolates, respectively. Spore concentrations used in this study and those of strawberry fruits in Florida until 1980. of the two isolates were not equalized previous studies (2,3). The ascospores X ,m. Since then, although most isolates because we had found in previous work G. cingulata averaged 16.1 5.8 obtained from fruit lesions have been C. (unpublished)that, under our conditions, fragariae, a small percentage have been spore concentrations ranging from 250 to DISCUSSION Glomerella cingulata (Stonem.) Spauld. 10,000 per milliliter had little effect on the All G. cingulata isolates we obtained & Schrenk (telemorph of C. gloeo- numbers of lesions that developed on from in Florida (whether sporioides Penz.). This is believed to be fruit within 7 days of inoculation, from crowns, stolons, or fruit) produced the first report of naturally occurring Ripe fruits of the Tufts cultivar were colonies that became dark gray to nearly strawberry fruit rot caused by G. surface-sterilized by immersion in 95% black as they enlarged. Perithecia, which cingulata, although Simmonds (7) ethyl alcohol for 30 sec followed by 15 were covered with flexuous appendages, reported infection of strawberry fruits min in a 0.525% sodium hypochlorite developed in the cultures within 1-2 wk. after inoculation with G. cingulata from solution. They were rinsed four times in The appendages later collapsed and papaw and passion fruit. This report sterilized distilled water and placed disappeared. Perithecia were formed describes experiments to determine aseptically into autoclaved jars, one fruit primarily on the surface of the medium pathogenicity of Florida isolates of G. per jar. After drying, each fruit was but some were suspended in the aerial cingulata to strawberry fruit. inoculated at two points with small mycelium. Most isolates failed to droplets of spore suspension. Ten fruits produce perithecia, or produced them Journai Series Paper No. 5469. University of Fiorida, were inoculated with each isolate. sparcely after they were subcultured two Institute of Food and Agricuitural Sciences. Control fruits received sterilized distilled to five times. Accepted for publication 4 June 1984. water. Jars containing inoculated fruit Although von Arx (11) placed C. were placed under fluorescent lights fragariae in synonomy with C. The publication costs of this article were defrayed inpart (1,880 lux) in the laboratory, where gloeosporioides (anamorph of G. by page charge payment. This article must therefore be temperatures fluctuated between 20 and cingulata), researchers have retained the hereby marked "adverfisement" in accordance with 18 29 C. The number of lesions in each series name C.fragariaewhen dealing with this U.S.C. § 1734 solely to indicate this fact. was recorded after 5 and 7 days of pathogen on strawberries. We have © 1984 The American Phytopathological Society incubation, isolated Colletotrichum spp. from plants

824 Plant Disease/Vol. 6t3 No. 9 40-75 times each year since 1968 and time from fruit in Florida in 1980. In fruit in Maryland. Plant Dis. Rep. 62:488-492. from fruit an estimated 3-10 times during 1982, it was isolated for the first time 5. Martinez, A. L., and del Rio Mora, A. 0. 1975. Principales enfermedades de la fresa en el valle de each of most of those years. Until 1980, from Florida-grown plants. Thus, if C. Zamora, Mich. Instituto Nac. Invest. Agric. all isolates obtained from fruit, and until fragariaeis a variant of C.gloeosporioides SAG, Cent. Invest. Agric. Bajio Folleto Misc. 27. 1982, all isolates obtained from plants (= G. cingulata),the variant characteristics 22 pp. grown in Florida, conformed to the remained stable for many years and G. 6. Mena, A. J., De Garcia, M. E. P., and Gonzalez, M. A. 1974. Presencia de la antracnosis original description of C.fragariaeexcept cingulata was not isolated from fruit or frutilla en la Republica Argentina. Rev. Agron.de la for slight differences in spore size. These from Florida-grown plants until after it Noroesta Argent. 11:307-312. isolates never formed perithecia and had been introduced into the state many 7. Simmonds, J. H. 1965. A study of the species of acervulispores were always salmon- times over a period of several years in Colletotrichum causing ripe fruit rots in colored en mass. Since 1977, most plants from other areas. 22:437-459.Queensland. Queensl. J. Agric. Anim. Sci. isolates obtained from plants that had 8. Singh, S. J. 1974. A ripe fruit rot of strawberry been grown, and apparently infected (3), LITERATURE CITED caused by . Indian in nurseries in Arkansas, Tennessee, or 1. Beraha, L., and Wright, W. R. 1973. A new Phytopathol. 27:433-434. North Carolina and had then wilted from anthracnose of strawberry caused by Colleto- 9. Sturgess, 0. W. 1954. A strawberry ripe fruit rot. trichum dematium. Plant Dis. Rep. 57:455-448. Queensl. Agric. J. 78:269-270. crown rot after being transplanted into 2. Howard, C. M. 1972. A strawberry fruit rot 10. Sturgess, 0. W. 1958. A ripe fruit rot of fruit production fields in Florida were G. caused by Colletotrichum fragariae. strawberry caused by a species of Gloeosporium. cingulata. These isolates always formed Phytopathology 62:600-602. Queensl. J. Agric. Sci. 14:241-251. perithecia when first cultured and 3. Howard, C. M., and Albregts, E. E. 1983. Black 11. von Arx, J. A. 1957. Die Arten der Gattung acervulispores were always whitish or leaf spot phase of strawberry anthracnose caused Colletotrichum Cda. Phytopathol. Z. 29:413-469. by Colletotrichum gloeosporioides (= C. 12. Wright, W. R., Smith, M. A., Ramsey, G. B., and translucent en mass. fragariae). Plant Dis. 67:1144-1146. Beraha, L. 1960. Gloeosporium rot of strawberry G. cingulata was isolated for the first 4. Maas, J. L. 1978. Anthracnose of strawberry fruit. Plant Dis. Rep. 44:212-213.

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