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313 Alw. J. Agric. Res. 25 (2) 313 -317, 1977. ASCOCHYTA LEAF SPOT OF CRASSULA, A NEW DISEASE IN EGYPT KAMARA, A.M., M.T. ABOL- WAFA and M.A. EL-WAK.IL ABSTRACT A Deutromycet fungus belongs to the order Sphaeropsidales, described and identified as Ascochyta sp. was found to be associated with a characteristic leaf spot symptoms of Crassuia at Alexandria region. The fungus was isolated on PDA medium on which it grew well in pure culture. Pathogenicity test proved the fungus to be pathogenic. This has been considered as the first record of this disease in Egypt. INTRODUCTION Several species under the genus Ascochyta has been reported to cause serious damages to cultivated plants as they induce leaf spots (6), stem and fruit lesion (14). Field crops (9) vegetable crops (23) as well as ornamental plants (11) have been recognized as hosts to different species of Ascochyta. DISEASE SYMPTOMS The symptoms seems to be restricted to the leaves. It appear at first as a mere round purplish brown dots. Each spot soon becomes furnished with a dark red edge surrounding a paller tan center. The typically developed spots become round, spindle shaped or irrigular, vary in size, definitely sunken especially on the upper surface of the leaf. Spots on the lower surface, however, appear with much wider dark red edges and ashy white center (Fig. 1). The dried central area of the spots often craks and parts of it may drop out giving a "shot hole" like effect (Fig. 2). ISOLATION and IDENTIFICATION The disease was observed in several gardens at Alexandria region. Isolation trials, from infected plants, were carried out on PDA medium in order to recover the causal pathogen in a pure culture. It was observed that a fungal species belongs to the order Sphaeropsidales was consistantly associated with the disease symptoms. The isolated fungus grew on PDA .medium at room temperature (20 - 25•). It produced numerous globose postulated embeded dark pycnidia with average diameter of 160 by 220 /J. (Fig. 3). When pycnidia were squeezed a mass of pycnidiospores oozed out through the o-stiole (Fig. 4) . Pycnidiospores were ovoid to oblong, hyaline, two-celled and ranged from 2 to 2.5 by 2.5 to 10 p. with average dimentions of 2.4 x 6.25 P.· From the microscopic studies of the isolated pathogen and according to the taxonomical keys of Barnett (3) the isolated fungus was found to be a species under the genus Ascochyta. The specific name, however, was not achieved since the measurements of the pycnidia along with pycnidiospores of the pathogen did not fit with any of the available known species of Ascochyta (Table 1). Inoculation of Crassula plants, grown in pots, with spore suspention of the isolated fungus induced the typical leaf spots on the inoculated plants. According to the available literature (1, 10) Ascochyta sp. is considered a new pathogen of Crassula in Egypt. 314 A. M. KAMARA et at Fig. 1 Fig. 3 Fig. 2 Fifi. 4 "' TABLE 1 : Size of Pycnidia and Pycnidiospores and hosts of some species of the genus Ascochyta. Measurments in p. Ascochyta sp. Host Author A. A. A. A. A. A. A. A. A. A. A. A. A. A. A. A. A. A. A. A. asters cannabina diplodina fabae graminicola kashmiriana lentis majalis meliloti onobrychidis pinodella pinoides pisi pisi pisi pisi pis~ pteridis trifolii tritici Isolated species ) ' Neergaard (18) Rober (20) Kuhnholtz (17) Bondartzeva ( 4) Frandsen ( 12) Padwick et al ( 19) Bondartzeva ( 4) Jenkins (15) Jones (16) Bondarlzerva et al. ( 4) Here & Walker (13) Here & Walker (13) Here & Walker (13) Brooks (5) Ibrahim et al. ( 10) Bondartzenva et al. Darpoux (8) Tobisch (22) Chorin (7) Scharen et al. (2) Pycnidia Spores - 6.9 x 2.4 - 4.5 17 - 20 X 5.3 - 5.G 11 x 2 18.6 x 4.5 13 - 18 x 3 - 5 19.2 x 8.8 14.9 - 4.7 18 - 29 x 4 - 6 13 - 20 x 5 - 6 15.4 x 4.9 8.0 x 3.7 4.5 x 13.3 4.2 x 17.2 3 - 5 x 10 - 14 4 x 12.7 4.1x13.3 2,3 x 7.5 4 - 6 x 12 - 20 3 - 5 x 15 - 20 4.5 x 18.5 2 - 2.5 x 2.5 - 10 (2.4 x 6.025) 100 - 150 85 175 140 100 115 - 171 300 180 150 250 85 - 233 150 90 - 90 - 150 142 - 157 270 x 90 - 360 (160 x 220) Callistephus chinensis Cannabis sativa Hedera helix Vicia faba Wheat, Barley, Rye Hyoscy-:imus niger Lentils L J iun sp . S',-/eet d over Q;wbrychis sativa P;:.;um sativum Pisum sativum Pisum sativum Pisum sativum Pisum sativum Pisum sativum Soy-bean Petridium aquilinum Trif olium alexandrinum Triticium vulgare Crassula 316 A . M . KAMARA DISCUSSION Crassula spp. are fleshy and leafy green house plants (2) grown for their grotesque appearance. Several species are cultivated in Egypt and they are regarded as disease-free plants (1 , 10 ). The occurrence of Ascochyta sp . on Crassula is considered the first recognition of the disease in Egypt. Due to the fact that Ascochyta spp. has a quite wide host range, much emphasis should be placed on their occurence, even, on the unimportant plants e.g. weeds, or ornamintal plants in order to minimize their inoculum potantialities. LITERATURE CITED Aly, M.D., A .A. Morsi and M.A. El-Shrif. 1972. Agriculture Research in Egypt (1900-1970) . Part I Plant Pathology. (In Arabic . Academy of Scientific Research and Technology, Cairo. Baily, L.H. 1966. Manual of cultivated plants. The Macmillan Comp. New York. Barnett, H.L. 1960. Illustrated Genera of imperfect fungi. Burgess Publishing Company Minneapolis 15, Minn. Bondartzeva-Monteverde (Mme V.N.), and N.I. Vassilievsky. 1940. A contribution to the biology and morphology of some species of Ascochyta on leguminosae. Acta Inst. Bot. Acad. Sci. U.R.S.S., 1938, Ser. 2, 345. (Rev. Appl. Mycol. 20, 232). Brooks, F.T. 1953. Plant diseases . Oxford University Press, London. Butler, E.J. and S.G. Jones. 1961. Plant Pathology Macmillan & Co. London. Chorin (Matilda) 1944. Leaf and stem spot of Egyptian clover. Palest. I. Bot., R. Ser. 4, 2, 175. (Rev. Appl. Mycol., 24, 193). Darpoux H. 1954. A contribution to the diseases of oleaginous plants in France. Ann. Epiphyt., N.S., 2, 1- 2, 71. (Rev. Appl. Mycol. 25, 416). Dickson, J.G. 1956. Diseases of field crops. Mc-GrawHill. N .Y . et al El-Helaly, A.F., I.A . Ibrahim, M. W. Assawah, H.M. Elarosi, M.K. Abo-El-Dahab, S.H. Michail MA . Abdel-Rehim, E .H. Wasfy and M.A. El-Goorani 1966. General survey of Plant diseases and pathogenic organisms in the U.A.R. (Egypt). Until 1965. Alex. Jour. Agric. Res. Bul. 15. Forsbery, J.L . 1963. Diseases of ornamental plants. Univ. Ill. College of Agric. Special Publication No. 3. Frandsen, N.O. 1943. Septoria species of creals and other grasses. Afd. Kbh., 26, 92. (Rev. Appl. Mycol. 25, 155). Hare, W.W. and Walker J.C., 1944. Ascochyta diseases of canning pea . Rea. Bull. Wis. agric. Exp. Ibrahim I.A. and H.M. Elarosi. 1968. Identification of an ascochyta disease on garden Pea. Alex. Jour. Agric. Res. Vol. 16 : 185 -190. Jenkins Anna E., 1942. Ascochyta majalis identified on Lily of the Valley in United States. Phytopath. 32, 259. Jones, F.R., 1945. Ascochyta meloloti (Trel.) Davis as the conidial stage of Mycosphaerella lethalis Stone. Tran. Wis. Acad. Sci. Arts Lett., 35, 137. (Rev. Appl. Mycol. 24, 315). Kuhnholtz-Lordat M. and I .M. Gastaud, 1946. Plant Pathological notes. Ann. Epyphyt., N.S., 4, 2, 207. (Rev. Appl. Mycol. 25, 381). Neergaard P., 1940. Fifth annual report of the phytopathological laboratory of J.E. Ohlsen's widow from 1st April, 1939, to 31st March, 1940. (Rev. Appl. Mycol. 20, 516). Padwick G.W. and J.L. Merh, 1943. Notes on Indian fungi 1. Mycol. Pad. Imp. Mycol. Inst. 7, 7. (Rev. Appl. Mycol. 23, 151). Roder K., 1939. On a new Hemp Pathogen, Didymella arcuata n . sp. and its imperfect stage. Phytopath. Z., 12, 321. (Rev. Appl. Mycol. 23, 151). Scharen A.L. and J.M. Krupinsky, 1971. Ascochyta tritici on wheat. Phytopath. 61, 673 - 680. Tobisch J., 1938. Contributions to the knowledge of the fungus flora of Carinthia. Ost. bot. Z. (Rev. Appl. Mycol., 18, 57). Wakler, J.C. 1952. Diseases of vegetable crops. McGraw-Hill, N. York. ' ... -. ASCOCHYTA LEAF SPOT OF CRASSULA Y~'fl' JtJJI 317 iL!' ..11.,. \:.!V'~'JaiJ' ~ ~· ~ <.Yl.l.>J ji\.....t... o~ ~ ~WI ~>::-1.fJI .::..~ JIJJi ~ ~ ~JJ M' ..1>Y:, ~u ~ w-"4 ~ J~iJ r~~ ~J_,ll ~~ ;;;~ Jbl:.S ~1 ~~ .JJJ , ~.J..w:......~1 lt1..:,.. • ~IJ '-:'_,A) -O°J\i ojl?.1 ~ Ja.i..,..j' ..IJJ ~I ,f.r ~. ~L.~I r~J •y\S"_,(....1 Al c7'.. ti 4.il J,r fa Y" ~' wi ~\· .a" • .r4-0 ~ View publication stats ' o.r-- ~~ ~l-J i,SJ...WIJ J_:,.JI '-:')~ ·~~-.;:·~·;;J ,_,;,}I 1.l+J ~ JJi I~ ~J