Journal of Plant Pathology (2011), 93 (4, Supplement), S4.63-S4.89 S4.65

DISEASE NOTE DISEASE NOTE FIRST REPORT OF MYCOGONE FIRST REPORT OF LEAF BLIGHT PERNICIOSA ON CULTIVATED BY DRECHSLERA HAWAIIENSIS ON MUSHROOM AGARICUS BISPORUS MARSILEA MINUTA IN PAKISTAN IN SYRIA N. Rabbani, R. Bajwa and A. Javaid A. Al Ghazzawi and N. Al Beig Institute of Plant Pathology, University of the Punjab, General Commission for Scientific Agricultural Research, Lahore, Pakistan P.O. Box 113, Douma, Syria Dwarf waterclover (Marsilea minuta L.) is an aquatic In 2008, typical symptoms of wet bubble disease were fern of the family Marsileaceae native to Africa and India observed on the cultivated mushroom Agaricus bisporus in and widely distributed in Trinidad, Tobago, northeastern Al Kiswa region (Damascus, southern Syria). Symptoms Brazil, Vietnam, Indonesia, Malaysia, Australia and New prevailed in places with high humidity. Early infection badly Caledonia (Waterhouse, 1993; Staples and Herbst, 2005). affected carpophores, turning them into a shapeless mass It is one of the most problematic and common weeds of covered with the parasite’s white and fluffy mycelium. Then, rice in Pakistan (Rabbani and Bajwa, 2001). During a the deformed carpophores became brown and started to de- survey of rice fields of Punjab province (Pakistan) from cay. Internal tissues were also discoloured, watery and July to November 2005, a blight disease of the leaves of showed holes resulting from decay. Symptoms were accom- M. minuta was observed, with an incidence and severity panied by an unpleasant odour. Under dryer conditions, tis- that gradually increased from July/August to November, sues remained dry as in the case of infections caused by Ver- concomitantly with the decrease of temperature. The low- ticillium. When the stipe was affected, it decayed and est disease incidence (10%) was recorded in July and Au- turned red-brown. The putative pathogen was isolated on gust, and the highest (78%) in November. Maximum 2% potato-dextrose agar medium. Microscopic examination mortality of leaf tissues (50%) was recorded in Novem- revealed the presence of cylindrical and branched conidio- ber. Initially small brown spots appeared on the leaves, phores like those of Verticillium. The phialospores were which gradually enlarged and coalesced to form larger cylindrical, hyaline, one-celled, thin-walled and, like in Verti- blight patches. From diseased leaf portions plated on pota- cillium, they formed at the tip of phialides. The aleu- to dextrose agar (PDA) and incubated at 25ºC effuse a n d riospores were bicellular, the apical cell being globose, pig- black fungal colonies were obtained. Hyphae were mented and warty, the lower cell smooth and smaller, in smooth, conidiophores were septate and up to 120 µm agreement with descriptions of Mycogone perniciosa (Bar- long, conidia w e r e straight, rounded at both ends and nett et al., 1998). Two-celled phialospores were also ob- had 2-7 pseudosepta. Based on these characters, the fun- served as reported previously (Glamclija et al., 2008). The gus was identified as Drechslera hawaiiensis (Ellis, 1971). upper aleuriospore cells were 13-30×16-31 µm in size, Pathogenicity tests were carried out in July 2006 by spray- whereas lower cells were 8-13×8-17 µm in size. The unicel- ing a 1×109 ml-1 aqueous conidial suspension on plants lular phialospores were 0-1 septate, 11-15×2.5-3.5 µm in at the 5-6 leaf stage, grown in plastic pots. Disease size. For pathogenicity testing a 100 ml of 4×105/ml aleu- symptoms appeared on the leaves within two weeks. The riospore suspension was sprayed on the casing. Emerged fungus was re-isolated from diseased tissues and its fruiting bodies showed the same symptoms as those seen in identity with D. hawaiiensis was confirmed. To our naturally infected mushrooms. This is the first report of knowledge, this is the first report of leaf blight of M. min- Mycogone perniciosa on Agaricus bisporus in Syria. uta by D. hawaiiensis in Pakistan.

The authors would like to thank Dr. B. Bayaa, Dr. B. Ellis M.B., 1971. Dematiaceous Hyphomycetes. Commonwealth Nasraoui and Mr. A. Nehlawi for their assistance. Mycological Institute, Kew, UK. Rabbani N., Bajwa R., 2001. Weed distribution in rice fields of five districts of the Punjab. Pakistan Journal of Botany 13: Barnett H.L., Hunter B.B., 1998. Illustrated Genera of Imperfect 541-549. Fungi. 4th Ed., pp. 82-83. APS Press, St. Paul, MN, USA. Staples G.W., Herbst D.R., 2005. A Tropical Garden Flora: Glamclija J., Sokovi M., Ljaljevi-Grbi M., Vukojevi J., Milenkovi Plants Cultivated in the Hawaiian Islands and Other Tropical I., Van Griensven L., 2008. Morphological characteristics and Places. Bishop Museum Press, Honolulu, HI, USA. mycelial compatibility of different Mycogone perniciosa iso- Waterhouse D.F., 1993. The Major Arthropod Pests and Weeds lates. Journal of Microscopy 232: 489-492. of Agriculture in Southeast Asia. The Australian Centre for International Agricultural Research, Canberra, Australia.

Corresponding author. A. Al Ghazzawi Corresponding author: A. Javaid Fax: +963.11.57386312 Fax : +92.429.9231187 E-mail: [email protected] E-mail: [email protected]

Received October 12, 2010 Received November 1st, 2010 Accepted December 20, 2010 Accepted February 13, 2011