First Report of Pestalotiopsis guepini on Loquat in Argentina

Loquat, Eriobotrya japonica (Thunb.) Lindl., is used as an ornamental plant in home gardens in the La Plata area of Buenos Aires, Argentina. During spring 1998, loquat branches with spotted leaves and fruits were submitted to the Plant Disease Diagnostic Laboratory. Symptoms on leaves consisted of small (2 to 5 mm in diameter), circular to oblong, greenish brown lesions that expanded to amphigenous, isolated, or confluent, dark brown spots. On fruits the disease appeared as circular to elongated, sunken spots. Advancing lesions spread over the surface resulting in the death of the fruit. Acervuli were observed within lesions. Isolations from symptomatic tissue onto acidified potato dextrose agar medium consistently yielded white fungal colonies of sparse aerial mycelium with acervuli containing black, slimy spore masses. The fungus was initially identified as Pestalotiopsis guepini (Desmaz.) Steyaert based on conidial and cultural characteristics (1), and the identification was confirmed by Institute Spegazzini, La Plata, Buenos Aires, Argen-tina. Loquat branches with fruit and 3- to 6-month-old loquat plants were mechanically injured and sprayed with a conidial suspension of one of the P. guepini isolates (4.5 × 10 5 per ml). Plants were incubated in a moist chamber for 48 h and then maintained in a greenhouse. After 6 days, lesions similar to the original symptoms were observed on the inoculated plant and P. guepini was reisolated, confirming Koch's postulates. Control plants sprayed with distilled water remained symptomless. This is the first report of P. guepini causing leaf and fruit spots on loquat in Argentina. Reference: (1) J. B. H. J. Desmazières. Ann. Sci. Nat. Ser. 2. 13:181, 1840.