First report of pink mold (Trichothecium roseum (Pers.:Fr.) Link) on pecan nuts in Argentina

MANTZ G.; ROLLÁN C.; RONCO L.; MAIALE S.

JOURNAL OF PLANT PATHOLOGY

EDIZIONI ETS

Lugar: Pisa; Año: 2009 vol. 91 p. 238 - 238

Pecan (Carya illinoinensis (W) K. Koch) has become an important fruit crop in Buenos Aires and Entre Ríos provinces.  The cultivated area is approximately of 4000 ha. In summer 2007, nuts showing pink mold growing on scab lesions were observed from plants of cultivar “Don Sala” (UNLP), grown in the Experimental Station “Julio Hirschhorn”, Universidad Nacional de La Plata (Buenos Aires, Argentina). Diseased nuts were placed in humidity chamber and pink mold isolates were obtained and cultivated on 2% potato dextrose agar (2% PDA) medium. Colonies were initially white, then turned to pink. Microscopio examination revealed the presence of conidiophores simple, septate, hyaline, measuring 62.5 to 212.5 mm  x 5 to 7.5 mm (average 133 x 5.3 mm). Conidia were apical, single, hyaline, pink in mass, 2- celled, with well marked, truncate attachment point, measuring 12.5-22.5 mm x 7.5-10 mm (average 18 x 9.5 mm ). These morphological characteristics were typical of Trichothecium roseum as described by Barron (1968). Pathogenicity tests were preformed by spraying healthy nuts of cultivar Pawnee with a conidial suspension of a representative isolate (1 x 106 conidia/ml of sterile distilled water). Controls were sprayed with sterile distilled water. The inoculated nuts were incubated in plastic boxes with moisture and placed in a growth chamber with a 12-h photoperiod at 20 ± 2°C. After two days the boxes were uncovered and kept at the same temperature for 2 weeks. Inoculated nuts showed necrotic tissues on shucks and Trichotecium roseum was constantly re-isolated. Trichothecium roseum has been reported on Pecan nuts in USA as weakly parasitic after scab disease (Farr et al, 1989). This is the first record of Pink Mold (Trichothecium roseum) on Pecan nuts in Argentina