ABSTRACT
COLLAR ROT OF STONE FRUIT IN SEEDLINGS AND TWO YEAR OLD APRICOTS AND ALMONDS IN CHILE CAUSED BY Pythium ultimun TROW

Adriana Pinto de Torres1 y Srecko M. Mircetich2
 

An isolate of Pythium ultimun Trow, recovered from storksbill (Pelargonium roseum) plants cultivated in the Quillota area (Aconcagua Valley) in Chile, induced stem canker in artificially inoculated apricot and almond plants.
In a greenthouse experiment 6-month-old apricot and almond seedlings developed crown rot within 10 days when muycelia of the storksbill P. ultimun isolate were planced directly in the wounds at the root crown. Apricot were more susceptible than almond seedlings. the same isolate induced in 2-year-old apricot cv. Royal and almond cv. Mission, 121 mm and 27 mm long stem canker, respectively, within 10 days after the inoculum was placed in the bark wounds. No stem canker developed in the 2-year-old Mahaled seedlings which were inoculated in the same manner as the apricot and almond plants.
On basis of the cited literature Pythium ultimun Trow was not considered to be a pathogen of fruit trees in Chile prior to this study.

Keywords:
1Ing. Agr. Programa Frutales y Viñas, Estación Experimental La Platina, Instituto de Investigaciones Agropecuarias (INIA), Casilla 5427, Santiago, Chile.
2Research Plant Pathologist, ARS, USDA, Plant Pathology Department, University of California, Davis, California 95616, USA.