ABSTRACT


ADRIANA PINTO DE TORRES1
 
The production of nuts and stone fruits is of gieat importance to Chile, due to the high quality and value of these crops. For this reason the large seedling losses in nurseries and new orchards have greatly concerned the producers as well as the technicians.A large number of newlyestablished nurseries and orchards in the fruitgrowing area of the country were visited. It was determined that the average annual loss of plants reached 30%, and in the northern part of the country several small nurseries were totally destroyed.The objective of this work was to determine the cause of the death of these trees and to isolate ana identify the organisms in the diseased plants in order to test their pathogenicity.The fungi isolated from the roots and crowns of diseased peaches, almonds and apricots wereidentified as: Fusarium oxysporum Sch., Pythiurn interrnediurn De Bary, Pythium debaryanum Hesse, Rhyzoctonia solani Kühn and Phytophthora cactorum (L y C) Schroeter. These fungi are capable of causing the death of the above mentioned plants.
On the basis of the cited literature (4) (5), F. oxysporum Sch., P. intermedium De Bary. P. debaryanum Hesse, R. solani Kühn and P. cactorum (Ly C) Schröeter were not considered to be pathogens of fruit trees in Chile prior to be studies performed by the author (6) (1). Rayuskinia (7) of the URSS and Miller (3) of the USA are the only references concerning the pathogenicity to fruit trees of the species analysed in the study. Each one of these pathogens can act individually; the presence of the fungus complex is not necessary to produce the damage found in the seedling in the nurseries.
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1 Ingeniero Agrónomo, Proyecto Fitopatología, Estación Experimental La Platina, Instituto de Investigaciones Agropecuarias.Profesor Cátedra de Patología Frutal, Escuela de Agronomía, Universidad de Chile.