|Chondrostereum purpureum from apple and blueberry: temperatures for spore release and germination, and virulence of mono and dikaryotic mycelia|
R. A. FRANCE (1), D. E. Grinbergs (1). (1) Inst de Investigaciones Agropecuarias, Chillan, Chile
<i>Chondrostereum purpureum</i> is a Basidiomycete that produces Silverleaf disease in numerous plants, including important fruit crops such as apple, cherry, kiwi, peach, pear and plum. In 2005 this fungus was determined in blueberry causing severe damage to commercial orchards. Although this fungus is already present in the major blueberry production areas of the world, only in Chile is reported as a disease. <i>Chondrostereum purpureum </i>reproduce by basidiospores, necessary for infection of recently pruned stems. The objective was to compare the performance of spores and mono or dikaryotic mycelia of <i>C. purpureum</i> isolated from apple and blueberry. The effect of the temperature (10 to 35ºC) was evaluated in the spore release from basidiocap, germination, and mycelia growth of mono and dikaryotic colonies. The results showed that both type of colonies from blueberry grew better than those from apple. Later, these colonies were used for cuttings inoculations of apple and blueberry, indicating in both cases that the cuttings were more susceptible (90%) to mono or dikaryotic blueberry isolates. The monokaryotic isolates of apple were unable to colonize, and the dikaryotic ones colonized the stems but at lower rate. The genetic variability of <i>C. purpureum</i> may explain the differences in pathogenicty and virulence. Because of the better performance, it is expected that the blueberry strain will be the dominant one on fruit trees affected by silverleaf in the coming years.