Etiology of the Resinous Stem Canker of Chamaecyparis obtusa: Cistella japonica as the Causal Agent
1997
Suto, Yasuo
In order to confirm the pathogenicity of Cistella japonica, inoculation experiments were conducted onto several coniferous trees. Resinous lesions similar to those of the resinous stem canker developed by the inoculation with Ci. japonica only on Chamaecyparis obtusa. Chamaecyparis trees were heavily affected when inoculated with the fungus in November, but slightly in May and August. Resin flows occurred when inocula of Ci. japonica were put into the holes made on stem barks and on pruning scars. Isolates of Ci. japonica varied greatly in the pathogenicity. On the lesions caused by the fungus, resinous and necrotic areas expanded in fusiform or oblong shape, and resin cysts were formed in inner barks. Beneath some necrotic inner barks, sapwood was suppressed in growth for the damages in cambial cells and stained. Ci. japonica was reisolated from the inoculated lesion tissues, though isolation frequency of the fungus became lower in some lesions two or more years after the inoculation. The results of these inoculations proved that Ci. japonica was the causal agent of the resinous stem canker of Ch. obtusa.
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