On the twig blight of the tree peony and its causal fungus Pestalotia paeoniicola sp. nov.

Abstract

1. This paper deals with results of some physiologial, pathological and also taxonomical studies on the causal fungus of twig blight of tree peony. The fungus was collected at first by the senior writer at Akita City, on March 15, 1952. The disease is of much economic importance but no one has yet studied about it.
2. The writers give new name Pestalotia paeoniicola Tsukamoto et Hino to the causal fungus, and propose a common name, twig blight of tree peony for the disease.
3. The first symptom of the disease is indicated by numerous, scattered, dark blackish, minute points produced on the bark of living branches. Then the infected bark becomes to gray in colour. Eventually, all the diseased brances dry out.
4. Optimum temperature of the mycelial growth of the fungus at 28° to 30°C, minimum at 8° to 10°C, maximum about 33°C, it does not grow above 35°C and 5°C., spores are produced from 15° to 35°C, the optimum temperature 28° to 30°C. Optimum hydrogenion concentration for the growth of the fungus on potato agar is pH 5.6 to 5.7.