A shoot dieback in Pinus radiata caused by Diplodia pinea. 1. Symptoms, disease development, and isolation of pathogen.

Abstract

A locally occurring dieback, similar to previously reported red top, shoot blight, and tip blight, was investigated during 1971-73 in Pinus radiata in Tarawera Forest. Observations of symptoms and disease development, and isolation of fungi indicated that the dieback originated in necrotic stem lesions from which Diplodia pinea was invariably isolated. Succulent green shoots became infected in late spring and early summer while ripened shoots were apparently resistant, so dieback was restricted mainly to current season's growth. There was no evidence that infection was associated with wounds or frost damage, but there was every indication that it occurred through intact host tissue.