Fluorescence immunohistochemical detection of Armillaria and Heterobasidion in Norway spruce

Armillaria mellea ss. lato and Heterobasidion annosum were identified in infected Norway spruce using an indirect immunohistochemical test. Unspecific binding sites were masked by incubating the specimen with preimmune serum followed by protein A. Subsequent labeling with monospecific rabbit antibodies and fluorochrome‐conjugated protein A yielded a strong and specific fluorescent signal.