Abstract
Antisera were made to both a whole cell and cell wall preparation of E. armeniacae. Rhodamine isothiocyanate (RITC) conjugated antisera were tested for reactivity with various fungi on glass slides. Both antisera showed low specificity, but specificity was improved by cross-adsorption of the RITC-conjugated cell wall antiserum with Phomopsis viticola. Woody cross sections from ''Concord'' grapevines [Vitis labrusca] inoculated with E. armeniacae and also inhabited by various other fungi were stained directly with the conjugated anti-Eutypa rabbit serum. In an indirect staining procedure, sections were treated with anti-Eutypa rabbit serum then stained with RITC-labeled goat anti-rabbit .gamma. globulin. Both procedures specifically stained hyphae in wood sections. Hyphae stained indirectly in woody vine sections showed a much brighter fluorescence than analogous hyphae stained by the direct method. Fungi of some species that reacted strongly with the direct method on glass slides did not always react when stained indirectly in woody vine sections in which they were growing.