Differential Growth Inhibition of Diaporthe and Phomopsis Isolates by the Metabolic Activity of Five Actinomycetes

Fifty!_ve cultures derived from Diaporthe perithecia and Phomopsis pycnidia found on diverse host plant species collected at di}erent times and sites in Vojvodina\ Yugos! lavia\ showed distinguishing quantitative reactions to the fungistatic activity of _ve actinomycetes obtained as for! tuitous laboratory contaminants coming from _eld material[ Streptomyces albido~avus\ S[ albus\ S[ diastaticus\ Streptomyces sp[\ and Streptoverticillium sp[ could be ranked by their growth!inhibitory potentialwith S[ albus showing the strongest\ and Streptomyces sp[ the lowest[ The responses of the fungi varied depend! ing on the tested actinomycetes\ but two major groups could be distinguished] A\ which encompased the isolates that were less a}ected by the proximity of the acti! nomycetes^ and B\ with those which exhibited high sen! sitivity in all the experiments[ Group A was typically represented by Diaporthe arctii\ Phomopsis lon`icollaand the Phomopsis type!0 cultures from Xanthium ita! licum^ group B was typically represented by Diapor! the:Phomopsis helianthi\ Phomopsis type!1 cultures from X[ italicum\ and isolates from Lactuca serriola[ The results obtained underscore the dissimilarities between D[ arctii and D[ helianthi\ and corroborate the value of the physio! logical aspects of congeneric isolates in considering taxo! nomic problems in the coelomicete genus Phomopsis