Fungi Resident in Chickpea Debris and their Suppression of Growth and Reproduction of Didymella rabiei under Laboratory Conditions

Fungi colonizing senescent chickpea (Cicer arietinum) stems and postharvest debris from Pullman, WA, were enumerated and identified with the objective of finding species potentially useful for biological control of Didymella rabiei (conidial state ¼ Ascochyta rabiei), causal agent of Ascochyta blight. In addition to D. rabiei, primary colonizers were, in order of decreasing abundance, Alternaria tenuissima, Al. infectoria, Ulocladium consortiale, Epicoccum purpurascens, U. atrum and Fusarium pseudograminearum. Present at lower frequencies were Al. malorum, Cladosporium herbarum, Aureobasidium pullulans, Clonostachys rosea and miscellaneous anamorphic ascomycetes. On agar media and autoclaved chickpea stems, Au. pullulans consistently grew faster than As. rabiei, and excluded As. rabiei from the substrate. When stems received prior inoculation with Au. pullulans or Cl. rosea, followed by inoculation with compatible mating types of D. rabiei, formation of pseudothecia and pycnidia of D. rabiei was suppressed. Results suggest that Au. pullulans and Cl. rosea can inhibit As. rabiei and its sexual stage, D. rabiei, on chickpea debris. Clonostachys rosea formed appressoria on, then invaded, hyphae of D. rabiei. Small-scale field experiments using Au. pullulans and Cl. rosea have been initiate