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

Abstract

Abstract 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 = 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 initiated.