A. Perello et al., Greenhouse screening of the saprophytic resident microflora for control ofleaf spots of wheat (Triticum aestivum), PHYTOPARASI, 29(4), 2001, pp. 341-351
Ten microorganisms of the epiphytic microflora of wheat leaves in Buenos Ai
res Province, Argentina, were evaluated under greenhouse conditions as pote
ntial biocontrol agents of the pathogens Alternaria triticimaculans, Bipola
ris sorokiniana, Drechslera tritici-repentis and Septoria tritici in two ap
plication sequences (prior to or together with the pathogens). The antagoni
sts significantly reduced the expression of the diseases on wheat plants co
mpared with control plants not inoculated with the antagonists. Maximum per
centage of reduction of the necrotic lesion area (NLA) (40-55%) of S. triti
ci resulted when Cryptococcus sp., Rhodotorula rubra and Penicillium lilaci
num were sprayed on leaves prior to inoculations with the pathogen. Bacillu
s sp., Cryptococcus sp., Fusarium moniliforme var. anthophylium, P. lilacin
um and R. rubra reduced significantly (34-52%) the NLA of B. sorokiniana in
both of the application sequences. The best antagonistic effect against A.
triticimaculans was shown by Aspergillus niger Bacillus sp., Chaetomium gl
obosum, F. moniliforme var. anthophylium and Nigrospora sphaerica, with a N
LA reduction from 21% to 35% in the co-inoculation or in the sequential app
lication. All microorganisms except N. sphaerica performed better than the
control against D. tritici-repentis. The area under disease progress curve
(AUDPC) of the pathogens appeared to progress similarly, but at lower value
s, in treated plants than in untreated controls. The two yeasts and the bac
teria decreased AUDPC to 50-55% of S. tritici and B. sorokiniana compared w
ith the control in both application sequences, whereas the maximum efficacy
against A. triticimaculans was reached by N. sphaerica and A. niger for th
e sequential application and by F moniliforme var. anthophylium for the co-
inoculation. If the parasitism occurs also in nature, application of antago
nists for biological control might provide the opportunity to compete with
the pathogens and regulate their colonization in wheat leaves.