| dc.description.abstract | Pyrenophora teres the causal organism of barley net blotch disease is responsible for
substantial loss in crop yield with yield losses as high as 40% under favourable
conditions. Current control measures are achieved using an integrated approach,
combining chemical control, the use of resistant cultivars and crop hygiene practices.
In this study several bacterial isolates from soils around Ireland were screened for
their potential to act as biological control agents against this pathogen. In vitro and in
vivo tests identified four bacterial isolates, namely; Pseudomonas fluorescens strain
MKB100 and MKB156, Pseudomonas sp. MKB158 and MKB194 having the
potential to reduce disease development compared to control test plants. There was a
significant positive correlation between the effects of P. teres alone, or in combination
with Ps. fluorescens strain MKB100 or MKB156, Pseudomonas sp. MKB158 or
Pseudomonas sp. MKB194 on net blotch disease development on seedling and
detached leaf assays of barley cultivars Lux and Tavern (r = 0.996 and 0.932, P
<0.01, P < 0.05 respectively). Under glasshouse conditions, Ps. fluorescens MKB100
and MKB156 bacterial isolates reduced disease development in barley seedlings by 70
and 69%, respectively when compared to control plants. Pseudomonas fluorescens
strains MKB100 and MKB156 significantly inhibited the development of disease
symptoms in the barley cultivar Lux under field conditions, with Ps. fluorescens
MKB156 reducing the percentage diseased leaf area by 54% compared to P. teres
inoculated control plants. Irrespective of bacterial isolate, bacterial application pre-
fungal inoculation was generally more effective in reducing the AUDPC for net
blotch disease than was application post-P. teres inoculation. Future success of these
potential biological control agents will depend on their ability to consistently suppress
net blotch under field conditions and on their ability to remain viable if integrated into
a disease control program | en |
