Project Abstract: Controlling White Mould Disease through Microclimate Management
Dry bean (Phaseolus
vulgaris L.) is the most profitable pulse crop grown under
irrigation in southern Alberta. White mold (WM) caused by the fungus Sclerotinia
sclerotiorum (Lib.) de Bary is a major constraint to dry bean
Due to the absence of any complete genetic resistance to this
pathogen, microclimate within the canopy and prevailing environmental
conditions are the most important determinants of white mould progression.
Therefore, the proposed research would aim to determine whether microclimate
management, provided by changes in irrigation scheduling and dry bean canopy
architecture, could decrease the rate of ascospore release during the
susceptible flowering period, without negatively affecting bean yield.
studies were conducted at AAFC-Lethbridge in 2014, 2015 and 2016 to determine
the effect of irrigation and plant architecture on canopy microclimate, white
mold disease development and yield. Three levels of irrigation (high, medium
and low) and five cultivars with different canopy architecture
(semi-upright bush, upright bush and prostrate) were arranged in a
split-plot design and plots were evaluated for WM incidence and severity,
flower infection, yield and thousand seed weight (TSW). Microclimate variables,
such as soil water content, leaf wetness, soil temperature, and canopy porosity
were monitored using data loggers and sensors.
Statistical analysis indicated
that there were significant interactions between cultivars, microclimate and
WM. In all 3 years, WM incidence, severity and flower infection were
significantly higher in high irrigation plots compared to medium and low
irrigation plots. However, plots grown under medium and low irrigation had
similar WM levels, but yield and TSW were reduced under low irrigation. Higher
water content within the top 5-cm of soil, prolonged leaf wetness and cooler
canopy temperatures were maintained in high irrigation plots compared to medium
and low irrigation plots. Soil temperatures favourable to apothecia development
and ascospore release were only maintained in high irrigation plots.
all 3 years, WM development in AAC Burdett and I9365-31, lines with partial
field and genetic resistance, respectively, were not affected by irrigation
regime. In 2016, ascospore release was also monitored using Burkard 7-day spore
samplers, and quantification of airborne inoculum using real-time PCR with S.
sclerotiorum specific primers and TaqMan probe, but data
analysis and interpretation is ongoing. This trial will be conducted for 1
more year and data from all 4 years will be combined and analyzed.
preliminary WM prediction model was developed by correlating WM severity with
microclimate data. Pearson’s correlation coefficient revealed significant
relationship of WM severity with soil moisture, leaf wetness and soil
temperature. Lodging was positively correlated with WM severity while the
relationship was negative for canopy porosity. Flower infection was highly
correlated with WM severity and explained maximum variability.
Results from the
trials indicate that irrigation schedule and choice of cultivars can be
effective tools for WM management in Alberta.
Project lead: Dr. Syama Chatterton (403) 317-2226 firstname.lastname@example.org