The aim of this project was to determine if UV light can be used to reduce or eliminate the incidence of powdery and downy mildew in vineyards.
Project layout:
Two different UV light treatments (100 J/m2 and 200 J/m2) were applied weekly to Chardonnay vines using a UV light array on a tractor drawn carriage. Based on previous laboratory trials, it was expected that these treatments should stop 80% – 100% of the powdery mildew conidia from germinating.
Treated vines received only UV light, no other fungicides.
In another treatment, vines received only conventional fungicides.
There was also a control where no fungicides or UV light were applied.
The trial was done in a year where powdery mildew pressure was moderate and downy mildew pressure was severely high.
Results
Powdery mildew
– Severity of powdery mildew in the control vines were 15%.
– Both UV treatments significantly reduced the severity of powdery mildew on berries to 5%.
– Fungicide treatments reduced severity to 1%.
Downy mildew
– Both UV treatments suppressed foliar downy mildew better that the conventional fungicides.
Preliminary results also indicated that UV treatments can suppress mite populations.
Significance of the study:
It is widely known that there is increasing pressure on growers to reduce the use of fungicides and pesticides. Resistant varieties is still a new field and consumers’ reaction to unknown varieties is a concern. Using UV light has promising potential to be an alternative to fungicides in an integrated management strategy.
Reference:
The Potential of Light Treatments to Suppress Certain Plant Pathogens and Pests, David M. Gadoury, Research Focus 2019-2: Cornell Viticulture and Enology.
Link to article:
https://grapesandwine.cals.cornell.edu/sites/grapesandwine.cals.cornell.edu/files/shared/Research%20Focus%202019-3.pdf
Image source: https://www.osram.com/pia/phytofy-research-light/index.jsp?mkt=/phytofy/
