Influence™ WP

POWDERY MILDEW IN GREENHOUSE VEGETABLES
Powdery mildew is a severe disease causing significant economical losses to greenhouse
producers. Influence TM WP has shown an excellent control of powdery mildew on two
major vegetables grown in greenhouses: cucumbers and tomatoes.
Cucumber
Trials were performed with greenhouse cucumbers at Université Laval in 2007. Results
showed that the disease infection was maintained at a low level with Influence TM WP
during the trial period even though it was constantly increasing for the untreated plants.
After three weeks, the leaves’ area covered by the powdery mildew (Podosphaerae
xanthii) was four times less contaminated for Influence TM WP compared with untreated
plants and was comparable with the chemical fungicide (figure 1).
Tomato
The efficacy of Influence TM WP to control powdery mildew (Oïdium neolycopersici)
on greenhouse tomatoes was demonstrated in trials performed by Horti-Protection in
2008. After three weeks, results showed a 99% reduction of the presence of powdery
mildew compared to the untreated plants and were comparable to the control fungicide
(figure 2).
FUNGICIDE INFLUENCE CONTROL
DAY 0 DAY 2 DAY 8
DAY 12
© UNIVERSITÉ LAVAL
Percentage of disease (%)
100
80
60
40
20
0
0 3 6 9 12 15 18 21
FUNGICIDE
INFLUENCE
CONTROL
APPLICATIONS
Days
WITHOUT POWDERY MILDEW
WITH POWDERY MILDEW
Disease rate
(0: no disease; 10: 100% of covering)
3
2
1
0
0 3 6 9 12 15 18 21 24
FUNGICIDE
INFLUENCE
CONTROL
APPLICATIONS
Days
Picture 1: Powdery mildew symptoms on greenhouse
cucumber leaves from day 0 to day 12, Université Laval
(Québec), 2007
Figure 1: Covering percentage of powdery mildew
on greenhouse cucumber leaves, Université Laval
(Québec), 2007
Picture 2: Powdery mildew on tomato leaves,
Horti-Protection (Québec), 2008.
Figure 2: Disease incidence of powdery mildew
on greenhouse tomato leaves, Horti-Protection
(Québec), 2008.