Articles
SUMMER OUTBREAKS OF FIRE BLIGHT IN TREE NURSERIES IN SOUTH ALBERTA, CANADA
Article number
896_41
Pages
293 – 300
Language
English
Abstract
Fire blight is the #1 cause of plant mortality in commercial tree nurseries in South Alberta, Canada.
Hundreds of trees are destroyed every year after disease infection is confirmed by visual symptoms or laboratory culturing.
The region is prone to violent storms almost annually between late June and mid July.
Winds gusting over 50 km/h combined with rain and hail cause extensive leaf damage such as holes and ripping.
The storms are followed by outbreaks of fire blight on susceptible hosts, especially Malus, visible within 10 to 14 days as shoot blight and ooze on affected twigs and leaf petioles.
The inoculum is found inside the nursery on trees previously infected, on native plants growing around the nurseries or possibly as epiphytic population on purchased liners.
From 2007 to 2010, almost 5500 trees were destroyed at a cost of Cdn$ 1,4 million in lost sales.
In spring, the disease is successfully managed with strict sanitation of hold-over cankers, avoidance of overhead irrigation during bloom, and repeated spray applications during early bloom with biological fungicides in rotation with an antibiotic.
During summer, management is done by prompt removal and burning of infected trees, yet new strikes are found repeatedly until late summer.
The label of the antibiotic product does not allow for sprays during summer months following trauma blight caused by hail or wind.
New management tools are needed for management of summer strikes, including technology for earlier detection of infection after a storm, effective pesticide products to reduce disease incidence after hail and on-site confirmation of disease infection on native hosts.
Hundreds of trees are destroyed every year after disease infection is confirmed by visual symptoms or laboratory culturing.
The region is prone to violent storms almost annually between late June and mid July.
Winds gusting over 50 km/h combined with rain and hail cause extensive leaf damage such as holes and ripping.
The storms are followed by outbreaks of fire blight on susceptible hosts, especially Malus, visible within 10 to 14 days as shoot blight and ooze on affected twigs and leaf petioles.
The inoculum is found inside the nursery on trees previously infected, on native plants growing around the nurseries or possibly as epiphytic population on purchased liners.
From 2007 to 2010, almost 5500 trees were destroyed at a cost of Cdn$ 1,4 million in lost sales.
In spring, the disease is successfully managed with strict sanitation of hold-over cankers, avoidance of overhead irrigation during bloom, and repeated spray applications during early bloom with biological fungicides in rotation with an antibiotic.
During summer, management is done by prompt removal and burning of infected trees, yet new strikes are found repeatedly until late summer.
The label of the antibiotic product does not allow for sprays during summer months following trauma blight caused by hail or wind.
New management tools are needed for management of summer strikes, including technology for earlier detection of infection after a storm, effective pesticide products to reduce disease incidence after hail and on-site confirmation of disease infection on native hosts.
Publication
Authors
M. Lanthier
Keywords
hail, wind, biological control, Cotoneaster, Crataegus, Malus
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