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Eastern filbert blight (EFB) on hazelnut is caused by the fungus
Anisogramma anomala. Vigour and productivity decline significantly when
trees are infected with this fungus, resulting in an economically
unproductive orchard. EFB has become a common and serious disease in
hazelnut orchards throughout the Pacific North-western United States. In
British Columbia, EFB was first detected on hazelnut in 2001 at a few
non-commercial sites in Abbotsford. In 2005, the disease was found in
orchards in Langley and, most recently and of greatest concern, it was
detected in a commercial orchard in Yarrow in 2008. It is apparent that EFB
has now become established in the southern part of B.C. and will continue to
spread throughout commercial hazelnut production areas. To help prevent
further spread and protect commercial hazelnut production areas, it is
critical that all orchards are inspected for the disease and that prevention
measures are implemented.
Spread
In spring, spores are released from mature cankers of infected hazelnut trees.
Spores are spread by rain and splashing water droplets driven by wind. Young and
developing shoots, during bud-break to shoot elongation, are highly susceptible
to new infection. Newly infected trees do not show any symptoms for 12-15 months
(latent period). The second summer following infection, the fungus begins to
produce dark-brown to black spore-producing structures called “stroma” within
cankers on infected stems (an important diagnostic feature in field and
laboratory). The mature stroma begin releasing spores the following spring. The
fungus continues to produce new stroma and releases spores as the canker expands
each year.
Symptoms
Infected trees may show sudden dieback of twigs and branches in summer months.
When closely observed, elongated, sunken cankers, expanding lengthwise on
branches can be seen. Cankers are infected areas of sunken, dying tissues formed
along a branch. Stroma are produced within cankers in relatively straight rows
lengthwise along the branch (Fig. 1). Cankers expand from year to year and
girdle the branch, resulting in branch dieback. The disease also resembles
another fungal disease caused by Eutypella cerviculata. Eutypella
produces similar spore producing structures; however, they are smaller in size
and produced on dead wood.
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Figure 1. Dark-brown to black stroma, bearing spores, are produced on infected
cankers by the fungus Anisogramma anomala.
Photo credit: Oregon State University and Jeff Stone |
Disease Control
Monitoring
As EFB continues to spread within and around commercial orchards, all
orchards must be scouted intensively. Control of EFB will be much more
effective if the disease is detected early. Scouting should be done twice a
year. In late summer, look for dying branches (dieback). In the dormant
season (late fall and winter), look for the cankers and stroma; mostly found
near the top of the canopy.
Suspicious samples should be submitted to the Ministry of Agriculture Plant Health Laboratory for disease confirmation.
Management
- Prune out any diseased branches with cankers about 2-3 feet below
the site of infection and burn diseased wood. Alternatively, infected
wood can be chipped, covered with plastic film and allowed to compost.
This must be done before bud-break in spring. Because initial infection
is often found in the top of trees, it is best to use a “cherry picker”
to gain better viewing during scouting for disease and access for
pruning out infections.
- If EFB has been detected in your orchard or in the vicinity,
fungicide sprays are essential to help prevent new infections and slow
down the progress of the disease. Since new growth in spring and early
summer is highly susceptible to infection, spraying must begin soon
after bud-break. In Oregon, 4 applications at 10-14 day intervals, from
bud-break to new shoot growth, are considered necessary to provide
adequate protection. In coastal B.C., the spray period will generally be
from late March until early May. The fungicides registered for EFB can
only protect young shoots from initial infection, i.e. they need to be
applied before the fungal spores land on vulnerable young tissues so
that germinating spores are killed before they infect and enter young
plant tissues. It is essential to set up the sprayer to obtain coverage
of all new growth. Given the density and height of many Fraser Valley
orchards, this can be a challenge even with the best air-blast sprayers.
Because of EFB’s latent period, the effect of fungicides on disease
control will only be evident several years after application.
The
following fungicides are registered for EFB in Canada:
- Copper Oxychloride 50 or Copper Spray at 3.0 to 9.0 kg/ha (1.2
to 3.6 kg/acre) in at least 1,000 L/ha (400 L/acre) of water. Use
the low rate on small trees and the high rate on mature trees. Do
not apply within1 day of harvest.
Note: Copper is generally acceptable for organic production. Check
with your certifying agency.
- Flint 50 WG (50% trifloxystrobin) at 140 to 280 g/ha (56 to 112
g/acre) in at least 1,000 L/ha (400 L/acre) of water. Use the higher
rate when disease pressure is severe. Do not apply more than 4 times
per season. Do not apply more than two consecutive applications of
Flint. Do not apply within 60 days of harvest.
- Quadris Flowable (250 g/L azoxystrobin) at 900 mL/ha (360 mL/acre). For
mature trees, use at least 1,000 L/ha (400 L/acre) of water. Do not apply
more than 4 times per season. Do not apply more that two consecutive
applications of Quadris. Do not apply within 45 days of harvest.
Note:
Use Copper Oxychloride preventatively in orchards that have not been exposed
to or detected with EFB (low risk orchards).
Use Copper Oxychloride in rotation with Flint and Quadris for orchards
infected with EFB or in close proximity to an infected orchard (moderate to
high risk orchards).
Caution: Quadris will cause severe damage to many varieties of apple.
Do not allow drift onto nearby apple plantings.
Caution: Flint and Quadris are in the same fungicide class (strobilurin)
and both have a same mode of action. If used consecutively, the pathogen may
soon develop resistance against these fungicides. Therefore, these two
fungicides should be rotated with copper to prevent development of
resistance.
Registration of other products is being pursued.
More information
Disease cycle and symptoms can be seen on the Oregon Eastern Filbert Blight
Help Page website:
http://oregonstate.edu/dept/botany/epp/EFB/
Note: Many of the chemicals registered for EFB in the USA are not registered
in Canada.
For more information, contact:
Siva Sabaratnam (Plant Pathologist) or Mark Sweeney (Industry Specialist)
B.C. Ministry of Agriculture
Abbotsford Agriculture Centre
1767 Angus Campbell Road
Abbotsford, BC V3G 2M3
Phone: (604) 556-3001
Fax: (604) 556-3030
January 2009
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