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SOD Management Topics
There are five sudden oak death management topics covered in
this presentation:
1. SOD monitoring and management overview
2. Selective removal of California Bay Laurel
3. Phosphonate applications and gypsum soil amendments
4. Bark scribing to remove SOD cankers
5. Drought and oaks
1. Disease Management - 1st step
• Do I live in an area at risk for SOD?
• Are there California Bay Laurels and/or tanoaks where I live?
• Are my oak species:
– California Coast Live Oak
– California Black oak
– Shreve’s oak (Santa Cruz to Santa Barbara)
– Canyon Live Oak
– Tanoak
2. Selective removal of Bay
Oaks are infected by spores produced on leaves
of California Bay laurels
– Selectively remove bay laurels around high value
oaks
– Reduce overall bay density on property
Choose line depending on size of your oak. Risk should be no more than 0.2. Draw horizontal line from
0.2 until it intersects the line you picked based on size of oak. Draw vertical line at intersection point.
On x axis is the minimum buffer zone where you should remove bay laurels
Oak Diameter
My oak has a diameter of 70 cm (yellow curve)
To reduce risk at 0.2 level need to remove bays
for a buffer of 6 m around trunk (gray lines)
If I want to reach risk of 0.15, then I have to remove
Bays for 10 m (red lines)
Oak Diameter
Reducing overall bay density beneficial (red line infection rate when it
rains a lot; black line infection levels when dry)
Phosphite Treatments
• One injection treatment every two years between
Halloween and Christmas
• One topical treatment in the fall each year, but with
gypsum amendment one topical treatment every two
years may be reasonable
• Soil amendment with gypsum highly recommended but
only if treating with phosphites. Gypsum amendments are
not effective by themselves
Phosphite Use Guidelines
and Application Protocol
This protocol is designed to give the applicator practical
information for successfully applying phosphonate (aka phosphite)
(ex. Reliant®, Agri-Fos® systemic fungicides) to Oak and Tanoak
trees for the treatment of sudden oak death (SOD). Two application
methods are currently available; injection under the bark directly
into the sapwood, and topical application of the product, mixed with
a spreader/sticker surfactant (ex. Pentra-Bark™ penetrating
surfactant), onto the trunk of the tree. Both methods have been
found to be effective at controlling the growth of Phytophthora
ramorum, the causal agent of the disease, in oaks and tanoaks.
Application Protocol Pt. 2
Injection treatments require additional equipment in the form of
spring-loaded, hydraulic, or air pressure injectors that maintain a
positive pressure required for introducing the diluted product into
the tree. The injections are made through holes drilled into the trunk
and use relatively small amount of chemical usually about 50-
200ml (1.5 – 7oz), to treat a tree.
The topical application, on the other hand, uses commonly available
liquid spray equipment and does not leave holes in the tree. The
topical method however requires considerably more product (2-
15L, 0.5-4gal) and overspray may damage surrounding vegetation,
including moss and lichens.
Phosphite Application Materials and Supplies
Disinfectant
MeasuringInjectorsGloves
Pentra-bark
Surfactant
Water
Phosphonate
Mixing Bucket
Face Shield
Spray Rig
Drill
Drill Bit
Application Protocol Pt. 3
Applications should be made when the tree is actively transpiring.
Avoid treating trees during very hot or very cold weather, or when
new leaves are emerging.
Currently in Northern California one injection application every
two years is recommended or apply a spray application every year,
preferably in the Fall or late winter. Subsequent injection treatments
should be made once every two years, preferably in the Fall, you
can alternate between injection and topical application methods.
Preventative treatment, before infection has occurred, has been
found to be more effective than curative treatments. At least 4
weeks are necessary for the applied chemical to take full effect.
List of Application Materials and Supplies
Checklist for injection treatments:
- Phosphonate (Reliant®, Agri-fos®,
etc.)
- Water
- Disinfectant
- Liquid measuring devices, pipettes,
conical tubes, or beakers
- Plastic mixing containers, beakers, etc.
- 5 gal bucket for carrying syringes,
washing, and disinfecting
- Rechargeable cordless drill and bit
- Syringe-type tree injectors Chemjet®,
Arborjet®, Sidewinder®, etc.
- Examination gloves
- Safety glasses or face shield
Checklist for topical application:
- Phosphonate (Reliant®, Agri-fos®,
etc.)
- Pentra-Bark surfactant
- Water
- Liquid measuring devices, pipettes,
conical tubes, or beakers
- Plastic mixing containers, beakers, etc.
- Spray equipment, hydraulic, pump-up
type, or backpack mounted.
- Examination gloves
- Safety glasses or face shield
Mention of commercial products does not constitute endorsement by the
University of California or the UC Cooperative Extension Service.
Always follow the manufacturer’s directions, restrictions, and
precautions on the product label.
Topical (spray) Application
Prepare the treatment solution as per the label:
1.9 L phosphonate + 1.9 L water + 95 ml Pentra-Bark surfactant
which in English measurements equals
62.4 oz phosphonate + 62.4 oz water + 3.2 oz Pentra-Bark surfactant
Adult trees may require between 2 and 15 L (0.5 - 4gal) of mix per tree
depending on their size.
Measure Pentra-Bark
surfactant and add to
tank just prior to
application.
Stir to mix tank
contents.
The mixture will
foam if shaken or
agitated heavily.
Apply treatment solution
uniformly to the tree trunk
from 3-4m (9-12’) height, or as
high as you can reach without
spraying the foliage.
Soak the tree trunk thoroughly
until the application solution
just starts to run off at the base
of the tree.
Avoid overspray. Application
to foliage will cause damage to
the leaves of most plants
including oaks.
Injection Application
Formulations that you can use depending on the type of injection
equipment available.
1 part phosphonate + 29 parts water = 1:30 delivered in 20ml
doses (typical of the Chemjet type injector – 20psi).
1 part phosphonate + 59 parts water = 1:60 delivered in 40ml
doses (typical of the Arborjet type injector – 35psi).
1 injection per 6 inches of trunk
circumference measured at 4 feet above
the soil line.
or
1 injection per 1 yard of canopy diameter,
measured at the drip line.
Example: Trunk circumference = 48
inches (48/6=8) and the canopy diameter
= 24 feet (8 yards). Prepare 8 injections of
phosphonate.
Multiple trunks or an asymmetrical crown
may make it difficult to calculate the
number of injections. If in doubt take both
measurements and use the one that results
in the higher dose.
Calculate the number of
injection sites:
Prepare injectors.
Place injections where there is a clear
translocation path up the tree. Avoid
drilling below limb stubs or near
shakes, cracks, depressions, or into
soft or punky wood.
Drill injection holes in bark.
Sharp bits and slower drill speeds
perform better as they cut rather than
tear the wood.
The drill depth is dependent upon the
type and age of the tree as well as the
thickness of the bark. There is a slight
“pop” as the drill enters the sapwood.
The hole should be drilled
perpendicular to the tree trunk or at a
very slight downward angle.
Run the bit in and out of the completed
hole to clear out wood chips that may
interfere with the injection.
Insert Injectors
Check for leaks around the
injection site. On actively
transpiring trees the treatment
solution will be absorbed in 5 to 15
minutes.
If the injection fails to be absorbed
by the tree try cleaning out the hole
with the drill bit or move to another
site and drill a new hole.
Injection holes may be left open,
covered with a sealant such as
grafting wax, or plugged with
specifically designed plastic pegs.
Sanitation
Use Lysol or diluted bleach to
disinfect equipment and prevent the
spread of SOD.
Clean and rinse injectors between
applications.
Disinfect boots, vehicles, and
equipment thoroughly.
Safety
Read and follow all label
instructions.
Follow safety guidelines.
Wear appropriate clothing
and equipment.
Mention of commercial products does not constitute
endorsement by the University of California or the UC
Cooperative Extension Service. Always follow the
manufacturer’s directions, restrictions, and precautions
on the product label.
Gypsum Amendments(Anhydrous Calcium Sulfate)
• 3 to 5 lbs of granular Gypsum per tree, depending on tree size
• Mix with top layer, in an area with radius of about 3 feet around trunk
• Apply possibly one or two weeks before phosphonate treatment, or at the latest at the same time as treatment
• Increases efficiency of both injections and bark treatments
• Bark treatments plus gypsum can be applied once every two years rather than yearly
About 3 feet around trunk
Can we excise cankers from oaks stems, if we catch them early on?
– Ran experiment during the dry 2012-2014 period at 3 sites in
Northern California
– Results show that, during drought, 75% of oaks are not easily
infected
– Using the remaining 25% we can say with strong statistical
support that:
P. ramorum was detected in an equal number of scribed vs. non
scribed trees
Canker Scribing for SOD infections
Based on our results we cannot recommend scribing
5. Drought and oaks
• Water deficiency due to prolonged diminished
precipitation and increasing temperatures
• Physiological changes:
– Direct effects such as thinner canopy, leaf abscission,
stunted growth
– Indirect effects: secondary pathogens and pests
• Some effects reversible: direct physiological changes,
branch and foliage issues, stem decay
• Some effects irreversible: stem issues, some root rots
Stunted growth
Fungal twig dieback
Cryptocline Fungal branch dieback
Diplodia
Twig girdlers Agrilicus
Foliar insects, oak pit scale
Canker rots, HymenochaetalesRoot rots, Armillaria
Soilborne Phytophthoras
Trunk insects &
associated fungi
Stem cankers & terminal
secondary decay fungi
Managing drought (1 - short term)
• Ameliorate conditions to avoid onsite of irreversible symptoms, normally done during drought:
– Place ground cover around (not on) tree base to lower evaporation and increase absorption
– In case of prolonged drought and onsite of symptoms, water deeply (12 inches) once a month, November to June, only
– Within a tree species, there is variable resistance to drought among individuals this is both genetic and site dependent. Learn to speak “tree”, to understand which ones need help
– When irreversible symptoms are obvious; there is nothing you can do except for making sure windthrows will not cause damages or fatalities
Managing drought (2 - Long Term)
• South aspect, shallow sandy or rocky soils, midslope are most impacted by drought
• Maintain a density appropriate for the site: thin, thin, thin: but do so before or after drought
• Make sure canopy is pruned back, important when trees are isolated or in low density stands
• When landscaping, avoid planting under trees. Also when making compositions use species with comparable drought resistance
• Individual trees growing in drier sites are more drought tolerant: saplings growing in these sites may be more drought tolerant.