SOD Disease Management

Transcription

1 SOD Disease Management Revised 10/20/2016

2 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

3 1. Disease Management - 1 st 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

4 Use SODmap Mobile app for disease assessment Available free for Apple ios and Android

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9 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

10 Oak Diameter 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

11 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

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13 Reducing overall bay density beneficial (red line infection rate when it rains a lot; black line infection levels when dry)

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15 3. Preventive applications with phosphonate (phosphite) injections and gypsum amendments

16 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

17 Phosphite injection dosages Treatment once every two years

18 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.

19 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 ml (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.

20 Phosphite Application Materials and Supplies Face Shield Water Spray Rig Drill Bit Mixing Bucket Drill Disinfectant Measuring Gloves Injectors Pentra-bark Surfactant Phosphonate

21 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.

22 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.

23 Topical (spray) Application Prepare the treatment solution as per the label: 1.9 L phosphonate L water + 95 ml Pentra-Bark surfactant which in English measurements equals 62.4 oz phosphonate oz water oz Pentra-Bark surfactant Adult trees may require between 2 and 15 L (0.5-4gal) of mix per tree depending on their size.

24 Measure phosphonate and water and mix in tank.

25 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.

26 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.

27 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).

28 Calculate the number of 1 injection per 6 inches of trunk circumference measured at 4 feet above the soil line. or injection sites: 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.

29 Measure volume of phosphite and water.

30 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.

31 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.

32 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.

33 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.

34 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.

35 Gypsum Amendments (Anhydrous Calcium Sulfate) About 3 feet around trunk 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

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37 4. Canker Scribing for SOD infections

38 Canker Scribing for SOD infections Can we excise cankers from oaks stems, if we catch them early on? Ran experiment during the dry 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 Based on our results we cannot recommend scribing

39 Positive control (infected but not scribed) lesion 1cm

40 Infected/scribed lesion New lesions outside scribed area 1cm Initial infection site Scribed Area

41 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

42 Stunted growth Fungal twig dieback Cryptocline Fungal branch dieback Diplodia Stem cankers & terminal secondary decay fungi Twig girdlers Agrilicus Foliar insects, oak pit scale Trunk insects & associated fungi Root rots, Armillaria Soilborne Phytophthoras Canker rots, Hymenochaetale

43 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

44 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.

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