How often do you administer phosphonate to oaks to help protect them from sudden oak death?

Phosphonate injection treatments to help prevent sudden oak death infection of susceptible oak species (coast live oak; California black oak, Shreve’s oak, and canyon live oak), if applied in the fall (after October 30th ), need only to be applied once every other year (biannual frequency). If your first phosphonate treatment is in the spring, then […]

How do I determine the distance from trees on my property to P. ramorum-positive trees on SODmap?

When looking at SODmap, you may wonder if P. ramorum-positive trees are close enough to pose a threat to trees on your property. Use the free App SODmap mobile to get the answer. Just tap the App risk function and it will tell you whether  infected trees trees are within 200 m (high risk) or […]

Does rain affect preventative phosphite (e.g. Agri-Fos®) treatments for oaks?

When treating oak trees with phosphites to help prevent SOD, it may be beneficial to apply the topical treatment to bark that is dry.  Rain occurring after the treatment (even immediately after) does not affect the application. If injecting phosphites, it may be better to avoid rainy days, as lower evapotranspiration is often documented for […]

When treating large oak trees with phosphonate, is it more effective to topically apply or inject the material?

Injections may be better for large trees with a regular shape, while topical applications may be better for large, irregular, gnarly trees.

What temperature range is acceptable for treating oak trees with phosphonate?

In order to obtain maximum efficacy with oak phosphonate treatments, minimum temperatures should not be below 50 ºF. Maximum daytime temperatures should be higher than 60 ºF, but not exceed 85 ºF.    

Do azomite fertilization and lime wash treatments help control SOD?

Based on the study published by the UC Berkeley Garbelotto lab in California Agriculture (http://nature.berkeley.edu/garbelotto/downloads/calag2009.pdf), azomite and/or lime washes alone are not effective in controlling SOD.

Will the spray application for SOD prevention be updated like the injection application was?

While phosphonate injections to help control SOD are now recommended once every 2 years, spray applications should still be applied to the bark of oak trees annually.

How often should SOD phosphite treatments be applied?

If SOD phosphite treatments are being applied by injection November 1st – December 15th, data has shown that treating every 2 years is sufficient. When preparing the injections, be sure to use the most current dosage recommendations as they have recently been updated. Current recommendations can be found at http://nature.berkeley.edu/garbelottowp/?page_id=2345. The new dosages are significantly […]

Does phosphonate act as a vaccine, keeping trees from getting SOD?

Phosphonate is only intended to be used on trees that do NOT have sudden oak death (SOD). Once a tree is infected, it is of no use. It helps to boost the tree’s own immunity system against the pathogen. So, if a tree is very susceptible to P. ramorum (the pathogen that causes SOD), then […]

Are there any P. ramorum-resistant coast live oaks or tanoaks commercially available?

Research has identified coast live oak individuals that may be somewhat resistant to SOD, possibly because of the presence of some chemicals in the bark and phloem.  However, there is no information yet on how genetics and the environment may affect this trait. Tanoak has some mother trees that produce SOD-tolerant seedlings and some that […]

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