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 […]

I have an oak in the Bay Area that is oozing liquid from the trunk base. Should I test it for SOD? If so, how?

When trying to determine if an oak may have SOD (caused by the plant pathogen Phytophthora ramorum), the first step is to determine if the tree lies within 1 km of a known outbreak.  This can be done by accessing SODMAP at www.sodmap.org or by uploading the free “SODMAP Mobile” app to your smartphone.  Stand next to […]

How long can Phytophthora ramorum survive in wood chip mulch?

Survival of P. ramorum (SOD pathogen) in wood chips depends on a few factors: Were the chips allowed to become wet? What size are the chips? Is green waste present? What time of year was the wood chipped? Where in California are the chips located? Chips that are piled wet or tarped and include infected […]

How long can Phytophthora ramorum survive in soil moved from an infested area?

Survival of P. ramorum (SOD pathogen) in dead hosts or non-plant substrates is extremely variable and strongly affected by climatic factors. Although a comprehensive study on this topic has not conducted, extrapolating from several studies we can say the following: Soil becomes more infectious from late winter to early summer in the presence of rainfall, […]

When will the 2016 SOD Blitz and training sessions be held?

SOD Blitzes include a training session for blitz volunteers on SOD and proper sampling, followed by time in the field  for collecting and marking sample locations. All necessary collection materials are provided to volunteers during the training session for use either the same day of the training or the day after. All samples are to […]

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.

Can poison oak leaves be infected by Phytophthora ramorum?

The stems of poison oak plants can be infected by Phytophthora ramorum (the plant pathogen known to cause SOD); however, we do not know if leaves can be.

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