2012 Update on the Distribution and Incidence of SOD in California

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1 2012 Update on the Distribution and Incidence of SOD in California Matteo Garbelotto & Katie Palmieri, U.C. Berkeley Dave Rizzo, U.C. Davis Yana Valachovic, UCCE Humboldt Co. Jack Marshall, Cal Fire

2 Keeping Tabs on SOD in California Stream monitoring (mostly +/-) Broad ground surveys Ad hoc sampling (allow for quantification)

3 Stream baiting (UC Davis and collaborators): 117 baiting stations 1- North Coast (emphasis on leading front of infestation: Del Norte, Humboldt and Mendocino) 2- Southern Big Sur (Monterey and San Luis Obispo CO.) 3- Inland: Sierra Nevada. Negative until Not done in 2012

4 All baits still negative in Del Norte County

5 Humboldt County Redwood Creek (aka Orrick infestation) still positive. Arcata area: positives in vicinity of nursery Central County: two drainages positives Southern County: Eel river mostly positive in Redway area but also upstream at Mendocino border. Mattole river now with several positives

6 Mendocino County Eel River at the Humboldt border Fort Bragg area: both immediately North (MacKerricher State Park, Grange) and South (Brush Creek; with possible nursery association) Mendocino area: South of Mendocino positives have been previously found. Russian Gulch is now PCR-positive north of Mendocino Cleone area: positive previously not yet positive this year

7 Broad Surveys: SOD Blitzes ( Greater bay area (Sonoma to Carmel) Trained volunteers do the sampling Samples processed by culturing, Elisa, PCR at UCB Positive and negative mapped on Google Earth, map goes public on October 1 st each year

8 2012 SOD Blitz Results ( 19 Blitzes with 516 participants Surveyed 10,455 trees; sampled 2,087 Overall positive rate was 30% (32% in 2011) Estimated regional infection rate (6-30%): local rates difficult to assess because surveys are not systematic In 2011, % positive tripled or more compared to In 2012 it remained comparable, but with local differences

9 Significant Infestation in Golden Gate Park (Southeastern part, not close to Strybing Arboretum) SOD found only once before at AIDS Memorial Grove on non-infectious oaks In 2012, three bays were positive in a significant, but contiguous sector of park and others species are symptomatic Presidio negative in 2012 (one oak positive in 2011) No connection with private gardens, but possibly linked to rhododendron planting (within last 5 yrs)

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11 Great Expansion of Disease in East Bay Residential, Urban Neighborhoods SOD significantly established on west side of Berkeley-Oakland Hills only in 2011 Spread rate increased dramatically last year on western slopes of hills (downhill movement & all year round cool climate favor disease) Bay infection rate now at epidemic level (oak infection likely) in West Richmond, Kensington, North Berkeley, Claremont, Montclair-Piedmont

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13 SOD is Pervasively Established in Residential Burlingame Hills, South of San Francisco Percent of positives was a staggering 38%. Positives throughout the neighborhood, absence of a clear initial infested area. This is the Northernmost outbreak in San Mateo County. Genetic analysis shows that: A single introduction responsible for outbreak Given number of different genotypes, it probably arrived in 2001 Genotypes not linked to San Mateo County, but to Marin (hence it did not spread naturally from nearby SFPUC but introduced by human activity)

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15 Atherton Bay Eradication Effort has Lead to Successful Local Eradication In 2010 and 2011 an outbreak was identified in Atherton Outbreak was several miles from natural infestation of wildlands In 2011, infected bays and their neighbors were removed. In 2012, remaining bays were P. ramorum negative

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17 Summary of Other Results from In general P. ramorum more established in strictly urban areas throughout Bay Area (Marin, Sonoma, Napa, East Bay, Peninsula, San Francisco, Santa Cruz) We have a clear natural pathway of spread stemming from Scott s Valley (Santa Cruz-original release site of P. ramorum) all the way to Woodside (San Mateo) Spread rate of P. ramorum not predictable based on age of infestation and county. In East Bay, P.ramorum introduced in Contra Costa long ago and moved slowly maybe because of warmer conditions, now in cooler condition it is spreading fast. The opposite seems true for Peninsula and Carmel Valley: it spread rapidly at first and now slowing down as areas get warmer Once we have a wave year with high rainfall (2011), the following year also has high disease incidence

18 Ad hoc Surveys (UCCE and Cal Fire) Redwood infestation, Northern Humboldt: bay removal performed in Based on tree mortality, great expansion in 2011 Redway infestation: based on tree mortality great expansion in Noticeably, expansion was reported eastward rather than along the North-South axis Mendocino county; New infestation west of Ukiah on Running Springs road in drainage that is tributary of Russian River. Jackson State Forest intensively monitored but nothing substantial to report yet

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20 Aerial Detection (ac) by Year

21 Conclusions Not great change in overall range of P. ramorum distribution in the last year; however, following a very favorable 2011, great local expansion Expansion rate not easily predictable, but seems to be modulated by local climate. P. ramorum slows as it approaches warmer areas and accelerates as it gets into cooler ones. We should think of years immediately following wave years as years conducive to spread. Surveys based on bay laurel infection provide great early warning (jump in infection rate on bays will well predict oak mortality to come later) In Mendocino, Northern Sonoma, and Northern Monterey County, slowly but surely new discrete infestations are appearing. Most, potentially moving from the south but a Northern Mendocino outbreak linked to Humboldt P. ramorum in urban situations. Some urban outbreaks were originally missed: now widespread and may require different approaches (local eradication being one of them, aggressive monitoring and treatment). Presence/absence insufficient to predict risk for oak infection. Incidence needed