Two of the most important invasive Phytophthora pathways into California wildlands Commercial Nursery 1 Landscape to Wildland Restoration Nursery Restored Wildlands Commercial Nursery 2 Restoration Nursery
Concern because new species of Phytophthora in California restoration nurseries and now found in restored wildlands Phytophthora tentaculata Described in Germany in 1993 from Chrysanthemums and other commercial nursery plants First IDed in North America in 2012 in Monterrey Co., California Nursery Kills the California native Diplacus (syn. Mimulus) aurantiacus symptoms typical of other root rotting Phytophthora species Symptoms: root and stem rot, with the roots and stem collars developing necrotic, sunken lesions and few feeder roots, stunting, leaf russeting, and chlorosis, defoliation and dieback of twigs, brown to black lesions girdling the basal stem, and eventually plant death Been identified from nurseries in Butte, Alameda, Placer and Santa Cruz Counties Been recovered from restoration sites in Alameda Co.
Close evaluation of restoration sites and nurseries has found many different Phytophthora species from many different plant species Plant species Restoration county Symptoms Phytophthora species Heteromeles arbutifolia San Francisco root rot, root collar canker, foliage discoloration (chlorosis), death P. rosacearum, P. cryptogea, P. cactorum, P. inundata, P. gonapodyides Frangula californica Marin main stem dieback with resprout, chlorosis, root rot, top dieback P. cryptogea, P. multivora Ceanothus thyrsiflorus San Francisco stem and branch dieback, wilting, root-rot, death P. cryptogea, P. cactorum, P. multivora Eriophyllum staechadifolium Marin, San Francisco, San Mateo root rot, dieback, and death P. cryptogea, Phytophthora "megasperma - like", P. crassamura, P. gonapodyides Baccharis pilularis Marin chlorosis, stem necrosis, death Phytophthora "cryptogea -like", P. cryptogea, P. inundata Artemisia californica Marin stem and foliar dieback, necrosis Phytophthora "cryptogea-like" Stuckenia pectinata San Francisco necrotic spotting on seed collected from pond water Phytophthora gonapodyides, P. crassamura Lupinus arboreus Marin Necrosis, foliage dieback, wilting Phytophthora cryptogea
Evaluation of toyon field symptoms, plants infected with P. cryptogea root rot root collar canker Phytophthora cryptogea from diseased restoration H. arbutifolia plants
Frangula californica infected with Phytophthora multivora No obvious symptoms Phytophthora root rot
Phytophthora cactorum and Ceanothus thyrsiflorus Ceanothous root rot caused by Phytophthora species, especially Phytophthora cactorum Symptoms: Root rot, dieback, branch dieback, and death
Photos by: Lew Stringer dieback of Ceanothus thyrsiflorus, associated with Phytophthora cryptogea, which was isolated in the field from plants with these types of symptoms -Although in this case not from these particular plants
Site with planted Eriophyllum st., and Ceanothus thrys., both associated with P. cryptogea, also remnant Ceanothus thrys. downhill from planting area was positive for P. cryptogea, plants were dying, dead, or had dieback. Photo by: Lew Stringer of the Presidio Trust
Frangula california dieback associated with P. multivora Photos by Alison Forestel of NPS
With many different Phytophthora species, involved comes differing levels of pathogenicity. Isolate species, and then evaluate which species are responsible for disease observed.
How to keep Phytophthora out of wildlands...
Nurseries: Integrated approach of sanitation, water management, monitoring, and host selection Start clean stay clean Pathogen free: benches, soil (and other planting media components) containers, and plant propagules -leads to pathogen free plants for landscapes group plants on benches based on their watering needs water appropriately using tensiometers if necessary monitor plants for symptoms weekly select plants that are not hosts
Land managers: Prevention first! Prevention: Purchase clean materials Have sites tested first if Phytophthora is present avoid host species Cultural control: Good drainage No sprinklers watering trunks of trees Correct drainage Chemical control: Several fungicides such as Aliette, Alude, Fosphite, Mefenoxam or Subdue may be effective if not phytotoxic to the plants. Fungicides combined with cultural controls work better than either alone
Native to AZ and Mexico Introduced on firewood Goldspotted Oak Borer 1 st detected in CA in 2004 San Diego Co survey traps Linked to tree mortality in 2008 Tens of thousands of coast live oak, CA black oak, and canyon live oak trees killed gsob.org
California Distribution
Risk Sea level to 6,000 feet Prepupae cold tolerance of about -0.4 F
Study - Cost of GSOB Remediation Greater San Diego County RCD Project: Removal of Dead Oaks in Descanso Tree removals 12-60 in diameter Avg height 40 ft Oaks Removed Parcel Acreage house present no house Total Approximate cost $9,000 per parcel $1,200 per acre $1,500 per oak <1 218 125 343 1 to 5 358 127 485 >5 391 113 504 967 365 1332 Slide courtesy of Tom Scott, UCR
GSOB mitigation costs to date: ~$16 M Possible financial impacts if GSOB becomes established in more populated location? Slide courtesy of Tom Scott, UCR
Remediation/Removal Costs for Communities with Oaks Oak density Cost/mile sq Pasadena (23 sq mi) Oaks per acre Oaks per sq mile low medium high low medium high Street Trees 0.50 320 240,000 480,000 1,600,000 5,520,000 11,040,000 36,800,000 Yard Trees 4 2,560 1,920,000 3,840,000 12,800,000 44,160,000 88,320,000 294,400,000 Property Value Losses Associated with Loss of Oaks acre Oak density Cost/mile sq Pasadena (23 sq mi) sq mile Street Trees 0.5 320 Yard Trees 4 2,560 Low $5K 1.6 million 13 million Medium $10K High $30K low medium high 3.2 million 26 million 9.6 million 77 million 36 million 294 million 73 million 588 million 220 million 1.8 billion Slide courtesy of Tom Scott, UCR
Polyphagous & Kuroshio Shot Hole Borers Female PSHB. A. Eskalen, UC Riverside
Invasive Beetle/Disease Complex Polyphagous shot hole borer (PSHB) LA, Orange, Riverside, San Bernardino, and Ventura Counties 3 fungal species Kuroshio shot hole borer (KSHB) San Diego and Orange Counties Closely related to PSHB 2 fungal species Beetle farmer Affects seemingly healthy trees Beetle/fungus affect vascular tissue Internal symptoms on coast live oak. A. Eskalen, UC Riverside
More than 200 known hosts Hosts Common urban landscape trees and agriculturally important species Avocado, olive, persimmon At least 35 reproductive hosts 13 native CA species Dead box elder tree, Ontario, CA. A. Eskalen, UC Riverside
Distribution of Infestation 2012 2013 2014 2015 http://eskalenlab.ucr.edu/distribution.html A. Eskalen, UCR
KSHB infestation December 9 2015 in southwestern San Diego County. Kevin Turner UC Riverside (kevint@ucr.edu) Tijuana River Valley Regional Park
Photo point December 9, 2015 willows dead, brittle, tops snapping off and falling into the water channel. Note that arundo is the living green plant in the background. Flooding is a concern with so much dead wood falling into the waterway, especially anticipating El Nino.