xylella fastidiosa en californie et stratégies de lutte mises en … · rodrigo almeida dept....
TRANSCRIPT
Rodrigo Almeida Dept. Environmental Science, Policy, and Management
University of California, Berkeley
Historique de l’épidémie causée par
Xylella fastidiosa en Californie
et stratégies de lutte mises en place
Host
Disease
Pathogen Host
Time
Vector
What factors affect plant disease epidemics?
Pathogen
Plant Vector
Layers of ecological complexity:
environment (e.g. temperature)
vector ecology
pathogen ecology
host plant ecology
outcome of various interactions
disease management
Today…
• Overview of Xylella fastidiosa
• Case study:
– Pierce’s disease of grapevines in California
• Ecology
• Management strategies
• Management at State level
“California Vine Disease”: First detected in Anaheim in 1884 and in the San Joaquin Valley in 1917
Newton B. Pierce
Pierce’s disease costs California US$104 million per year (Tumber et al. 2014. Calif. Agric. 68, 20-29)
Xylella fastidiosa
Xylella fastidiosa
• Xylem-limited bacterium
• Colonizes a wide range of host plants, usually
without causing disease
• Present in the Americas, Taiwan, Italy, France, Iran
– Causing disease in grape at least since the 1880s
– Major crops affected
• Grape, citrus, alfalfa, peach, almond, plum, coffee, etc
• Xylem sap-feeding insects are only vectors
• Pierce’s disease in grapes
• Alfalfa dwarf
• Almond leaf scorch
• Phony peach disease
• Plum leaf scald
• Citrus variegated chlorosis
• Elm, oak, sycamore leaf scorch
• Oleander leaf scorch
* and a very large list of new emerging
diseases of crops and ornamentals
Plant colonization
Newman et al. 2003 Appl. Env. Microbiol.
Vectors: xylem sap feeding insects
Today…
• Overview of Xylella fastidiosa
• Case study:
– Pierce’s disease of grapevines in California
• Ecology
• Management strategies
• Management at State level
Here I will focus on one disease caused by X. fastidiosa in California. It
should be mentioned that diseases such as oleander leaf scorch and
almond leaf scorch, for example, are very important as well as and
caused by other genotypes of this pathogen.
In addition, in other areas of the USA, X. fastidiosa causes diseases of
economic importance on a variety of plants, from pecans and blueberries
to oaks and elm trees.
What is the X. fastidiosa that causes
Pierce’s disease of grapevine in the USA?
late 1800s
1930s -40s
late 1990s
early 2000s
Late 1800s: Anaheim vine disease
1930s and 40s: Central Valley -alfalfa
Late 90s - early 2000s: Temecula Valley and Kern County -invasive GWSS
North coast: consistent, moderate PD -native BGSS
Severe Pierce’s disease outbreaks are unusual
Photo A.H. Purcell
Pierce’s disease epidemiology
- what we know for Northern California-
How do farmers in Northern California
manage Pierce’s disease today?
Management action % growers
Insecticides in vineyard 17.67
Insecticides outside vineyard 1.51
Roguing 38.88
Severe pruning 3.53
Weed control 3.53
Riparian management 8.58
Vector or Disease Monitoring 14.64
How much do farmers in Northern California
believe they are loosing to Pierce’s disease today?
What happened in Southern California?
Glassy-winged sharpshooter invaded ~1990 By late 90s GWSS populations were tremendous
-”100s to 1000s” per vine
-proximity to citrus Severe Pierce’s disease outbreaks
-Up to 100% infection within a year
~40% loss for Temecula region overall
Glassy-winged sharpshooter
(Homalodisca vitripennis)
Photo A.H. Purcell
Temecula Valley, CA -3 years after first symptomatic plant-
General impact of GWSS introduction into California
GWSS large populations
More X. fastidiosa-vector encounters
More successful infections New vector-pathogen associations?
and/or
New X. fastidiosa strains?
Higher disease incidence
New diseases
The response to the Temecula outbreak
Replanted majority of acreage
-removed inoculum source Area-wide vector control
1. sharpshooter monitoring
2. biological control
3. chemical control in citrus Appropriate vineyard management
-vine removal
-vector control
Chemical control of GWSS
Two scales of chemical control of GWSS 1. Area-wide application of insecticides to citrus
-citrus is a preferred reproductive hosts -strong gradient in Pierce’s disease risk as a function of vineyard proximity to citrus
2. Application of insecticides to individual vineyards -treat grapevines to reduce vector pressure
Area-wide treatment of citrus
Reducing disease risk for vineyards requires cooperation of citrus growers ~2000 acres grapevines, ~1000 acres of citrus in Temecula Since 2000, up to 1000+ acres of citrus treated with insecticides (primarily imidacloprid)
-significant reductions in vector pressure in vineyards next to treated citrus -regional GWSS populations are a greatly reduced since the program started
X
Chemical control of GWSS
Area-wide treatments in citrus to limit GWSS incursion into vineyards Grape-growers also commonly treat grapevines as a means of further reducing vector pressure >70% of Temecula vineyards treated consistently with imidacloprid
Response to the Temecula outbreak
GWSS populations are greatly reduced compared to 15 years ago
Pierce’s disease prevalence is currently very low
<1% on average, treated fields lower
<0.01
Main Pierce’s disease management options in California? Monitor regularly for sharpshooters
Conventional or organic foliar insecticides
-timing based on monitoring data
Within-vineyard weed control?
Remove diseased vines to ensure they are not sources of infection
Management of riparian plants
Today…
• Overview of Xylella fastidiosa
• Case study:
– Pierce’s disease of grapevines in California
• Ecology
• Management strategies
• Management at State level
Pierce’s Disease Control Program
Mission & Strategy Mission: Minimize the statewide impact of
Pierce’s disease in California.
Strategy: Contain the spread of the new
vector to allow time to develop solutions.
Host
(Grapes) Vector
(GWSS)
Pathogen (Xf)
Tom Esser, CDFA
How is management done in
California at the State level?
Components
• Containment
• Statewide Survey
• Rapid Response
• Public Outreach
• Research
Activities
• Biological Control
• Area-wide Projects Tom Esser, CDFA
Cooperative Program
• USDA
• CDFA
• County Agricultural Commissioners
• University of California
• Industry Groups
• Stakeholders
• Public
Tom Esser, CDFA
GWSS in California
June 2002
Tom Esser, CDFA
Containment
Nursery Bulk Citrus Bulk Grape
• Prevent GWSS from moving to new areas
Tom Esser, CDFA
Statewide Survey
• Verify that at-risk areas are still uninfested
• Look for new/unknown infestations of GWSS
• Currently being conducted in 49 counties (6 generally infested, 36 uninfested, 7 partially infested)
• Approximately 38,000 traps deployed in nursery
and urban/residential areas during peak season
Tom Esser, CDFA
Rapid Response
• Delimitation, regulatory, treatment, & monitoring
• 17 infestations eradicated
Tom Esser, CDFA
Public Outreach
• Meetings, brochures, website, mailings, news
stories, word-of-mouth, posters, etc.
• Awareness and compliance increased rapidly;
public helped discover new infestations
Tom Esser, CDFA
Research
• Over 200 projects conducted since 1999
• 13 Symposia held; 990 reports in 15 years
of Proceedings
• Field trials in progress
Tom Esser, CDFA
Funding for PD/GWSS (cumulative, 17 years)
$440 497 000
$66 966 000
$56 692 000
$2 171 000
Federal State Industry Local
Tom Esser, CDFA
Uses of Industry PD/GWSS Assessment Funds (Cumulative, 15 years)
$29 024 000
$7 240 000
$3 997 000
$3 645 000
$3 184 000
$2 681 000 $1 265 000
Basic Research Applied Research & Field Trials
Program Support Administration & Grower Votes
Research-Related Services Public Outreach
Other Designated Pests & Diseases
Tom Esser, CDFA
Take home messages…
. California has ‘four’ X. fastidiosa problems that are very different from each other:
. Pierce’s disease in Northern California, has been a problem for 100 years, new
epidemic ongoing.
. Pierce’s disease in Southern California, now driven by an introduced vector,
major effort by state/federal governments to control it.
. Small epidemics of almond leaf scorch and oleander leaf scorch, which are
localized and have limited impact.
. Unknown or poorly characterized diseases, such as urban trees and trees in
California forests.
. Millions have been invested in pest monitoring, area wide control efforts, research,
outreach and extension (last 15 years). However, there is still no cure to X. fastidiosa
infection of grapevines. Despite all recent efforts, epidemics have emerged in the last
couple of years in Northern and Southern California. The best alternative, in my opinion,
is an integrated approach to disease management that includes a range of strategies to
control vectors and reduce pathogen prevalence in the environment.
. Advice? Invest in monitoring, research, outreach, and extension. Support all disciplines
and approaches, do not ignore paths that seem ‘traditional’ or ‘cutting edge’. Different X.
fastidiosa diseases are handled in different ways in different crops and parts of the world.
Each solution is system and location based, there is no ‘one size fits all’ answer. But all
answers integrate plant, insect, pathogen, social, economic, environmental and
agricultural practices.