Citrus Greening in Texas

TDA Critical Entry Point Inspector Training August 21, 2012

Sheila McBride Texas AgriLife Extension Program Specialist – Diagnostician at Texas Plant Disease Diagnostic Laboratory Department of Plant Pathology & Microbiology, Texas A&M University, College Station, Tx

Understanding Citrus Greening

• Importance • Vector of the bacterium Candidatus Liberibacter asiaticus • Citrus Greening Symptoms • Sample Submission to Lab for In Lab Sample Processing Why is Citrus Greening Important To Texas?

Citrus Greening was detected in Texas!!!! On January 13, 2012 in Cameron County • Texas is the second-leading state in grapefruit production and ranks third in orange production with about 28,295 acres in commercial citrus production in the primary citrus counties of Cameron, Hidalgo and Willacy. • A statewide economic impact of more than $140 million • To date there have been 47 orange trees and 13 grapefruit trees tested positive for HLB • 4 ACP’s tested positive for the bacteria HLB is caused by

š A bacterium – Candidatus Liberibacter

š Is present only in phloem

š Slow moving

š Not uniformly distributed in the plant, causing “sectoring” in symptoms Vector - Asian Citrus Psyllid (ACP) (Diaphorina citri Kuwayama)

45° Citrus Greening Symptoms

Photo: T Riley, USDA APHIS PPQ

Classic symptom: Leaf blotchy mottle Blotchy mottle Asymmetrical Look on both sides of the leaf. Leaf miner can mimic citrus greening (yellowing) symptoms

Front Back HLB symptoms vs. nutritional mottling

Blotchy mottle effect crosses leaf veins whereas a deficiency related mottle does not. Veins can turn yellow.

Nutritional deficiency is symmetrical Taking a closer look

š Blotchy mottle symptoms may not be visible to just an exterior canopy.

š Examine the tree closer by parting branches to view older leaves within the canopy.

š Pay attention to bud Classic blotchy mottle breaks, new flush or re- symptom growth after pruning. Additional symptoms on leaves

• Corky veins

• Vein yellowing

• Thickened leaves Zinc-like deficiency

Leaf mottling

“Zinc deficiency” Classic Blotchy Mottle

Citrus limon Lemon

Citrus aurantiifolia Key lime (lima de los cayos)

Citrus x paradisi Grapefruit Citrus sinensis Sweet orange Citrus aurantium Sour orange Symptoms on the tree

Yellow Shoot Twig dieback Approaching a grove (orchard) block:

Viewing from a distance allows you to judge abnormalities on a macro scale.

(How does one tree compare to another?)

Severe leaf drop

Premature fruit drop Symptoms on the fruit

š Lopsided fruit and hard š Poor coloration, hence the name“greening” š Seeds abort š Juice is high in acids and low in soluble solids š Abnormally bitter to the taste What Measures are being taken?

š Scouting, sampling and testing for HLB in the groves in the entire Rio Grande Valley and dooryard citrus š Quarantine in a 5 mile radius around infected grove š Area-wide pesticide applications to control the vector the ACP š Education to the growers and the public š Research efforts to better understand the bacterial organism and possible control. The Texas Plant Disease Diagnostic Laboratory

Citrus Greening/ Huanglongbing Sampling and Submission Citrus greening/ Huanglongbing testing in TEXAS

• Samples from the 8 counties in the Rio Grande Valley: Cameron, Hidalgo, Willacy, Starr, Zapata, Jim Hogg, Brooks, and Kenedy Send to Texas A&M Kingsville – Citrus Center (Weslaco)

• Samples from rest of Texas Send to the Texas Plant Disease Diagnostic Lab (College Station) • http://plantclinic.tamu.edu

Collect Sample

• Scout tree (s) for symptoms • Keep your eyes open for the Asian Citrus Psyllid on new flush • Preferably collect more than 10-12 leaves still attached to branches. • Place collected sample in a zipper bag or plastic bag, label and secure tightly Sample submission

When submitting multiple samples:

• Treat each submitted sample separately. • Label bags clearly so that samples can be differentiated. Sample submission

• Fill out the appropriate form(s) as completely as possible. • Forms can be found at our website: http:// plantclinic.tamu.ed u Sample submission

• Place completed form(s) in a separate zipper bag or plastic bag and secure tightly. • Place all samples and form(s) into one (1) zipper or plastic bag and secure. • Make sure basic information portion of the form is easily visible

Shipping Sample Biology and Epidemiology of Other Citrus Diseases of Concern

š Sweet Orange Scab š Sour Orange Scab š Citrus Canker š Citrus Black Spot š Citrus Leprosis š Citrus Trizteza Virus Sweet Orange Scab- SOS (Elinosoe australis)

Division of Plant Industry Archive, Florida Department of Agriculture and Consumer Services, Bugwood.org

Sweet Orange Scab - SOS

š On July 23, 2011, APHIS, PPQ confirmed SOS on residential lemon and tangerine trees in Harris County, TX. The first confirmation of sweet orange scab in the United States. š Occurs on sweet oranges, limes, lemons, mandarins, satsumas, kumquat, grapefruit, tangerines and tangerine hybrids. š Causes cosmetic problems of the fruit and renders the fresh fruit unmarketable.

Citrus Samples collected from Orange Co. TX. 2010

Sour Orange Scab ( Elsinoe fawcettii)

Division of Plant Industry Archive, Florida Department of Agriculture and dpi.nsw.gov.au/agriculture/ Consumer Services, Bugwood.org horticulture/citrus/ management/other-information/ garden Sour Orange Scab

š Present in Alabama, Florida, Georgia, Hawaii, Louisiana, Mississippi, Texas. š Affects the fruit, leaves, and twigs of susceptible varieties of citrus ie: grapefruit and lemons, rare on sweet oranges. š Fruits severely attacked when very young often become misshapen, with predominant warty projections, cracked and deeply fissured with age. Citrus Canker (Xanthomonas axonopodis pv. citri) Citrus Canker

š The most recent outbreak of citrus canker was discovered in Miami, Dade County Florida on Sept. 28, 1995 š All varieties of citrus are susceptible š Infects leaf, fruit and stem causing tree debilitation and losses in quality and quantity of fruit š Damage caused by citrus leaf miner larvae can be sites for infection to occur Citrus Black Spot –CBS (Guignardia citricarpa)

Cesar Calderon, USDA APHIS PPQ, Bugwood.org P. Barkley, Biological and Chemical Research Institute, Bugwood.org

Citrus Black Spot - CBS

š Detected in Florida March 8, 2010 on Valencia sweet orange š Previously the nearest location of infestations was Argentina and Brazil š Affects fruit rind and leaves š It causes early fruit drop, reduces crop yield, and renders the highly blemished fruit unmarketable. š All citrus varieties are susceptible, but the most vulnerable are lemon and late-maturing varieties like Valencia. Citrus Leprosis – CiLV (Rhabdovirus)

Citrus Leprosis

š Distribution- South America, Central America, North America—Mexico (2003) and only 150 miles from Texas š Symptoms on twigs, leaves, and fruit š Transmitted by the flat mite (Wind dispersed) š Extensive crop loss and tree defoliation š Is not systemic (does not move throughout the tree) Citrus Tristeza Virus – CTV (Closterovirus )

Division of Plant Industry Archive, Florida Department of Agriculture and Consumer Services, Bugwood.org L. Navarro, Instituto Valenciano de Investigaciones Agrarias, Bugwood.org

Citrus Tristeza Virus š Citrus tristeza virus strains vary from mild to severe, causing little damage to severe decline, especially on trees grafted on sour orange rootstock. š Trees grown on susceptible rootstocks, trees may be reduced in size, vigor, and fruit yields. š Trees with a severe strain may quickly decline and die, with the first symptoms being leaf wilt and ultimate tree death. š Additionally, other strains may cause stem- pitting in limes, grapefruit, and sweet orange. Fortunately, stem pitting strains are not currently a problem Agrilifebookstore.org

• E-264 and E-265 Questions???

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