2. Virus & Virus-like? Graft transmissible; Some vectored (insect, mite, fungus); Some mechanical True viruses Viroids Procaryotes Unknown

5. Major Citrus Virus & Virus-like Agents/Vectors Tristeza Quick decline; stem pitting - Citrus tristeza virus /Aphids Huanglongbing (Greening) - Liberibacter spp./ Psylla Psorosis/Scaly bark- Citrus psorosis virus/ Fungus? Stubborn - Spiroplasma citri / Leafhoppers Leprosis -Citrus leprosis virus / Mites Variegated chlorosis- Xylella fastidiosa / Sharpshooters Witches’ broom of lime - Phytoplasma / Leafhopper Blight – cause / vector unknown Exocortis - Citrus exocortis viroid / Mechanical Cachexia - Hop stunt viroid / Mechanical Tatterleaf – Citrus tatterleaf virus / Mechanical

6. Other Virus & Virus-like Diseases Concave gum, Cristacortis, Impietratura Infectious variegation, Leaf rugose Vein enation/Woody gall (Aphids) Satsuma dwarf, Citrus mosaic (soil vector?) Citrus yellow mosaic (Mealy bugs) Dweet mottle (= Citrus leaf blotch?) Rubbery wood Multiple sprouting Measles Chlorotic dwarf (Whitefly) Indian ringspots + other ringspot diseases Concentric ring blotch/Zonate chlorosis (mites) Gum pocket, gummy bark, Kassala Corky vein Yellow vein clearing/ Yellow mottle Australian decline (leafhopper?) Sudden death – NEW – SERIOUS (aphids?) Etc.

7. History of Major Diseases 1880’s - yellow shoot disease (HLB, greening) - China 1890’s - blight - Florida 1890’s - sour orange rootstock problems - South Africa 1896 - psorosis described – Florida 1930s – tristeza disease in S.America 1934 - psorosis graft transmitted - Florida 1943 - HLB graft transmitted - China 1946/48 - aphid & graft transmission of tristeza - Brazil 1965 - psylla transmission of HLB - South Africa 1988 - graft transmission of blight - Florida

12. Brown citrus aphid

13. Acknowledgement ;Tim Gottwald

14. Tristeza destruction of trees on sour orange rootstock South America – approx. 40 million killed since 1930 (BCA) Spain – 45 million since 1960 (No BCA) Florida – 3 million in 2000-02 Total worldwide – over 100 million Italy – 98% on sour – decline widespread (No BCA) 200 million to go? (TX, Mex., Med.)

17. Exocortis

18. Cachexia

19. Psorosis

21. Psylla

22. Tatterleaf

23. Blight

24. Witches’ broom disease of lime

25. Citrus variegated chlorosis

28. Control Prevention : - Used certified disease-free bud/graftwood - Quarantine - Prevent mechanical spread- chlorox disinfection - Mild strain protection (eg CTV) Vector control ? Difficult to get 100% (eg. Biocontrol of psylla in Reunion)