14 Nasty Citrus Diseases that You MUST Avoid

Citrus diseases are a significant threat to our citrus trees in California and all citrus growing regions. This video shows 14 of the nastiest ones and gives some tips for avoiding them. Citrus tree diseases of great concern include Huanglongbing (HLB) or citrus greening, citrus tristeza virus, citrus stubborn disease, cachexia, exocortis, psorosis, citrus variegated chlorosis, citrus tatter leaf virus, leprosis, citrus leaf blotch virus, canker, sudden death, black spot, and chlorotic dwarf. The video also shows some of the insects and mites that spread citrus diseases. These include Asian citrus psyllids, cotton aphids, brown citrus aphids, leafhopper insects, sharpshooter insects, and flat mites.

You can find University of California ANR farm advisers and specialists who can help with citrus disease questions via the link below:
https://ucanr.edu/About/Locations

How to order pathogen-free budwood from the CCPP:
   • Ordering Citrus Budwood for Grafting ...  

How to introduce new citrus varieties to California legally and without the threat of introducing diseases:
   • Grafting Citrus Trees under a Microscope  

Current distribution of Huanglongbing and Asian citrus psyllids in California:
https://ucanr.edu/sites/ACP/Distribut...

Portion of the video with the citrus disease and the associated citrus disease pictures:
0:00 Introduction
0:23 Huanglongbing (citrus greening)
0:54 Citrus Tristeza Virus
1:46 Citrus Stubborn Disease
2:10 Cachexia
2:40 Exocortis
3:17 Psorosis
3:35 Citrus variegated chlorosis
4:09 Citrus tatter leaf virus
4:39 Leprosis
5:08 Citrus Leaf Blotch Virus
6:09 Canker
6:17 Sudden Death
6:21 Black Spot
6:25 Chlorotic Dwarf

Photo Credits:
Georgios Vidalakis
David Gumpf
C. N. Roistacher
Susan Halbert
Grant Chambers, NSW DPI
CDFA Plant Data Analysis Services (PDAS)
USGS Native Bee Inventory and Monitoring Program
Jeffrey Weston Lotz
Scot Nelson
Steve Garnsey
Deborah Pagliaccia
E. C. Calavan
Jack Kelly Clark
Alex Wild
Beth Grafton-Cardwell
USDA ARS, Electron and Confocal Microscopy Unit

Flat mite photos are from Beth Grafton-Cardwell and from the USDA ARS.
The USDA photo was used in the following article, “Identifying Mites That Spread Citrus Leprosis”:
https://agresearchmag.ars.usda.gov/20...

Information on identifying Flat Mites can be found here:
https://idtools.org/id/mites/flatmite...

Cotton aphid (aphis gossypii) photos are also public domain photos from Scot Nelson, University of Hawaii:
https://flic.kr/p/9Ei3Xc
https://flic.kr/p/eFGQoh

Some brown citrus aphid photos are also public domain photos from Scot Nelson:
https://flic.kr/p/eFAJyn
https://flic.kr/p/eFAJUT
https://flic.kr/p/fAmftZ

The Glassy Winged Sharpshooter photo is a public domain photo from Alex Wild, taken as part of the insects Unlocked project at the University of Texas at Austin:
https://flic.kr/p/qNVvv3

Potato leafhopper, Empoasca fabae photo is from by Jack Kelly Clark, UC Statewide IPM program:
http://ipm.ucanr.edu/PMG/E/I-HO-EFAB-...

Citrus Leaf Blotch Virus:
Leaf symptom photos are from Georgios Vidalakis.
Bud union disorder photos are from Grant Chambers, NSW Department of Primary Industries.

References:
_Compendium of Citrus Diseases, Second Edition_, The American Phytopathological Society (APS):
https://apsjournals.apsnet.org/doi/10...
http://ipm.ucanr.edu/PMG/selectnewpes...
https://cisr.ucr.edu/brown_citrus_aph...
https://idtools.org/id/citrus/pests/f...
https://www.ars.usda.gov/ARSUserFiles...
https://ucanr.edu/blogs/blogcore/post...
http://iocv.org is also a great resource with information on these diseases.