Citrus psorosis virus Citrus scaly bark

11/11/2021 Comments from
Georgios Vidalakis, Ph.D.
Professor & UC Extension Specialist in Plant Pathology
Director, Citrus Clonal Protection Program (CCPP)
Presidential Researcher, CRB & UC ANR Endowment for Sustainable Citrus Clonal Protection

My thanks to the team for giving me the opportunity to review this. Very nicely done! Bravo!
Attached a few minor comments and thoughts for your consideration. Two different PDF formats are attached for your convenience.
If you need anything more from me just let me know.
All the best, Georgios

Summary of Comments on Citrus psorosis virus
Page: 1
Number: 1 Author: Reviewer Subject: Comment on Text Date: 11/11/2021 7:34:09 AM
if you want to pay tribute to our own Dr. Fawcett the original 1930’s references are:
-Fawcett, H. S. 1933. New symptoms of psorosis indicating a virus disease of citrus. Phytopathdogy 23: 930 (abstr.).
-Fawcett, H. S. 1934. Is psorosis of citrus a virus disease? Phytopathology 24: 659-668.
Number: 2 Author: Reviewer Subject: Comment on Text Date: 11/11/2021 7:36:58 AM
I thought that “certification” means something very specific “legally/regulatorily” and at least here in CA we do not have a “certification” program
we have a “registration” or “testing program”, correct?
I think it is OK to leave it as “budwood testing program” but your are the experts.
Number: 3 Author: Reviewer Subject: Comment on Text Date: 11/11/2021 7:20:26 AM
The reference I use for this one is the citrus industry book chapter by Calavan writing about the “The Psorosis (Interim) Program (1937-1973)”.
-Calavan CE, Mather SM, McEachern EH (1978) Registration, certification, and indexing of citrus trees. In: Reuther W, Calavan CE, Carman GE,
editors. The citrus industry Vol IV Crop protection. Berkeley: University of California, Division of Agricultural Sciences. pp. 185-222.
Number: 4 Author: Reviewer Subject: Comment on Text Date: 11/11/2021 7:27:52 AM
Another very nice Ps review from Roistacher is here if you want to use it. It could have a use below in transmission section.
-Roistacher, C. N. (1993). Psorosis — A Review. International Organization of Citrus Virologists Conference Proceedings (1957-2010), 12(12).
http://dx.doi.org/10.5070/C555b675jm Retrieved from https://escholarship.org/uc/item/55b675jm
Page: 3
Number: 1 Author: Reviewer Subject: Comment on Text Date: 11/11/2021 7:10:31 AM
As above
Number: 2 Author: Reviewer Subject: Comment on Text Date: 11/11/2021 7:27:25 AM
Similarly to seed, per Roistacher’s 1993 review the Ps virus is also “pollen borne” but not transmissible.
Use if you see fit.
“However, Navarro (personal communication) observed transmission of psorosis-A when pollen taken from flowers of psorosis-A infected trees
was placed under the bark of indicator seedlings. There is no experimental
evidence that psorosis can be transmitted via pollination of flowers and through the seed.”
—————————-
Roistacher, C. N. (1993). Psorosis — A Review. International Organization of Citrus Virologists Conference Proceedings (1957-2010), 12(12). http://
dx.doi.org/10.5070/C555b675jm Retrieved from https://escholarship.org/uc/item/55b675jm
Number: 3 Author: Reviewer Subject: Comment on Text Date: 11/11/2021 6:09:02 AM
Greece as well-If you need reference is
Kyriakopoulou, P. E. (2002). Virus and Virus-like Diseases of Citrus in Greece and the Greek Certification Program. International Organization of
Citrus Virologists Conference Proceedings (1957-2010), 15(15). http://dx.doi.org/10.5070/C52tp05430 Retrieved from https://escholarship.org/uc/
item/2tp05430
Page: 4
Number: 1 Author: Reviewer Subject: Comment on Text Date: 11/11/2021 6:59:20 AM
What do we mean by that?
FYI use as you think is appropriate.
At the CCPP we have interspersing Ps every now and then/here and there:
1. At the nursery testing program we had 1-2 Ps positive trees in 1999-00, 2000-01, 2005-06, 2006-07, 2008-09, 2009-10, 20014-15, 2015-16 &
2019-20
2. In 2018, at the CA survey CA-1a outside the HLB Q zone and orchards (1080 trees), we found 2 Ps (+)
3. In 2018, at the CA survey CA-1b inside the HLB Q zone urban (89 trees) we found 2 Ps (+)
4. I do not see in our recent varieties introductions any Ps interceptions but historically the CCPP has been intercepting Ps in new introductions
from around the world
Number: 2 Author: Reviewer Subject: Comment on Text Date: 11/11/2021 6:52:47 AM
The virus has been mechanically transmitted in Chenopodium indicators.
Theoretically it could established in weeds/native plants.
Is that a factor you need to consider?
I do not think it is critical, just asking the question.
Number: 3 Author: Reviewer Subject: Comment on Text Date: 11/11/2021 6:55:25 AM
As above,
maybe better “pathogen-tested budwood” or “pathogen testing citrus programs”
For this sentence maybe better
“Modern citrus germplasm programs can detect and eliminate ….”

Page: 5
Number: 1 Author: Reviewer Subject: Comment on Text Date: 11/11/2021 6:58:34 AM
See numbers of findings in earlier comment.
If compatible with term/definition of “eradicated” good.
If not consider alternatives
maybe
“practically eliminated” or other appropriate term per your “official” definitions.
Page: 6
Number: 1 Author: Reviewer Subject: Comment on Text Date: 11/11/2021 7:02:30 AM
See comment above about finds at the CDFA nursery pest cleanliness program change statement if needed.

Reply to Comments:
Thank you Dr. Vidalakis for your helpful comments. I appreciate your deep knowledge of the literature and history of this disease in California as it far exceeds my own.

From Page 1 – I have added the references for Drs. Fawcett, Calavan and Roistacher. I changed the word from “certification” to ” budwood testing” in all locations.
From Page 2- I added information about pollen transmission with the reference from Roistacher and the country of Greece to the world wide distribution list with the publication from Kyriakopoulou.
From Page 4 – the word “interceptions” in this context means what we have detected at the border. I added the information of your detections in the CCPP program to the post-entry distribution. This was very helpful.
I did not add to the host range as usually it is limited to hosts that are naturally infected.
Page 5 – I changed eradicated to practically eliminated
Page 6 – I added finds in the nursery program to the Post-Entry distribution and Survey Information
-Heather Scheck, Primary State Plant Pathologist, CDFA
11/15/2021

One thought on “Citrus psorosis virus Citrus scaly bark”

Heather Scheck says:

November 15, 2021 at 2:25 pm

11/11/2021 Comments from
Georgios Vidalakis, Ph.D.
Professor & UC Extension Specialist in Plant Pathology
Director, Citrus Clonal Protection Program (CCPP)
Presidential Researcher, CRB & UC ANR Endowment for Sustainable Citrus Clonal Protection

My thanks to the team for giving me the opportunity to review this. Very nicely done! Bravo!
Attached a few minor comments and thoughts for your consideration. Two different PDF formats are attached for your convenience.
If you need anything more from me just let me know.
All the best, Georgios

Summary of Comments on Citrus psorosis virus
Page: 1
Number: 1 Author: Reviewer Subject: Comment on Text Date: 11/11/2021 7:34:09 AM
if you want to pay tribute to our own Dr. Fawcett the original 1930’s references are:
-Fawcett, H. S. 1933. New symptoms of psorosis indicating a virus disease of citrus. Phytopathdogy 23: 930 (abstr.).
-Fawcett, H. S. 1934. Is psorosis of citrus a virus disease? Phytopathology 24: 659-668.
Number: 2 Author: Reviewer Subject: Comment on Text Date: 11/11/2021 7:36:58 AM
I thought that “certification” means something very specific “legally/regulatorily” and at least here in CA we do not have a “certification” program
we have a “registration” or “testing program”, correct?
I think it is OK to leave it as “budwood testing program” but your are the experts.
Number: 3 Author: Reviewer Subject: Comment on Text Date: 11/11/2021 7:20:26 AM
The reference I use for this one is the citrus industry book chapter by Calavan writing about the “The Psorosis (Interim) Program (1937-1973)”.
-Calavan CE, Mather SM, McEachern EH (1978) Registration, certification, and indexing of citrus trees. In: Reuther W, Calavan CE, Carman GE,
editors. The citrus industry Vol IV Crop protection. Berkeley: University of California, Division of Agricultural Sciences. pp. 185-222.
Number: 4 Author: Reviewer Subject: Comment on Text Date: 11/11/2021 7:27:52 AM
Another very nice Ps review from Roistacher is here if you want to use it. It could have a use below in transmission section.
-Roistacher, C. N. (1993). Psorosis — A Review. International Organization of Citrus Virologists Conference Proceedings (1957-2010), 12(12).
http://dx.doi.org/10.5070/C555b675jm Retrieved from https://escholarship.org/uc/item/55b675jm
Page: 3
Number: 1 Author: Reviewer Subject: Comment on Text Date: 11/11/2021 7:10:31 AM
As above
Number: 2 Author: Reviewer Subject: Comment on Text Date: 11/11/2021 7:27:25 AM
Similarly to seed, per Roistacher’s 1993 review the Ps virus is also “pollen borne” but not transmissible.
Use if you see fit.
“However, Navarro (personal communication) observed transmission of psorosis-A when pollen taken from flowers of psorosis-A infected trees
was placed under the bark of indicator seedlings. There is no experimental
evidence that psorosis can be transmitted via pollination of flowers and through the seed.”
—————————-
Roistacher, C. N. (1993). Psorosis — A Review. International Organization of Citrus Virologists Conference Proceedings (1957-2010), 12(12). http://
dx.doi.org/10.5070/C555b675jm Retrieved from https://escholarship.org/uc/item/55b675jm
Number: 3 Author: Reviewer Subject: Comment on Text Date: 11/11/2021 6:09:02 AM
Greece as well-If you need reference is
Kyriakopoulou, P. E. (2002). Virus and Virus-like Diseases of Citrus in Greece and the Greek Certification Program. International Organization of
Citrus Virologists Conference Proceedings (1957-2010), 15(15). http://dx.doi.org/10.5070/C52tp05430 Retrieved from https://escholarship.org/uc/
item/2tp05430
Page: 4
Number: 1 Author: Reviewer Subject: Comment on Text Date: 11/11/2021 6:59:20 AM
What do we mean by that?
FYI use as you think is appropriate.
At the CCPP we have interspersing Ps every now and then/here and there:
1. At the nursery testing program we had 1-2 Ps positive trees in 1999-00, 2000-01, 2005-06, 2006-07, 2008-09, 2009-10, 20014-15, 2015-16 &
2019-20
2. In 2018, at the CA survey CA-1a outside the HLB Q zone and orchards (1080 trees), we found 2 Ps (+)
3. In 2018, at the CA survey CA-1b inside the HLB Q zone urban (89 trees) we found 2 Ps (+)
4. I do not see in our recent varieties introductions any Ps interceptions but historically the CCPP has been intercepting Ps in new introductions
from around the world
Number: 2 Author: Reviewer Subject: Comment on Text Date: 11/11/2021 6:52:47 AM
The virus has been mechanically transmitted in Chenopodium indicators.
Theoretically it could established in weeds/native plants.
Is that a factor you need to consider?
I do not think it is critical, just asking the question.
Number: 3 Author: Reviewer Subject: Comment on Text Date: 11/11/2021 6:55:25 AM
As above,
maybe better “pathogen-tested budwood” or “pathogen testing citrus programs”
For this sentence maybe better
“Modern citrus germplasm programs can detect and eliminate ….”

Page: 5
Number: 1 Author: Reviewer Subject: Comment on Text Date: 11/11/2021 6:58:34 AM
See numbers of findings in earlier comment.
If compatible with term/definition of “eradicated” good.
If not consider alternatives
maybe
“practically eliminated” or other appropriate term per your “official” definitions.
Page: 6
Number: 1 Author: Reviewer Subject: Comment on Text Date: 11/11/2021 7:02:30 AM
See comment above about finds at the CDFA nursery pest cleanliness program change statement if needed.

Reply to Comments:
Thank you Dr. Vidalakis for your helpful comments. I appreciate your deep knowledge of the literature and history of this disease in California as it far exceeds my own.

From Page 1 – I have added the references for Drs. Fawcett, Calavan and Roistacher. I changed the word from “certification” to ” budwood testing” in all locations.
From Page 2- I added information about pollen transmission with the reference from Roistacher and the country of Greece to the world wide distribution list with the publication from Kyriakopoulou.
From Page 4 – the word “interceptions” in this context means what we have detected at the border. I added the information of your detections in the CCPP program to the post-entry distribution. This was very helpful.
I did not add to the host range as usually it is limited to hosts that are naturally infected.
Page 5 – I changed eradicated to practically eliminated
Page 6 – I added finds in the nursery program to the Post-Entry distribution and Survey Information
-Heather Scheck, Primary State Plant Pathologist, CDFA
11/15/2021