July 2022 - 20

PLANT HEALTH
Bacteria
&
Pathogens have been busy this spring in
greenhouses. 'Oh my, what a year!' writes
Margery Daughtrey of Cornell University's
Long Island Horticultural Research &
Extension Center.
BY MARGERY DAUGHTREY
P
athogens had a field day in spring 2022, while we made trips to
the dumpster.
The big problems this year required that plants be discarded, not
treated. We just do not have highly effective preventive treatments for
bacteria and viruses: we need reliable clean stock production.
GERANIUM AFFLICTIONS
Bacterial blight of geraniums (Xanthomonas hortorum pv. pelargonii), a
common plague in the 20th century, had of late become a distant, distasteful
memory. Important threats like Western flower thrips and Ralstonia
solanacearum have been the nightmares of the new century. After troubles in
2003-2004 with Ralstonia solanacearum Race 3 Biovar 2 (RsR3Bv2, a USDA
Select Agent subject to a quarantine order) were so disastrous, stringent
guidelines were put into place for geranium cutting production, so it became
a much safer crop to grow. In 2020, for the first time in a long while,
RsR3Bv2 snuck into the U.S. on a few cultivars, but there was no return of
the contagion in the next year.
But this year, our old nemesis Xanthomonas struck again! Our
diagnostic lab alone handled over a hundred samples. Although not as
20 JULY 2022 GPNMAG.COM
Bacterial blight on geranium -
chlorosis and leaf spots and
necrotic wedges
(Photos: Margery
Daughtrey)
Viruses

http://www.GPNMAG.COM

July 2022

Table of Contents for the Digital Edition of July 2022

July 2022 - 1
July 2022 - 2
July 2022 - 3
July 2022 - 4
July 2022 - 5
July 2022 - 6
July 2022 - 7
July 2022 - 8
July 2022 - 9
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July 2022 - 30
July 2022 - 31
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July 2022 - 34
July 2022 - 35
July 2022 - 36
July 2022 - 37
July 2022 - 38
July 2022 - 39
July 2022 - 40
July 2022 - 41
July 2022 - 42
July 2022 - 43
July 2022 - 44
July 2022 - 45
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July 2022 - 47
July 2022 - 48
July 2022 - 49
July 2022 - 50
July 2022 - 51
July 2022 - 52
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https://www.nxtbook.com/greatamericanmediaservices/GPN/october-2024
https://www.nxtbook.com/greatamericanmediaservices/GPN/new-varieties-digital-guide-2025
https://www.nxtbook.com/greatamericanmediaservices/GPN/september-2024
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https://www.nxtbook.com/greatamericanmediaservices/GPN/january-2024
https://www.nxtbook.com/greatamericanmediaservices/GPN/2024-guide-to-cannabis-production
https://www.nxtbook.com/greatamericanmediaservices/GPN/november-december-2023
https://www.nxtbook.com/greatamericanmediaservices/GPN/october-2023
https://www.nxtbook.com/greatamericanmediaservices/GPN/new-varieties-digital-guide-2024
https://www.nxtbook.com/greatamericanmediaservices/GPN/september-2023
https://www.nxtbook.com/greatamericanmediaservices/GPN/august-2023
https://www.nxtbook.com/greatamericanmediaservices/GPN/july-2023
https://www.nxtbook.com/greatamericanmediaservices/GPN/big-grower-july-2023
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https://www.nxtbook.com/greatamericanmediaservices/GPN/april-2023
https://www.nxtbook.com/greatamericanmediaservices/GPN/big-grower-april-2023
https://www.nxtbook.com/greatamericanmediaservices/GPN/2023-guide-to-hemp-production
https://www.nxtbook.com/greatamericanmediaservices/GPN/march-2023
https://www.nxtbook.com/greatamericanmediaservices/GPN/february-2023
https://www.nxtbook.com/greatamericanmediaservices/GPN/big-grower-january-2023
https://www.nxtbook.com/greatamericanmediaservices/GPN/january-2023
https://www.nxtbook.com/greatamericanmediaservices/GPN/2023-guide-to-cannabis-production
https://www.nxtbook.com/greatamericanmediaservices/GPN/november-december-2022
https://www.nxtbook.com/greatamericanmediaservices/GPN/big-grower-october-2022
https://www.nxtbook.com/greatamericanmediaservices/GPN/october-2022
https://www.nxtbook.com/greatamericanmediaservices/GPN/gpn-new-varieties-digital-guide-2023
https://www.nxtbook.com/greatamericanmediaservices/GPN/september-2022
https://www.nxtbook.com/greatamericanmediaservices/GPN/august-2022
https://www.nxtbook.com/greatamericanmediaservices/GPN/big-grower-july-2022
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https://www.nxtbook.com/greatamericanmediaservices/GPN/big-grower-april-2022
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https://www.nxtbook.com/greatamericanmediaservices/GPN/march-2022
https://www.nxtbook.com/greatamericanmediaservices/GPN/february-2022
https://www.nxtbook.com/greatamericanmediaservices/GPN/cannabisguide-2022
https://www.nxtbook.com/greatamericanmediaservices/GPN/hempguide-2022
https://www.nxtbook.com/greatamericanmediaservices/GPN/newvarieties-2022
https://www.nxtbook.com/greatamericanmediaservices/GPN/big-grower-january-2022
https://www.nxtbook.com/greatamericanmediaservices/GPN/january-2022
https://www.nxtbook.com/greatamericanmediaservices/GPN/december-2021
https://www.nxtbook.com/greatamericanmediaservices/GPN/big-grower-november-2021
https://www.nxtbook.com/greatamericanmediaservices/GPN/november-2021
https://www.nxtbook.com/greatamericanmediaservices/GPN/october-2021
https://www.nxtbook.com/greatamericanmediaservices/GPN/big-grower-september-2021
https://www.nxtbook.com/greatamericanmediaservices/GPN/september-2021
https://www.nxtbook.com/greatamericanmediaservices/GPN/august-2021
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https://www.nxtbook.com/greatamericanmediaservices/GPN/february-2021
https://www.nxtbook.com/greatamericanmediaservices/GPN/cannabisguide-2021
https://www.nxtbook.com/greatamericanmediaservices/GPN/hempguide-2021
https://www.nxtbook.com/greatamericanmediaservices/GPN/newvarieties-2021
https://www.nxtbook.com/greatamericanmediaservices/GPN/big-grower-january-2021
https://www.nxtbook.com/greatamericanmediaservices/GPN/january-2021
https://www.nxtbook.com/greatamericanmediaservices/GPN/december-2020
https://www.nxtbook.com/greatamericanmediaservices/GPN/big-grower-november-2020
https://www.nxtbook.com/greatamericanmediaservices/GPN/november-2020
https://www.nxtbook.com/greatamericanmediaservices/GPN/october-2020
https://www.nxtbook.com/greatamericanmediaservices/GPN/big-grower-september-2020
https://www.nxtbook.com/greatamericanmediaservices/GPN/september-2020
https://www.nxtbook.com/greatamericanmediaservices/GPN/august-2020
https://www.nxtbook.com/greatamericanmediaservices/GPN/big-grower-july-2020
https://www.nxtbook.com/greatamericanmediaservices/GPN/july-2020
https://www.nxtbook.com/greatamericanmediaservices/GPN/june-2020
https://www.nxtbook.com/greatamericanmediaservices/GPN/may-2020
https://www.nxtbook.com/greatamericanmediaservices/GPN/april-2020
https://www.nxtbook.com/greatamericanmediaservices/GPN/californiaspringtrials-2020
https://www.nxtbook.com/greatamericanmediaservices/GPN/big-grower-march-2020
https://www.nxtbook.com/greatamericanmediaservices/GPN/march-2020
https://www.nxtbook.com/greatamericanmediaservices/GPN/february-2020
https://www.nxtbook.com/greatamericanmediaservices/GPN/cannabisguide-2020
https://www.nxtbook.com/greatamericanmediaservices/GPN/hempguide-2020
https://www.nxtbook.com/greatamericanmediaservices/GPN/big-grower-january-2020
https://www.nxtbook.com/greatamericanmediaservices/GPN/january-2020
https://www.nxtbook.com/greatamericanmediaservices/GPN/december-2019
https://www.nxtbook.com/greatamericanmediaservices/GPN/big-grower-november-2019
https://www.nxtbook.com/greatamericanmediaservices/GPN/november-2019
https://www.nxtbook.com/greatamericanmediaservices/GPN/october-2019
https://www.nxtbook.com/greatamericanmediaservices/GPN/big-grower-september-2019
https://www.nxtbook.com/greatamericanmediaservices/GPN/september-2019
https://www.nxtbook.com/greatamericanmediaservices/GPN/august-2019
https://www.nxtbook.com/greatamericanmediaservices/GPN/big-grower-july-2019
https://www.nxtbook.com/greatamericanmediaservices/GPN/july-2019
https://www.nxtbook.com/greatamericanmediaservices/GPN/june-2019
https://www.nxtbook.com/greatamericanmediaservices/GPN/may-2019
https://www.nxtbook.com/greatamericanmediaservices/GPN/april-2019
https://www.nxtbook.com/greatamericanmediaservices/GPN/californiaspringtrials-2019
https://www.nxtbook.com/greatamericanmediaservices/GPN/big-grower-march-2019
https://www.nxtbook.com/greatamericanmediaservices/GPN/march-2019
https://www.nxtbook.com/greatamericanmediaservices/GPN/february-2019
https://www.nxtbook.com/greatamericanmediaservices/GPN/undercontrol-2019
https://www.nxtbook.com/greatamericanmediaservices/GPN/big-grower-january-2019
https://www.nxtbook.com/greatamericanmediaservices/GPN/january-2019
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