Abstract
Dieback caused by Colletotrichum spp. is an emerging disease in California citrus groves. A large-scale survey with emphasis on seasonal variations of latent infections was conducted throughout citrus orchards in Fresno, Kern, and Tulare counties in 2019 and 2020. Latent infections on citrus leaves and twigs varied markedly between years. Isolates of Colletotrichum spp. were obtained from asymptomatic tissue, and two groups were formed based on colony and spore morphology. The morphological groups were further identified based on multigene sequence analysis using the DNA regions ITS1-5.8S-ITS2, TUB2, and GAPDH. Results revealed that isolates belong to two phylogenetic species, C. gloeosporioides and C. karstii, being C. karstii more frequently isolated. Representative isolates of each species were further selected and characterized based on the response of physiological variables to temperature. Both species had similar optimum growth temperatures but differed in maximum growth rates, with C. gloeosporioides exhibiting a greater growth rate than that of C. karstii on media. Pathogenicity tests on citrus trees demonstrated the ability of C. gloeosporioides and C. karstii to cause lesions on twigs and no differences in aggressiveness. A fungicide screening performed in this study determined that the DMI fungicides were the most effective in reducing the mycelial growth of C. gloeosporioides and C. karstii. The QoI fungicides showed a remarkably inhibitory impact on spore germination of both species. On average, C. karstii was more sensitive to the DMI fungicides than C. gloeosporioides. The findings of this study provide new information to understand the Colletotrichum dieback of citrus.
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Claims 11
Claim · model-written summary
Latent citrus infections varied markedly between years.
- Organ / stage
- leaves and twigse0
- Outcome
- Latent infectionse0
- Direction
- varied markedlye0
- Comparator
- between yearse0
CitrusOrganisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Latent infections on citrus leaves and twigs varied markedly between years.”
Claim · model-written summary
Citrus isolates belonged to C. gloeosporioides.
- Interactor
- C. gloeosporioides
Colletotrichum gloeosporioidese0pathogen - Outcome
- isolates belong to two phylogenetic speciese0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Results revealed that isolates belong to two phylogenetic species, C. gloeosporioides and C. karstii, being C. karstii more frequently isolated.”
t0“Citrus”
Claim · model-written summary
C. karstii was identified and isolated more frequently than C. gloeosporioides.
- Interactor
- C. karstiie0pathogen
- Outcome
- C. karstii more frequently isolatede0
- Direction
- more frequentlye0
- Comparator
- C. gloeosporioidese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Results revealed that isolates belong to two phylogenetic species, C. gloeosporioides and C. karstii, being C. karstii more frequently isolated.”
t0“Citrus”
Claim · model-written summary
The two Colletotrichum species had similar optimal growth temperatures.
- Interactor
- C. gloeosporioidesColletotrichum gloeosporioidese0pathogen
- Second interactor
- C. karstiie0pathogen
- Outcome
- optimum growth temperaturese0
- Direction
- similare0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Both species had similar optimum growth temperatures but differed in maximum growth rates, with C. gloeosporioides exhibiting a greater growth rate than that of C. karstii on media.”
t0“Citrus”
Claim · model-written summary
C. gloeosporioides grew faster than C. karstii on media.
- Interactor
- C. gloeosporioidesColletotrichum gloeosporioidese0pathogen
- Second interactor
- C. karstiie0pathogen
- Outcome
- growth ratee0
- Direction
- greatere0
- Setting
- on mediae0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Both species had similar optimum growth temperatures but differed in maximum growth rates, with C. gloeosporioides exhibiting a greater growth rate than that of C. karstii on media.”
t0“Citrus”
Claim · model-written summary
C. gloeosporioides caused citrus twig lesions.
- Interactor
- C. gloeosporioidesColletotrichum gloeosporioidese0pathogen
- Outcome
- lesions on twigse0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Pathogenicity tests on citrus trees demonstrated the ability of C. gloeosporioides and C. karstii to cause lesions on twigs and no differences in aggressiveness.”
Claim · model-written summary
C. karstii caused citrus twig lesions.
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Pathogenicity tests on citrus trees demonstrated the ability of C. gloeosporioides and C. karstii to cause lesions on twigs and no differences in aggressiveness.”
Claim · model-written summary
The two species did not differ in aggressiveness on citrus.
- Interactor
- C. gloeosporioidesColletotrichum gloeosporioidese0pathogen
- Second interactor
- C. karstiie0pathogen
- Outcome
- aggressivenesse0
- Direction
- no differencese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Pathogenicity tests on citrus trees demonstrated the ability of C. gloeosporioides and C. karstii to cause lesions on twigs and no differences in aggressiveness.”
Claim · model-written summary
DMI fungicides most effectively reduced mycelial growth of both Colletotrichum species.
- Treatment
- DMI fungicidese0
- Interactor
- C. gloeosporioidesColletotrichum gloeosporioidese0pathogen
- Second interactor
- C. karstiie0pathogen
- Outcome
- mycelial growth of C. gloeosporioides and C. karstiie0
- Direction
- reducinge0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The DMI fungicides were the most effective in reducing the mycelial growth of C. gloeosporioides and C. karstii.”
t0“Citrus”
Claim · model-written summary
QoI fungicides inhibited spore germination of both species.
- Treatment
- QoI fungicidese0
- Interactor
- Colletotrichum
Colletotrichumt0pathogen - Outcome
- spore germination of both speciese0
- Direction
- inhibitorye0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The QoI fungicides showed a remarkably inhibitory impact on spore germination of both species.”
t0“Colletotrichum Isolates Causing Colletotrichum Dieback of Citrus”
Claim · model-written summary
C. karstii was more sensitive to DMI fungicides than C. gloeosporioides.
- Interactor
- C. karstiie0pathogen
- Outcome
- sensitive to the DMI fungicidese0
- Direction
- more sensitivee0
- Comparator
- C. gloeosporioidese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“On average, C. karstii was more sensitive to the DMI fungicides than C. gloeosporioides.”
t0“Citrus”
The same questions in other papers
fungicide · Colletotrichum · CitrusResults agree
1 paper in the same direction as this paper
- positive
fungicide · Colletotrichum gloeosporioides · CitrusResults agree
2 papers in the same direction as this paper
- positive
- positive
Claims are grouped by organism, treatment and what was measured or targeted. A paper counts as positive when any of its claims in the group is positive.