Cercosporella rubi

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Cercosporella rubi
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Fungi
Division: Ascomycota
Class: Dothideomycetes
Order: Capnodiales
Family: Mycosphaerellaceae
Genus: Cercosporella
Species:
C. rubi
Binomial name
Cercosporella rubi
(G. Winter) Plakidas, (1937)
Synonyms

Fusisporium rubiG. Winter, (1885)
Ramularia rubi(G. Winter) Wollenw., (1916)

Contents

Cercosporella rubi is a plant pathogenic fungus which causes blackberry rosette, [1] a disease that is also known as double blossom [2] or witches' broom [3] of blackberry. In infected plants, the symptoms that C. rubi causes are double blossoms as well as witches' brooms. [1] [4] Diseased canes do not produce fruit, and as a result, this pathogen poses one of the largest threats to commercial blackberry production. [1] [2] [5] The disease is most prevalent in the southeast United States. [6] [1] [5]

Hosts and Range

The hosts of C. rubi are limited to the genus Rubus, which encompasses blackberries (both erect and trailing varieties), raspberries, dewberries, and boysenberries. [1] Blackberries are the most common host of this disease, though it's possible for boysenberries to serve as hosts as well. [1] Blackberry cultivars with thorns are much more susceptible to rosette than thornless varieties. [1] [4] [7] [8]

In the United States, rosette disease of blackberry is commonly found in the southeast parts of the country encompassed by New Jersey, Illinois, and Texas. [1] The disease spreads to new areas through infected nursery stock or the dispersion of wind borne spores. [8]

Life Cycle

The life cycle of C. rubi follows the biennial life cycle of blackberry canes. [1] The first-year non-flowering canes, known as primocanes, are infected by conidia that are dispersed by C. rubi fruiting bodies. [1] These fungal bodies lie within the infected flowers of second-year canes, which are known as floricanes. [1] C. rubi overwinters within axillary buds of the primocanes until the springtime when they become floricanes and flower. [1] At this stage, conidia are released, they infect new primocanes, and the cycle begins anew. [6]

Control

Preventative Control

The most reliable way to control C. rubi and prevent the spread of rosette disease is to use disease-free planting stock and plant resistant cultivars. [1] Root stocks or cutting from roots can be used, as the disease is not systemic. [9] The spread of C. rubi can also be mitigated by removing wild blackberries or dewberries from an area prior to planting crop blackberries. [8] [1] This is because these wild plants can also serve as hosts for C. rubi, and if left alone will grow vigorously and spread the disease to cultivated blackberry plants in the area.

Sanitation & Pruning

Low to Moderate Infections

Plants with low to moderate levels of C. rubi infection should be pruned to remove infected biomass. [1] [7] Diseased canes can be identified by the presence of witches' brooms or elongated flower buds that are a deeper pink color than healthy flowers. [8] Ideally, the biomass should be removed before the blossoms open to prevent further spread of the fungus. [1] [9] Once removed, the infected biomass should be destroyed with a controlled burn to prevent the spread of the fungus post-pruning.

Severe Infections

In the case of severely infected plants, one can cut both the primocanes and floricanes down to the ground immediately after harvest. [1] [10] This removes infected tissue and fungal bodies. This practice works best for blackberry varieties that grow vigorously as opposed to those that are slower growing, as it heavily reduces fruit production.

Fungicides

Fungicides in the strobilurin group, such as pyraclostrobin or azoxystrobin, as well as those in the anilinopyrimidine group can control C. rubi. [1] For fungicides to work properly, they must be applied when infected flowers are open. Therefore, they should be applied from the time when buds start to swell up until all flowers are spent. [1] [7]

Related Research Articles

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<i>Peronospora sparsa</i> Species of single-celled organism

Peronospora sparsa is an oomycete plant pathogen that causes downy mildew in berry producing plants; especially in the genus's Rubus and Rosa. Downy mildew plant pathogens are often host specific and cause problems in cloudberries, blackberries, boysenberries, strawberries, and arctic bramble. Since they are host specific, Peronospora sparsa will not cause downy mildew in grapes because a different plant pathogen causes downy mildew in grapes; Plasmopara viticola. Although it depends on the cultivar, symptoms do not normally start until later stages of disease and can look different on different plants. The most common symptoms include red lesions in the veins of leaves, with dry and deformed berries.

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Oidium mangiferae is a plant pathogen that infects mango trees causing powdery mildew. Powdery mildew of mango is an Ascomycete pathogen of the Erysiphales family that was initially described by Berthet in 1914, using samples collected from Brazil. O. mangiferae is found in all areas where mangoes have been raised long term, but is particularly widespread in India where both the host and the pathogen are native. Currently no teleomorph stage has been identified, but due to certain morphological characteristics it has been suggested that O. mangiferae belongs in the Erysiphe polygony group. Mango is the only known host for this pathogen, though O. mangiferae appears to be identical to fungi responsible for powdery mildew diseases on various other plant species, particularly oak, though some differences may be observed. In particular, the number of cells in conidiophores varies from 2 on mango to 3-5 on oak. O. mangiferae has been known to infect oak leaves in the laboratory, however due to the lack of a known teleomorph stage O. mangiferae is still considered to only be a pathogen of mango. Recent analysis of its ribosomal DNA suggests it is conspecific with Erysiphe alphitoides, the causative agent of powdery mildew in European oaks.

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References

  1. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 R. R. Martin; Michael A. Ellis; Brian Williamson; Roger N. Williams (2017). Compendium of raspberry and blackberry diseases and pests (2nd ed.). St. Paul, Minnesota. ISBN   978-0-89054-572-0. OCLC   1104852400.{{cite book}}: CS1 maint: location missing publisher (link)
  2. 1 2 Fernandez, Gina; Ballington, James. "Growing blackberries in North Carolina". North Carolina Cooperative Extension Service & North Carolina University Press. p. 1. Archived from the original on 8 January 2016. Retrieved 9 October 2015.
  3. "Blackberry, Dewberry, and Boysenberry". Texas Plant Disease Handbook. Texas A&M AgriLife Extension. Retrieved 9 October 2015.
  4. 1 2 Smith, Barbara J. (March 29, 2023). "ROSETTE (DOUBLE BLOSSOM) OF BLACKBERRY" . Retrieved March 29, 2023.
  5. 1 2 Lyman, MR; Curry KJ; Smith BJ; Diehl SV (2004). "Effect of Cercosporella rubi on Blackberry Floral Bud Development". Plant Disease. 88 (2). APS: 195–204. doi: 10.1094/PDIS.2004.88.2.195 . PMID   30812428.
  6. 1 2 Andersen, Peter (June 2020). "The Blackberry". askifas. Retrieved 3 May 2024.
  7. 1 2 3 Ivey, Melanie Lewis. "Blackberry Rosette: Cercosporella rubi" (PDF). Disease Identification and Management Series. Louisiana Plant Pathology. Retrieved 2023-03-16.
  8. 1 2 3 4 Stanton, Michele; Ward Gauthier, Nicole (December 2017). "Plant Pathology Fact Sheet: Blackberry Rosette (Double Blossom)" (PDF). University of Kentucky Plant Pathology Department. Retrieved 3 May 2024.
  9. 1 2 Lewis Ivey, Melanie (March 2016). "Louisiana Plant Pathology Disease Identification and Management Series Blackberry Rosette" (PDF). LSU AgCenter. Retrieved 3 May 2024.
  10. Smith, Sherrie (18 August 2014). "Arkansas Plant Health Clinic Newsletter" (PDF). U of A Division of Agriculture Research & Extension. Retrieved 3 May 2024.