Epidemiology of Botrytis cinerea on Grape: Wound Infection by Dry, Airborne Conidia

Infection of grapes by different densities of airborne conidia of Botrytis cinerea was investigated on table grapes (cultivar Dauphine) harvested ripe (16°Brix) and inoculated fresh, or after SO2 treatment and 8-week storage at -0.5°C. Berries were detached at each inoculation and dusted with dry conidia in a settling tower. Following inoculation, the fresh berries were incubated for 24 h at high relative humidity (≥93%), or were overlaid with wet sterile paper towels. Cold-stored berries were incubated at high relative humidity. The effect of conidial density on surface colonization, penetration, and lesion formation was determined by surface sterilization, isolation, and freezing studies on fresh berries. Only symptom expression was determined on cold-stored berries. Fluorescence microscopy of skin segments showed that conidia were consistently deposited as single cells, and not in pairs or groups, on berry surfaces. Individual conidia, at all densities tested, readily infected the cold-stored berries and formed separate lesions after 2 days. Although the cold-stored berries were highly susceptible, lesion numbers were not related to conidial density at low inoculum dosages (0.67 to 2.60 conidia per mm2 berry surface). Lesion numbers tended to increase exponentially at higher dosages (3.24 to 3.88 conidia per mm2 berry surface). Individual conidia, however, did not induce any disease symptoms on fresh berries. Removal of the pathogen after 24-h incubation from the surface of fresh berries by ethanol, and subsequent incubation of excised skin segments revealed that, irrespective of the conidial density or the wetness regime, less than 2% of skin segments were penetrated. Furthermore, increasing densities of conidia did not lead to higher rates of surface colonization and skin penetration. The low incidence of disease caused on fresh berries and high disease incidence induced after prolonged cold storage indicated that infection was not governed by conidial density on berry surfaces, but by the level of host resistance.

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Wound infection of plum fruit by airborne conidia ofMonilinia laxa

Australasian Plant Pathology ◽

10.1071/ap06042 ◽

2006 ◽

Vol 35 (4) ◽

pp. 435 ◽

Cited By ~ 3

Author(s):

P. H. Fourie ◽

G. Holz

Keyword(s):

Wound Infection ◽

Airborne Conidia

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Horizontal and vertical distribution of airborne conidia of Botrytis cinerea in a gerbera crop grown under glass

Netherlands Journal of Plant Pathology ◽

10.1007/bf01974311 ◽

1993 ◽

Vol 99 (5-6) ◽

pp. 303-311 ◽

Cited By ~ 6

Author(s):

A. Kerssies

Keyword(s):

Vertical Distribution ◽

Botrytis Cinerea ◽

Airborne Conidia ◽

Horizontal And Vertical Distribution

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Injury to currants during mechanical harvesting and subsequent fungal infection

Agricultural and Food Science ◽

10.23986/afsci.72007 ◽

1979 ◽

Vol 51 (1) ◽

pp. 421-431

Author(s):

Risto Tahvonen

Keyword(s):

Fungal Infection ◽

Wound Infection ◽

Botrytis Cinerea ◽

Fungal Species ◽

Significant Damage ◽

Methyl Thiophanate ◽

Alternaria Tenuis ◽

Made In

Mechanical harvesting did not cause significant damage to blackcurrants. Redcurrants suffered extensive injuries, which gave rise to dieback. In addition to mechanical injuries, the pathogen Botrytis cinerea Pers. aggravated bieback of the branches, and severely inhibited healing of the wounds. In wounds on both red- and blackcurrants, the commonest fungus was Alternaria tenuis auct. This fungus did not inhibit healing of the wounds, indeed it appeared to reduce the incidence of B. cinerea wound infection. The wounds contained 19 other fungal species and genera of no pathogenic importance. In a colder-than-average autumn, B. cinerea infection was more severe, and dieback during the subsequent season more extensive than usual. A methyl thiophanate application made in a cold autumn after harvesting reduced the incidence of B. cinerea in wounds, and little dieback resulted the following year. In mild autumns maneb and dichlofluanid reduced dieback, too. When the harvesting was followed by a cold autumn, mechanical harvesting reduced the following year’s yield compared with hand-picking.

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Relationship of Airborne Botrytis cinerea Conidium Concentration to Tomato Flower and Stem Infections: A Threshold for De-leafing Operations

Plant Disease ◽

10.1094/pdis-05-14-0490-re ◽

2015 ◽

Vol 99 (1) ◽

pp. 137-142 ◽

Cited By ~ 10

Author(s):

O. Carisse ◽

H. Van der Heyden

Keyword(s):

Botrytis Cinerea ◽

Gray Mold ◽

Wound Infections ◽

Action Threshold ◽

Airborne Conidia ◽

Infected Wounds ◽

The Mean ◽

Unique Source ◽

Relationship Of ◽

Real Time Qpcr

Gray mold, caused by Botrytis cinerea, is an important threat for tomato greenhouse producers. The influence of airborne conidia concentration (ACC) on both flower and stem-wound infections was studied in a greenhouse maintained at a temperature of 15, 20, or 25°C using diseased tomato leaves as the unique source of dry inoculum. Spore samplers were used to monitor ACC, and a previously developed real-time qPCR assay was used to quantify airborne B. cinerea conidia. The proportion of infected flowers remained low at ACC < 10 conidia/m3; above this concentration, flower infection increased with increasing ACC. The influence of ACC on proportion of infected flowers was well described by a sigmoid model (R2 = 0.90 to 0.92). The mean proportion of infected stem wounds over the three trials was 0.021; no infected wounds were observed at ACC < 100 conidia/m3. Based on logistic regression, the probability that a stem becomes infected increased rapidly with mean probabilities of 0.24 and 0.87 at ACCs of 315 and 3,161 conidia/m3, respectively. The results suggest that the amount of airborne B. cinerea inoculum in the greenhouse is often above the action threshold for flower infection and that monitoring airborne B. cinerea inoculum could help in timing de-leafing operations.

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