colletotrichum-fioriniae-development-water-chloroform-based-blueberry

<em>Colletotrichum fioriniae</em> Development in Water and Chloroform-based Blueberry and Cranberry Floral Extracts

To accurately monitor the phenology of the bloom period and the temporal dynamics of floral chemical cues on fungal fruit rotting pathogens, floral ...

Rutgers University

Blueberry anthracnose, caused by Colletotrichum fioriniae, is a pre- and postharvest disease of cultivated highbush blueberry (Vaccinium corymbosum). During disease development, the pathogen undergoes several lifestyle changes during host colonization, including epiphytic, quiescent, and necrotrophic phases. It is not clear, however, what if any host signals alter the pattern of colonization during the initial epiphytic phase and infection. This research investigated the role of blueberry floral extracts (FE) on fungal development. Results show that FE significantly increased both the quantity and rate of secondary conidiation and appressorial formation in vitro, suggesting that floral components could decrease the minimum time required for infection. Activity of FE was readily detected in water collected from field samples, where secondary conidiation and appressorial formation decreased as rainwater collections were further removed from flowers. A comparison of FE from four blueberry cultivars with different levels of field susceptibility revealed that appressorial formation but not secondary conidiation significantly increased with the FE from susceptible cultivars versus resistant cultivars. Inoculum supplemented with FE produced higher levels of disease on ripe blueberry fruit as compared with inoculum with water only. Flowers from other ericaceous species were found to also induce secondary conidiation and appressorial formation of C. fioriniae. This research provides strong evidence that flowers can contribute substantially to the infection process of C. fioriniae, signifying the importance of the bloom period for developing effective disease management strategies.

Evidence that Blueberry Floral Extracts Influence Secondary Conidiation and Appressorial Formation of Colletotrichum fioriniae.

Fairy ring is a disease of cultivated cranberry common in the eastern growing regions of the United States, especially New Jersey and Massachusetts. Rings may persist for many years, and current control recommendations are costly and largely ineffective. The goal of this study was to accurately assess the impact of this disease on cranberry, a long-lived, high-value, perennial crop. The rate of fairy ring expansion, rate of formation of new rings, and distribution of rings across three cultivars were determined using a geographical information system (GIS) database that incorporated aerial and satellite imagery. Ring growth rates, estimated from imagery collected over a 10-year period in cv. Ben Lear, averaged 0.455 m in radius per year. Rings were observed in 'Ben Lear' three times more frequently than in either 'Early Black' or 'Stevens' cultivars. Direct sampling showed that estimates for yield within rings were 22 to 68% less than unaffected areas of the field for cv. Ben Lear. These estimates included the effects of fruit rot, which was elevated within rings to 18 to 29% of the total harvest. The impact on yield of 'Stevens' and 'Early Black' was lower than in 'Ben Lear'. Most cranberry cultivars are clonal and variation in fruit morphology within rings, particularly in 'Ben Lear', prompted an analysis of vine genotype. Areas affected by fairy ring in 'Ben Lear' showed an increase in genetic diversity at least 0.4 to 4 times that of unaffected areas. Therefore, it appears that fairy ring not only directly reduces yield but also can increase the host genetic diversity. This likely is due to increased seedling establishment resulting from seed drop when fruit decompose. Because seedlings typically yield less than the parental cultivar, the increase in genetic diversity also may contribute to long-term reduction of productivity in a cranberry field.

Fairy Ring Disease of Cranberry: Assessment of Crop Losses and Impact on Cultivar Genotype.

Monilinia vaccinii-corymbosi, the causal agent of mummy berry disease, infects blueberry flowers via the gynoecial pathway. To describe the expression of host resistance in highbush blueberry (Vaccinium corymbosum), fungal growth in the styles and colonization of the locules were compared among five blueberry cultivars in a series of controlled greenhouse experiments. Styles were harvested 1 and 4 days postinoculation, and the length colonized by hyphae was determined using fluorescence microscopy. At 8 weeks after inoculation, fruit were harvested and scored for the presence of hyphae in the locules. The infection frequency of styles ranged from 0.33 to 0.71, and only cv. Weymouth had significantly lower infection frequency than the other cultivars. The mean length of the colonized portion of the stylar canal ranged from 0.126 to 0.434 mm after 1 day and 1.62 to 3.59 mm after 4 days. Hyphae in the styles of cv. Weymouth exhibited the least growth, whereas hyphae in the styles of cultivars Jersey and Rancocas were significantly longer. The distance of style penetrated for cultivars Bluecrop and Coville was intermediate. The mean disease incidence of locules differed significantly. Values for cultivars Weymouth and Jersey were the smallest (0.038 and 0.039) and largest (0.249 and 0.236), respectively. The results demonstrate that a component of resistance to infection by M. vaccinii-corymbosi is expressed during growth in the gynoecial pathway.

Article	Year
Evidence that Blueberry Floral Extracts Influence Secondary Conidiation and Appressorial Formation of Colletotrichum fioriniae. Phytopathology\| PubMed ID: 29264959	2018
Fairy Ring Disease of Cranberry: Assessment of Crop Losses and Impact on Cultivar Genotype. Plant disease\| PubMed ID: 30769638	2008
Host Resistance to Monilinia vaccinii-corymbosi in Flowers and Fruits of Highbush Blueberry. Plant disease\| PubMed ID: 30780396	2007

Peter V. Oudemans

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