Scab-Resist ant Apples for the Northeastern United States: New Prospects and Old Problems

Merwin, Ian A.; Brown, Susan K.; Rosenberger, D. A.; Cooley, Daniel R.; Berkett, L.P.

doi:10.1094/pd-78-0004

Cited by 35 publications

(14 citation statements)

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“…By using DNA markers, it would be possible to screen progeny of appropriate parents for resistance markers. This way, laborious progreny testing for phenotypic, disease resistant behaviour against various pathogen races (sensu Gessler et al [8]) could be avoided [ 16]. The use of two molecular markers bracketing the resistance gene should further improve the reliability of such a selection method [24].…”

Section: Discussionmentioning

confidence: 99%

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DNA markers linked to Malus floribunda 821 scab resistance

et al. 1994

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Breeding resistant apple plants is an alternative way to control fungal pathogens reducing the environmental impact due to the use of pesticides. The breeding of apple cultivars resistant to Venturia inaequalis could be much improved by marker-assisted selection. A molecular marker closely linked to the resistance locus called Vf could replace selection based on infection studies. To find such molecular markers, DNA of progenies from crossings of a resistant and a susceptible apple tree was subject to bulked segregant analysis. Two markers were found with a genetic distance of 10.6% and 19.7% recombination frequency to the Vf locus.

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Section: Discussionmentioning

confidence: 99%

“…Testing such resistances may even be impractical, if by some reason the pathogen to be tested cannot be used in the test location. Breeding programmes also vary in classification of scab-resistant plants, depending on what classes are considered as resistant [ 16].…”

Section: Introductionmentioning

confidence: 99%

DNA markers linked to Malus floribunda 821 scab resistance

et al. 1994

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“…In North America and Europe, SBFS is an increasing threat to profitable apple production due to recent restrictions on the use of highly effective fungicides and the increased hectarage of organic apples (Merwin et al 1994;Williamson and Sutton 2000;Späth and Mayr 2008). The presence of SBFS on the apple surface lowers quality and market value of the fruit because the fungal colonies cause an unacceptable appearance of the fruit to consumers (Williamson and Sutton 2000).…”

mentioning

confidence: 99%

Improving sooty blotch and flyspeck severity estimation on apple fruit with the aid of standard area diagrams

Spolti

Schneider

Sanhueza³

et al. 2010

Eur J Plant Pathol

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Sooty blotch and flyspeck is caused by numerous species of fungi that colonize the surface of apple fruit and thereby lower its market value. Although this disease poses a substantial threat to apple growers' profitability in some regions, reliable and cost-effective methods for epidemiological and disease control studies have not been validated, nor are they widely available. We modified a standard area diagram to aid sooty blotch and flyspeck severity assessments and quantified its impact on accuracy and precision of visual estimates. Samples of 'Fuji' and 'Mutsu' fruit were photographed both from the top and laterally. Severity was assessed from a subsample of 160 images using image analysis software. Validation of the diagram was performed by eight raters who independently assessed severity in two series of selected images representing the lateral view and the top view, initially unaided and subsequently with the aid of the scale. Severity estimates ranged from 0.4% to 98% (most fruit had <10% severity). Accuracy and precision of the estimates were significantly improved when using the diagrammatic scale; concordance correlation coefficient values increased from 0.81 to 0.95. A strong tendency to underestimate severity for the mid-range to high levels was minimized when using the aid, which also improved reproducibility of the estimates among raters. In addition to strengthening evidence that a standard area diagram can be used reliably in sooty blotch and flyspeck studies, we expanded its application to disease assessment in the peduncle region, which enhances the usefulness of the method for evaluating efficacy of management practices.

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“…Cultivars résistant to scab are reputed to hâve low fruit quality, poor storability, low yield, and lack of market acceptance (Crosby et al 1992;MacHardy 1996;Merwin et al 1994). Producers are often hésitant to plant them, especially when they are relatively unknown by consumers (Crosby et al 1992;Korban and Morrisey 1989;Merwin et al 1994).…”

Section: Genetic Controlmentioning

confidence: 99%

“…The actual procé-dure to test for résistance can be problematic also; inoculum distribution may be patchy, environmental conditions between sites are rarely the same, and growth may affect management practices and influence rates of infection (King et al 1998). The release of a new cultivar can take 20 yr after the initial cross and the resulting characteristics are difficult to predict (Gardiner et al 1996;Merwin et al 1994;Shay et al 1953). To compound the breeder's problems, apples are self-incompatible and hâve a relatively long juvénile period (Gianfranceschi et al 1996).…”

Section: Molecular Explorations Of Resistancementioning

confidence: 99%

A review of non-fungicidal approaches for the control of apple scab

Carisse¹,

Dewdney²

2005

phyto

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Apple scab is the single most important disease of apple in Canada and the most costly to control. Failure to control apple scab results in severe yield losses and a reduction in market value of harvested fruits. Currently, the strategy to control apple scab relies on multiple applications of fungicides. These sprays are a significant cost to growers and the indirect environmental impact may be substantial. Reliance on fungicides can be reduced by the integration of non-fungicidal control measures that include genetic, physical, and biological approaches. Recommendations for chemical control of apple scab are often based on the highly susceptible cultivar McIntosh. This was justified because up to 60 to 70% of orchards in northeastern North America were planted with this cultivar. Today, the situation is changing as more and more growers are planting new cultivars, some of which are less susceptible to apple scab. A change in the recommendations to account for cultivar susceptibility could result in a reduction in the number of fungicide applications required. In addition, there has been long-standing research on resistant cultivars, but none of the scab-resistant cultivars have been widely accepted. However, with new molecular techniques to identify and locate the resistance genes, there is potential for progress on this front. Furthermore, fungicide applications for primary infections can be delayed if the number of ascospores is reduced after fall treatments that include leaf shredding, the application of biological control agents, or urea. These methods are preventive and can be integrated into existing management programs. However, the integration of all or some of these methods is more complex than simply the use of fungicides. Nevertheless, integrated management of apple scab may prove more sustainable on a long-term basis, mainly because it does not depend on the use of a single method. Hence the risk of the development of fungicide resistance in the pathogen population is reduced.

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Scab-Resist ant Apples for the Northeastern United States: New Prospects and Old Problems

Abstract: Fruit growers and the p t d u c e industry have been under intense public scrutiny during the past decade. Apples

Cited by 35 publications

References 0 publications

DNA markers linked to Malus floribunda 821 scab resistance

DNA markers linked to Malus floribunda 821 scab resistance

Improving sooty blotch and flyspeck severity estimation on apple fruit with the aid of standard area diagrams

A review of non-fungicidal approaches for the control of apple scab

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