Variability Among Forecast Models for the Apple Sooty Blotch/Flyspeck Disease Complex

Abstract

2011. Variability among forecast models for (he apple sooty blotch/flyspeck disease complex. Plant Dis. 95:1179-1186.Several disease forecast models have been developed to guide treatment of the sooty blotch and flyspeck (SBFS) disease complex of apple. Generally, these empirical models are based on the accumulation of hours of leaf wetness (leaf wetness duration [LWD]) from a biofix at or near the phenological growth stage petal fall, when apple fiower petals senesce and drop. The models recommend timing of the initial fungicide application targeting SBFS. However, there are significant differences among SBFS forecast models in terms of biofix and the length of LWD thresholds. A comparison of models using a single input data set generated recommendations for the first SBFS fungicide application that differed by up to 5 weeks. In an attempt to improve consistency among models, potential sources for differences were examined. Leaf wetness (LW) is a particularly variable parameter among models, depending on whether on-site or remote weather data were used, the types of sensors and their placement for on-site monitors, and the models used to estimate LW remotely. When SBFS models are applied in the field, recommended treatment thresholds do not always match the method of data acquisition, leading to potential failures. Horticultural factors, such as tree size, canopy density, and cultivar, and orchard site factors such as the distance to potential inoculum sources can impact risk of SBFS and should also be considered in forecast models. The number of fungal species identified as contributors to the SBFS disease complex has expanded tremendously in recent years. A lack of understanding of key epidemiological factors for different fungi in the complex, and which fungi represent the most challenging management problems, are obvious issues in the development of improved SBFS models. If SBFS forecast models are to be adopted, researchers will need to address these issues.Sooty blotch and flyspeck (SBFS). a disease complex caused by numerous fungal species, impacts pome fruit production in humid regions worldwide (4,5.18,21.35.58,60). Although the disea.se is limited to waxy cuticles and does little damage to trees or fruit, the blemishes it causes can substantially decrease apple fruit quality and. therefore, value. In the eastern production regions of the United States, growers generally apply from 30 to 50% of a season's fungicides, usually from four to eight applications, to manage a set of summer diseases, including SBFS, black rot {Botryosphae-ria obtusa (Schwein.) Shoemaker), bitter rot {Glomerella cingutata (Stoneman) Spauld. & H. Schrenk), white rot or bot rot {B. dothidea (Moug.) Ces. & De Not.). Brooks fruit spot {Mycosphae-rella potni (Pass.) Lindau), and Alternaria blotch {Alternarla niali Roberts) ( 54). SBFS is the only consistent summer disease problem in northem regions such as New England but the other diseases become increasingly important going from north to south.Calendar-based management programs of ...

Control of sooty blotch and black rot of apple through removal of fruit mummies

“…The ability to overwinter within the orchard is all the more important because P. cerophilus has not been observed to produce ascospores that could be transported over long distances by air currents. This is in contrast to other sooty-blotch fungi and especially the flyspeck fungus Schizothyrium pomi (Cooley et al 2011. Because the infection biology of Peltaster spp.…”

Decision Support Systems for Plant Disease and Insect Management in Commercial Nurseries in the Midwest: A Perspective Review1

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“…There are several epiphytic fungi which cause sooty blotch and flyspeck disease on the epicuticular wax layer of fruits, leaves and stems of various plants (Batzer et al 2005, 2010, Yang et al 2010, Cooley et al 2011, Miñarro & Dapena 2012, Hao et al 2013, Zhang et al 2015. Sooty blotch and flyspeck disease fungi have a wide distribution, and are common in humid temperate regions (Yang et al 2010, Singtripop et al 2016.…”