on vulnerable tissue, growers are advised to monitor watering periods and avoid using overhead watering systems. Doing so may ultimately aid in reducing infection periods caused by natural precipitation. Chemical controls The management of apple scab using chemical controls is primarily concerned with preventing the initiation of primary infection cycles by reducing the germination of ascospores. As such, fungicides are typically applied early in the season, when ascospores are first released. However, fungicide applications may also be made later in the season to prevent infection of old leaves, which can help reduce the amount of primary inoculum for the following season. Benzimidazole fungicides are among the most commonly-used classes of fungicide for managing apple scab in conventional orchards; however, there is some evidence that the disease is developing resistance to this class of fungicides, along with several others, including demethylation inhibitors and quinone outside inhibitors. To manage the development of fungicide resistance, growers can reduce the number of applications made throughout the season and alternate between different classes of fungicide. In organic production systems, growers commonly use copper- or sulfur-based protectant sprays to reduce the efficacy of primary inoculum. Although these sprays were among the earliest methods of preventing the development of apple scab, they do little to manage pre-existing infections and application may significantly damage the foliage of treated trees. Moreover, research has indicated that applications of copper-based fungicides may result in changes in the structure and functionality of soil microbiota, thus having a negative effect on soil health. As such, alternative management strategies appropriate for organic production systems are currently being developed. Biological Control Biological control refers to the use of a population of one organism (a biological control agent) to suppress the population of another. There are very few biological control agents registered for the control of apple scab. One of the most widely-recognized products is Serenade® ASO, a microbial biofungicide which uses Bacillus subtilis as its active ingredient and may be used to control foliar diseases caused by bacteria or fungi. Furthermore, several fungal antagonists have been isolated and identified as potential biocontrols. One of such antagonists is Cladosporium cladosporioides (strain H39). This antagonistic fungus has demonstrated significant bioactivity against apple scab. This was indicated in a 2015 study, which found that applications of C. cladosporioides could reduce leaf scab incidence by 42-98% and apple scab incidence by 41-94% in both conventionally and organically managed orchards.