Pest management considerations in cider apple systems

Because cosmetic finish is not a major concern for cider apples, IPM programs are an area where input and management reductions may be made without compromising the profitability of the orchard. There are multiple considerations in tailoring an IPM approach in a cider orchard. First, as mentioned above, if any substantial portion of the crop will be sold to a higher-value, higher-quality standard market, then the IPM program should be tailored to meet that highest market. This means that growers who plan to sell the majority of their crop as fresh fruit and the off-grade fruit to cideries should manage the orchard to maximize fresh market fruit, which may eliminate any potential management savings from reduced inputs. If a crop is managed from the beginning of the season, or after a hail storm or other event that reduces fruit finish, as intended for cider, then there may be some opportunities to reduce inputs and management compared to a fresh market crop.

Only a handful of diseases and insect pests in New England may be considered purely cosmetic and thus may warrant not managing at all in cider orchards. For example, tarnished plant bug causes cosmetic fruit damage, especially early in the season prior to bloom. In cider orchards, insecticide treatment for this pest at pink bud stage may be skipped. Likewise, the summer diseases sooty blotch and flyspeck are not of concern on cider apples, and their management may be skipped. However, there may be other pests and diseases that are active at those same times which could negatively affect crop quantity or quality. Many cider apple cultivars appear to be especially susceptible to summer fruit rots, so complete elimination of disease management in summer after primary apple scab ascospore release may not be prudent.

Apple scab deserves discussion in regards to its potential to impact profitability of cider apple production. Scab is often considered a cosmetic disease, and thus one for which management on cider apples may be reduced. In an orchard where scab is managed, but some disease incidence breaks through because of poor fungicide coverage, missed infection periods, or fungicide resistance, the visual effects often do appear cosmetic. But the apple scab fungus derives all of its energy from the host, and may weaken trees even when infection is only moderate. Apple scab infection may reduce crop yield and quality, and severe fruit scab can lead to secondary fruit rots. Scab is best managed through a preventative approach, including reduction of overwintering inoculum and avoidance of primary ascospore infections which can prevent season-long disease management. The urge to lighten up on scab management in cider apples may be strong, but it is still best to protect trees from the disease rigorously during primary ascospore release to reduce management needs later in the season.

Fire blight is one disease which the cider apple grower should be especially vigilant. Many European bittersweet and bittersharp cider cultivars are highly susceptible to this disease. Such cultivars also tend to bloom one to two weeks after most dessert cultivars grown in New England. This shifts the management of blossom fire blight on these cultivars into early summer when temperatures are typically warmer, which further increases infection potential. The management practices for cider cultivars are the same as for dessert cultivars, so as long as growers are fastidious in performing them, the disease should be manageable. It is especially important to maintain a comprehensive management program against the disease, including inoculum reduction, nutrient management, reduction of vegetative growth, and application of antibiotics during blossom infection.

Insect pests often cause cosmetic damage to fruit for which cider apple growers may be relatively tolerant. Some pests, e.g., plum curculio and European apple sawfly, may cause fruit significant abscission that can reduce crop yield at harvest; others, e.g., codling moth and other lepidopteran pests may cause damage that can leave fruit susceptible to rots that can leave fruit unusable for cider making. Therefore, insect pest management on cider apples should not be ignored. For example, growers may consider reducing applications targeting certain pest generations, such as targeting plum curculio with a single well-timed insecticide application as opposed to 2-3 applications using the standard degree day model. More research on adaptation of scouting thresholds and damage tolerance levels on cider apples is needed before recommendations for specific cider IPM programs may be developed.