Because most of next year's scab spores come from this year's old leaves, raking helps minimize spore survival into the new millennium. Be sure to burn, bury or dispose of the scabby leaves, because they will probably survive the winter very well in your yard-waste pile. One approach would be to scramble your crab-planting plans. In other words, rather than planting 20 crabs of the same resistant variety together in a grove or colonnade, intermix them with other crab cultivars or, even better, with other tree species. Because they avoid concentrating one type of crab in the same area, these strategies can put the brakes on selection for resistance-tolerant scab.
Fungicides can be part of scab management too.
Three sprays in the spring, starting a few days before the flowers open and repeated at 10-day intervals thereafter, can provide fairly good control of scab in most years. But almost nobody is willing to wage annual chemical warfare against scab, because it's expensive, tedious and liable to be unpopular with the neighbors. With a little planning and maintenance, you can keep your crabs looking great, and avoid the perils of yard rage. And caped plant pathologists can give it a rest.