text: Orchard management and harvesting While cultivation of pears has been to some extent modernised, they remain a difficult crop to grow. Perry pear trees can live to a great age, and can be fully productive for 250 years. Pear trees, both domestic and perry varieties, grow incredibly slowly, taking up to, if not over, a decade before they bear enough fruit for harvest. They also grow to a considerable height and can have very large canopies; the largest recorded, a tree at Holme Lacy, which still partly survives, covered three-quarters of an acre and yielded a crop of 5–7 tons in 1790. Given the long maturing period of pear trees, they can be difficult to manage against diseases. Their size makes it difficult to apply pesticides, which makes preventing fire blight, a disease caused by the bacterium Erwinia amylovora that pears are even more susceptible to than cider apples, quite challenging. These difficulties, along with demand for perry pears having (until recently) taken a decline, have prompted a national collection of perry pear cultivars to be gathered, housed, and cared for at the Three Counties Agricultural Showground at Malvern in Worcestershire, to maintain genetic resources, which has now become the National Perry Pear Centre at Hartpury. Similar germplasm repositories can be found at the National Clonal Germplasm Repository in Corvallis, Oregon.
  Also, key differences between cider and perry production exist in the harvesting and growing processes. Perry trees famously take more time to mature than cider trees. While cider trees may come to bear fruit in three to five years, traditionally managed perry trees typically take much longer, so much so that people say that one plants "pears for your heirs".