Cody Stiles wrote:
Some natural fruit drop is to be expected - the tree is simply thinning out fruit that it cannot support. If ALL the fruit is dropping, that is symptomatic of more significant problems. Lawn right up to base of a fruit tree is not a great idea. Lawns tend to hog nutrients and soil mositure and might be depriving the tree of the conditions it needs to thrive, Also, to encourage consistant production, apple trees should be pruned annually to remove excessive interior branches which may be blocking needed sunlight and to develop new fruiting spurs. Old spurs will gradually lose their productivity over time and need to be replaced. Additional fertilizing may be necessary also if the tree has not been maintained properly.
Despite several posts encouraging a regular spray program, a dormant season spray to help control fungal problems and to smother overwintering insect eggs is typically all that is recommended for home orchardists in the PNW. There is no spray product available to the consumer for the control of apple maggots and coddling moths - these insect pests need to be controlled by trapping. It is too late in the season for this type of control now - traps should be initiated in early spring just as the blossoms are starting to emerge and remain in place through the season. It can sometimes take several seasons before you get very complete control.
Finally, 50 years is a good lifetime for an apple tree - commercial orchardists replace their trees after a much shorter period of time due to a natural decline in productivity. You might just want to consider your tree simply a venerable addition to your landscape and take whatever edible fruit it does produce as a bonus. Plant a new, disease resistant and climate suitable apple cultivar for serious fruit production.
pam - gardengal