And...take a look at Cornell's information for home fruit growers. Second opinion. Cornell is highly respected by fruit growers.
Maybe your university is giving you information from the 1960's. Perhaps you do not need the captan. Perhaps you don't need the Immunox fungicide either. The only important disease Cornell mentions is brown rot. And the main insect is curculio.
Certain insecticides like sevin can cause fruit to drop. And you don't want too many fruit--as that results in many small inferior fruit. They must be spaced out--say 3 to 6 inches apart.
About fruit drop:
And thanks for the comment, Greendoc...sevin makes mites worse. And kills bees which would otherwise pollinate your fruit blossoms.