Sentence:  Excellent control of a storage rot of apples, caused by Gloeosporium album, was obtained with an orchard spraying program of captan in the <WSD>precover</WSD> followed by 3 regular and 2 late cover sprays of captan or a mixture of captan and zineb. 
Meaning of the word marked with <WSD> tags:  Something that occurs in preparation for a covering.