Rest in deciduous fruit trees begins in mid-summer and is completed after a cold requirement is satisfied in the winter.
Endogenous growth substances have been linked with rest, though their specific roles remain undefined.
Abscisic acid (a growth inhibitor) increases during the rest period and decreases at or shortly after rest.
During this period growth promoters are at a minimum level but increase sharply in early spring.
A promoter/inhibitor growth substance balance appears to be operative.