There is no effective treatment other than avoiding planting on infested soils and removing damaged trees and branches. A bacterial disease known as olive knot is spread by pruning with infected tools during rainy months. Because the olive has fewer natural enemies than other crops, and because the oil in olives retains the odor of chemical treatments, the olive is one of the least sprayed crops. They can also be picked for processing at any later stage up through full ripeness. Ripe olives bruise easily and should be handled with care.
Mold is also a problem for the fruit between picking and curing.
There are several classical ways of curing olives. Other processing methods include water curing, salt curing and Greek-style curing. Agricultural Sciences Publications Leaflet 21131. For California canned commercial olives, black olives are identical to green olives. The black color is obtained by exposure to air after lye extraction and has nothing to do with ripeness.