Understanding and Managing Sudden Oak Death in California Sprout regrowth / retreatment intervals—

California bay typically resprouts from cut stumps. The amount of regrowth that occurs within a season varies with climate and stump size. In Humboldt County, California bay resprouts can grow to a height of 2-3 m (6-10 ft) in a year, whereas regrowth in drier sites in Sonoma, Solano, and San Mateo Counties has been less than 1 m per year. Where sprout growth rates are relatively low, browsing by deer and/or other animals can be sufficient to completely suppress sprout regrowth (fig. 3-4). 

Monitor sprout regrowth after cutting to determine when sprouts should be cut. As long as sprouts remain short (1 m or less), spores produced on infected leaves are unlikely to be dispersed more than about 2 m.  In addition, sprouts that develop during the dry season will normally remain free of P. ramorum lesions at least until the next substantial infection period. Thus, California bay sprouts that are well away from oak stems may not serve as significant sources of inoculum for at least several years.

If stump sprout removal is done while shoots are still small, sprouts can be removed using various hand tools and the amount of material to dispose of will be minimal.  Repeatedly removing sprouts will eventually deplete stored carbohydrates in the bay root system, leading to weaker sprout regrowth and eventual death of the stump.  This depletion will occur faster if sprouts are not allowed to regrow substantially before recutting.

As discussed above (see in Herbicides—), sprout regrowth can be suppressed by treating freshly-cut stems with appropriate herbicides. . In sites where the survival of oaks is questionable and where California bay would be acceptable as a replacement canopy species, it may be preferable to suppress resprouting by cutting rather than herbicides. This allows the possibility of recruiting California bay resprouts as replacement canopy if needed.