The effects of night interruption (NI) and fertilizer (F) on the overwinter survival of rooted cuttings, collected on May 15 and June 18, of Quercus lyrata Walter, Q. phellos L., Q. robur L., Q. rubra L., and Q. virginiana Mill., were determined. Ideally, after Quercus cuttings root, a growth flush must be induced in order to insure overwinter survival (OS). For the May 15 cuttings that produced at least one flush of growth prior to dormancy, OS was 100%, regardless of species or treatment. Quercus lyrata survived 100% regardless of treatment or cutting date. Quercus phellos survived best under a night interruption-no fertilizer (NI-NF) treatment. When no growth flush occurred prior to overwintering, cuttings of Q. robur under short day-no fertilizer (SD-NF) and NI-NF survived in the highest percentages.
Cuttings from the June 18 sample data generally overwintered best under NI-NF treatment. Quercus lyrata OS was 100% under the SD-NF and NI-NF treatments. NI-NF produced the greatest OS of Q. phellos, Q. rubra and Q. virginiana. With the exception of Q. lyrata, all rooted cuttings that broke bud prior to overwintering survived 100%.
Shoot growth produced by the rooted cuttings was greatest under NI-F for all species except Q. rubra. The amount of growth varied according to species.
This work was supported in part by an award from the Horticultural Research Institute, Inc., 1250 I Street, N.W., Suite 500, Washington, DC 20005.
2Master of Science graduate and Professors, respectively.