season of all cultivars. Imperial Gala, Myra Red Fuji and JonaGoRed were vary lightly cropped on
both stocks, and Gingergold did not bear at all this season.
Established in 1998, this trial compares CG 16 to the standard M9 EMLA for precocity, woolly apple
aphid and fireblight resistance, as well as overall performance. There are 6 replicates to this trial with
only the cultivar Jonagold as the scion variety. Training of the block was established as a modified
Vertical Ax system with drip irrigation being installed at the time of planting.
Leaders were left unheaded and trained to the poles with a tapener. Minimal dormant pruning was
done to correct structural defects and vigorous watersprouts, which consisted of a few selective
pruning cuts of 'nuisance' branches. Primary scaffold limbs were trained horizontally to wires at 34
cm and 3.6 meters respectively to establish proper tree structure and encourage flower bud initiation,
throughout the course of the summer.
Due to the fact that this trial was planted at the end of, but contained in the same block as, the
1995 NE-183 trial, many of the horticultural practices followed such as irrigation and nutrition are
dictated by the needs and protocols of that planting.
Because of a severe regional drought, no measurable amounts of rainfall occurred between the
end of May and the end of August. Irrigation was applied on a weekly basis beginning 18 May and
continuing on a 7-day schedule until 14 September.
Based on soil, leaf analysis and as per protocol of the 1995 NE-183 trial, 30 lb./a (actual) N
(broadcast) was soil applied to the trial. Also applied were 2 foliar applications of Zinc Chelate
(1qt./100), 2 foliar applications of SoluborTM(1 lb./100), 1 foliar application of Manganese Sulfate (4
lb./100), and 2 foliar applications of Magnesium Sulfate (15 lb./100).
The block was under a minimal IPM spray schedule that was determined by weekly scouting. An
application of Lorsban 50WP (3 lb/100) was made on 9 Aug. for dogwood borers.
On 16 Sept. Hurricane Floyd hit our site with 23 mph sustained winds and contained gusts up
to 65 mph. It also dropped an estimated 10.57" of rain on our site. No tree damage occurred.
All data is preliminary as final data collection and statistical analysis is still pending.
Neither rootstock produced a crop in 1999. A visual observation of M9 shows a comparative trunk
caliper and canopy volume to that of CG16 at this point, but a few burrknots have developed on the
shank of the M9 stocks.
Usefulness of Findings:
Although we understand the highly precocious nature of the CG 30 rootstock, we may be seeing a
sensitivity to heavy soils in the 1994 NC-140 Semi-Dwarf Rootstock trial that has not been widely
Work Planned for Next Year:
Further evaluation and documentation of rootstock sensitivity to Phytophthoraspp. may provide
stronger documentation as to how these rootstocks perform in heavy soil conditions.