Fruit Notes

VIRGINIA FRUIT NOTES
January/February - 1998, Vol. 18, No. 1

Richard P. Marini
Extension Horticulturist, Tree Fruits
VPI & SU
Blacksburg, VA 24061-0327

Early Results From the 1994 NC-140 Dwarf Rootstock Trial
In the spring of 1994 a dwarf rootstock trial was established by 24 cooperators in the U.S. and Canada. Eighteen dwarfing rootstocks were budded to `TRECO Red Gala #42' by TRECO in Oregon. `StarSpur Supreme Delicious'/M.26, `Liberty'/M.9, and `TRECO Red Fuji TAL-114'/MARK were used as pollinizers. Annually each cooperator sends data to me for summarization. In this report, we present data for the first four years for the planting at Blacksburg, Virginia that is managed by Dr. John Barden and myself.

The experiment is a randomized complete block design with 10 single-tree reps per rootstock. The trial has a total of 220 trees planted 11.5' by 18.0' (210 trees/acre). Each tree is tied to a 8' tall 3/4" conduit supported at 7' with a single wire. Trees are being trained to a vertical axe system, which involves no heading of the central leader or scaffold branches. All branches above 2' with wide crotch angles have been retained. About 8 to 10 buds per tree were notched before bloom in 1995 to induce lateral branching along the central leader. Each year data are recorded for tree survival, trunk cross-sectional area (TCSA), rootsuckers/tree, fruit/tree, and yield. Some trees bloomed in 1995 so blossom clusters and fruit set/100 clusters were recorded. In 1995 crop load was adjusted by hand to 6 to 8 fruit/cm2 TCSA. In 1996 and 1997 trees were chemically thinned and additional hand thinning was required on most trees.

Results

Vegetative Growth. Trees grew very well in 1994 and 1995 and some trees were 9' tall by the end of the second season. Rootstocks with the largest trunks in 1995 were M.9 Pajam 2, V.1, and MARK, whereas M.27 EMLA, B.491, P.16, and P.22 had the smallest trunks. The most rootsuckers were produced by M.9 Pajam 2, P.16, V.1, and MARK.

In October 1997, all rootstocks had at least 80% survival; all but M.26 EMLA, 0.3, MARK, B.469, and M.9 Fleuren 56 have 100% survival (Table 1). TCSA is largest for V.1 and smallest for M.27 EMLA, B.491, P.16, and P.22. The rank of TCSA for the six M.9 clones from smallest to largest are Fleuren 56, NAKBT 337, M.9 EMLA, RN29, Pajam 1, and Pajam 2.

Fruiting Characteristics. The year after planting (1995), rootstocks with the highest yield included P.16, P.22, M.27 EMLA and B.469, whereas trees with lowest yields were on V.3, B.491, and MARK (Table 2). Cumulative yield for 1995 to 1997 was highest for V.1 and O.3 and lowest for M.27 EMLA, P.22, and B.469. Of the six M.9 clones, M.9 EMLA , RN29, Pajam 1 and Pajam 2 had similar yields, whereas NAKBT 337 and Fleuren 56 had cumulative yields about 30% lower than the other four clones. Cumulative yield efficiency is a measure of the amount of photosynthate a tree partitions into fruit rather than wood. High values indicate that more carbon is directed into fruit production. Rootstocks with low cumulative yield efficiencies included M.27 EMLA, B.491, V.3, and M.26 EMLA, whereas rootstocks with the highest yield efficiencies included P.22, M.9 Fleuren 56, MARK, and O.3. All six M.9 clones had yield efficiencies between 1.1 and 1.3.

Conclusions. We have only completed four years of this 10-year trial, so results are still preliminary. After four years these 18 dwarfing rootstocks seem to be separating into four vigor classes based on TCSA as indicated in the following table.

Most Dwarfing	Moderately Dwarfing	Moderately Vigorous	Most Vigorous
P.22	B.469	P.2	M.26 EMLA
M.27 EMLA	M.9 Fleuren 56	M.9 EMLA	V.1
P.16	B.9	0.3
B.491	V.3	M.9 RN29
	M.9 NAKBT 337	M.9 Pajam 1
	MARK	M.9 Pajam 2

At this point the trees have been pruned very little, so yield efficiency can be used to compare rootstocks within a vigor category. The most productive rootstocks in their vigor class appear to be P.16, M.9 Fleuren 56, MARK, 0.3 and V.1. Some rootstocks that are very productive early in the life of the tree tend to stop growing and become relatively nonproductive due to inadequate canopy volume. Therefore, we will have to wait a few more years before making any recommendations.

Below is a brief description of some of the rootstocks in this trial.

B.9 (Budagovsky 9): (M.8 x `Red Standard') Introduced in 1946, not patented. Has red leaves and bark, anchorage is medium to good, has moderate winter hardiness, roots well in stool bed. Few burrknots and suckers. Susceptible to fireblight, woolly aphids, and very susceptible to collar rot.

B.491 (Budagovsky 57-491). Originated at Michurinsk, College of Agriculture, the former Soviet Union. Wood is brittle and cold hardy, wood is pink, few burr knots, little sucking, very susceptible to fireblight and woolly aphids, susceptible to collar rot.

M.9 (Malling 1X). Originated in Maidstone, Kent, England, by East Malling Research Station. Selected in 1914. Roots well in stool bed.

M.9 NAKBT 337. (Malling 9-T337): A Dutch selection of M.9. Tree vigor reportedly is intermediate in the M.9 range.

M.26 (Malling 26). (M.16 x M.9): Selected in 1929 at the East Malling Res. Stat. Vigor is between M.9 and M.7, better anchored than M.9, resistant to collar rot, susceptible to fireblight.

M.27 (Malling 27). (M.13 x M.9: Cross made in 1929, selectd in 1934, tested as Malling 3431 and patented in 1975. More dwarfing than M.9.

MARK (MAC-9). Originated in East Lansing, Michigan, by R. F. Carlson. Selected in 1959, patented and introduced in 1979, sublicensed to TRECO®. This is the result of an M.9 open-pollination so the male parent is unknown. More dwarfing and productive at an early age than M.9. Very cold tolerant, tolerant to collar rot, susceptible to fireblight and wooly apple aphid. Tolerates heavy soils, irrigation required on light sands. Soil line proliferation sometimes leads to tree decline.

O.3 (Ottawa 3). (M.9 x Robin Crab): Originated in Ottawa, Canada in 1974. Not patented. Very cold hardy, degree of vigor is similar to M.9. Roots poorly in stoolbeds. Produces few burrknots or suckers. Very resistant to collar rot, susceptible to fireblight and woolly aphids.

P.2. (M.9 x Comon Antonovka): Originated in Skierniewice, Poland at the Institute of Pomology. Fairly cold hardy, produces few burrknots, roots well in stool bed, moderately susceptible to fireblight, susceptible to woolly apple aphid, resistant to collar rot, may be susceptible to tomato ringspot virus.

P.16 (M.9 x Common Antonovka): Low temperature tolerance similar to M.9, burrknots and suckers are rare. Susceptible to fireblight and wooly apple aphid.

P.22. (M.9 x Common Antonovka): Originated in Skierniewice Poland. Fairly cold hardy, produces few burrknots and suckers, moderately susceptible to fireblight, very susceptible to woolly aphids, resistant to collar rot.

Table 1. Vegetative growth characteristics for 18 dwarf apple rootstocks planted in 1994.

Root Stock	% Survival 1997	TCSA (cm2) 1995	TCSA 1996	TCSA 1997
P.22	100	5.3	5.7	6.3	0.5
M.27 EMLA	100	4.6	6.1	7.4	0.1
P.16	100	5.7	8.1	9.1	6.6
B.491	100	5.2	8.2	9.7	0.3
B.469	90	7.6	10.7	14.2	0.4
M.9 Fleuren 56	90	9.6	13.3	15.5	0.8
B.9	100	9.4	13.9	16.3	0.6
V.3	100	8.4	14.6	16.8
M.9 NAKBT 337	100	8.1	14.5	18.4	1.4
MARK	90	12.4	16.9	18.8	2.2
P.2	100	10.6	17.4	21.0	0.0
M.9 EMLA	100	10.0	17.8	21.5	0.3
O.3	90	10.8	18.3	22.4	1.1
M.9 RN29	100	10.6	19.3	23.5
M.9 Pajam 1	100	10.8	19.8	24.3	1.2
M.9 Pajam 2	100	11.8	21.5	25.7	4.2
M.26 EMLA	80	12.9	25.9	31.9	0.0
V.1	100	13.9	28.2	37.6	2.3

Table 2. Annual and cumulative yield, fruit size and yield efficiency (YE) of four year-old `Gala' trees on 18 dwarf rootstocks.

Root Stock	Yield lbs/tree 1995	Yield lbs/tree 1996	Yield lbs/tree 1997	Yield lbs/tree Cum	Fruit/box 1997	Cum.YE 1997
P.22	4.6	4.6	10.6	19.8	107	1.4
M.27 EMLA	4.2	3.5	5.3	13.0	112	0.8
P.16	7.9	8.6	15.0	31.5	120	1.6
B.491	0.9	5.7	13.0	19.6	112	0.9
B.469	4.2	11.0	16.1	31.3	114	1.0
M.9 Fleuren 56	1.5	11.9	31.7	45.1	110	1.3
B.9	1.1	12.1	22.4	35.6	116	1.0
V.3	0.7	8.6	22.0	31.3	110	0.8
M.9 NAKBT 337	1.1	14.1	30.4	45.6	110	1.1
MARK	0.9	20.7	30.6	52.2	129	1.3
P.2	2.9	14.7	30.6	48.2	110	1.0
M.9 EMLA	1.8	15.4	39.4	56.6	110	1.2
O.3	2.2	21.8	46.6	70.6	113	1.4
M.9 RN29	2.2	16.3	44.9	63.4	110	1.2
M.9 Pajam 1	1.3	16.7	45.8	63.8	109	1.2
M.9 Pajam 2	1.5	13.9	46.6	62.0	116	1.1
M.26 EMLA	1.1	13.2	50.4	64.7	114	0.9
V.1	2.4	11.7	64.9	79.0	112	1.0

Apple Information on the Net
Several growers have asked me what kind of information is pertinent to fruit production on the Internet. Most state Extension programs are regularly putting up newsletters and extension bulletins and information is being added daily. Below are some web sites that should be of interest to Virginia Fruit Growers.

Virginia Apples
http://www.ento.vt.edu/fruitfiles/VirginiaAppleSite.html
This site, maintained by Dr. Doug Pfeiffer, contains information on tree fruit acreage by county, pesticide information, horticultural information and weather information.

Virginia Apple Growers Association
http://www.vvac.org/vaapples
This site contains information on apple varieties, trade releases and consumer releases relevant to the Virginia Apple Industry, and newsletters to promote Virginia apples.

Virtual Virginia Agricultural Community
http://www.vvac.org
This is a collaborative effort between Virginia Cooperative Extension, the Virginia Department of Agriculture and Consumer Services and Virginia Tech's College of Agriculture and Life Sciences. It is designed for those who are involved in Virginia Agriculture to enhance communications, further the education, and provide a means of sharing information among members of Virginia's agricultural community.

Scaffolds Fruit Journal
http://www.nysaes.cornell.edu/ent/scafolds/
A weekly update on pest management and crop development. Scaffolds is published by Cornell University–NYS Agricultural Experiment Station (Geneva) and Ithaca–with the assistance of Cornell Cooperative Extension.

Integrated Pest Management West Virginia University Extension Service
http://www.wvu.edu/~agexten/ipm
Solutions to pest problems provided by the West Virginia Extension Service include, plant disease, insects, weeds and pest animals.

The University Experiment Farm at Kearneysville
Tree Fruit Research and Education Center
http://www.caf.wvu.edu/kearneysville/wvufarm1.html
Search what's new about Insect Pests, Diseases, Current Conditions, Orchard News.

The Mid-Atlantic Regional Fruit Loop
http://www.caf.wvu.edu/kearneysville/fruitloop.html
This cooperative Web site provides information on all aspects of deciduous tree fruit production in the mid-Atlantic region. Content for the "Loop" is provided by fruit professionals from Maryland, New Jersey, Pennsylvania, the USDA/ARS, Virginia, and West Virginia.

National Weather Service - Interactive Weather Information Network (IWIN)
http://iwin.nws.noaa.gov/
The National Weather Service's Internet data source.

Welcome to the Virtual Orchard
http://orchard.uvm.edu/
The Virginia Orchard provides a Web site forum for research and extension projects dealing with commercial apple production and marketing issues. A clearinghouse for apple information concerning commercial fruit growers.

North Carolina Cooperative Extension Service Apple Production Newsletter
http://henderson.ces.state.nc.us/newsletters/apple/
Read Henderson County Apple Production Newsletters from their WWW site. Choose the current month and year to read or choose information from previous months or last years issues.

Appalachian Fruit Research Station
http://www.intrepid.net/afrs/afrs.htm
The mission of the Appalachian Fruit Research Station is to identify critical problems of temperate fruit production; develop the science, technology, and genetic base needed to maximize productivity and quality of fruit crops; and minimize the adverse effects of biotic and environmental factors on these crops.

Gempler's
http://www.gemplers.com/
Welcome to Gempler's online mail catalog. A direct marketer serving Agriculture, Horticulture, Grounds Maintenance, Forestry, and Serious Gardeners and Hobbyists.