plum rootstock trials in Geneva - New York State Horticultural Society

Plum Rootstock Trials at
Geneva: A Progress
Report
Robert Andersen, Jay Freer and
Terence Robinson
Department of Horticultural Sciences, NYSAES, Cornell University,
Geneva, NY
New York fruit growers with an
interest in diversifying their crop
mix by adding plum plantings face
the issue of choosing rootstocks suited to
their conditions. An important problem
with plum rootstocks in some New York
districts is plum brown line decline.
About 25 years ago, research in California
first connected plum brown line decline
with the presence of the tomato ringspot
virus in grafted plum trees. Infected trees
can die from a hypersensitivity reaction
at the graft union. The tree may come with
the virus infection from the nursery or it
can become infected after planting by a
nematode vector, which moves the virus
from a natural reservoir in orchard weeds.
Orchard sites that have recently had
peaches often are infested with the virus.
Plum tree losses due to this disease have
apparently been highest with European
scions on either Myrobalan or peach
stocks.
Current Plum rootstocks
Myrobalan is the predominant
plum rootstock offered throughout the
nursery industry in the U.S. Dr. Jim
Cummins reports that the European scions
Stanley, Iroquois, and Richard’s Early
Italian are known to be susceptible to Tomato
Ringspot Virus on Myrobalan. Dr.
Dave Rosenberger reports that in a trial
in the 1980’s, he was unable to obtain
brown line on either Shiro or Methley on
Myrobalan. Evidence in the literature suggests
that you can reduce but not eliminate
the risk of trouble with plum brown
line by use of the Mariana 2624 stock.
There are also some plums offered on
peach stocks. Locally in upstate New
York, we are aware of some plums which
have been planted on the Mariana GF 8-
1, and on the St. Julien GF 655-2.
Most New York growers considering
fresh market plum plantings would
welcome a hardy plum rootstock with
both dwarfing and high precocity. Our
plum rootstock research at Geneva focuses
on finding new stocks meeting these
criteria.
Cornell-Geneva Plum
Rootstock Trials
In 1989 the national rootstock
testing group known as the NC 140
project organized a 10 year plum
rootstock experiment. This trial included
14 stocks under the European plum scion,
Stanley. The six most productive stocks
in Geneva were in descending order:
Mariana 4001, Mariana GF 8-1,
Myrobalan GF-31, Mariana 2624,
Myrobalan seedling, and St. Julien A.
None of the six were statistically different
in their cumulative yield. Neither were
they statistically different in their
cumulative yield efficiency. However we
did observe differences in their suckering.
Three stocks out of the six listed above
exhibited severe suckering in Geneva. In
descending order these were: Mariana
2624, Mariana GF 8-1, and Mairana 4001.
No stocks in this trial stood out for
precocity and dwarfing. The Citation
stock, which is somewhat dwarfing and
has had considerable commercial success
in California for plums and peaches, did
not survive well in Geneva. Mariana 4001
and Mariana GF 8-1 were identified as the
outstanding performers on a nationwide
basis.
Most New York growers
considering fresh
market plum plantings
would welcome a
hardy plum rootstock
with both dwarfing and
high precocity. Torinel,
and Jaspi are two new
semi-dwarfing plum
rootstocks that have
good hardiness and
high precocity. There
are several other new
stocks that also are
promising.
Having failed to identify any
outstanding new plum stocks in the 1989
trial, we acquired a new set of candidates
in which to look for excellent cold
hardiness combined with dwarfing and
high precocity. We have planted four
young plum rootstock trials in Geneva
which have just begun to yield useful data
in the 2005 season. All four of the trials
were planted in 2002. The first trial has
the European plum, ‘Empress’ on seven
stocks – in descending order of current
trunk size: Cadaman, Penta, Ishtara,
Mariana GF 8-1, Torinel, Jaspi, and
Krymsk 1 (=VVA-1). In 2005 the Jaspi
stock under ‘Empress’ stood out for high
yield efficiency and Ishtara was second
highest. Jaspi is a tree with a significant
degree of dwarfing. Krymsk 1 has
comparable dwarfing to Jaspi. However
in 2005, Krymsk 1 was much lower in
yield than Jaspi. The average fruit size of
Empress on Jaspi was only 46 grams,
whereas the more vigorous stocks yielded
fruit weights in the range 54-62 grams.
These more vigorous stocks were more
lightly set than Jaspi. It is likely that if the
fruit loads had been more uniform across
the stocks, the difference in fruit size
would have disappeared.
A second experiment has the same
seven stocks under the Asian diploid
scion, ‘Obilinaja’. As in the Empress
experiment, the stock which provided the
NEW YORK FRUIT QUARTERLY • VOLUME 14 NUMBER 1 • 2006 27

earliest ripening fruit was Krymsk 1 (=VVA-1). A third
experiment has a Japanese diploid scion, NY 61J, on eight
rootstocks. This rootstock group includes the same seven
stocks as for Empress plus American plum. In these two trials
with diploid scions, the three smaller stocks in both cases were
Jaspi, Krymsk 1, and Torinel. Under the Obilinaja scion,
Krymsk 1 produced no suckers in 2005, whereas under the
NY 61J scion, Krymsk 1 suckered quite heavily. This probably
reflects much greater winter cold injury to the trunks of the
NY 61J scion. The NY 61J scion on Torinel had less winter
injury than on Krymsk 1 and also fewer suckers. Trees on
Torinel were 60-75% smaller than on vigorous stocks, which
is similar to the dwarfing level shown by Krymsk 1.
Our fourth plum rootstock experiment planted in 2002,
contrasts the semi-dwarfing St. Julien stock, GF 655-2 to the
full vigor Mariana GF 8-1, under three European plum scions.
Contrary to our expectations, the GF 8-1 stock outperformed
the GF 655-2 in both yield and yield efficiency.
Figure 1. Obilinaja plum trees on three new rootstocks. Krymsk 1 on right,
Cadaman in center and Ishtara on left.
Additional Rootstock Candidates
for Future Consideration
California researchers plan to
introduce a new Mariana stock, (M 40) in
the near future. This stock is reported to
be very similar to M 2624 but with many
fewer suckers. This stock and other
Mariana types have similar susceptibility
to brown line decline of Mariana 2624.
Ted DeJong and others in California
recently named two new dwarfing stocks,
Controller 5 and Controller 9, which may
have promise under plums since they are
both peach by plum hybrids. We have
Controller 5 in our peach rootstock trial in
Geneva. It is dwarfing to about 50% of
Lovell size and it has shown much better
cold hardiness than Lovell (see peach
rootstock article in the last issue). We do
not know the cold hardiness of Controller
9. Hiawatha is another new stock to try
under plums in the east. It was bred in
South Dakota as a scion variety which
tolerates the prairie states’ winters. It has
shown considerable promise in California
as a rootstock that is intermediate in its
dwarfing between Controller 5 and
Controller 9.
References
DeJong, T.M. et al., 2005. Research yields
size-controlling rootstocks for
peach production. California Agriculture
59: 80-83.
Mircetich, S.M., and J.W. Hoy. 1981.
Brownline of prune trees, a disease
associated with tomato ringspot virus
infection of Myrobalan and
peach rootstocks. Phytopathology 71
(1) 30-35.
Ogawa, J.M. et al., eds. 1995. Compendium
of Stone Fruit Diseases, APS Press,
Minnesota.
Okie, W.R. 1987. Plum Rootstocks –
Chapter 10 in: Rootstocks for Fruit
Crops, ed. by Roy C. Rom and Robert
F. Carlson. John Wiley & Sons.
New York.
Ramsdell, D.C. et al.. 1998. A Study of
Tomato Ringspot Virus and Prune
Brown Line Resistance in Twentyfive
Rootstock-Scion Combinations.
Hort Technology 8 (3) 349-353.
Wertheim, S.J. 1998. Rootstock Guide –
Apple, Pear, Cherry, European
Plum. Fruit Research Station,
Wilhelminadorp, The Netherlands.
144 pp.
Westwood, M.N. 1993. Temperate Zone
Pomology. Timber Press. Portland,
Oregon.
Robert Andersen is a recently retired
emeritus professor of Horticulture at
Cornell’s Geneva Experiment Station who
specializes in the breeding and culture of
stone fruits. He led Cornell’s breeding,
culture and extension program on stone
fruits from 1990 to 2005. Jay Freer is a
research technician that works with Terence
Robinson and Bob Andersen. Terence
Robinson is a research and extension
professor at Cornell’s Geneva Experiment
Station who leads Cornell’s research and
extension program in high density orchard
systems.
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