Group Title: Citrus Station mimeo report - Florida Citrus Experiment Station ; CES 65-1
Title: Vegetative propagation of nematode tolerant and resistant rootstocks
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 Material Information
Title: Vegetative propagation of nematode tolerant and resistant rootstocks
Series Title: Citrus Station mimeo report
Physical Description: 3 leaves : ; 28 cm.
Language: English
Creator: Ford, Harry W., 1922-
Citrus Experiment Station (Lake Alfred, Fla.)
Publisher: University of Florida, Citrus Experiment Station
Place of Publication: Lake Alfred FL
Publication Date: 1964
Subject: Citrus -- Rootstocks -- Florida   ( lcsh )
Citrus -- Propagation -- Florida   ( lcsh )
Nematoda -- Control -- Florida   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
non-fiction   ( marcgt )
Statement of Responsibility: H.W. Ford.
General Note: Caption title.
General Note: "July 29, 1964."
 Record Information
Bibliographic ID: UF00072423
Volume ID: VID00001
Source Institution: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: oclc - 75956945

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Citrus Station Mimeo Report CES 65-1
July 29, 1964

Vegetative Propagation of Nematode
STolerant and Resistant Rootstocks

H. W. Ford
University of Florida
S- Citrus Experiment Station
--- Lake Alfred, Florida

There has been interest in propagating certain of the burrowing nema-
tode resistant rootstocks by means of leaf bud and leafy tip cuttings because
of the scarcity of seed, particularly for 'Milam' and 'Ridge Pineapple'

Vegetative propagation under most circumstances is not to be recom-
mended primarily because of the problem of transmitting certain virus
diseases. The virus problem is more severe with a vegetatively propagated
rootstock because it will carry everything that was in the mother clonal
plant, whereas, seedlings used as rootstocks usually do not carry viruses
even though the parent plant may be infected. It is, therefore, absolutely
necessary that anyone considering vegetative propagation be certain that
his source of material is as free of viruses as possible.

The best method to obtain cuttings for propagation purposes would be
to use a minimum of 25 to 100 seedlings and take an equal number of cuttings
from each of these seedlings to minimize the chances of genetic variation.
If the clonal parent was known to be free of viruses and was topworked to a
seedling tree, then presumably, it will be free of xyloporosis and exocortis
but it might contain tristeza if an insect vector had transmitted that partic-
ular virus in the vicinity of the clonal parent tree.

It is to be recommended that a nurseryman using a cutting rootstock
should also use the best virus-free budwood available, because the sus-
ceptibility, particularly of 'Milam' to exocortis and xyloporosis is unknown.
One should also consider that a cutting used for a rootstock cannot be used
at present to develop a registered tree under the present regulations of the
Bureau of Plant Industry. If you are thinking in terms of developing a tree
that can be registered, then you should talk with Mr. Norman of the Bureau
of Plant Industry in Winter Haven.

Mist propagation is a satisfactory method of propagating 'Milam,'
'Ridge Pineapple' and 'Estes' rough lemon. The 'Estes' rough lemon will
root readily under a wide variety of conditions so that my special comments
for 'Milam' and 'Ridge Pineapple' will certainly be more than satisfactory
for rooting rough lemon. There is an Agricultural Extension Circular No.
127A on mist propagation that may be helpful. Our propagating beds consist
of a bench about three to four feet in width and any desirable length for
the size of the operation. The bed should be six to eight inches or more
in depth and a heating cable should be placed in the bottom of the bed.
The cable is placed about six inches apart in the bed and should be con-
trolled by a thermostat. The thermostat should be set so that the tempera-
ture of the medium does not fall below 850 F. Preferably, the temperature
should be at 900 F. The medium above the cable should consist of a mixture

of German peat and perlite agricultural grade rock. The amounts of these
two materials should be in equal proportions. There should be at least four
to five inches of medium above the heating cable.

One nozzle of the mist system should cover the width of the bed and
the number of nozzles required will depend on the length of the propagating
bed. There are numerous types of nozzles on the market. The types that
will deliver no more than several gallons per hour with a minimum of work-
ing parts will work satisfactorily. It is necessary to have an electric
solenoid valve to control the mist which should be coupled to a time clock
so that the mist will be intermittent by prearranged schedule. The basic
objective is to wet the leaves and then wet them again before they are dry.
Too much water results in leaching. I prefer an intermittent time clock
that has a six minute total cycle with a selection for six second intervals.
This means that one can select any number of six second moisture cycles in
any given six minute period. Usually during the summer, one cycle every
three minutes will probably be adequate. During the winter, we use one
cycle every six minutes. It is also necessary to have a simple clock that
will turn off the mist at 5:00-6:00 p.m. in the evening and turn it on
about 7:00-8:00 a.m. in the morning. It is essential that you have this
clock and do not rely on your own memory because if you forget one day,
then the plants will be lost.

During the summer, propagation can be done in the open but you must
protect the leaves from being blown by the wind and also from having the
mist blown away from the leaves. One method by which this can be overcome
is to use a 2 X 4" galvanized wire mesh bent in the shape of a quonset hut
and then partially covered with clear plastic. The amount of cover will
depend on the heat since full cover might result in too high a temperature
within the bed. This can be determined by trial and error. Temperatures
above 100* F. could be detrimental.

There are two types of cuttings that can be used for propagating
'Milam' and 'Ridge Pineapple.' The first is called a leaf bud cutting
which consists of a leaf and a single bud in which the stem is cut just
above the bud and about one-quarter to one-half inch below the bud. Thus,
the cutting has a portion of the stem, the bud, and the leaf. The stem is
inserted in the medium so that the bud is at the medium level or slightly
below. Rooting will occur from the base of the stem. No additional hormones
or other additives are necessary.

The leafy shoot method consists of taking tip cuttings containing several
leaves and inserting them into the medium. These cuttings do not root any
faster than the leaf bud cutting but they are stronger once they have rooted.
The tip cutting will "grow off" faster than the leaf bud cutting but it is.
not possible to obtain as many plants from a given quantity of scarce clonal
parent material.

After the plants have rooted, which may take six weeks to two months,
they should be transplanted into containers and permitted to sprout. They
can be lined out in a nursery row when they have a good root system but it
is absolutely essential that you have complete moisture control because
cuttings are more difficult to handle in the nursery than a seedling. A

cutting will also be more of a problem during the first year that they are
grown in the grove. They may require more water and may have to be staked
until they are well-established.

Even with ideal cuttings, 'Milam' and particularly 'Ridge Pineapple'
are difficult to propagate. The older the propagating material is from
seed, the more difficult it will be to root a cutting. In the case of
'Milam,' we have found it extremely difficult to root material obtained
from trees that are more than six years of age. 'Ridge Pineapple' is
proving rather difficult to root after the parent trees are three years
of age.

Citrus Experiment Station
Lake Alfred, Florida

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