Lab
II. T-budding
Print out T-Budding
Flash Card for concise summary of this method.
A.
Background
For information about the use and commercial applications of T-budding, including
links to several Web sites which describe it in detail, go to T-budding
in the List
of Grafting and Budding Methods.
B. T-budding Exercise Check List
- Before beginning this section, you should read over the
Lab Introduction and Overview. Then, review the steps involved in T-budding
below, including the videos.
- Is your knife very sharp? Remember, a dull knife is more dangerous than
a sharp one, when it come to grafting. If you need instruction on knife sharpen
go to Lab Introduction
and Overview.
Materials:
- Potted hibiscus plants
- Grafting knife
- Budding rubbers
- Parafilm
C. Procedure
1. Rootstock preparation.
- Choose a hibiscus stock plant which is actively growing (to insure that
the bark will be slipping), and locate a straight section of stem at least
10 to 15 cm above the soil line, or higher if you prefer highworking.
- The diameter of the stock should be approx. 7 to 10 mm (pencil thick,
at least) at the point you wish to insert the bud.
- There should be a sufficiently long internode at that point to insert the
t-bud without involing a node. Nodal tissue, where leaf and bud join the stem,
tends to be more difficult to cut and the bark more difficult to peal away
from the underlying wood, than it is at internodes.
- Using your knife, cut off any leaves for at least one or two nodes above
and below, so that you can see clearly and have plenty of room to work. Remove
these leaves by cutting the petiole about 1 cm out from its point of attachment..
2. Cutting the stock plant
Note: The upright
T-bud is the most common approach, especially in the temperate zone.
In regions of high rainfall, an inverted T-bud is often used, so that rain water
can drain from the bud pocket.
After reading through the following steps view the first video:
NOTE: To
view the videos click on the down-arrow on the bottom-right portion of the player
screen and choose "Open Link."
- Make the first horizontal cut with your grafting (or budding) knife, by
pushing the blade of the knife through the bark, down to, but not deeply into,
the underlying wood. This can be done with a roll motion rather than with
the tip of the knife. This horizontal cut should extend no more than half
way around the stem, and should not exceed about one cm in length.
- Next make a vertical cut from the center of the horizontal cut and perpendicular
to it, downwards, 2.5 to 4 cm long.
- Using the back (dull) side of the blade of a grafting knife (or the blunt-ended
tool at the end of a budding knife opposite the blade), gently separate the
two flaps of bark created by the T-shaped cut from the underlying wood, to
create a "pouch". It is critical that the bark be slipping as described above;
otherwise the bark will tear.
Rose
- Making 1st
horizontal cut. Note Field T-budding is done very close to the
ground. Outer bark has been scraped away before T cut is made
Citrus
- Inverted
T-budding, used in areas of high rainfall, so excess water will
drain from pocket.
Apple
3. Preparing the Scion bud
After reading through the following steps view the second video:
- Select a healthy looking bud (incipient shoot) from a scion donor plant,
preferably of another hibiscus variety, and remove the leaf by cutting its
petiole approx. 1 cm out from its point of attachment with the stem.
- Starting 1 to 2 cm below this scion bud, cut the bud shield (scion bud)
by drawing the knife upwards, underneath the bud and reemerging 1 to 2 cm
above it. The knife should pass just under the bark and slightly into the
underlying wood (xylem). Some budders prefer to remove the sliver of wood
from back of the bud piece before inserting the bud into the rootstock pocket.
4. Inserting the scion bud into the stock
After reading through the following steps view the third video:
- Holding the bud shield by the "handle" formed by its petiole stump, insert
it into the rootstock pouch by sliding its bottom (pointed) end downwards
from the top of the "T" and under the bark flaps.
- Once the bottom end of the bud is pushed all the way into the T-shaped
pocket of the rootstock, any (upper) portion of the bud shield which does
not fit into the pocket and protrudes out above the horizontal cut, should
be cut off with a solling motion of your knife, so that the bud fits entirely
within the pocket. This is to insure that the cut surface of the bud makes
tight contact with the underlying wood of the rootstock.
5. Tying the bud
After reading through the following steps click the view the final video.
- Begin tying a few millimeters below the bottom of the bud. Trap the bottom
end of the budding rubber beneath the first turn by holding the end at an
ascending angle with the thumb and forefinger of your left hand while simultaneously
stretching and wrapping the band in a counter clockwise direction, creating
an "X". Continue turning, overlapping
each turn by about half the diameter of the budding rubber. Go around
rather than over the bud itself, or small lateral shoot in the
case of hibiscus, continuing up about 1 cm above the bud. In some cases
with apple and other fruit trees, if the bud is small and hard, it may be
completely
covered by the budding rubber.
6. Post budding management of the T-budded plant
- Place the budded hibiscus under shade in the greenhouse for several weeks.
A good early sign of a successful graft union is abscission of the petiole
stump attached to the scion bud piece. If it dries up, but remains attached
to the bud, the graft has probably failed.
Question: Why is non-abscission an indicator
of failure to form a graft union?
- After several weeks, if the graft has taken, callusing of the graft union
should be apparent. New shoot growth from the bud may also occur, but often
the bud remains dormant. It can be forced into growth by bending the stem
of rootstock over (but not breaking it off entirely) several cm above the
bud graft. If you have chosen to place a T-bud on the same hibiscus rootstock
as you have done a top wedge graft on, you will not be able to force the bud
in this fashion (without destroying the top wedge graft).