PISTACHIO GRAFTING TUTORIAL UNDER CONTROLLED TEMPERATURE CONDITIONS
Below is a grafting system for pistachio, with three main objectives:
- Being able to graft with graft cuttings in a state of winter dormancy, which is tremendously important, since the cuttings in a vegetative state have a short shelf life and cannot withstand days of travel, and it is ideal if you have friends who send you graft cuttings of the varieties originating from their countries (Tunisia, Syria, Italy, Greece, Cyprus, Iran, Australia , etc… )
- A very high success rate
- Great speed in the process.
This is a very effective system for the hobbyist, who will be able to graft a “reasonable” number of plants, at a very low cost.
- An electric heater, with a thermostat.
- A small, well-lit room, preferably with good sunlight (this space depends on the number of rootstocks), and if the natural light conditions are not adequate, a couple of fluorescent tubes with daylight white light are perfect.
This technique is suitable for any pistachio rootstock (Pistacea Terebinthus, Atlántica, Integérrima, UCB-1, Platinum, Adex…), but it is more interesting to buy rootstock with one sap rather than two (the result is the same, and the cost three times cheaper).
In nurseries, the rootstocks of one sap , are usually extremely cheap, and they normally go in Forest tray containers.
Before starting the process, you must transplant them to larger pots.
You should always choose thicker rootstocks (even if they are shorter in height), the thickness of a pencil is ideal.
PERIOD OF REALIZATION:
At the end of winter, around the middle of February, which is when nurseries have rootstocks for pistachio available.
The choice of cuttings to graft is the usual one for any fruit tree, in a state of total winter dormancy, without necrotic areas, and looking in good health.
Logically, the cuttings should be chosen with a caliber according to the rootstocks, generally a one sap rootstock have around 5-7 mm.
Great care must be taken to avoid cuttings that have flower buds (the wooden bud is much smaller than the flower bud).
Look at these examples:
Bad choice, the branches are twisted, aged and necrotic.
Good choice, but be careful with the flower buds.
This is the best option (for both Chip Budding and Whip and Tongue grafting systems), they work best without apical bud.
These are cuttings with all wooden buds.
TEMPERATURE FORCING OF THE ROOTSTOCKS:
An optimal height length for the rootstocks is around 35 centimeters. If they are much longer, it makes grafting difficult, so it is advisable to decapitate them and seal the cut area with pruning mastic.
It is advisable to eliminate the buds below the future grafting area, in order to concentrate the sap towards the upper part of the rootstock.
Place the rootstocks in the chosen “mini-greenhouse” room, and regulate the heater temperature to 26º C. (78-79° Fahrenheit)
It is important to control irrigation, since at that temperature, there is usually evaporation and small, frequent irrigations are convenient to avoid root asphyxiation.
And now the fun begins:
After two weeks, or two and a half weeks, our rootstocks are ready and vigorous to be grafted, and we can choose two grafting methods.
- Whip and tongue
It is recommended to cut the rootstock, since normally the apical area is the one that contains the flower buds, and sealing it with putty gives fantastic results, I personally like it better, but it is just a matter of taste.
- Chip Budding
It gives excellent results.
Please note that I emphasize that it is very important to recognize flower buds and wood buds.
Grafting one Chip with a flower bud leads to failure, however grafting two Chips with wooden buds multiplies the chances of success.
It is very important to keep a small sprout as a sap strip near the graft area, for both graft systems, and remove the rest of the buds to avoid undesirable sprouting.
A “sap-pulling” twig that is too vigorous can affect the proper development of our graft, so it is advisable to control it by decapitating the twig.
Rootstock before temperature forcing.
Rootstock days after temperature forcing, ready to be grafted
Bevel of the Whip and Tongue graft (note that the sap-pulling twig is right in the back area of the bevel)
It is very likely that this bud is from a flower, so it is advisable to eliminate it, and leave the upper ones.
Assembled and tied with Budy tappe
Anti-dehydration protection of the cutting with a few turns of Budy Tappe
Chip extracted and ready to be graft
Notch made in the rootstock, the same size as the chip.
Rootstock with two Chip Buds tied with Budy Tappe (note the sap-pulling twig at the top)
After a few days (week/s), the graft will have developed sufficiently strong, with leaves and good branching, and then the twig “sap pulling” can be removed.
The dates when we can take our pistachios outside will be around the end of April, and the first half of May (depending on the temperatures).
So we have two options.
1st- Let our plants develop in the warm room, until the dates approach, gradually lowering the thermostat, to equalize the interior temperature with the exterior temperature, without the plant suffering great stress.
2ª- After a month and a half, the plants that we have successfully grafted, we can take them to a room in our house with heating at a normal temperature and well lit, waiting for the arrival of good weather outside.
Pistachio trees are very resistant plants, but to acclimatize them to the outdoors, it is recommended to follow the basic principles (watering control, sun little by little, etc…)
Avdat variety, grafted whip and tongue system, without apical bud
Askar variety grafted to whip and tongue system with apical bud
Mateur variety grafted to Chip Budding
Bronte variety , whip and tongue graft system
Lathwardy variety, whip and tongue graft system
Ashouri variety grafted to chip budding
P.S. : Forgive the spelling errors, since I am fluent in French, but not English, and Google Translate is more bad than Caín .