Propagating Citrus by Seed, Budding, and Grafting.
Presentation by Mits Kawahara at the June Inland Empire CRFG meeting
Mits began his presentation by taking a few minutes to elucidate upon the eveningís topic: He prefers grafting because it can be done pretty much all year around. Mits explained that one can graft from January through October, while budding can only be done in the summer time. He feels that a grafted tree grows faster than one started from the budding process. Budding is easier, but requires time to ascertain whether it took. Commercial nurseries bud on an assembly line basis because it takes less labor to get more trees. We are the only country that buds. By comparison, a professional can bud a tree in twenty seconds and do as many as 2000 trees/day. Where as it is only possible to do 200/day by grafting. A commercial budding teamís efforts can easily produce a staggering one million trees a season. Slowly but surely, the industry is switching over to Trifoliate root stock. A Coriso root stock will render a standard size tree while Trifoliate will grow to 2/3 that size (10'). There is a dual dividend in using Trifoliate root stock. The tree will be more cold tolerant and the fruit will be of a better quality. Therefore countries like China, Japan, and Israel are all converting over to Trifoliate. Unfortunately, our nursery's donít like Trifoliateís comparable slow growth rate. (Trifoliate 2 years to sale vs. Coriso 1 year to sale).
We received a super-sized order of Mits that night. Not only did he demonstrate how to graft mandarin scion wood onto Trifoliate root stock, but he also held a budding workshop so that we all would be indoctrinated in that technique as well. Mits generously brought bags of four kinds of citrus scion wood for teaching purposes as well as samples for the budding grafter to try later at home; Gold nugget, Murcott, and Kishu mandarins and Cara Cara orange. He elected to use the citrus industryís new buzzword, the Gold nugget mandarin, for his tutorial. Mits cannot stress enough how important it is to disinfect oneís tools with rubbing alcohol before starting. This easy step will minimize the chances of disseminating diseases from tree to tree which are spread primarily by cutting tools. Mits first skinned a single bud from the scion wood and placed it in his mouth to keep it from drying out. Next, he cut a "T" shaped groove six inches from the ground level just inside the bark of the host tree. The bark should "slip" easily. Like tucking a sleeping infant between the coverlets of its crib, Mits gently wedged the single bud into the folds of the T-cut. The next step was to completely cover the area by tightly winding Parafilm around it. Using a China marker, one should then label a piece of grafting tape with the budís varietal name & surgery date and wind it up firmly over the Parafilm. After a sixty day waiting period, the grafting tape is gingerly removed to see if the bud is still green and ready. If it passes inspection, a small slit is cut just above it to force nutrients into the bud instead of up the tree. Mits says that one can attempt to bud up to two buds per tree at a time, but he has found that they invariably both either succeed or fail, so he only does one per tree.
Moving on, Mits instructed the group in the propagation method he likes more than anything else; the modified whip graft because, as pragmatical Mits puts it, "Itís easier." This time it is important to label the grafting tape first. Then select a piece of scion wood with at least four buds. Make a nice even, flat cut with a sharp grafting knife. This could take several strokes to get it right. Place the fresh cut end into your mouth. Next, choose a nice straight area on the root stock from which to cut a wide shallow slice the same width as the scion wood. Match the scion to the host and wrap the joined area tightly with the grafting tape making sure to keep it aligned along the way. Finally, cover the entire graft site and scion with Parafilm. Hopefully, you will see new growth in about a month. By contrast, budding takes longer to see if it took. The only down side to this grafting method is that if you donít succeed, you could loose the rook stock too. He cautioned us to not fertilize for a while (he uses a 5-2-4 formulation derived from turkey dung) as over-fertilization is the biggest mistake made. According to Mits, now is a good time to collect citrus scion wood. He feels that it is edifying to practice/learn using small caliper wood with citrus.
There is no problem securing Trifoliate root stock if you are a member of our organization. Mits donates 10,000 seeds a year to the CRFG seed bank. In January and February, he brings in a big bag of its fruit to our meetings so that local members can collect seeds to grow their own. Mits has found that it is near impossible to purchase root stock commercially as the growers will only consider minimum orders of a million trees. Mits advises that you plant fifteen seeds in a two gallon container of potting soil. Crowd the seeds together so that they will be more likely to grow up straight and tall. After the first year, you should separate and repot the young trees individually. A pencil sized, two year seeding should be ready to graft.