Cherry Tree: pruning, grafting and rootstock questions
Cherry Tree Rootstocks, pruning and grafting questions I came across your pruning page and it was not specific, in particular to cherry trees. I need to prune but don't want to damage/hurt my cherry trees like before; apparently I cut to much off on a younger tree (aprox 4 years old) and that whole branch died! A) The trees I have is one 30+ year old at 30+ feet tall; this tree has never been pruned. What would be my approach on this? B) The 10 others cherry trees range from 5-10 years old and too have never been pruned, what about these? C) And Root-Stocks & Grafting help: Any branches I prune, I would like to graft them into root-stocks. But access to these root-stocks is a heavily guarded secret; I have placed many calls and performed hours of on-line searches, with no help/success-any links lead to dead-ends (being unavailable). This much I know, there are about five common root-stocks that are used for cherry trees (Performer, Gisela 12, Gisela 6, Mahaleb, and Mazzard ), each one having advantage and disadvantages over the others. Tough choices with this, one must know everything about the disadvantages (i.e. diseases) and which ones are the most critical and the ones that are most easily dealt with. Can you help here? Thanks, Chris
Lots of Questions,
Most pruning is done in the winter and early spring because it is easier to see the structure of the tree. Pruning a 30 year old tree that has never been pruned? What is your objective? Do you want to shorten the tree? How high are you going to pick? I would not recommend removing more than a third of the height of the tree in any one season. For the renovation of an old tree which has not been pruned for many years I recommend a three year process. Removing large limbs in the top of the tree the first year. Removing smaller limbs and crossovers and any limbs that are too close together the second. Then continuing to clean up the middle and top of the tree the third. If you try to do it all in one year you will be pruning out vigorous water sprouts for many years trying to settle the tree down to setting fruit on spurs rather than growing vigorous shoots.
To shorten the tree. You can choose a limb to be the new top of the tree and remove the rest of the top. That will be a big cut and I would suggest painting the wound with a pruning compound or a diluted interior grade latex paint as soon as you can after the cut. For cuts smaller than a quarter you do not need to do that. You will get vigorous growth from these cuts and I would suggest removing all but the weakest shoot. I call this a vigor sink and you are forcing the growth into this branch rather than growing a lot of new shoots. The next dormant period you can keep or remove the one you left.
You should probably open up the tree to allow more light penetration into the canopy. I assume this is a sweet cherry. Sweet cherries bear their fruit at the base of last years growth and on fruiting spurs on older wood. If those spurs are shaded they will be less fruitful and eventually die so that all the fruit is on the exterior of the tree. You do need to make some cuts in the top of the tree to promote flower bud formation and fruiting in the interior of the tree. Remove several large limbs from the top of the tree to allow light to penetrate into the interior of the tree.
So the first year most of your cuts are made in the top of the tree. The second year, you should see some growth in the middle of the tree and this will help you decide which limbs to keep (ones that show growth) and which to remove. Remove any limbs that are to close to together and ones that cross over and shade branches below. You will need to look at these crossovers and choose which branch to save. Try not to cut off all the interior lower branches as we are trying to promote growth growth and fruiting here. The goal is to have fruit all the way to the trunk and leaves in the interior that are exposed to light.
I suggest making fewer large cuts rather than lots of little detail cuts in the first two years and in the third year you can start to select small branches to save or remove. You will need to cut ladder bays for ladder placement during pruning and harvest.
For the younger trees decide which of the lower limbs will be your permanent scaffold limbs. These are the major limbs that you will retain for the life of the tree. We want 3 to 5 scaffolds in each whorl of scaffolds and the whorls should be about 3 feet apart on the trunk. Each scaffold should head in a different direction and they should be separated by at least 6 to 8 inches on the trunk. If they are too close to together on the trunk they will merge as they grow forming a solid ring of branches at on point of the trunk and choking the central leader reducing its growth. None of the scaffolds should be more that half the diameter of the trunk. The branch angle should be wide. You can cut off limbs you know you need to remove at any time. The worst time to prune is in the fall when the trees are preparing for winter. Sweet cherries often branch at the shoot tips with 3 vigorous branch coming from the buds at the tip of the shoot. Generally we remove all but one of the vigorous branches and also leave less vigorous branches below.
Cherry rootstocks are undergoing a revolution now with the release of dwarfing rootstocks developed in Europe. Mazzard (sweet cherry) and Mahaleb (perfume cherry) were the industry standard for centuries before. Mahaleb is the industry standard yielding a smaller tree and more fruit. Mazzard is preferred in wet sites or when Armillaria root rot (oak root fungus) is a known problem. The Gisela rootstocks give various degrees of dwarfing and commercial growers who by thousands of trees a year have to purchase their trees 3 to 4 years in advance. These rootstocks are patented and are only produced by a few nurseries which cannot keep up with the demand. smaller retail and mail order nurseries have not been able to compete with the demand for these rootstocks. I do not know how you would get your hands on them. You can probably find Mazzard and Mahaleb rootstocks from small independent nurseries, especially if they grow their own rootstock. Mazzard and Mahaleb are seeding rootstocks produced from seed rather than the clonal dwarfing rootstocks which are produced by stool beds or tissue culture. A small nursery might sell you a small lot of liners.
Grafting is done in the early spring before growth begins. One year old shoots are selected in the dormant season and kept cold and dormant until needed in the spring. You can search the internet for videos on grafting. I would suggest that you also consider budding which is the way commercial nurseries graft trees by the thousands. Budding is usually done in late July and August. Again you can find videos on budding on the internet.