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Friday, June 2, 2017

Remove Suckers from the Graft Union

Q. You mentioned that citrus trees are often grafted. Are full size trees grafted like dwarf trees? Do I need to remove anything from these grafts? The only tree that really produced was a grapefruit while my orange and tangerine, produced very little over a span of 9 years. They flowered in the spring and work protected from wind and freezing temperatures. Will I have more success in getting fruit from full size trees?
suckers coming from the rootstock
A. All citrus bought from commercial nurseries are grafted with another tree. This grafting gives it a different set of roots. This new set of roots is called the rootstock. Most fruit trees are not intentionally grafted to rootstocks to dwarf the tree. But some dwarfing can result from rootstocks that are not terribly fast growers. If the rootstock dwarfs the tree, it should be mentioned on the label.
            There are five major citrus rootstocks, each with different characteristics that benefit the tree. A citrus rootstock may be added because of soil problems, disease issues, dry soils or survival during freezing temperatures. Knowing the type of rootstock can be extremely important to commercial growers with a certain set of growing problems.
            Nurseries that buy citrus to sell in the Las Vegas market usually focus on rootstocks that survive freezing temperatures. A little of this tolerance to cold temperatures is passed on to the tree itself.
bud union on fruit tree making a dogleg
            Look at the base of your citrus tree trunk. You will see a “dogleg” or bend (or noticeably swollen) where the two trees were grafted together at a very young age. Any shoots growing at or below this “dogleg”, called suckers, must be removed since this growth will not give you desirable fruit or benefit the tree in any way.
            Remove suckers now and continue to remove them as soon as you see them. If you remove them when they are very young, they will break away easily from the tree. Don’t wait or let them get older or they will be more difficult to remove.
            Older trees stop producing suckers from the rootstock if you start removing them early, when the tree is young. But if the top is killed from freezing temperatures, the rootstock will start suckering, even from older trees, and produce a vigorous new tree from or below the dogleg. It looks pretty but this “new” tree will have very poor quality fruit.
Many citrus flower and begin fruiting at the same time we have freezing temperatures. If your citrus is in a warm, protected spot you have a better chance of getting fruit. You can protect them with lights, blankets, burlap, etc. but if the temperature and wind are bad enough, protection will not guarantee fruit and a lack of damage. The tree may require temperatures of 20 - 25° F for damage to occur. However, all flowers and fruit are killed at 30 - 32° F regardless of the temperatures required for tree damage to occur.
            Citrus is “iffy” in this climate. Some years you may have fruit, other years you may not. Some years they may freeze to the ground and other years sail through the winter without damage. This is the nature of our climate and growing citrus here.

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