Tips for Successful Citrus Grafting Including Tips for Grafting a Cocktail Tree by Dan Willey
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©2016 fruitmentor, Inc. All Rights Reserved.
In grafting citrus for more than 10 years, I have learned not only the factors that lead to success, but also many causes of failure. By sharing what I have learned on my YouTube channel and on fruitmentor.com, I have also learned from viewers and readers. Questions and feedback from readers have helped me to understand the most common beginner mistakes and questions. I have addressed those in this ebook and by doing so I hope to help you to succeed with your citrus grafting.
Please note, however, that citrus is one of the more challenging fruit trees to graft. Despite what I have learned, I still have failures. Even with the tips in this ebook, a beginner should expect some failures. As with many things in life, persistence leads to success in grafting citrus.
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General Tips for Grafting Citrus Budwood Citrus budwood has the potential to spread tree-killing diseases. It is often not apparent when a tree is infected with a fatal disease. Depending upon location it may be necessary to order citrus budwood from a registered disease-free source. In California hobbyists now avoid the use of cuttings taken from backyard trees and instead order cuttings from a program called the Citrus Clonal Protection Program. Similar programs exist in many parts of the world.
Time of Year and Temperature Temperature is a very important factor when grafting citrus. I believe that many people think that citrus grafting is more difficult than it really is because they graft at the wrong time and the scions dry out and die before the graft heals. The ideal time of year to graft citrus depends upon the local climate. The temperature at which citrus wounds best heal is between 70°F and 85°F (21°C to 29°C). Citrus should ideally be grafted when temperatures in this range are forecast.
Weekly Temperature Forecast Favorable for Grafting v1.0
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Watering Before Grafting The soil of the tree receiving the graft should be moist, but not excessively moist. If the soil is dry, then the tree should be watered prior to grafting. On the other hand, too much moisture in the soil could result in too much sap flow, which could cause the graft to fail. So if watering is necessary before grafting, it is preferable to water long enough prior to grafting so that the soil is not excessively moist at the time of grafting. This may vary depending upon the soil and depending upon whether the tree is in the ground or in a pot. I have had grafts start growing and then die due to mold under the parafilm wrapping. I suspect that a contributing cause was that the soil was too moist, causing excessive sap flow, too much moisture under the parafilm, and then the growth of mold.
Sterilizing Tools It is important to sterilize tools both to prevent the spread of diseases from tree to tree and also to kill pathogens that may harm the graft and cause it to fail. Grafting tools should be sterilized, preferably with bleach at a concentration of 1.5% or higher. I like to use a product called Clorox Clean-Up to spray my tools. When sterilizing tools with bleach, it is important to get all of the bleach off of the tools. I have written a more detailed article on sterilizing tools here: http://www.fruitmentor.com/sterilizing-grafting-tools
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Time of Day Since citrus is best grafted during warm parts of the year, high temperatures can cause the graft to dry out during the grafting procedure. To avoid this, it is important to graft at the right time of day. It is best to graft in a cooler part of the day. I like to graft either at dawn or at dusk.
Working Quickly If the scion or rootstock dries up during the grafting procedure, the graft will be more likely to fail. Working quickly will help to avoid this sort of failure.
Using the Correct Supplies Using the correct supplies for the type of graft being performed can make the difference between the failure of the graft and the success of the graft. I have had T-buds fail because I wrapped them with parafilm rather than vinyl tape. The bark lifted up and broke through the parafilm, causing the graft to dry up and die. The next time I tried to compensate by wrapping with a rubber band on top of the parafilm and had another graft failure. If I had simply used the correct wrapping material I would have saved not only the money that I wasted on budwood but also my precious time. I have created a web page with my favorite supplies and tools for grafting citrus. I hope that you find it helpful: http://www.fruitmentor.com/grafting-supplies-and-tools
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Wrapping the Graft When wrapping a graft, wrap from the bottom up and overlap the layers. If rainwater gets inside of a graft, it can cause it to fail. Wrapping the graft from the bottom up will help to keep the water out like shingles on a roof. The graft should not be wrapped excessively, however.
Sprinklers One time my graft of a new variety to someone’s tree ended up failing. When I went to see the failed graft, I found that it was wet and there was a sprinkler pointed directly at the graft. Perhaps more careful wrapping would have saved the graft from the sprinkler, but my conclusion is that it is best to make sure that there are no sprinklers pointing at citrus grafts.
Grafting on a Rainy Day I have read that citrus should not be grafted on a rainy day because the increased humidity favors fungal diseases that can cause the graft to fail. In California where I live this is not much of a factor because the temperatures most favorable for grafting citrus are during the dry season. This may be important for those in other climates, however.
Unwrapping the Graft I unwrap bud grafts after three or four weeks. For scion grafts, the wrapping material provides support that helps keep the scion in place while healing. If unwrapped too soon, a scion graft is much easier to break than a bud graft. The graft will grow well with the wrapping material in place, so there is usually no urgent need to unwrap the graft. Often the wrapping material will deteriorate on its own. The one case where v1.0
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I found it helpful to unwrap the grafts sooner was when some of my grafts started to mold under the parafilm (see Watering Before Grafting above). When I noticed this happening, the grafts were already growing and I was able to save most of them by unwrapping them.
The Scion One beginner mistake is to graft a bud or scion upside down. The scion to the right shows three buds and two petioles. The orientation of the scion can be determined by looking at the buds and the petioles. A bud appears above a petiole. In some cases as with the bottom bud here, the petiole has fallen off. A scar where the petiole was attached is still clearly visible below the bud and can be used to orient the scion. When scion grafting, the length of the scion is also important. Another beginner mistake is to graft an entire scion without pruning any of it off. If the scion is too long, it can make the graft more likely to fail. The extra surface area may cause the graft to dry out before it heals. I recommend leaving 3 or 4 buds of the scion above the graft bud union. I tend to favor fewer buds, but if I have grafted a scion where the buds are spaced closely together then I might choose 4.
Budding vs. Scion Grafting In almost any situation my preference is to graft citrus using scion grafts rather than bud grafts. This applies to both grafting new trees and adding new varieties to existing trees. In all situations I have observed that scion grafts grow much faster than bud grafts.
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Multi-grafted Cocktail Tree Tips Grafts Need Sunlight The location of a graft on the tree is important. Pick a location on a target branch that receives plenty of sunlight. Citrus grafts will heal regardless of the light levels. However, if there is not enough light reaching the graft, other branches of the tree will overtake it and it may eventually die.
Leave Room for Mistakes When cutting off the end of a branch to do a scion graft, it can be helpful to leave a little extra room on the branch in case of mistakes. What this means is that it may be helpful to cut a little bit above what may seem like the perfect spot for the graft. If the graft fails or there is a mistake when performing the graft, the extra branch length gives an opportunity for a second chance. The tip of the branch can be cut off and another graft attempt can be made lower on the branch. Otherwise it might be necessary to cut the branch off entirely or wait for it to grow out again before trying another graft.
Understanding Apical Dominance A natural phenomenon called apical dominance governs the growth of citrus buds and is important to understand when grafting a multi-variety tree. Natural hormones from the buds at the ends of citrus branches prevent buds lower down from growing. In order for a grafted bud to grow, the effect of these hormones must be overcome. I suspect that one reason scion grafts grow so much more quickly than bud grafts is that a scion graft more readily overcomes the effect of apical dominance. It is also helpful to keep apical dominance in mind when choosing the location on a tree for a graft.
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Adding New Varieties at the End of a Branch I have seen people graft to the main trunk of a citrus tree. Apical dominance prevents these grafts from growing. The only hope to get buds grafted to the main trunk of a tree to grow would be to severely prune the tree because every terminal bud above is producing hormones that prevent buds on the trunk from growing. When adding new varieties, it is best to add them at the end of a pruned branch. This helps to overcome apical dominance which would stop the buds from growing.
Adding Multiple Scions per Branch When grafting to a large diameter branch, it is useful to graft multiple scions at the same time. This will increase the likelihood of success and also help the large wound to heal faster. As the wound heals the strongest branch should be retained and all other scions should be pruned off. This will make for a stronger graft union than if multiple scions remained. When adding multiple scions to the end of a branch, it is best to graft only one variety since the weaker scions will be removed.
Whitewashing When the ends of branches are removed from a citrus tree to make way for grafts, the formerly-shaded lower parts of the branches can be vulnerable to sunburn. The bark can potentially crack and be severely damaged. This can also happen after a severe freeze that defoliates a citrus tree. In order to avoid sunburn, branches can be whitewashed. I use a mixture of one half white latex paint and one half water.
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Unbalanced Growth A factor to consider when grafting multiple varieties to a citrus tree is that some citrus varieties grow faster than others and the tree can become unbalanced. One reader who has experience with multi-grafting citrus trees reported that he has seen one variety outgrow the others by a factor of 5 to 1, resulting in a lopsided tree. Citrus trees normally do not require much pruning, but pruning can compensate. My first multi-grafted tree was a large navel orange tree. I grafted around 30 varieties of citrus to it. A photo is to the right. I would not say that it became lopsided, but I did observe that some slower-growing varieties were overtaken. I believe that young citrus trees grafted with multiple varieties may have more of a tendency to become lopsided than older trees.
Citrus Hedges For those who are daunted by the prospect of pruning a lopsided tree and who have the space, planting multiple closely-spaced trees in a hedge is an alternative way to grow more citrus varieties. I have been very pleased with this approach. The hedge to the right has eight trees spaced 27.5 inches (70 cm) apart. It is on the north side of my house where I had been uncertain that there would be enough light. It has performed very well, producing some of my most delicious citrus fruit. I turned a couple of these v1.0
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trees into two-in-one trees, with the second variety grafted to the single main trunk of the tree. Because the first variety is only on the bottom, the tree remains balanced.
Thank you! Thank you for reading this ebook! I hope that you have found it valuable and that it helps you to succeed with your citrus grafting. If you know someone who you think may benefit from this ebook, please feel free to share it with them by sending them a link to the following web page where they can download a free copy of the ebook and join the fruitmentor newsletter: http://fruitmentor.com/GraftingTips If you somehow received this ebook without subscribing to the newsletter, you can subscribe via the link above and at the same time be sure that you have the most up-to-date version of the ebook. If you have any feedback on the ebook, I would love to hear it. Thanks again and I wish you success!
Dan Willey
[email protected]
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