Fruit Tree Grafting Tips and Scion Selection

Fruit Tree Grafting Tips and Scion Selection

It’s mid-February, cloudy, and cold. It’s time to get outside and take cuttings for fruit and nut tree grafting. The cuttings that are grafted onto other trees are called scions. The trees or saplings that the scions are grafted to are called rootstocks. Grafting should be done when plants start to show signs of new growth, but for best results, scion wood should be cut in February and early March.

Scion Selection

Straight and smooth wood with the diameter of a pencil should be selected for scions. Water sprouts that grow upright in the center of trees work well for scion wood.  Scions should be cut to 12-18″ for storage. They should only need two to three buds each.

Scions

Scions ready for grafting. Photo Credit: Matt Lollar, University of Florida/IFAS Extension – Santa Rosa County

Scion Storage

Scions should be cut during the dormant season and refrigerated at 35-40°F until the time of grafting. If cuttings are taken in the field or far from home, then simply place them in a cooler with an ice pack until they can be refrigerated. Cuttings should be placed in a produce or zip top bag along with some damp paper towels or sphagnum moss.

Grafting

It is better to be late than early when it comes to grafting. Some years it’s still cold on Easter Sunday. Generally, mid-March to early April is a good time to graft in North Florida. Whip and tongue or bench grafting are most commonly used for fruit and nut trees. This type of graft is accomplished by cutting a diagonal cut across both the scion and the rootstock, followed by a vertical cut parallel to the grain of the wood. For more information on this type of graft please visit the Grafting Fruit Trees in the Home Orchard from the University of New Hampshire Extension.

Bench Graft

A bench graft union. Photo Credit: Matt Lollar, University of Florida/IFAS Extension – Santa Rosa County

Achieving good bench graft unions takes skill and some practice. Some people have better success using a four-flap or banana graft technique. This type of graft is accomplished by stripping most of the bark and cambium layer from a 1.5″ section of the base of the scion and by folding the back and removing a 1.5″ section of wood from the top of the rootstock.  A guide to this type of graft can be found on the Texas A&M factsheet “The Four-Flap Graft”.

Grafting is a gardening skill that can add a lot of diversity to a garden. With a little practice, patience, and knowledge any gardener can have success with grafting.

Proper Tree Planting

Proper Tree Planting

A newly planted tree with water retention berm.

A planted tree with water retention berm. Photo Credit: Matt Lollar, University of Florida/IFAS Extension – Santa Rosa County

Often, Extension agents are tasked with evaluation of unhealthy plants in the landscape.  They diagnose all sorts of plant problems including those caused by disease infection, insect infiltration, or improper culture.

When evaluating trees, one problem that often comes to the surface is improper tree installation.  Although poorly installed trees may survive for 10 or 15 years after planting, they rarely thrive and often experience a slow death.

Fall/winter is an excellent time to plant a tree in Florida.  Here are 11 easy steps to follow for proper tree installation:

  1. Look around and up for wire, light poles, and buildings that may interfere with growth;
  2. Dig a shallow planting hole as wide as possible;
  3. Find the point where the top-most root emerges from the trunk;
  4. Slide the tree carefully into the planting hole;
  5. Position the point where the top-most root emerges from the trunk slightly above the landscape soil surface;
  6. Straighten the tree in the hole;
  7. Remove synthetic materials from around trunk and root ball;
  8. Slice a shovel down in to the back fill;
  9. Cover the exposed sides of the root ball with mulch and create water retention berm;
  10. Stake the tree if necessary;
  11. Come back to remove hardware.
A hole being dug for a tree to be planted.

Digging a properly sized hole for planting a tree. Photo Credit: Matt Lollar, University of Florida/IFAS Extension – Santa Rosa County

Removing synthetic material from the root ball.

Removing synthetic material from the root ball. Photo Credit: Matt Lollar, University of Florida/IFAS Extension – Santa Rosa County

Straightening a tree and adjusting planting height.

Straightening a tree and adjusting planting height. Photo Credit: Matt Lollar, University of Florida – Santa Rosa County

For more detailed information on planting trees and shrubs visit this UF/IFAS Website – “Steps to Planting a Tree”.

For more information Nuttall Oaks visit this University of Arkansas Website.

Why Are My Oranges Sour?

Why Are My Oranges Sour?

From time to time we get questions from clients who are unsatisfied with the flavor of the fruit from their citrus trees.  Usually the complaints are because of dry or fibrous fruit.  This is usually due to irregular irrigation and/or excessive rains during fruit development.  However, we sometimes get asked about fruit that is too sour.  There are three common reasons why fruit may taste more sour than expected: 1) The fruit came from the rootstock portion of the tree; 2) The fruit wasn’t fully mature when picked; or 3) the tree is infected with Huanglongbing (HLB) a.k.a. citrus greening or yellow dragon disease.

Rootstock

The majority of citrus trees are grafted onto a rootstock.  Grafting is the practice of conjoining a plant with desirable fruiting characteristics onto a plant with specific disease resistance, stress tolerance (such as cold tolerance), and/or growth characteristics (such as rooting depth characteristics or dwarfing characteristics).  Citrus trees are usually true to seed, but the majority of trees available at nurseries and garden centers are grafted onto a completely different citrus species.  Some of the commonly available rootstocks produce sweet fruit, but most produce sour or poor tasting fruit.  Common citrus rootstocks include: Swingle orange; sour orange; and trifoliate orange.  For a comprehensive list of citrus rootstocks, please visit the Florida Citrus Rootstock Selection Guide.  A rootstock will still produce viable shoots, which can become dominant leaders on a tree.  In the picture below, a sour orange rootstock is producing a portion of the fruit on the left hand side of this tangerine tree.  The trunk coming from the sour orange rootstock has many more spines than the tangerine producing trunks.

A tangerine tree on a sour orange rootstock that is producing fruit on the left hand side of the tree.

A tangerine tree on a sour orange rootstock that is producing fruit on the left hand side of the tree. Photo Credit: Matt Lollar, University of Florida/IFAS Extension

Fruit Maturity

Florida grown citrus generally matures from the months of October through May depending on species and variety.  Satsumas mature in October and taste best after nighttime temperatures drop into the 50s.  Most tangerines are mature in late November and December.  Oranges and grapefruit are mature December through April depending on variety.  The interesting thing about citrus fruit is that they can be stored on the tree after becoming ripe.  So when in doubt, harvest only a few fruit at a time to determine the maturity window for your particular tree.  A table with Florida citrus ripeness dates can be found at this Florida Citrus Harvest Calendar.

Citrus Greening

Citrus Greening (HLB) is a plant disease caused by the bacterium Candidatus Liberibacter asiaticus, which is vectored by the Asian citrus psyllid.  The disease causes the fruit to be misshapen and discolored.  The fruit from infected trees does not ripen properly and rarely sweetens up.  A list of publications about citrus greening can be found at the link Citrus Greening (Huanglongbing, HLB).

A graphic of various citrus greening symptoms.

A graphic of various citrus greening symptoms. Photo Credit: University of Florida/IFAS Extension

Meet Matt Lollar

Meet Matt Lollar

Matt has served as a Horticulture Agent with the University of Florida/IFAS Extension for the past 10 years.  He began his career in Seminole County, FL as a multi-county agent focusing on vegetable crops and landscape installation and maintenance.  Being an Alabama native, Matt was ready to relocate closer to home.  After 5 years in Central Florida, he moved to Jackson County to become the Horticulture Agent.  In Jackson County he mainly focused on fruit and vegetable crops and coordinated Master Gardeners.  Matt became the Commercial Horticulture Agent in Santa Rosa County in the spring of 2018 and plans to be there for a long time.

Matt Lollar inspecting a persimmon tree

Inspecting persimmons at the West Florida Research and Education Center in Jay, FL.

Matt received his B.S. and M.S. degrees in Horticulture from Auburn University.  He became interested in horticulture in college and thought he would become a landscaper after college.  However, upon completion of his undergraduate degree, he decided to continue his education and work on a masters degree and conduct research on vegetable crops.  Matt’s major professor, Dr. Wheeler Foshee, had an extension appointment and instilled in Matt the value of helping others.  Matt says the most rewarding part of his job is the opportunity to build relationships with farmers, peers, and researchers.

In his free time, Matt enjoys spending time with his wife and two children, woodworking, and, of course, gardening.  He and his family enjoy exploring nature and playing board and card games together.  Matt also enjoys reading nonfiction political and war history books.

Clean Up for the Fall Vegetable Garden

Clean Up for the Fall Vegetable Garden

A common question for gardeners at the end of the season is if one should till the soil or use no till practices.  Opinions vary regarding this question, even among Extension Agents.  However old crops harbor insects, both good and bad.  This phenomenon was noticed on some recently cut back tomato plants.  The intention was to cut the leftover spring garden tomatoes back to encourage fall production.  Instead, a host plant for mealybugs was provided.

Whitefly larvae on a tomato plant.

Mealybugs on a tomato plant. Photo Credit: Matt Lollar, University of Florida/IFAS Extension – Santa Rosa County

Mealybugs are soft-bodied insects that possess a covering of flocculent, white, waxy filaments.  They are about 1/8 inch in length and usually pinkish or yellowish in color.  Mealybugs have piercing-sucking mouthparts which they use to siphon fluids from the leaves, stems, and sometimes roots of many ornamental and vegetable plants.  Mealybug damage produces discolored, wilted, and deformed leaves.

One very common example of an insect pest likely to claim residence in your garden’s crop residue, are squash bugs. They like to overwinter on squash, cucumber, and other cucurbit crop residue.  If you choose to not till your garden and leave a portion of last seasons crop in your garden, then you should consider applying an insecticide to your spent crop at the end of the season.  A product containing a pyrethrin or pyrethroid as an active ingredient would be a good broad spectrum insecticide to control any pest that may reside on plant residue.  More information on pyrethrins and pyrehtroids can be found at the EPA webpage: Pyrethrins and Pyrethroids.  If you choose to apply an insecticide, it is important that you follow the information on the label regarding pollinator protection.  Another option is to plant a trap crop on the edge of your garden to help attract pest insects away from your desired crops.  More information on trap crops can be found in the EDIS PublicationIntercropping, Pest Management and Crop Diversity.

An adult squash bug on a zucchini leaf.

An adult squash bug on a zucchini leaf. Photo Credit: Matt Lollar, University of Florida/IFAS Extension – Santa Rosa County

So the answer to the till or no till question is…it depends.  It is really up to the gardener.  Yes, the residue from crops will add nutrients and organic matter to your soil, but it could also increase pest pressure in your garden.  If you don’t plan to remove crop residue and don’t plan to till, then keep an eye out for what could be hiding in your garden.