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December 15, 2017
By Virginia Ruschhaupt - Victoria County Master Gardener
Edited by Charla Borchers Leon
PHOTO CONTRIBUTED BY SHUTTERSTOCK.COM
Peach trees are self-fertile with flowers having both male and female parts. Only one tree is required for pollination, which occurs with little movement from the wind or pollinators like the bee shown on these beautiful, pink peach tree blooms.
PHOTO BY PAT PLOWMAN/VICTORIA COUNTY MASTER GARDENER
Rio Red grapefruit trees produce an abundance of fruit without the necessity of cross-pollination. It is a good citrus variety that does well in the Crossroads growing environment.
Meyer lemons generally have perfect flowers and do not require cross-pollination. The off-white blossom opens from a purplish-white bud that has a sweet, perfumed scent and attracts bees and butterflies, particularly the swallowtail. They thrive in this area and are a popular citrus tree for landscapes or containers/pots.
Chilling requirement hours for a tree to break dormancy have been determined by Texas A&M AgriLife Extension for each county. It is the number of hours at or below 45 degrees, beginning in November. Average hours for Victoria and nearby counties range from 400 to 600 and are considered Medium Chill.
Editor's note: Today's author is in Texas Master Gardener training for Home Fruit and Nut Tree Specialist - Southern Texas 2017, which serves as a major source for this article. Since there have been various articles published previously on citrus and recently on persimmon in this column, other various fruit and nut trees are included in today's publication.
When buying a fruit or pecan tree, one of the first questions people ask is, "Do I need one or two trees?" Some fruit trees are self-fertile, while others require a pollinator. We might think that means a second tree of the same variety, but choosing an appropriate pollinator is more complex, with each type of tree having specific requirements.
It's important to select the right trees for our climate, keep our trees healthy and understand pollination issues. These factors are interrelated with one problem causing another, resulting in minimum crop yield - or none at all.
Let's evaluate some fruit and nut-bearing trees and their pollination requirements, starting with simple self-fertile trees and moving on to more complex variations.
Self-fertile
Since peaches are self-fertile, with each flower having male and female parts, only one tree is needed. Pollination of peaches is easily accomplished with minimum motion from wind or bees.
Choose a variety with chilling requirements close to the average hours of chilling for your location. A simplified definition of "chilling requirement" is the number of hours at or below 45 degrees, beginning in November, which would be required for a tree to break dormancy. Average chilling hours have been determined for each county.
If the hours of actual chilling in an area exceed the hours required by a specific variety of tree, the tree is likely to bloom too early and risk chance of freezing. If the hours of actual chilling are less than the hours required, the tree won't properly break dormancy, resulting in poorly formed flowers and few, if any, peaches.
Figs are self-fertile but don't have chilling requirements. Note that a tree's "chilling requirement" and tolerance of temperatures below freezing are two separate issues.
Most varieties of citrus are self-fertile with a few exceptions.
Pomegranates are self-fertile, but cross-pollination by insects increases fruit production. High humidity can interfere with fruit formation.
Olives
Olives are self-fertile, but according to Monte Nesbitt, TAMU Extension Fruit Specialist, one of the many problems with growing olives in our Coastal Bend region is that temperatures by blooming time may create loss of fertility.
Some variations
Pear trees require appropriate chilling and cross-pollination; that is, pollination by a second tree of a different variety blooming at the same period of time. Thanks to bees, some varieties may still produce fruit without that second tree in your backyard. Disease susceptibility further limits the varieties of pears grown in our Crossroads area.
Apples have more pollination challenges than pears, including: appropriate chilling, cross-pollination by a different variety in close proximity, blooming at the same time and substantial bee activity to the extent that commercial growers maintain their bees.
Although I grew up on a farm with lots of pecan trees, including many grafted by my grandfather, I never gave much thought to pollination of pecans necessitating more than one tree. But there are definite requirements because of separate male and female flowers borne on each tree.
A Type I tree (protandrous - with pollen shedding first) should be paired with a Type II tree (protogynous - female flowers receptive first), which need to be pollen shedding and pollen receptive at the same time. Good selections can be made based on pollination charts that set out the timing of shedding and receptivity for various Type I and II cultivars.
If native pecans are within sight of your planting location, you may not need to purchase a second tree for pollination, since it is assumed that about half the native trees are Type I and half are Type II.
Increase chances of successful pecan yields by selecting varieties designated for East Texas and with excellent pecan scab resistance. Weather conditions in this area are conducive to the spread of this fungus, which can decimate your pecan crop.
Climate can determine whether or not avocados need a cross-pollinator. For example, in California, a cross-pollinator is necessary, matching a Type I and Type II tree; however, in South Texas, climate generally creates some overlap in Type I and II conditions allowing avocados to self-pollinate.
Choose tree variety based on factors
Knowing whether to choose one or two trees is not the only factor for maximum fruit and nut production. Choose the appropriate variety of tree for your area based on climate, chilling requirements and disease resistance coupled with a suitable pollinator if applicable.
Do some research to determine the best choices. Keep your trees healthy. Use pesticides judiciously for the protection of bees that are vital for successful pollination and production of fruit.
The Gardeners' Dirt is written by members of the Victoria County Master Gardener Association, an educational outreach of Texas A&M AgriLife Extension - Victoria County. Mail your questions in care of the Advocate, P.O. Box 1518, Victoria, TX 77901; or vcmga@vicad.com.
Why does satsuma not bear fruit every year?
• Without proper nitrogen control, some citrus trees, particularly satsumas, may bear a large crop one year and then nothing the following year. This is not a pollination issue.
Why are there seeds in my clementine Mandarin?
• Clementines are self-fertile and seedless; however, if they are cross-pollinated by any citrus, you may have unexpected seeds in your clementine.
Since persimmon trees bear either male or female flowers, do I need both trees?
• Generally a male persimmon tree is required to pollinate a female tree. There are exceptions like Hachiya, Fuyu, and a few others that bear only pistillate or female flowers and still manage to produce a full crop of fruit as if they were self-fertile.
• WHAT: Lunch and Learn with the Masters
• WHEN: Jan. 8
• WHERE: Dr. Pattie Dodson Public Health Center
• TOPIC: "Growing Peach Trees in the Victoria Area"
• Calhoun, Goliad, Jackson, Refugio, Victoria - 400 hours (250-550)
• DeWitt, Lavaca - 500 hours (350-650)
• Fayette, Gonzales - 600 hours (450-750)
• All of these areas are considered medium chill
ph: 361-935-1556
nancyk