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November Gardening Topics


  • Controlling Broadleaf Winter Weeds in Home Lawns - David Hillock, Consumer Horticulturist

    Winter weeds such as dandelions and clover in bermudagrass, Kentucky bluegrass, centipedegrass, perennial ryegrass, tall fescue, and zoysiagrass can be controlled in November with products containing 2,4-D, dicamba, and MCPP combinations. Air temperatures should be above 50o F for best control. Examples of commonly found winter annual broadleaf weeds include chickweed, dwarf fleabane, and henbit.


    Postemergence herbicides are applied following weed emergence when they are young and actively growing. Most are foliar absorbed, so they must remain on weed foliage for 24 to 48 hours following application. Postemergence broadleaf herbicides kill target weeds without injuring turfgrasses when applied at recommended rates. Examples include, 2,4-D, dicamba, MCPP and various other herbicides. Normally, two to three spray applications, spaced 10 to 14 days apart, are required for effective weed control. Broadleaf herbicides can damage desirable landscape plants if misapplied; be sure to read and follow label directions to protect landscape plants.

  • Top 5 Columnar Trees - Casey Hentges, Associate Extension Specialist and Bailey Lockhart, Extension Assistant

    Often when talking about trees, large shade trees come to mind. Unfortunately, some urban landscapes don’t afford the space to have large shade trees, but that doesn’t mean there isn’t a place for trees in the narrowest of locations.  In fact, it may be even more important to add vertical vegetation to soften the look of taller buildings or create a screen from neighbors. 

    Here are five columnar trees to consider:

    1. Oak trees are a staple across the American landscape. One columnar cultivar is called ‘Birthday Candle’ Quercus x warei.  It is hardy across much of the U.S., from zones 4-9.  It will reach a mature height of 45 feet while only expanding out about 18 feet.  It has traditional oak shaped leaves that turn a yellow-orange color in the fall. 

    An oak that gets a bit larger, around 50-60 feet tall with a width of 20 feet, is a cultivar called ‘Chimney Fire’ (Quercus x reifii var. warei).  As the name implies, it will have red fall foliage.

    1. Sweetgums often get a bad rep because of those annoying spiney seed balls they produce. However, the cultivar ‘Slender Silhouette’ Liquidambar styraciflua, adds just the right amount to any landscape.  With a height of 35-50 feet, it will maintain an impressively narrow spread of only 4 feet.  Although this one will still produce those seed balls, they are fewer in number.  Because the canopy is much smaller, they are not going to be littered all over your yard.  A nurseryman named Don Shadow, discovered the original plant that was 60 feet tall and 3 feet wide growing near a railroad track.  It is native in low, moist areas in the eastern half of North America, from just shy of New England down to Central America.  
    2. Just because we are talking about trees doesn’t mean they can’t add some flowers to the garden.  While we aren’t talking about a magnolia, it is in the magnolia family.  The tulip tree, Liriodendron tulipifera is native to the eastern U.S., but this cultivar is called ‘Arnold’.  Just like the traditional native, it too has large yellow-green tulip shaped flowers in late spring to early summer.  These flowers often go unnoticed until the petals begin to fall because they can be so high up in the canopy.  Planting ‘Arnold’ next to a multistory building will allow these flowers to reveal themselves to an audience up above.  ‘Arnold’ will max out at about 50 feet with a 15 foot spread. 
    3. Common Hornbeam, Carpinus betulus, is also called musclewood for its mature trunk that tends to look like muscles and happens to be a strong wood.  In fact, it is such an extremely hardwood, it was once used to make wooden yokes for oxen.  A yoke is a beam placed on the neck behind the horns, hence the common name hornbeam.  This tree offers up a columnar habit with the cultivar ‘fastigiata’.  Fastigiata is a word sometimes associated with other plants.  It means the plant has more upright, sometimes a columnar branching structure.  With a mature height of 40 feet, this fastigiata hornbeam will be narrower and more columnar in its earlier years but will gradually have more of an oval vase shape with age. 
    4. Zelkova serrata is another great urban tree.  It traditionally has a vase shape canopy which is nice to allow some sunlight in order to grow turfgrass around the base of the tree.  The cultivar ‘Musashino’ will reach 45 feet tall and maintain a narrow 10-15 foot width.  This fast-growing tree performs well in zones 5-9 and needs very little pruning. 

    Although each of these trees are familiar in their more standard form, it’s the skinny columnar cultivars that can add a unique touch to the narrowest garden spaces.


  • Fall Cleanup - David Hillock, Consumer Horticulturist 

    As plants in the landscape go dormant or are killed off by colder temperatures, it is a good time to do some fall cleaning in the landscape.


    Leaves falling from trees are a good source of mulch and compost. In wooded areas where there is little understory growth it is best to leave the leaves to decay naturally. If there are groundcovers or turfgrasses growing in the area then it is best to remove the leaves and compost them or use them as mulch.


    Most landscape debris can be chipped or ground up to be used in compost piles or as mulch. However, if plants have been plagued with diseases and insects it may be best to remove them completely from the garden by burning them (if allowed in your community) or sending them off to collection facilities. Debris infected with diseases or insects remaining in the landscape will only become a source for infection next year.


    Sanitation is an important step in reducing outbreaks of pest problems. A good example is the twigs that frequently fall from trees like pecan. It is very possible they are infected with the larvae of a twig girdler. Larvae overwinter in the dead twigs, eventually pupating in the twig and emerging as an adult next summer. Another good example is the numerous foliar diseases that also overwinter on dead leaves and debris only to spread to new growth the following spring. Removing these organisms from your garden will reduce the chances of them recurring the following year.


    Another practice during the fall and winter months that helps keep pests at bay is occasionally tilling fallow ground. Flower or vegetable beds that remain empty during the winter months can be tilled just before freezing temperatures. Hibernating insects are brought to the surface where they will be exposed to and killed by the cold temperatures.

  • Winter Protection of Broadleaf Evergreens - David Hillock, Consumer Horticulturist 

    A group of plants that often experience winter damage are the broadleaf evergreens such as hollies and boxwood. Water loss can cause severe damage to broadleaf evergreens during winter when high winds or temporary warm weather causes a plant to give off an unusually high amount of moisture.


    When this water loss occurs at times when there is little or no winter precipitation and the soil is dry, or the ground is frozen, roots cannot take up moisture to replace lost water. The result is a browning or burning of the foliage. When soils are dry, they can also get colder which could result in root damage too.


    Various management practices may help to prevent winter damage. Make sure the plants enter the dormant season in a healthy and vigorous condition with adequate soil moisture. Check to see that the center of the plant is free of dead leaves and other debris. And be sure to continue watering during the dry winter months. Monitor weather conditions and water during extended dry periods or about one to two times per month. Water only when air temperatures are well above 40 degrees F. Apply water at midday so it will have time to soak in before possible freezing at night. Mulch the plant with wood chips to reduce water loss from the soil. Mulch also protects the plant by preventing rapid temperature changes at the soil surface.


    Boxwoods seem to be more susceptible to winter damage. Boxwoods placed in sites exposed to winter winds tend to experience more damage. Provide wind protection for plants in exposed situations by creating a simple wind break. Use snow fences or stretch burlap between stakes or over a lattice frame set next to the boxwood. Or you can stick pine boughs in the ground around plants to form a wind break. When planting boxwoods, it is best to avoid exposed, windy sites.


    Large boxwoods and other evergreens prone to ice damage may be protected by wrapping the outer branches with strong nylon cord. Tie the cord securely to a low branch, pressing the boughs upwards and inward; wrap cord in an upward spiral around the bush, having cords 8 to 10 inches apart. Have cord tight enough to prevent breakage from excess weight of snow or ice, but not tight enough to exclude air circulation around the plant.

  • Controlling Deer Damage - David Hillock, Consumer Horticulturist 

    Oklahoma’s white-tailed deer (Odocoileus virgin­ianus) population has increased from 40,000 to more than 250,000 since the 1960s. As the deer population expanded, deer moved into peripheral suburban areas. Increasingly, homeowners at the rural/urban interface must deal with damage to ornamental and garden plants. As deer begin moving into an area, homeowners initially enjoy seeing them and may actu­ally encourage deer to come into their yard by feeding them. Rural subdivisions may ban hunting or place restrictions on firearm use to protect their deer or for safety reasons. Homeowner attitudes begin changing after deer numbers increase to the extent that shrubbery shows heavy browsing and gardens become difficult to grow because of continued depredation. In addition to browsing, damage may occur in the fall when bucks begin rubbing antlers on small trees or young nursery stock.


    Commonly Used Control Methods

    The problem of damage control is not an easy one to solve. Trapping and moving excess deer is often suggested by homeowners as a humane alternative to hunting with guns or even limited hunting with archery tackle. However, the cost to move enough deer to lower damage to tolerable levels is prohibitive. It should be recognized that most areas of Oklahoma are well populated with deer. Any deer moved to another area will only shorten food supplies for both resident and transplanted animals. Nature will then control the excess through starvation or decreased reproductive success because of chronic malnutrition. At best, trapping and relocating problem deer is only a short-term solution.


    Deer damage control methods fit into six catego­ries:

    1. exclusion—by electric fence or eight-foot high, deer-proof fence,
    2. scare or frightening tactics—with tethered dogs, gas exploders, fireworks or discharging firearms,
    3. habitat modification,
    4. population reduction through sport hunting,
    5. repellents—area repellents repel by smell and contact repellents repel by taste, and
    6. alternative plantings.

    Control methods other than an eight-foot high, deer-proof fence or an electric fence reduce damage by 50 to 75 percent at best, and often much less. A deer-proof fence does not fit well with most landscaping plans and can be expensive if large areas are to be protected. For small gardens, a deer-proof fence can be cost effective. For best results they should be constructed before serious damage occurs.


    Scare tactics work for only short periods of time but may be useful by providing enough protection to allow the crop to be harvested. Habitat modification is expensive and may attract deer if misapplied. A professional wildlife biologist should be consulted if this is the desired course of action. Population reduction by sport hunting is the most cost effective, long-term solution and should be seriously considered if damage is widespread.


    Repellents which provide an unpleasant taste or odor can be used, but damage will not be entirely eliminated. Effectiveness will vary with deer density, season, and availability of alternate foods. To be effective, repellents must be applied before deer begin actively browsing in the affected area. Area repellents are generally less effective than contact repellents. Research results on the relative effectiveness of area and contact repellents from several sources can be found in OSU fact sheet HLA-6427 Ornamental and Garden Plants: Controlling Deer Damage. Bear in mind that repellents will not completely eliminate damage and that a given method’s effectiveness will change seasonally, based on what natural foods are available to deer. Many repellents do not weather well and will need to be reapplied after a rain.


    To see a list of plant material that may or may not be affected by deer or for more information on control see fact sheet HLA-6427 Ornamental and Garden Plants: Controlling Deer Damage.


  • 2022 - Another Tough Year for Pecan Growers - Becky Carroll, Associate Extension Specialist, Fruit and Pecans

    Hopes were high for the 2022 pecan season, many growers that had faced late April freezes in the 2020 and 2021 seasons had made it through without the early cold temperatures and damage. Moisture was limited but abundant May and early June rains looked promising but a little worrisome on the disease front. Many growers were busy applying fungicides to control pecan scab infections. Growers were making difficult decisions on whether to apply fertilizer or skip this season. Fertilizer prices were peaking during pecan application times.


    Then it seems around the 2nd week of June, the rain stopped. Lack of moisture during the pecan sizing stage set the crop up to be smaller due to limited nut size. Many of the outlooks or crop forecasts had set Oklahoma to bring in around 11 million pounds before the drought settled in strong. The average of 17 million pounds produced in the state was not going to come to fruition in 2022.


    As the summer months passed with no moisture, many growers reported their crops were spotty in areas. Native producers began to realize their crops were going to be short and nut size was suffering. Nut quality in areas without irrigation could be impacted with adherence to the kernels, poor nut fill making kernel percentages low, and nut drop were all possible. Pecan trees need about 2 inches of water during the sizing process and more importantly during nut fill from August to nut ripening. During these critical stages of pecan development, Oklahoma experienced some of the driest conditions in over 100 years.


    Probably the one good thing about dry conditions was little pecan weevil activity. The lack of moisture limits the emergence of weevil from the soil. Those with irrigation and others still holding out hope of a crop monitored and sprayed insecticides to protect from weevil feeding and egg laying.


    On October 19, Oklahoma pecan growers in many areas suffered from an abnormally early freeze event. Two to three weeks earlier than normal, many cultivars and native pecans had not begun shuck split. Those with early ripening cultivars like Pawnee & Kanza had most pecans signaling they were ripe and ready to harvest with open shucks. Those later ripening and many native pecans were still ripening and filling the kernels. With the drought conditions, some shucks did not open on cue. Water stress can delay or inhibit shuck opening. Temperatures below 28 degrees for more than an hour will usually cause leaf or shuck damage. Stage of development plus low temperatures will determine crop loss for many growers especially in the Northeastern section of Oklahoma. So, the freeze on top of the drought was the one-two punch that will knock many growers out of getting their harvesters out of the barn.


    Visiting with growers around the state, projections had dropped to around 8 or 9 million pounds prior to the freeze event. Now, those forecasts look highly unlikely. Oklahoma will be lucky to bring in 3-4 million pounds this season. Those growers with the ability to irrigate adequately, and with early ripening cultivars have been busy the last two weeks harvesting what they can. Prices will be good starting out for those that have a crop.


    This drought will not only affect the pecan industry this year but will continue to provide problems for the upcoming seasons. Going into the winter under drought conditions can set pecans trees up for winter injury. The drought may show up in branch and tree loss in the next year or two. Another issue will be lack of fruit bud development this fall and little to no crop next year. Also, the early freeze in many areas got down into the teens. Without acclimating temperatures, younger vigorously growing trees may have freeze damage and tree loss.

    There is always next year.


    Oklahoma Pecan Industry acres


    Drought map from October 18, 2022


    Drought map verses Top pecan acreage

    Pecan kernels with adherence due to stress.

    Pecan kernels with adherence due to stress.


    Pecan cluster after October 19, 2022 freeze.

    Pecan cluster after October 19, 2022 freeze.

    These pecans will not be salvageable.


    October 19, 2022 low temperatures

    Low temperatures on October 19, 2022. Temperatures below 28 degrees can cause damage to green growing tissue like leaves and shucks.



  • 2022 Oklahoma State Pecan Show - Becky Carroll, Associate Extension Specialist, Fruit and Pecans

    The 2022 pecan harvest is quickly approaching, shucks are splitting, orchard floors are being groomed, and equipment is being serviced. Even with the severe drought conditions, pecan quality looks good in many areas. Pecans may be slightly smaller due to the lack of moisture during sizing but hopefully they will be well-filled.  Don’t forget to set aside some of your best pecans to enter in the Oklahoma State Pecan Show.  


    If you’d like to learn more about the Oklahoma State Pecan show and how to submit a winning sample, the Pecan Topics for November 2020 webinar has a presentation that you can view at -


    If no county/area show is available, growers may enter pecans directly by sending samples to:

    Cimarron Valley Research Station

    Attn: Becky Carroll

    10820 South Jardot

    Perkins, OK 74059


    Samples should arrive by January 27, 2023. 


    Samples should be entered in a sealed plastic or paper bag.  Label the bag on the outside and place a label inside the bag. Information should include exhibitor’s name and address, county, and type of pecan entered. Be sure to follow the guidelines that are listed below before sending entries. 


    A few helpful hints: Take the time to select pecans that are all the same cultivar, or same size and shape natives – don’t send mixed pecans.  Select uniform, clean, uncracked pecans. Presentation can make the difference between two very similar samples. Make sure to send two pounds of pecans in a labeled and sealed bag.


    General Rules and Guidelines

    • All entries must be grown in Oklahoma during the current season.
    • Each entry shall consist of two pounds of nuts.
    • Entries deemed unworthy by the judges will not compete for awards.
    • Label each entry as to exhibitor’s name, address and cultivar of nuts.  If more than one native (seedling) pecan exhibit is made, identify the nuts from separate trees by numbers.  Only one exhibit of each cultivar or native tree may be entered by one individual.
    • Each entry will compete in one of the following 26 classes:
    1. Barton
    2. Burkett
    3. Cheyenne
    4. Choctaw
    5. Comanche
    6. Gratex
    7. Kanza
    8. Kiowa
    9. Lakota
    10. Maramec
    11. Mohawk
    12. Nacono
    13. Oconee
    14. Pawnee
    15. Peruque
    16. Podsednik
    17. Schley (eastern)
    18. Shoshoni
    19. Squirrels Delight
    20. Stuart
    21. Waco
    22. Western
    23. Wichita
    24. Other Cultivars
    25. Large-Native (seedling) 60 nuts/lb or larger
    26. Small-Native (seedling) more than 60 nuts/lb

    Each grower is allowed to participate at one county show of his or her choice.

    • Each grower is allowed to enter one entry in each show class with the exception of Class 24 (Other Cultivars), Class 25 (Large-seedling) and Class 26 (Small- seedling)
    • Each grower may enter one entry from each native (seedling) tree.
    • Entries should be shipped or mailed to arrive at the show at least one day prior to the deadline.
    • County pecan shows will not be affected by these rules and procedures.
    • Samples will be placed in cold storage and judged prior to the Oklahoma Pecan Growers Annual Meeting.  At that time, the winning entries will be displayed with awards and recognitions.  All entries will become the property of the OPGA.
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