David Hillock

Trees and Shrubs

  • Prune and feed azaleas immediately after blooming.
  • Soak new transplants and newly planted trees unless rainfall is abundant.
  • Pine needle disease treatments are needed in mid-May.
Insect Alert: (EPP-7306)
  • Bagworms on juniper and arborvitae. (Late May)
  • Elm leaf beetles and larvae on elms. (Late May)
  • Mimosa webworms on mimosa and honeylocust.
  • Lace bugs on sycamore, pyracantha and azalea.


  • Cool-season lawns can be fertilized again. If you did not fertilize cool-season grasses in March and April, do so now.
  • Warm-season lawns may be fertilized again in May. (HLA-6420)
  • Seeding of warm-season grasses such as bermudagrass, buffalograss, zoysiagrass and centipedegrass is best performed in mid-May through the end of June. The soil temperatures are warm enough for germination and adequate growing season is present to promote winter hardiness.
  • Dollar spot disease of lawns can first become visible in mid-May. Make certain fertilizer applications have been adequate before ever applying a fungicide. (EPP-7658)
  • Nutsedge plants become visible during this month. Post-emergent treatments are best applied for the first time this month. Make certain warm-season grasses have completed green-up.
  • The second application of pre-emergent annual grass herbicides can be applied in late-May or early June, depending upon timing of first application. Check label for details.
  • Vegetative establishment of warm-season grasses can continue. (HLA-6419)


  • Annual bedding plants can be set out for summer color.
  • Plant summer bulbs such as cannas, dahlias, elephant ear, caladiums and gladiolus.
  • Shake a leaf over white paper to look for spider mites.  If the tiny specks begin to crawl, mites are present.

Water Gardens

  • Clean out water garden and prepare for season. Divide and repot water garden plants.
  • Begin feeding fish when water temperatures are over 50°F.

Fruits and Vegetables

  • Plant watermelon, cantaloupe, cucumber, eggplant, okra, sweet potatoes, etc.
  • Fruit spray programs should be faithfully continued during the next several weeks.
  • Late May is the best time to control borers in the orchard.  Check for label recommendations and controls.

Transplanting Tomatoes

David Hillock

Two main types of tomatoes are available, determinant and indeterminate types. Determinate types set all their fruit at one time, while indeterminate types produce fruit over a longer time period. We typically grow indeterminate types in the home garden; however, determinate tomatoes are ideal for small spaces and containers or if you plan to can your tomatoes for later use.

When selecting tomato cultivars for the vegetable garden one consideration is disease resistance. Consider selecting varieties resistant to Fusarium wilt and nematodes since these are problems in all areas of Oklahoma.

The ideal tomato transplant should be six to eight inches tall and dark green, with a stocky stem and well-developed root system. Normally, six to eight weeks are required to produce this type of plant from seed. When selecting plants at the garden center, don’t be fooled in to buying the biggest, tallest tomato plants, a short, stocky plant is a better choice.

The number of plants needed, will depend on your planned use. If your family is interested in having only fresh fruit, plant three to five plants per person. If you intend to can or freeze fruits, then five to ten plants per person should be grown.

Tomatoes should be set in the garden when the weather has warmed and the soil temperature is above 60°F. These conditions usually occur about April 5 in southern Oklahoma and about April 25 in northwestern Oklahoma. Temperatures below 50°F impair tomato growth. Tomatoes will produce roots along portions of the buried stem. So to help increase the root system, I plant my tomatoes fairly deep. Pull off the lowest set of leaves or even two sets if the stems are very compact, and then set the plants to the depth of the lowest set of remaining leaves. This is much different than the way we plant most other plants, but is very beneficial for establishing a strong root system.

Sometimes the only tomato transplants we can find are long and leggy. To plant these, we will dig short trenches about four inches deep and lay the plants down in the trench. Set the plant in the trench and turn the top upward, leaving the top six inches of the plant exposed above the soil line as you fill the soil back in. This will allow roots to develop along the buried portion of the stem and you will end up with a much stronger plant than if you left the long leggy stem above ground.

Tomatoes are set two feet apart. Planting them in a line will make it easier to stake the plants later. A stake and weave system works very well in holding up the plants.

It is best to set out tomato plants in the evening or on a cloudy day to keep the plants from wilting and getting too dry. Mulching tomatoes is very important to provide even moisture and prevent fruit from cracking. Place a two- to three-inch layer of organic material such as compost, leaves or hay around the growing plants. Compost, which is dark, will help keep the soil warm. Once the temperatures rise, cover the compost with straw, which has more of a cooling effect.

For more information on growing tomatoes refer to Extension Fact Sheet, HLA-6012 Growing Tomatoes in the Home Garden.

Pecan Grafting

by Becky Carroll

Depending on your location, late April or early May is usually the start of grafting season. When the bark is “slipping” (bark easily peels from wood), it signals the time to start grafting. Remember your graftwood should be stored properly to insure grafting success. Keep it in cold storage until just before going to the field. Then protect it from heat and wind.

The graftwood source list is available online on the pecan webpage at

Converting small seedlings? Refer to fact sheet HLA-6230 or Four-flap Grafting of Pecans ( The four-flap or banana graft is used on smaller trees or small limbs, usually less than an inch. The important thing to remember is to size your graftwood to the rootstock or cut portion. Your graftwood should be slightly larger than the rootstock portion.

If you are changing larger trees to another cultivar the bark graft will work best. Fact Sheet HLA‑6204 details the process to use on trees up to about 4 inches in diameter.

An addition to both the bark and four-flap graft fact sheets is the information on the “American Method” of these grafts. This technique replaces the masking tape, foil and plastic bag with duct tape. Several pecan growers have switched to this method and are having success. I put on several grafts this last week to try it out. If you are interested in how they turn out, I’ll post to the brand new Oklahoma Pecan Management Facebook page. Be sure to “like” the page for more pecan information.

The pecan management webpage also has several videos to help with grafting. Oklahoma Gardening and the Noble Foundation videos are posted here to demonstrate the process.


by David Hillock

Bagworms can be a real nuisance on many plants. In Oklahoma the most common hosts are eastern red cedar, other junipers, and arborvitae. Other hosts sometimes damaged include pines, spruce, bald cypress, maple, boxelder, sycamore, willow, black locust, oaks, and roses. The bagworm has been recorded on 128 different plant species in various parts of the United States. 

Symptoms: Bagworm larvae damage their hosts by feeding on the foliage. Heavy infestations can completely defoliate small plants. Defoliation usually kills hosts such as red cedar and other junipers. Broadleaf hosts are not killed but are weakened and become more susceptible to borers and diseases.

Life Cycle: The overwintered eggs (in the year-old female bags) begin to hatch in late April or early May and the young larvae begin to feed and construct bags immediately. The first evidence of an infestation is normally a small bag, about 1/4-inch long, standing almost on end. As larvae grow, silk and fragments of the host plant foliage are added to the bag until it reaches 1 1/2 or 2 inches long. When larvae are mature they fasten the bag to a plant stem with silk. Pupation occurs in the bag in August and males emerge in late August and September. They engage in a mating flight in search of the wingless females still inside their bags. After mating the female lays several hundred white eggs inside her old pupal case, drops from the bag, and dies. There is one generation per year.

Description: Adult males are small, clear winged moths with a black, hairy body and a wing-spread of about 1 inch. Adult females are wingless, have no functional legs, eyes or antennae, and are almost maggotlike in appearance. The females body is soft, yellowish white, and practically naked except for a circle of woolly hairs at the posterior end of the abdomen. Mature larvae have a dark brown abdomen and the head and thorax are white, spotted with black. They are about 1 inch long. Both larvae and adult females are found in silken bags on the host plants.

Cultural control: Infestations can be reduced by handpicking bags (and overwintering eggs within bags) during fall, winter or spring before eggs hatch. Eggs remain viable within bags so be sure to destroy bags upon removal by burning them. When larvae become active, bagworms can still be removed by hand if the numbers are small and the affected host plants are small enough to reach the canopy. Again, take care to destroy the bags once they are removed.

Biological control: There are several naturally occurring parasitic wasps and predatory insects that attack bagworms. The activity of these natural enemies apparently explains the fluctuation in bagworm populations observed from year to year. 

Chemical control: Chemical controls are most effective if applied early when larva are small. In Oklahoma, it is normally a good practice to make applications of insecticide by early June. Bacillus thuringiensis var. kurstaki, a bacterial insecticide, is reported to provide good control of bagworms. Also effective are products that contain the active ingredient spinosad, another microbial agent. These insecticides must be ingested by the caterpillars in order to achieve kill, so be patient as it will take some time to see results. Repeat applications may be needed later in the summer in order to keep susceptible plants free of bagworms. This is not due to the occurrence of multiple generations. Rather, not all eggs will hatch at the same time in some years and there may be migration of larvae between host plants. In most years, treatment in early June will catch most of the emerging larvae and provide fairly good, seasonlong control. The larger, older larvae can be controlled with products containing acephate (Orthene), carbaryl (Sevin), bifenthrin, cyfluthrin, and lambdacyhalothrin.

Plant Highlight – Solomon’s Seal 

by David Hillock

Solomon’s seal is a perennial plant belonging to the genus Polygonatum. Variegated Solomon’s Seal (Polygonatum odoratum 'Variegatum') has a very strong white margin along the leaf edges. The plant has graceful, arching burgundy-colored stems that reach up to two feet.

Plant Solomon’s Seal in heavy shade, it does not tolerate strong sun, and the white variegation certainly brightens up a shady corner of the garden. The plant has a rhizomatous root system and spreads much like iris to form a dense clump. The flowers are rather unusual in that they dangle below the stems like tiny bells. Because they are produced on the underside of the stem, they are often overlooked. The flowers are delicate, white bells produced in pairs at the base of each leaf from April to May. They have a light, lily-like fragrance. The flowers are sometimes followed by blue-black berries, but often the berries do not form.

The name "Solomon’s Seal" is taken from the shape of the scar on the rhizome where the stem attaches. In some species this scar takes the shape of two overlapped triangles, which was the symbol King Solomon of Israel used to symbolize the union of body and soul. Solomon’s Seal is fairly easy to grow, but will certainly benefit from the addition of organic matter in the soil. It is a delightful, elegant addition to the shade garden.

Oklahoma Pecan Growers 86th Annual Convention

by Becky Carroll

The 86th Annual Oklahoma Pecan Growers Association Convention will be held in Tulsa on June 2‑4, 2016. Registration material is available at This year conference registration can be completed online.

The meeting will be held at the Tulsa Convention Center with accommodations at the Downtown DoubleTree by Hilton. Room reservations should be made by May 16. Use the OPGA group rate (OPG) for best prices. Commercial exhibits, educational meeting, state pecan show and pecan food show will be the included for the three-day event. The Saturday Field Day will be held at Mike Spradling’s pecan farm. The schedule and meeting agenda are posted to the webpage.

Please encourage 4-H kids and adults to enter the state pecan food show. Entries are needed to make the food show successful. Grand Champion winners receive silver serving pieces for the adults and silver pecan necklaces or tie tacks for youth. Entries are accepted Friday from 7:30 – 10 a.m. More information is available in the meeting information pack.

Spring Irrigation and Water Conservation Seminars

Joshua Campbell and Justin Quetone Moss

The ThinkWater water conservation Extension program hosts water conservation workshops and seminars. This spring, ThinkWater will host a series of short seminars in Oklahoma City metro area libraries and at water conservation demonstration areas. These seminars will cover a range of topics related to landscape water conservation.

Scheduled workshops include:

Water Conservation Basics – May 5, 2016

Water is an important resource. In Oklahoma we can experience both extreme rainfall and periods of drought. Because of this, it is important to understand water resources and the need to use them as efficiently as possible. Small indoor leaks can be huge water wasters and outdoor water use can account for as much as 50% of a household’s consumption. This free one-hour class will explore water saving tips to help you implement water conservation at home.

Sprinkler Systems and Lawn Watering – May 12, 2016 and May 26, 2016

Come learn the basics about automatic sprinkler systems and how to properly water your lawn. Whether you water with an irrigation system or a garden hose, we will provide helpful tips on watering efficiently. At this free one-hour class you will learn about affordable smart irrigation controllers, soil moisture sensors and rain/freeze sensors – simple technologies that can make a big difference in your water bill. You will also learn simple sprinkler repairs, the basics of controller programming –as well as all the programs offered by the City’s water conservation program and the resources available through the Oklahoma Cooperative Extension Service.

Plant talk with Oklahoma Gardening Host Casey Hentges at Bluff Creek Park – June 17, 2016

Come visit the Bluff Creek Park water conservation garden area and enjoy a picnic in the park while we discuss water conservation and drought tolerant plants with the Host of the Oklahoma Gardening television show – Casey Hentges.

To register for these free events, please visit and select the Workshops and Seminars tab.



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