July 2013 / Volume 77       

In This Issue
July Lawn and Garden Tips
Become A Master Gardener
Upcoming MG Events
Maximize Your Harvest with Succession Planting
Hedge and Shrub Pruning: Why, When and How
Drying Out
Ask A Master Gardener...Knockout Rose disease

Weather Stats for Gardeners

Soil Temperature 2" below sod:   

79 degrees 


Rainfall total last 30 days:  

2.67 inches


4 Ways to Contact Us
Email us at:

See our website at: www.tulsamastergardeners.org 

Call: 918-746-3701 from 9-4, M-F 
Visit us at 4116 E. 15th Street, Gate 6 at the Fairgrounds

Whether you call or bring samples of plants to the office, trained Master Gardeners will answer your gardening questions with science-based information.
Need More Information?

Click on any of the links below:


All about butterfly gardening in Tulsa County 

How to Take a Soil Test

How to collect a good sample of soil from your lawn or garden and get it tested at the OSU lab.
Understanding Your Soil Test Results
Once you have collected your soil test and gotten the results back, now what? Find out here. 
How to Plant a Tree in Oklahoma Soil
Show and tell.
Cool Season Lawn Care (Fescue)
12-month maintenance calendar.
Warm-Season Lawn Care (Bermuda)
Ditto above.
Trees for Tulsa
A list of recommended trees with descriptions.
Crape Myrtles
A list of over 60, by size and color.
Demonstration Garden
Visit our demonstration garden on 
15th Street, open 7 days a week.  
Oklahoma Proven Plants
State horticulturists, nurseries and growers pick favorite plants, shrubs and trees for use in the Oklahoma landscape. See the winners for this year and years past.
Current and historical source of rainfall, air temperatures, soil temps and much more. Click on Bixby station.  

Back Issues  

Past issues of our eNewsletters can be read and downloaded.

Become a Master Gardener

Classes start in September each year. Register at our office on 15th Street for more information.

Oklahoma State University, in compliance with Title VI and VII of the Civil Rights Act of 1964, Executive Order 11246 as amended, Title IX of the Education Amendments of 1972, Americans with Disabilities Act of 1990, and other federal laws and regulations, does not discriminate on the basis of race, color, national origin, gender, age, religion, disability, or status as a veteran in any of its policies, practices or procedures. This includes but is not limited to admissions, employment, financial aid, and educational services.
July Lawn and Garden Tips 


  • Make fall vegetable garden plantings in late July, including tomatoes, pepper, eggplant, squash, pumpkins, beans and corn. Fact Sheet HLA-6009 gives planting recommendations.
  • Mulch is your plants best friend.
  • Continue insect combat and control in the orchard, garden, and landscape. EPP-7306, EPP-7313, EPP-7319)
  • Check pesticide labels for "stop" spraying recommendations prior to harvest.
  • Harvest fruit from the orchard early in the morning and refrigerate as soon as possible.
  • Soil tests are recommended for lawns and garden beds every three years. 
  • Brown patch disease of cool-season grasses can be a problem. (HLA-6420) 
  • Meet water requirements of turfgrasses. During the July and August heat, Bermuda lawns need one inch and fescue 2 inches of water per week. Water lawns 2-3 times weekly trying to wet the ground to 6 inches.  (HLA-6420) 
  • Fertilization of warm-season grasses can continue if water is present for growth. (HLA-6420) 
  • Vegetative establishment of warm-season grasses should be completed by the end of July to ensure the least risk of winter kill. 
  • Mowing heights for cool-season turf grasses should be at 3 inches during hot, dry summer months. Gradually raise mowing height of bermudagrass lawns from 1� to 2 inches.
  • Sharpen or replace mower blades as needed. Shredded leaf blades are an invitation to disease and allow more stress on the grass.


  • Control bermudagrass around trees and shrubs with Poast, Fusilade, or Glyphosate herbicides. Follow directions closely to avoid harming desirable plants.
  • Divide and replant crowded hybrid iris (Bearded Iris) after flowering until August. 
  • Water plants deeply and early in the morning. Most plants need approximately 1 to 2� inches of water per week.
  • Providing birdbaths, shelter and food will help turn your landscape into a backyard wildlife habitat.
  • Insect identification is important so you don't get rid of the "Good Guys" (EPP-7307). When using any insecticide spray early in the morning or late in the day when bees are not present.
  • The hotter and drier it gets, the larger the spider mite populations!
  • Expect some leaf fall, a normal reaction to drought. Water young plantings well.
  • Watch for bagworms on your arborvitae and junipers. See May's notes regarding control.
  • Providing birdbaths, shelter and food will help turn your backyard into a wildlife habitat.  

Want to Become a Master Gardener?    
The Tulsa Master Gardener program is looking for active adults that enjoy interacting with people, get along well with others, are life-long learners and are ready, willing and able to volunteer their time to enhance the numerous Master Gardener community outreach programs. The training program for new Master Gardener Volunteers is offered once a year beginning in September.

For those interested in 2013 training, two orientations will be held at the Tulsa County OSU Extension Center at 4116 E. 15th St. Tulsa; 1:00 pm on Wednesday, August 7, and 10:00 am on Wednesday, August 14. For further details, visit www.tulsamastergardeners.org.

Master Gardener Upcoming Events  

Fall Plant Sale

Tulsa Master Gardeners will be selling pansies, panolas and ornamental kale for fall planting. Online shopping cart will begin July 22 and continue through September 8. Delivery date is scheduled for October 11 at the OSU Extension Center. More information to come or visit www.tulsamastergardners.org.


The Home & Garden Expo of Oklahoma

Visit the Tulsa Master Gardeners Booth 131 in the River Spirit Expo Building at the Tulsa fairgrounds to get container-grown vegetable ideas, get help solving your pest problems, and share your success stories. OSU fact sheets will be available. 

Free Admission

Friday, July 25: 12pm - 8pm * Saturday, July 26: 10am - 8pm

Sunday, July 27: 11am - 5pm


Free Tuesday class 

Tulsa Master Gardeners are offering a free class on "Drip Irrigation the Easy Way" on Tuesday, July 30 at 5:30pm, with the lecture lasting approximately 30 minutes and another half hour for discussion. There is no need to register, just come to the auditorium at the OSU Extension Office, which is on 15th street at gate #6 into the Tulsa Fairgrounds.

Maximize Your Harvest
With Succession Planting
Now that spring has come to a close and hot weather has set in, those cool weather crops such as greens, peas, and cabbages have mostly phased out, while the much loved tomatoes, corn, peppers, etc. have started to come on. The harvest of cool season vegetables has probably left you with a large void of space to plant with the end of the growing season still several months away.

Once  you harvest your lettuces and peas, don't leave that space unoccupied! Maximize your garden space through the practice of succession planting. While succession planting can refer to the continuous sowing of one crop throughout the season to ensure a steady harvest, it can also refer to  following one outgoing crop with a different one, ensuring a steady supply of fresh vegetables on through summer and into fall.

July may be the dog days of summer. but there are several crops that can be started by mid-month for a fall harvest. For example:
  • Summer squash, winter squash, pumpkins, pole beans, and carrots can be sown directly in your garden bed in mid-July.  
  • If you can locate some transplants, or have the means to grow your own, broccoli and brussels sprout seedlings can be set out at the same time.
  • If the spider mites and squash bugs got to your tomatoes and squash before you did, don't worry; another crop can be planted now for a fall harvest.  
  • Other vegetables such as cucumbers, bush beans, cabbage, and lettuces can be sown directly into the garden in August.
For more information on late season planting dates see Fact Sheet Fall Gardening.

Hedge and Shrub Pruning:
Why, When, and How?
Although the type of pruner can make a gardener's life easier, knowing when to prune is just as important to create a vibrant, colorful garden. Proper pruning enhances the beauty of almost any landscape tree or shrub and is an essential maintenance practice in home landscaping. On the other hand, improper pruning can destroy the natural beauty of a tree or shrub and reduce its landscape potential by weakening and thus disposing plants to various maladies. Pruning, like any other skill, requires knowledge and practice to achieve success.

First, let's review why it's important to prune. First and foremost, removing dead, diseased, broken, and crossed/rubbed branches maintains and improves the health of any plant, shrub or tree. Second, it improves the flowers, fruit, foliage and stems. Third, pruning is done to train the plant to avoid power lines, structures, or remove weak crotches before high winds do it for you (and that won't be pretty!).  Finally, it is done to restrict the plant's size and/or control its natural shape and beauty.

Pruning is not difficult if you understand the basics and take the time to learn why, when, and how to prune. The necessity for pruning can be reduced or eliminated by selecting the proper plant for the location. Plants that might grow too large for the site will require pruning to keep them in bounds, destroying the original intent and also making the plants unsightly and possibly weak with age. If this is the case, consider replacing the plant with a smaller growing tree or shrub such as a dwarf (shorter) or columnar (more narrow in width) cultivar of the original species. Unless pruning is done to form a formal hedge, espalier, or topiary, it should not be utilized to destroy or alter the plant's natural shape. The general rule of thumb is to not remove any more than 1/3 of the branching system of any tree or 2/3 of a shrub or vine in any given year. Remove most inside branches that have become crowded or crossed to promote more air flow, which will reduce disease potential (such as fungus).

If needed, evergreen shrubs (yews, juniper, and boxwood, etc.) may be pruned in early spring before new growth begins or later in May through July; spring-flowering shrubs (forsythia, rhododendron, lilacs, etc.) should only be pruned, if needed, soon after blooming is completed; flowering perennials and annuals (deadheading to promote continued blooming throughout the summer); and roses, once they have bloomed (to promote the next set of blooms). Unless absolutely necessary, tree pruning should be held off until the winter months.

The right tools can make pruning and cutting much easier. Be sure to try out several varieties and find ones that easily fit into your hand. Most likely, paying a little more for higher quality tools now will pay off in the long run. And, after each use, be sure to clean and dry them thoroughly to promote sharpness and the overall life of the product. 

More information on this subject can be found on the OSU Fact Sheet Pruning Ornamental Trees, Shrubs, and Vines. For Annual Pruning of Fruit Trees, click here.

Drying Out       
Spring and early summer have been much different compared to last year, but have we really had more rainfall this growing season? And, are we still in a drought here in Tulsa?

The answer to the first question is yes...but barely. If we consider the period of April 1 to June 30, normally the wettest three-month period of the year, precipitation at Tulsa International Airport was slightly more than last year, but still about 4� inches below normal. Other parts of Tulsa County were luckier, such as Jenks Riverside Airport, which was only about an inch below normal and well ahead of the pace of last year. A bigger factor in vegetation health has probably been the cooler than normal temperatures this spring that have kept evaporation of soil moisture less than normal. But, throw in the inevitable hot weather that comes with summertime, and a recent dry spell, and things are starting to really dry out again.

As for the second question, we are not currently considered to be in a drought in Tulsa at this time, although we are back to "abnormally dry" after a respite this spring. But, precipitation is much more hit and miss through the summer, and with long term precipitation deficits still large, unless we are really lucky, we will likely see some degree of drought conditions return by later this summer. Stay up to date at the Climate Prediction Center.

But, speaking of lucky, how about the cooler-than-normal start to July! But, you know the heat will return...hopefully not to the degree we have seen the last few summers.

Question: I had heard that Knockout Roses were generally disease free, but lately some of mine have begun to look unhealthy with some strange growth patterns. What could be causing this?

Answer: Knockout roses were created and introduced to the market in 2000. Because of cold hardiness, disease resistance, nice form and continuous blooming, they rapidly became the bestselling landscape plant in the country. However, the idea of Knockouts being disease free lost some of its rosiness when the viral disease "rose rosette" appeared. Knockouts are very susceptible to the disease and once infected it usually is fatal.

The disease is caused by a virus spread by a tiny eriophyid mite. The virus causes the plant to develop many small deformed stems (witches broom) on the end of a limb. Several small reddish leaves develop and the stems produce large numbers of small thorns, almost appearing like a brush. The appearance is diagnostic, meaning that once the symptoms appear, the rest of the plant is already infected. There is no treatment at this point, the best approach is to remove the infected plants, roots and all and send them to the trash.

The mite feeds only on actively growing tissue found at the tips of stems and in developing flower buds. Since Knockout roses form many new flower buds continuously all season, they provide more food for the mite and thereby get more disease. There also may be some genetic factors contributing to their susceptibility. Other roses, such as hybrid teas, may get the disease, but they are much less attractive to the mite because of fewer meristems. Most of the Knockout roses in the US are produced on the west coast. OSU plant pathologists point out that there is no Rose Rosette disease in plants originating from this area. They have no mites and no disease. The disease comes later when the plants enter a mite infested area.

Prevention of the disease is complicated, and basically involves trying to control the virus carrying mite...only the mite can transmit the disease. One cannot infect a healthy plant by transferring sap from pruning shears, so there is no need for sterilization of pruning equipment. The mite is very small and cannot be easily seen without magnification. It is transmitted from plant to plant by wind, animals and gardeners. The mite may get in the clothes of gardeners and be carried, unknowingly, to a healthy plant. A brief tumble in a clothes dryer may eliminate this contamination.

No official OSU recommendations for pesticide use are yet available. However, it is thought that the use of horticultural oils and soaps may be helpful. Stronger insecticides such as Sevin or brands containing the pyrethroid bifenthrin should also be effective, but these chemicals also kill the beneficial insects. The time to spray should be both while the plant is dormant in late winter (to try to kill over-wintering mites) and regularly in spring during rapid growth of the rose. Thorough coverage is important, the tiny mites are adept at hiding in the nooks and crannies of plants.

Click here to send your question to the Tulsa Master Gardeners or see Answers to other Questions on the Web site