July 2012 / Volume 65           

In This Issue
July Lawn and Garden Tips
Summer Garden Invaders
Controlling Bermuda Grass
Roses: A Timeless Classic
Drought Update
Ask A Master Gardener

Weather Stats for Gardeners

Soil Temperature 2" below sod:   

85 degrees 


Rainfall total last 30 days:  

2.85 inches


4 Ways to Contact Us
Email us at:

See our website at: www.tulsamastergardeners.org 

Call: 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.
Fescue Lawn Care
12-month maintenance calendar.
Bermuda Lawn Care
Ditto above.
Trees for Tulsa
A list of 50 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. Register 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. (HLA-6419 )
  • 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. 

Summer Invaders 

These are just a few of the insect pests you may be seeing in your garden this summer.

Squash bug: If your squash plants begin to show signs of wilt, it is possible they are infested by the squash bug. These bugs feed by sucking the juices from squash, pumpkin, melon, and cucumber plants, in order of preference. Observe your plants regularly for clusters of tiny orange eggs on the leaves. If found, remove and destroy them. Unfortunately, squash bugs are almost impossible to control when mature because they have a hard body that insecticides have difficulty penetrating. Thus, spraying when the insects are small is important. We are now seeing the nymphs of the first generation. These nymphs will soon become adults and lay eggs that become the second generation, which is often huge and devastating. So, it is important to control as many squash bugs now as possible. Only insecticides that directly contact the insect will work. Some insecticides containing permethrin, malathion and rotenone provide control when directly applied to young, soft-bodied squash bugs. Make sure the insecticide is labeled for squash bugs. You MUST spray or dust the underside of the leaves where the insects live.


Colorado Potato Beetle: This beetle is identified by the five black stripes on each wing and a series of small black spots on the orange thorax. The adults overwinter in the soil, and emerge to lay their eggs in the spring; a reason to consider rotating your crops from year to year. The beetle feeds the leaves of a variety of hosts including potatoes, eggplant, tomatoes, and peppers. For small gardens, the beetles can be controlled simply by hand picking. Otherwise, insecticides such as pyrethrin, permethrin and malathion are recommended, but make sure the brand being used is labeled for use on the crop you are treating. 


Tomato Hornworm: This unsightly worm is most often found on tomatoes but can also be seen on peppers, potatoes, and eggplant. The hornworm will eat its way through large amounts of foliage and two or three worms together can defoliate an entire plant. For small gardens, hand picking is recommended. If chemical control is preferred, use B.t. var. kurstaki or spinosad.


Controlling Bermuda Grass in the Garden    

On one hand, Bermuda grass makes a great lawn because of its aggressive ability to spread, using both underground rhizomes and above ground stolons. But this same aggressiveness makes it very difficult to keep out of flower and vegetable gardens. 


A good strategy when starting a new garden is eliminating all Bermuda from the bed prior to planting. Use glyphosate herbicide, the one found in Roundup, until it is all killed from the bed. This may take two or more treatments. After the bed is established, a barrier such as steel edging is needed between Bermuda lawns and the bed. No barrier will be completely effective, however, and once inside an established bed, the grass will quickly put down new roots which, if left behind after hand pulling, will re-sprout.


After the invasion, you may either continue weeding by hand or use a Bermuda specific herbicide. There are two on the market and they can be found in most garden centers. The chemical names of the herbicides and samples of brand names are: fluazifop (Ortho Grass-B-Gon, Ferti-lome Over-the-Top ) or sethoxydim (Hi-Yield Grass Killer). These chemicals will not harm flowers in your garden bed, but should not be used on vegetables unless specifically labeled for them. Always read and follow the labeled directions.


Glyphosate, which kills all things green, can be used if desirable plants are protected. One strategy is to use glyphosate with a brush to paint the weed. Another is to use a plastic milk jug with the bottom removed. Place it over the weed and spray into it, protecting the desirable plants. Glyphosate is inactivated when it contacts the soil and does not spread in the soil.


Don't forget that mulching your beds not only benefits desired plants by preserving moisture and protecting soil, but it also helps to suppress weeds. Once your beds are clear of Bermuda and other weeds, put down a generous 1" layer of mulch to help wanted plants to thrive. See Fact Sheet HLA_6005 for more information the benefits and application of mulching the home garden bed and which control grass and weeds best. 

Roses: A Timeless Classic     

Roses remain one of the most popular flowers in Oklahoma. Although some roses are considered high maintenance landscape plants, several new varieties and species exist that are carefree, easy to grow, and look beautiful in the landscape. The following procedures should help you produce good quality plants:


Site Selection: Plant in a location that receives at least six hours of full sun and is protected from strong winds. To avoid reflected heat and sunburn, plant at least two feet away from any wall. Avoid planting under trees where they may suffer from a lack of sunlight and competition with tree roots.


Site Preparation: Like most plants, roses like a well-drained location rich in organic matter. Soils for roses should be slightly acidic, around 6.0 pH. A soil test is recommended before adding any amendments. As per the soil test, add sulfur to lower the pH or add hydrated lime to raise the pH.


Fertilization: Fertilize roses with organic or slow-release balanced fertilizer at pruning time. Apply a complete fertilizer or special rose fertilizer (too much nitrogen will decrease blooming). Always follow label directions. Work the fertilizer into the soil and around the plant, keeping it away from stems. Additional application may be made every 4-6 weeks during the growing season. Final fertilization should occur around August 15th, as excess nitrogen produces new soft growth that could be susceptible to winter kill.


Pruning: First pruning should be done around April 1 or 4-6 weeks after spring planting. Prune to maintain plant shape, to remove dead or diseased wood, and to regulate desired flower size. Prune moderately for more and average-sized blooms; prune more heavily for fewer, large flowers. 


Disease Control: Both cultural and chemical methods are recommended to control diseases. Avoid overhead watering, water early in the day so the plant dries out before dark, plant with good ventilation, remove and destroy infected leaves and limbs, mulch soil around plants, and purchase disease-resistant cultivars. The most common diseases are black spot and powdery mildew, although there are some nasty viruses that roses can get as well. Spray early and often with recommended fungicides (hot, dry weather like we are having helps to control this as well).


Don't let rose problems keep you from enjoying such a beautiful addition to your garden. Choose cultivars wisely and pay your garden a visit several times a week to check on them. For more information, refer to OSU Fact Sheet HLA-6403 for rose maintenance and EPP-7607 for rose disease identification and control.

Deja Vu All Over Again?!?!      

It was nice while it lasted. Remember the early spring rains that wiped drought off the map in most of Oklahoma as we were moving into the wettest months of the year? After the weather nightmare of 2011, it was a welcome change of pace.


Unfortunately, things haven't been working out too well lately, as May ended up being one of the driest on record in the Tulsa area...and easily would have been if not for some on the last day of the month. A cool, rainy start to June helped keep drought conditions at bay for a while longer, but, oh, how quickly things change!  


A few weeks with little significant rainfall, plus a stretch of late June weather even hotter than the same time last year, and guess where we start July...drought! Actually, Tulsa County is considered to be "abnormally dry" right now, whereas one year ago we were in moderate drought...a category higher on the drought scale. 


Obviously, we don't want to start July off in this spot again, as July and August are not normally thought of as a time to expect drought relief. Whether we actually see temperatures rivalling last summer remains to be seen. But, unfortunately, odds are in favor of the drought expanding through the summer, barring a major shift in the overall pattern.


Up-to-the-minute weather postings are available at Oklahoma's Mesonet, or visit the National Weather Service Tulsa office online or on Facebook.


Question: My tomato plants have been producing quite a bit this year, but many of the fruits look partially brown and rotten. What could be causing this?

Answer: Master Gardeners are seeing many problems with tomatoes daily at the OSU Extension office. One common problem is a condition called "blossom end rot". It is not a disease or insect problem and needs no treatment other than perhaps altering your management of the plants. This problem may also occur in other vegetables such as peppers, eggplant, squash, zucchini and watermelons. Several local gardeners have brought in cucumbers recently with end rot.


Blossom end rot is caused by calcium deficiency. Calcium is absorbed by the roots and delivered to the plant by the circulation or flow of sap. If there is not enough calcium delivered to the developing fruit, the part furthest from the stem, the blossom end, can develop a localized calcium deficiency. This will cause the blossom end to deteriorate and develop a leather-like brown discoloration called necrosis, which may rot. Most often, this involves a problem with calcium supply to the fruit...our soils typically have plenty. When the circulation is reduced, either due to dry soil or hot and windy weather (no shortage of that lately!), the plant sends most of the calcium containing sap to leaves, which are more important for survival.


Other possible factors are overly wet soils and too much nitrogen fertilizer. Excessive soil moisture smothers roots, preventing calcium absorption. Too much fertilizer causes tomato plants to grow more leaves than tomatoes, directing calcium flow into leaves. The type of fertilizer may also be important-ammonium types of nitrogen fertilizer can interfere with calcium absorption, while the nitrate forms do not.


To prevent the problem, water regularly, but don't overdo it. Most tomato plants need about 2 inches of water per week in 2-3 applications...avoid daily shallow watering. The goal is to moisten the soil down to 12 inches or so. Also, a 2-3 inch layer of organic mulch will help reduce water loss and moderate temperatures.


There are some varieties of tomatoes that are less susceptible to blossom end rot than others; including Celebrity, Jet Star, Mountain Pride, Pik Red and Sunny. Consider this group for your next tomato garden.


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