August 2013 / Volume 78        

In This Issue
August Lawn and Garden Tips
Fall Plant Sale is Online
Beekeeping 101 Free Class
Oklahoma Spiders
Preserve Your Harvest
July Relief
Ask A Master Gardener...Hypoxylon Canker in Pecan

Weather Stats for Gardeners

Soil Temperature 2" below sod:   

82 degrees 


Rainfall total last 30 days:  

4.70 inches


4 Ways to Contact Us
Email us at:

See our website at: 

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.
August Lawn and Garden Tips 


  • If the fall vegetable garden is not yet planted, do so now.
  • The hotter and drier it gets, the larger the spider mite populations become. They love marigolds and tomatoes. The foliage becomes pale and speckled. They are very small-shake a branch over white paper and watch for specks that crawl. Spider mites need early control. Use powerful jets of water to wash them off plants leaves and spray with horticultural soaps and/or horticultural oils such as Neem. 
  • Water all plantings thoroughly unless rainfall has been adequate.
  • Divide and replant spring blooming perennials, including crowded bearded iris.
  • Hedges and shrubs can be pruned, if necessary, about mid-August. Don't prune spring blooming shrubs, such as azaleas now.  
  • Discontinue dead-heading roses by mid-August to help initiate winter hardiness.
  • Fall webworm in late-August/early-September may be a problem, contact Master Gardeners for recommendations.


  • Irrigated warm-season lawns such as Bermuda and zoysia may be fertilized this month and into early September. Do not fertilize again until spring green-up next year.
  • Meet water requirements of turf. See July's notes.
    For areas being converted to tall fescue this fall, begin spraying bermudagrass with glyphosate products in early-August.  
  • Pre-emergent herbicides for winter-annual weed control should be applied between mid-August and Mid-September. A brand containing one of the chemicals dithiopyr, pendimethilin or prodiamine would be an excellent choice. Read and follow the label. They must be watered in to be effective and some will require a second application. Don't use on fescue if you plan on reseeding in September.  
  • Mowing heights for fescue lawns should be 3" during summer months, 2-1/2 inches for Bermuda lawns. See Master Gardener lawn care documents in this calendar.  

Fall Plants for Sale     
For the first time, Tulsa Master Gardeners are selling pansies, panolas and ornamental kale for your fall planting. We will begin offering these plants at our online shopping cart continuing through September 6. Delivery date is scheduled for October 11 at the OSU Extension Center.

More information will be posted on our website soon, so keep checking back. In the meantime, enjoy your summer garden knowing that it can be just as beautiful in the fall and winter.

Free Tuesday Class: Beekeeping 101     

Tulsa Master Gardeners will offer a class on Beekeeping Basics on Tuesday, August 27. Class starts at 5:30 pm and lasts for approximately 30 minutes, with another half hour for discussion.


This class is free and there is no need to register, just meet in the auditorium at the OSU Extension Office, which is on 15th street at gate #6 into the Tulsa Fairgrounds.

Oklahoma Spiders:
Most are good, but two are not!   
It may come as a surprise, but did you know that most spiders that we come across each day are actually harmless to humans and, in fact, beneficial to the environment?  Many spiders have a goal in life to rid our gardens of other pests because they prey upon flies, crickets, and other insects. They generally will not attempt to bite humans unless held or accidentally trapped. Moreover, the majority of spiders have fangs too small or weak to puncture human skin.

However, there are two native spiders that are venomous and we should be on the watch for, as their bite can be harmful to humans. The first is the black widow spider which is famously known by its round black body coupled with a red hourglass marking on its back. The other is the brown recluse, also called a "fiddle back".  It is about the size of a quarter and colored in either light tan or dark brown with a fiddle/violin shape on its back (with the neck pointing towards its rear).

Both spiders are generally nocturnal, hiding during the day and emerging at night to feed on other insects.  They prefer out-of-the-way places such as basements, cellars, attics, crawl spaces, closets and cardboard boxes used as storage. Unfortunately, they also like to hide in shoes, clothing, linens and furniture. Be especially careful putting on shoes and clothing that have not been worn for some time. They are not aggressive and will generally not attempt to bite humans unless held, accidentally trapped, or physically threatened or provoked. Bites can range from hardly noticeable to damaging to human tissue, so be sure to see a doctor if you believe you have been bitten by one.

As for control measures, several insecticides containing Carbaryl, bendiocarb, chlorpyrifos, or any of the synthetic pyrethroids (e.g., cypermethrin, cyfluthrin, lambda-cyhalothrin) are effective, but may need to be reapplied periodically throughout the summer. Wettable powder or microencapsulated ("slow-release") formulations are most effective. To reduce spider entry from outside, insecticides can be applied as a "barrier treatment" around the base of the foundation. Pay particular attention to door thresholds, garage and crawl space entrances, including foundation vents. If large populations of these spiders are found, it is recommended to call upon a trained and certified exterminator. There are also a few non-chemical control measures can also be effective such as:
  • A routine, thorough house cleaning using a vacuum cleaner or broom can effectively remove spiders, webs, and egg sacs.
  • Reduce clutter to make the area around your home less attractive to spiders. Large numbers of spiders often congregate outdoors around the perimeter of structures. Migration indoors can be reduced by moving firewood, building materials, and debris away from the foundation. Shrubs, vines and tree limbs should be clipped back from the side of the house.
  • Install tight-fitting window screens and door sweeps to exclude spiders and other insects. Inspect and clean behind outdoor window shutters.
  • Consider installing yellow or sodium vapor light bulbs at outside entrances. These lights are less attractive than incandescent bulbs to night-flying insects which, in turn, attract spiders.
So, do be on the watch for the two venomous spiders discussed here. However, before you completely "nuke" your yard or garden with a chemical insecticide to get rid of spiders, think again...most are beneficial if left alone. For more information, feel free to call the OSU Extension office and ask to speak to a Tulsa Master Gardener.

Preserve Your Harvest       
As the summer season progresses, and your garden begins to turn out more tomatoes, zucchini, corn, and green beans than you can even begin to eat, consider preserving some of those summer veggies to enjoy later on in the year. Canning may sound difficult, and even intimidating, but if instructions are carefully followed, the process is very simple and very rewarding.

Acidic foods such as fruits, jam, tomatoes, and pickles contain enough acid to block the growth of botulinum bacteria and can therefore be processed in a water bath canner. This piece of kitchen equipment is simply a large stock pot with a rack inside for lifting the jars in and out. If you don't have a canner, you can improvise with a stock pot. Make sure the jars will fit and the pot can be filled with enough water to cover the top of the lids. Use a towel on the bottom of the pot to keep the jars from rattling against the bottom of the pot and breaking. Recipes and instructions should always be followed to the letter. A current edition of the Ball Blue Book Guide to Preserving or a current edition of the USDA Complete Guide to Home Canning and Preserving are highly recommended.

Low acid foods such as green beans and corn will need to be processed in a pressure canner. A pressure canner is a very large, heavy pot with a lid that is clamped onto the base and fitted with a pressure gauge. While you may have heard stories of pressure canner explosions, if used properly, pressure canners are quite safe. Moreover, they are absolutely necessary for bringing low acid foods to the proper temperature to kill the botulinum bacteria. Pressure canners can be purchased online or at any home supply store and come with detailed instructions that are easy to follow. 

Regardless of the process a few things remain the same:
  • Always use clean jars and check carefully for chips and cracks. As a general rule: if water bath canning, the jars will need to be sterilized. Pressure canning brings the jars to a temperature where pre-sterilization is not always necessary; but the jars will still need to be properly cleaned. The recipe will give precise instructions for using clean or sterilized jars.
  • Always pay attention to the recommended amount of headspace. Bands should be screwed on with one hand so that they are secure but not too tight.
  • Unless you are working with the reusable lids and seals such as Tattler's, always use a new lid. The seals on the standard Ball lids are not reusable. Rings however, can be reused as long as they are not rusted.

Once the jars have been removed from the canner, allow them to cool completely in a draft free place, then check to see that they have sealed properly. Sometimes they will release a musical and rewarding "ping" as they cool, letting you know they have sealed. Otherwise you can press the small "button" on the lid, and if there is no give, the jar has properly sealed. Label with the contents and the date and store in a cool, dry place out of direct sunlight. Rings can be removed for storage if desired. Properly canned food will store several months, filling your pantry with healthy convenience food from your own garden.


For more information on canning contact the Family and Consumer Sciences Department at the Tulsa County Extension Office or visit their website.

July Relief       
I guess the "Law of Averages" can really be your friend sometimes! Going into July, we were once again beginning to dry out over northeast Oklahoma, and I know many of us (myself included) were beginning to think, "here we go again!" as the hottest part of summer was looming and unpleasant memories of the past two summers were fresh in our collective minds. But, nature often has a way of balancing things out over the long term, and this time, we were the beneficiary of an unusual summer weather pattern...which was, in a way, actually a continuation of the pattern that brought colder-than-normal weather through the spring.

What normally happens in the summer is the jet stream retreats into the more northern latitudes, leaving the southern states, including Oklahoma, under a ridge of high pressure, that you may hear referred to as a "heat dome". The ridge will occasionally weaken or move into a different region of the country to provide a short-lived break in the heat, but we remain under its influence the vast majority of the time from late June through about mid September. The last two summers have seen an exceptionally strong and persistent ridge over the plains states, leading to long stretches of very hot and dry weather.

This summer, the ridge has been present as always, but has tended to be weaker and not nearly as persistent in one area. If anything, the ridge has shown a tendency to set up over the western states, with the jet stream oriented more northwest to southeast over our region. This pattern has allowed for more weather systems and cold fronts to impact us than we typically see in the summer, which has led to above normal rainfall and below normal temperatures through July. The latter part of the month has been particularly wet, with most of the area recording about twice the average rainfall for the July 15-31 time frame.

So, will it last? The latest 8 to 14 day forecasts show a higher likelihood below-normal temperatures and above-normal precipitation through mid August. If that were to hold up, we should be in good shape as the days continue to get shorter and the potential evaporation of soil moisture becomes less. Stay up to date at the Climate Prediction Center.

Question: What is causing this damage to my pecan tree?

Answer: The most common disease of pecan is scab, but there is a new disease that is threatening trees in Oklahoma. This disease is common on other hardwood trees including oak, hickory and hackberry. Recently, we have observed Hypoxylon dieback and canker on pecan trees in Oklahoma. This disease has been a problem in East Texas for some time, so it is not surprising that the disease has shown up in our area. The disease is caused by the fungus Biscogniauxia atropunctata (formerly Hypoxylon atropunctatum). The common name for the disease is Biscogniauxia or Hypoxylon canker. I will refer to it as Hypoxylon canker since it is the older, more common name for the disease.
Hypoxylon dieback and canker is caused by an opportunistic fungus. The fungus will colonize outer and inner bark, and wait for an opportunity to invade the sapwood. As long as trees have adequate moisture and minimal stress, they are able to resist invasions by the fungus. When trees are stressed (particularly drought stressed), they are unable to resist the invasion.   
Trees affected by Hypoxylon dieback and canker may die quickly or after several years. As the canker (sunken or swollen area on a branch) develops, water and nutrient movement is slowed so that leaves may yellow and prematurely drop. Dieback may be visible in the upper branches. Over time, the canker will girdle the branch and it will die. Often, one or a few scaffolds are killed before the main trunk becomes affected as in this picture. When the disease is found at this point, it may be possible to stop the disease by removing symptomatic branches. Once the main trunk is diseased, it is only a matter of time before the tree dies.   
The Hypoxylon fungus spreads by wind-blown spores and the fruiting structure will appear when the branch or trunk is near death. The outer layers of bark will fall off and a discolored area will be visible (Figure 3). This is the stroma (fruiting structure) of the fungus. The stroma may be visible in small patches and overtime, the area will enlarge. Depending on the maturity of the fungus, the color of the stroma may be white, tan, brown or black. In pecan, the stroma is usually black when it becomes visible. The stroma releases spores which are blown to other susceptible trees in the area and new invasions are initiated. Trees under stress are more likely to become diseased than trees that are healthy and well-cared for.
Management of Hypoxylon canker begins with prevention.  Trees should be watered during periods of drought. Avoid injury to the trunk during mowing operations and practice proper pruning techniques. Remove dying and dead braches as they appear. Diseased wood should be disposed of by burning or burial.   
If you suspect that your trees have Hypoxylon canker and you would like to have the disease confirmed, please contact your local county extension educator. For more information, see: EPP-7620, Biscogniauxia (Hypoxylon) Canker and Dieback of Trees.

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