July 2014 / Volume 89        

In This Issue
June Lawn and Garden Tips
Summer Flowering Bulbs
Nail Bagworms
Rain is Relief...But How Much?
Ask A Master Gardener...Coneflower Root Rot

Weather Stats for Gardeners

Soil Temperature 2" below sod:   

75 degrees 


Rainfall total last 30 days:  

1.10 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

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.
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. Fact Sheet HLA-6009 gives planting recommendations.
  • Continue insect combat and control in the orchard, garden and landscape.  (EPP-7306, EPP7313, 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.  
  • Brown patch disease of cool-season grasses can be a problem. (HLA-6420)
  • Meet water requirements of turfgrasses. (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 turfgrasses 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)
  • 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.  
  • Have you visited The Botanic Garden in Stillwater for a group tour? 

What Happened to My Squash? 
I am sure any of you who have grown squash have experienced this heartache. You have a lovely, healthy looking plant ready to put out a bumper crop of tasty zucchini (or other squash of your choice). Then, one morning you walk out to the garden and a nightmare awaits you...your once thriving plants seem to have wilted to near death overnight! What could possibly have happened?

Sudden wilting of any plant is usually related to a lack of water or a problem with the plant's circulation. The two most common causes for blocked circulation, or flow of sap, in squash vines are squash vine borers and bacterial wilt disease.

Squash vine borer moths lay small, oval shaped eggs on the vines, usually close to the soil line. After hatching, the grub-like larva enters the stem to feed. It is large enough to block the flow of sap and cause sudden wilting. There is usually a hole and some yellow sawdust-like matter where the larva is.

Once in the vine, not much can be done. However, some people split open the stem, remove the grub and then cover the area with dirt to try to induce new root formation.

Squash borers prefer Hubbard squash; the butternut variety is somewhat resistant. They also attack zucchini, pumpkins and gourds, but usually not cucumbers and melons.

Bacterial wilt disease, on the other hand, is an infection in the plant's circulation. The squash becomes infected when a striped cucumber beetle, which carries the bacterium, feeds on the plant. After infection, the sap becomes very sticky, circulation stops, and the plant dies.

Prevention, both by selecting resistant varieties of plants and by practicing sanitation, will help control each of these problems.

Squash vine borers and bacterial wilt disease both overwinter in year-end garden trash and in the upper layer of the soil. Removing plant debris and tilling the soil after harvest will significantly reduce the chance for infection the following year. Covering the plants with row cover can also help keep insects off of the plants.

Insecticides containing pyrethrins, carbaryl (Sevin) and others will kill both insects, but timing is everything - it must be used before damage occurs. This means regular spraying of plants early in their growth. This is justified only if you have reason to believe your squash plants are at risk. Then use a preparation that is clearly labeled for use on squash and follow the labeled instructions exactly.

Read the Label
"Before" You Purchase a Pesticide
David Hillock 
Pesticides include such products as herbicides, insecticides, fungicides, bactericides, rodenticides, etc.; basically anything labeled to control a pest is a pesticide. Each category consists of many different active ingredients, concentrations and modes of action, each designed to target specific pests or sometimes a broad range of related pests. Therefore, it is very important to identify the type of pest you want to control, the site in which it is to be used, and then select the pesticide best designed to control the target pest.

With all the different products available, consumer labeling can be confusing. For example, Ortho has several products labeled Bug-b-gone or Weed-b-gone, but each one may have different chemicals in them, different sites in which they may be used, and pests they control. Another example is Roundup. Not all Roundup products contain just glyphosate anymore, which has been the main active ingredient for many years, and still is; instead, some of the products produced by Monsanto have other ingredients as well. The products are still labeled as Roundup, but those with added ingredients have an addition to the title, such as "Extended Control, Weed & Grass Killer, Plus Weed Preventer" or "Poison Ivy & Tough Brush Killer Plus."

The problem consumers run into is they see "Roundup" on the label, think it is just the traditional weed killer with glyphosate in it, purchase it, and apply it to an area it wasn't really meant for without reading the label!

I know of two cases in which the Roundup Extended Control, Weed & Grass Killer, Plus Weed Preventer was accidentally used instead of the traditional form. One was a friend who wanted to kill an area in her turf to install a vegetable bed, and the other used it in an area they wanted to plant trees and shrubs. The result in both cases, they were unable to plant anything in the area for about four months. The reason, because the second ingredient in this product provides up to four months weed control and can damage un-established plant material.

The moral of the story - Read the Label BEFORE you purchase any pesticide!

Please realize this is not an attack on Ortho or Monsanto's Roundup or any other manufacturer or product; I love and use many of their products! But it is extremely important for the consumer to do a little research and even read the label before they purchase a pesticide to avoid situations such as the one experienced by my friend. Eventually she was able to plant her garden, but it wasn't until the following year, after it was safe to plant again.

Dividing Perennials: Daylilies and Irises   
Daylilies are perennials that come in a variety of colors and produce awesome blooms for about a month in early summer. Like many perennials, they will eventually become overcrowded and their overall color and health will decline. For this reason, they need to be divided every three to five years. But when, you ask? Preferably, this should be done in the fall to allow for considerable root growth the following spring, but it can be done in spring if necessary. Before digging them up, cut the foliage back to about six inches and water the plants to loosen the soil. Dig the plant with a large root ball and thoroughly wash the soil from the roots. This will allow you to easily divide them without having to cut the roots. The goal is to have three to five leaf fans and a healthy clump of roots.  When replanting, prepare your site beforehand. Loosen the soil and mix in a good amount of organic compost. Make sure the new location will get several hours of sun.  Adding in a small amount of slow release fertilizer into the soil at planting is a good practice, but optional. (As a side tip: Hostas can be tended in the same way as daylilies.)

We all know there are several types of irises. They come in many colors...some have "beards" and some do not. They usually bloom in spring and early summer, and then go dormant until the fall. Therefore, irises should be divided in either July or August, every three to four years. Unlike many other perennials, irises have a root-like structure, called a rhizome, from which new plants grow. As the plants grow, baby rhizomes are produced at the edge of the parent bulb. It's these new rhizomes that will produce new plants, at which time the parent plant will no longer bloom. To divide, dig up the whole structure, trim the iris blades to six to eight inches in length, and separate the new rhizomes by cutting or breaking them away from the parent plant. The goal is to get new rhizomes that have one to three small buds, healthy leaves, and some roots. Discard all others that appear to be in poor health or diseased. As noted above, prepare the new location ahead of time. Irises do well from full sun to some afternoon shade. They must have well drained soil to prevent root rot. A small amount of slow-release fertilizer is okay, but go light on the nitrogen as too much can lead to disease susceptibility. When planting, cover the roots well but only lightly cover the rhizome, with no more than one inch of soil.  If planted deeper, they may not bloom. Do not mulch, which can also lead to disease.  Be aware some irises may not bloom the first year after transplanting, but be assured you are doing the right thing for the long-term good health of these beautiful plants.

Question: If you water plants in the middle of the day in summer, will that scorch leaves in the hot sun?

Answer: There is a garden myth that implies water droplets on leaves in full sun may concentrate the rays and scorch the leaves, like a magnifying glass.

This doesn't happen. Look to nature; plants do just fine after a summer shower followed by hot sun. Leaves don't scorch. Scorching of leaves - leaves turning brown along the edges - usually occurs in summer due to a lack of water, but may have other causes such as excess salt and fertilizers.

If a plant looks wilted midday, there is no reason not to water it at that time. This is backed by science. Here are other practical watering guidelines which can significantly improve your success as gardeners:

First, try to water plants and lawns in the mornings - for lawns, 5 to 9 a.m. is ideal. This allows the foliage to dry before nightfall and reduces likelihood of fungal diseases. Most plant disease fungi reproduce and grow best at night, especially when wet.

Another advantage to watering early is less water lost due to evaporation than if watered later. When it is hot and windy, evaporative water loss is significant, and preventing this loss is both economical and responsible. An additional watering suggestion is to water lawns and ornamental plants less often and more deeply. If you water when needed and wet the soil to 6 inches, larger and healthier root systems develop and are better able to tolerate the extremes of weather.

Mulch is also very important now. It not only prevents water evaporation, but keeps the root zone cool. This helps plants cope with the heat.

Drip irrigation is a useful tool for watering all plants. A system is easy to design and attach to an outdoor faucet. It can deliver water to the base of individual plants, avoiding the water-on-leaves myth altogether.

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