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February, 2010                                                                      Number 34
Ask a Master Gardener

When do I begin spraying my peach trees?  Last year I waited too long.

"Fruit Spray Schedules for the Homeowner" can be found on our website.  There are several strategic times for spraying the home peach trees.  The first scheduled spray is to be applied before buds swell in the spring.  Consecutive sprays should be done when buds show white, pink or red color.  Spray again when 25% of the buds are open, and again when most of the blossom petals have fallen.  Consult the schedule for specific times and pesticides to utilize.  Click here for the schedule.


Is there anything I should be doing now in the landscape?

There is actually much you can be doing to prepare the home landscape for the gardening season.  Besides staying indoors and ordering seed catalogs and planning new vegetable garden layouts, you can treat young pines for Pine Tip Moths this month, providing the ground is not water saturated.  It is also the time to prune the "bleeder" trees such as the maples, birches, elms and willows. Click here for the Landscape Maintenance schedule for details on these and other winter projects.  

Last summer I had little clusters of what looked like woven leaves on my possum haw bush.  When I opened one up, it was full of tiny little worms.  Some of the clusters are still on the end of the limbs.  Should I spray now?

Leaf rollers are small caterpillars that wrap leaves around themselves for protection and from these shelters they proceed to chew holes in flower buds and leaves. The insects eat the bulk of the leaf, leaving only a skeleton consisting of veins, which will then turn brown and drop in late summer.  It is a good idea to remove any leftover debris which might contain eggs now.  Wearing gloves, simply crush and pull off any remaining leaves that have been woven together.  The pests can be controlled in this manner on small shrubs even in the growing season.  For larger infestations, call the Master Gardener Helpline for the best insecticide to use.

My Russian Laurels look wilted and some of the leaves are turning brown after our Christmas Eve snow and the following rain storms.  What do you think is wrong with them? 

Russian laurels, Cherry laurels, and especially, Otto Luyken English laurels, are very susceptible to too much water standing in the root zone.  In areas where run-off water, rain water from roofs, etc. collects around plant roots or in shallow soils with underlying rock or compacted hard pans, setting woody plants deeper than the soil level in the nursery container, over-watering plants, or long periods of heavy rain also favor decline in these species.  Sometimes, simply raising the tree that has been planted too deeply (or cutting back on irrigation) can help remedy the problem.  If standing water is unavoidable in the present location, or if heavy clays or poorly drained soils are present, then moving the plant in late February, before spring flush of growth, might be necessary.

Mark Your Calendar

Annual Master Gardener plant sale.    Ask any Master Gardener or Click here for an order form.  Deadline for orders is Friday, March 26 and pick up is Thursday, April 15.

Tuesday Evening Gardening Classes start April 6 at the Extension Center on 15th Street.  Free.  5:30 to 6:30.  Click here for dates and topics.

See the Master Gardeners at the Tulsa Home and Garden Show March 11 thru March 14.

Showcase Garden Tour of six MG gardens, June 26 and 27.

Need more information?  Click on any of the links below
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.
Trade names and where to find them   
How to Plant a Tree in Oklahoma Soil
Show and tell.
Landscaping and Gardening for Birds
How to attract birds to your garden 
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 100, by size and color.
Oklahoma Proven Plants
The new list for 2010.  State horticulturists, nurseries and growers pick their favorite plants, shrubs and trees.
Current and historical source of rainfall, air temperatures, soil temps and much more.  Click on Bixby station. 
4 Ways to Contact Us 
Email us at:
See our website at:
Call us at: 746-3701 from 9-4,
Visit us at 4116 East 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.
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  February Lawn and Garden Tips

This is a good time to take a soil test. (OK.  Wait until the snow melts, then it would be a good time to take a soil test.)  The results will help you determine the best fertilizer amendments for a healthy and vigorous lawn and garden this spring and summer.  See below for details on how to collect a good soil sample.

Preemergent herbicides to prevent crabgrass and other weeds should be applied in February and no later than March 15.  Preemergents need to be applied before weeds germinate.  Crabgrass germinates when the soil reaches 55 to 60 degrees.  To be effective, be sure to water in after applying.  For more, see below.

Seed many cool season vegetables mid-February to mid-March.  Plant Irish potatoes and onion sets after mid-February.

You can start tilling spring garden beds now, weather permitting.   Be sure to add compost when tilling. 

Prune back monkey grass (Liriope) and ornamental grasses (such as Pampas grass) before new growth begins.

Wait until mid-March to prune back your roses.  Prune spring blooming plants after flowering.

Trees, shrubs and perennial plants needing fertilizer should be fertilized now.

Dormant fruit trees and other plants and shrubs at risk for aphids, scale and spider mites should be sprayed now with all-purpose horticultural oil.

If you missed planting trees and shrubs last fall, this is a good time to plant them. Late winter and early spring is the only time you should plant bare root trees and shrubs.  Planting now will give them a head start on summer heat.  When digging, remember that the hole should be wider, rather than deeper.  Click here for more information on planting trees in Oklahoma.

Be sure to mulch around the young tree.  Recent studies show that a mulched tree will grow two to three times faster in its early years.


Time for a Soil Test

If you haven't taken a soil test in two or three years, this would be a good time to do so.


The standard soil test measures the pH (soil acidity) and three nutrients-nitrogen, phosphorus and potassium (potash). Place soil samples in a zip-lock and take to the OSU extension center at 4116 E. 15th street. They are then sent for analysis at OSU's soil lab in Stillwater. The cost is $10.00 and the test takes about 2 weeks for completion. The report has specific suggestions to correct problems which may be uncovered.


Separate tests should be done for each unique area, such as lawns or garden beds. Use a trowel or similar tool to obtain samples of the top 6 inches of soil. Mix together and submit a pint of the mixture for analysis.


It is important to collect 10 or more samples at complete random from each region-if not, accuracy is reduced. Do not submit a soil sample from an area which has received fertilizer during the previous 2 months, this will also produce misleading results.


With results in hand, you will be able to make science based decisions about adjustments in soil acidity and fertilizer requirements.


Assistance in deciding the best amendments, based on the soil test results, can be found in OSU fact sheet HLA6007. Click here and download a copy.

Time for Preemergents

Preemergent herbicides are very effective if used properly. The two most common errors people make in usage is not applying before crabgrass sprouts and not activating it by watering it onto the soil.


Crabgrass usually germinates from late March through early May. Since preemergent herbicides should be applied at least two weeks before this germination, it is recommended they by applied from mid February through March 15 in our area.


Many homeowners dutifully buy and apply preemergents to the lawn and feel that the task is done. This is not so. The chemical comes bound to solid carrier particles. It will stay on these particles and deteriorate unless washed off with either rain or irrigation. This should be done as soon as possible after applying to the lawn. When rinsed from the carrier, the chemicals form a barrier on the soil surface that prevents weeds from sprouting. These herbicides do not move in the soil and do not enter the groundwater.


There is always a dilemma as to which preemergent herbicide is best. They all perform as advertised in preventing crabgrass. The big differences are how long they last after application and their ability to prevent weeds other than crabgrass.


The most widely used products are the ones containing dithiopyr (Dimension), prodiamine (Barricade) or pendimethilin (Halts). There are many other brands containing these products.


These products are longer lasting than others and have reasonably good preventative effect on weeds other than crabgrass. Some of the herbicides will allow a second application about 60 days after the first. This extends the time of coverage of late germinating crabgrass and goosegrass. Use a second application only if specifically allowed by the product label. Your lawn may be damaged if instructions are not followed carefully.


The Master Gardeners have prepared a summary sheet of examples of brands of preemergents available in Tulsa, along with information as to their use. It may be obtained at the OSU extension office on 15th street or online by clicking here.


Ice Damage to Shrubs 

Many homeowners are concerned that the recent ice and sub-freezing temperatures may have damaged  flowering shrubs. There is no good way to tell how much damage has been done to deciduous shrubs now. It is best to wait until spring and then identify and remove the stems of the shrub which do not have active bud growth. One can also scrape a bit of the bark back on stems which are suspect and see if there is a green color. Dead stems will be brown.


This also applies to evergreen shrubs, such as azaleas. If the normally green leaves turn brown and look dead, don't prune out until spring, they may easily leaf out and survive what appears to be a lethal event.


Wilting of evergreens, such as aucuba, is a plant defense mechanism which protects against cold. It involves a complicated shift of water and, in effect, creation of anti-freeze. This causes wilting of leaves and is reversible.


Most of the crapemyrtles grown in our area are rated to the USDA cold hardiness zone 7. This means that they should be able to tolerate temperatures down to zero degrees. We are at a junction of zone 6 and 7, and our recent lows were around zero. According to the USDA, this is  "normal" for us,  but it has been 13 years since we have seen zero or below temperatures in Tulsa. So we could be in for some surprises with our crapemyrtles and other cold sensitive plants when spring arrives.


This may not be a catastrophe with crapemyrtles.  They are one of the deciduous shrubs which can be cut back to the ground and be expected to not only recover, but bloom the same growing season.

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