Sunday, February 17, 2019 0 comments By: Ask A Master Gardener

Use Preemergent Herbicides Now to Prevent Crabgrass this Summer

Use Preemergent Herbicides to Prevent Crabgrass
Allan Robinson: Ask Master Gardener
Sunday, February 17, 2019
Q: When is the best time to apply preemergent herbicide to help control crabgrass? Johnathan W., Tulsa
A: Preemergent herbicides are definitely helpful in preventing weed establishment. They are used in early spring (mid-February through mid-March) to prevent crabgrass and other summer weeds. They also are useful in the fall (mid-August through mid-September) to prevent winter weeds such as henbit. Many of the herbicides will need a second application in spring 60 days after the first application for complete coverage of crabgrass. The product label will indicate if this is needed.
Many people are reluctant to use herbicides of any sort for weed control. That is a reasonable choice for those who are willing to tolerate some weeds. The best preventative is to maintain a healthy, well-established lawn, as this will help prevent much of the weed invasion. A healthy, thick lawn depends on good soil, proper turf grass for the area, adequate sunlight and supplemental irrigation. Most lawns need some fertilizer, and there are organic and synthetic sources available for nutrients.
The Tulsa Master Gardener website contains several helpful lawn maintenance calendars indicating what to do, what to use and when to use it for Bermuda and fescue lawns. Specifically, see the “Turf” section of the Master Gardener website for complete details.
Master Gardeners are often asked if there are any “organic” preemergent herbicides, as opposed to commercial or “synthetic” ones. Unfortunately, while there are other organic pesticides, there is no effective organic preemergent herbicide.
Corn gluten is an organic sold as crabgrass prevention. Some reports state that if it is applied during a narrow window in spring, there may be some benefit. OSU turf grass specialists cite studies that show little benefit.
For those wishing to use a synthetic pre-emergent herbicide, OSU has some recommendations. While there are several varieties of preemergents available on the market to prevent weeds, especially crabgrass, OSU feels that one of the many commercial brands containing the chemicals dithiopyr, pendimethalin or prodiamine are good choices. These preemergents cost a bit more than other types but last a lot longer and, in many cases, can kill crabgrass and other weeds after they have sprouted.
The labeled directions of all such products must be followed. These herbicides usually come on a dry particle such as fertilizer or other inert material. They may also be found less often as liquids. They must be washed onto the soil with at least ½ inch of water after application. After washed onto the soil, they form a barrier for weed prevention, which may last for months if undisturbed.
One of the benefits of these three products is that they are not soluble in water and, thus, do not leach into groundwater or spread from where they are applied. They are broken down in nature by sunlight and soil microorganisms.
Garden tips

• Now is a good time to cut back your perennial ornamental grasses, such as Pampas grass. Cut back to remove the dead grass, but avoid damaging new buds and early green growth at the base.
• Begin planting blackberries, raspberries, strawberries, grapes, asparagus and other perennial garden crops this month.
• Most bare-rooted trees and shrubs should be planted in February or March. The roots of these plants are easily damaged and should never be left exposed to air. Plant them at the same depth as in the nursery and make sure good root and soil contact is made by gentle tamping and irrigation after planting.
• Finish pruning shade trees, summer-flowering shrubs and hedges. Spring-blooming shrubs, such as forsythia and azaleas, may be pruned immediately after flowering (not before). Do not top trees or prune just for the sake of pruning.
• Applying preemergent herbicides earlier rather than later may be desirable to prevent crabgrass and other summer weeds.

Sunday, February 3, 2019 0 comments By: Ask A Master Gardener

Soil Tests of Lawn and Garden Beds Are Very Helpful

How Soil Tests are Helpful
Tom Ingram: Ask a Master Gardener
Sunday, February 3, 2019
Q: I wasn’t happy with how my yard looked last year or how my vegetables grew. How much and what kind of fertilizer should I use this year? DJ
A: This is a question we get quite often. The reality is that the question, while well-intentioned, is like me calling you on the phone and asking you how much gas I should put in my car. Your first response would be, “Well how much gas do you have in your tank now and where are you going?” To answer your question, I could look at the fuel gauge and tell you I have half a tank and I just plan on running some errands. In response you could say, “Well you don’t really need gas right now, but you better fill it up at the first of the week.”
It is the same way with soil. When someone asks how much and what kind of fertilizer they should use, we need to ask some questions. Or in this case, we need to take a soil test, which is similar to looking at the gauge to see how much fuel we have.
To perform a soil test, you will need something to collect your samples with and a bucket: a trowel or a bulb planter work well. We recommend you get between 15 to 20 samples of soil from locations scattered throughout your yard. Each individual sample does not need to be large, but you should dig to a depth of about 6 inches.
Once you have your samples in a bucket, mix them up and remove any sticks or debris. From this mixture of soil, bring a representative sample to the OSU Extension office. We will only need about a sandwich bag-sized amount of soil for your test.
When we receive your soil sample, we will send it to the Soil Science Lab at Oklahoma State University for analysis, and within 2 weeks, you should receive the results. Your results will contain the levels of nitrogen, phosphorus and potassium found in your soil, along with the pH level. Included will be a recommendation on the nutrients you need to add and how much, along with recommendations on perhaps the nutrients you need to stop adding. Not only is over-application detrimental to your growing environment, but it is also a waste of money.
The test costs $10, but likely, it will be the best $10 you have ever spent on your lawn or garden. If you want to test a smaller garden or flower bed, this will require a separate test as those environments would be unique from your lawn. The same instructions would apply. So grab a bucket and let’s find out what your soil really needs.
Garden tips
  • Early February through March is the recommended time to plant strawberries. It is important to plant them in full sun and in well-drained soil. There are several types to choose from. June-bearing varieties do best in our area. They have a single crop usually early May to mid-June. Ever-bearing strawberry is another variety which fruits May to June, a few during summer and again in the fall. The quality and size of this type of strawberry plant may not be as good as June-bearing varieties. For full information about plant selection and growing tips, visit the “Hot Topics” page of our website.
  • Mid-February is a good time to begin pruning and fertilizing trees and small fruits.