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K-State Turfgrass

Category: integrated pest management (IPM)

Flowering Ornamentals and Crabgrass Emergence

By Jack Fry and Ward Upham

Efficacy of some preemergence herbicides is strongly dependent upon the timing of application relative to crabgrass emergence.  For example, application of a preemergence herbicide that has a relatively short residual, such as pendimethalin, closer to crabgrass emergence, will extend the period of time which the herbicide is effective.  Herbicides with longer residuals, such as prodiamine (Barricade), are often applied well before crabgrass emergence, and can even be effective if applied late in the previous autumn.

In our climate, calendar dates don’t always adequately identify crabgrass emergence or herbicide application.  Biological indicators, such as flowering ornamentals, may be useful for predicting crabgrass emergence and preemergence herbicide application.

From 1995 to 1997, K-State researchers worked with those at the Univ. of Nebraska to identify ornamentals at each location which best represented crabgrass emergence and preemergence herbicide application time.  Ornamentals evaluated were bridal wreath spirea, callery pear, daffodil, flowering quince, forsythia, iris, lilac, redbud, saucer magnolia, tulip, and vanhoutte spirea.  Obviously, there may be ornamental cultivar differences in blooms, so this was an average of those observed.  In addition, crabgrass can vary in rate of emergence, but getting an herbicide out before the first plants emerge is preferable.  For this article, we’ll focus on results in Kansas.

Crabgrass emergence in bare soil and thin turf was evaluated at the Rocky Ford Research Center in Manhattan. Over three years, the earliest date of crabgrass emergence in bare soil was April 15 1995, whereas the latest date was May 9, 1996.  In the thin turf (10% bare soil evident while standing), the earliest date of emergence was May 5, 1997 and the latest date was May 22, 1995.

Withering of blooms was a better indicator of crabgrass emergence, particularly in thin turf.  In this case, we looked at bloom wither and then compared it to a date 2 weeks prior to emergence.  This 2-week window would allow time for the herbicide to be applied. In Kansas, withering of most ornamentals was not useful for estimating emergence of crabgrass in bare soil, as emergence often occurred before blooms had withered. However, a date 2 weeks prior to  crabgrass emergence in bare soil could be estimated by adding 6 to 12 days to the date of daffodil wither.

Bloom wither of flower ornamentals was used as a date to determine time of application of short-residual preemergence herbicides (a date 2 weeks prior to crabgrass emergence)

 

Flower wither of all ornamentals could be used indicators of emergence (and herbicide application date) in thin turf in Kansas (see Table 1 below). For example, by adding 28 to 33 days to the date of forsythia bloom wither, you will estimate a date 2 weeks prior to crabgrass emergence in thin turf, which would allow time for preemergence herbicide application.  This timeline is quite different from the often used theory that herbicides must be put down at the time forsythia blooms.  Ultimately, biological indicators, along with soil temperatures, will be better indicators of for crabgrass emergence and application of short-residual preemergence herbicides than calendar dates.

Table 1.  Ornamentals and the number of days to be added to flower wither to estimate the date 2 weeks prior to crabgrass emergence in thin turf.  Data were based upon observation of ornamental blooms and crabgrass emergence for a 3-year period.

Ornamental Number of days to add to bloom wither to estimate the date 2 weeks before crabgrass emergence (range allows for standard error)
Bridal wreath spirea 4 to 13
Callery pear 32 to 41
Flowering quince 36 to 42
Forsythia 28 to 33
Iris 8 to 15
Lilac 17 to 22
Redbud 25 to 32
Saucer magnolia 28 to 32
Tulip 21 to 29

 

Note – This article is based upon:

Fry, J., S. Rodie, R. Gaussoin, S. Wiest, W. Upham, and A. Zuk.  2001.  Using flowering ornamentals to guide preemergence herbicide application in the Midwest U.S.  International Turfgrass Society Research Journal.  p. 1009-1012.

The Star-of-Bethlehem makes an appearance….

By Brooke Garcia (Modified original post written by Dr. Jared Hoyle)

Photo taken by Brooke Garcia

Recognize this weed? This time of year, we are beginning to see a lot of star-of-bethlehem popping up in lawns throughout Manhattan, KS. In my neighborhood, which is one of the oldest areas in Manhattan, it seems to be in every lawn. We struggle with this particular weed every year in our turf, as well as our landscape beds.

Photo taken by Brooke Garcia

It is a very pretty plant with showy, 6-petaled white flowers that have a distinct green stripe underneath. It is a perennial bulb that sometime appears to look like clumps of grass. It can be hard to spot in a freshly-fertilized, green lawn. The green hues blend together. The leaves are linear and smooth, flat in cross-section and have a with midrib.

This plant likes shady and moist areas of the lawn, but I have also seen it grow in the sunniest locations of my lawn too. With the recent moisture and more on the way we are not short of moist areas in the lawn around Manhattan right now.

Although it is has very distinctive characteristics it can be confused with other plants that are commonly found in lawns; crowpoison (Nothoscordum bivalve),spring beauty (Claytonia virginica), wild garlic (Allium vineale) and wild onion (Allium canadense).

If you do not have a lot of this weed in your turf or landscape beds, it can be effective to hand-dig the plant and bulb completely out of the affected area. However, the leaves tear quite easily. Thus, it can be difficult to completely eradicate the entire plant using the hand-removal method.

For chemical control there are couple of options.  Both sulfentrazone and carfentrazone have shown to be very effective.

For additional information about Star of Bethlehem, see the recent post written by Ward Upham:

Wild Onion, Wild Garlic, and Star-of-Bethleham

***Mention of trade names or commercial products in this article is solely for identification purposes and does not imply recommendation or endorsement, nor is criticism implied of similar products not mentioned by Kansas State University.***

National Pesticide Safety Education Month

By: Frannie Miller

Did you know there are about 1 million certified pesticide applicators in the United States? There is somewhere between 11,000 to 15,000 pesticide products registered for use in each state. Common consumer products that contain pesticides include flea collars, weed and feed, and roach baits. Pesticides play an important role in improving the quality of food and feed yields. They also protect the public health, controlling pests in our homes, turf, forests, waterways, and right-of-way.

February is National Pesticide Safety Education Month, which is important in raising awareness and support for land-grant Pesticide Safety Education Programs (PSEP). Pesticide Safety Educations Programs like the one at Kansas State University deliver pesticide applicator trainings on safe use of pesticides in various settings, as well as deal with state-specific needs and laws.

Have you ever wondered how safe you are when using pesticides? You can take a self-assessment of personal pesticide safety practices to evaluate where you could do better:

Self-Assessment of Personal Pesticide Safety Practices

Natural needle drop, or plant disease?

(Megan Kennelly, KSU Plant Pathology)

Which of these is a disease, and which is natural needle drop?

If you guessed natural needle drop for the first and disease (Dothistroma needle blight) for the second, you are right!

If you were not sure, here are some resources to figure it out.

In a recent article in Horticulture News, Ward Upham mentioned some recent reports about natural needle drop on evergreens. You can read more about it here:

http://www.ksuhortnewsletter.org/newsletters/natural-needle-drop-on-spruce-arborvitae-and-pines

In addition, this publication talks about pine diseases and at the end there is a section about natural needle drop:

https://www.bookstore.ksre.ksu.edu/pubs/l722.pdf

If you see yellowing, browning, or dropping of needles and you still are not sure you can reach out to your local K-State Research and Extension office or contact the KSU Plant Disease Diagnostic Lab:

Plant Disease Diagnostic Lab

1712 Claflin Road
4032 Throckmorton PSC
Manhattan, Kansas 66506
(785) 532-5810
Fax: (785) 532 5692
clinic@ksu.edu

 

Upcoming Commercial Pesticide Applicator Training

By Brooke Garcia & Frannie Miller

Upcoming Commercial Pesticide Applicator Training

Date: November 12-14, 2019 in Salina, KS – Webster Conference Center

Website: https://conferences.k-state.edu/commercialpesticide/

Objective: The objective of this training program is for the Kansas State University Cooperative Education Service to provide a broad, practical training program and to help Kansas commercial pesticide applicators meet the requirements for renewal certification.

ALL commercial certified pesticide applicators are required to accumulate credit hours if re-certifying through training.

In Kansas, there are two ways to receive training for renewal certification: 1) study a manual and pass an examination and 2) attend training courses approved by the Kansas Secretary of Agriculture for required re-certification credit hour (CEU) accumulation. All applicators must now accumulate the necessary credit hours required for the appropriate category/subcategory in which they are certified. If you have not accumulated the required number of credit hours (1 core hour and either 3, 5 or 7 pest management hours) and paid the certification fee ($50 per category certified in) to the Kansas Department of Agriculture (KDA) by the expiration of your current certification, you must re-exam to obtain certification.

Questions?
If you have questions regarding the renewal requirements, please call the Kansas Department of Agriculture at 785-564-6688. To view your current certification credits, go to: https://www.kellysolutions.com/ks/applicators.
If you have questions concerning this training program or if you are interested in the additional training programs that the K-State Research and Extension Program has to offer, please call Frannie Miller at (620) 241-1523.

Are you using the right gloves for pesticide safety? And a new resource to translate safety info into Spanish

With pesticides, usually we are thinking about the active ingredient that targets the problematic insect, weed, or disease. But did you know that the different “carriers” in the formulation can affect applicator safety, too?

Here is a quick article that summarizes some of the key points of selecting the right gloves for applicator safety:

If the Glove Doesn’t Fit (the job!), You Must Quit

 

Speaking of pesticide safety, the EPA recently announced a new program to help translate information into Spanish.

https://www.epa.gov/pesticides/epa-offers-guide-help-translate-pesticide-safety-information-spanish

You can find the full guide here:

https://www.epa.gov/sites/production/files/2019-10/documents/spanish-translation-guide-for-pesticide-labeling.10.10.19.pdf