Spring Grub Control Not Your Best Bet

Spring is almost upon us and overwintering white grubs will soon be emerging from the depths to continue feeding for a short time before they pupate. These overwintering grubs typically spend the frigid months of December – February deep in the soil profile (up to 12 inches deep) to avoid freezing. As soil temperatures begin to rise (like they have this month), these grubs “wake up” and work their way into the thatch/soil interface to continue feeding. By mid-April spring feeding is usually in full swing and it is sometimes accompanied by an increase in skunk and raccoon foraging activity that can occasionally damage the turf.

Although it may be tempting to try to manage white grubs during this time, data clearly indicates that the effectiveness of chemical applications targeting white grubs in Spring is greatly diminished. Unless serious secondary damage resulting from animal foraging activity is observed, attempts to manage grubs at this time should be discourage. The window of opportunity and likelihood of success are so small that applications made at this time will almost certainly be wasted.

If secondary damage from animal foraging is simply too much to tolerate, an application of trichlorfon (Dylox) is the only course of action that stands a chance of being effective, and even then the odds are not in your favor. Also, remember that killing white grubs present in April will likely have no impact on white grub populations occurring later this year (July-October).

Instead, consider raking out and re-seeding damaged areas and forget about trying to control these overwintered grubs.

Doug Richmond, Turfgrass Entomologist

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Part III: Controlling broadleaf weeds in newly seeded areas

This turf tip is part of a three part series on spring seeding.

Most turfgrass herbicides are intended for use on established grasses. Thus, herbicide use on newly planted grasses should be very conservative. If possible, wait until the grass has gone through several mowings or a full growing season before using chemical weed control. However, as described in Part II of this turf tip (add part II link here) there are some postemergence broadleaf herbicides that are safer on newly seeded turf including Drive (quinclorac), Tenacity (mesotrione), SquareOne (quinclorac + carfentrazone), and Imprelis (aminocyclopyrachlor).

If weed competition is severe enough to warrant herbicide use, a good rule of thumb is to wait until a recently seeded lawn has been mown two to three times before using the three-way herbicides (2,4-D + dicamba + MCPP) or Q4 Plus (quinclorac + sulfentrazone + 2,4-D + dicamba), Onetime (quinclorac + MCPP + dicamba), or Solitare (quinclorac + sulfentrazone). See the label of the product you wish to use for complete directions.

Keep in mind that the best time to control weeds is in the fall. See our fall posting on broadleaf weed control for more information on fall application timings (http://www.agry.purdue.edu/turf/tips/2010/10182010_broadleafweeds.html ).

Just as with spring seeding dates, it is important that when turf is planted in the fall that new turf seedlings are mown 2-3 times before a fall postemergent herbicide application is made for broadleaf weeds or alternatively that a herbicide is used that is typically very safe on new seedling such as Drive (quinclorac), Tenacity (mesotrione), SquareOne (quinclorac + carfentrazone), or Imprelis (aminocyclopyrachlor).

Aaron Patton, Assistant Professor/Turfgrass Extension Specialist

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Snow mold damage - 2011

Melting snows revealed some significant snow mold damage. As you know there are two types of snow mold diseases, gray snow mold (aka Typhula blight) and pink snow mold (Microdochium patch). Although they create similar symptoms (circular patches of tan turf—sometimes with orange/brown margins, Fig. A, C, D) the pathogens are not closely related and they have different temperature requirements for infection. Infection by the gray snow mold pathogen occurs within a narrow range of cold temperatures (32 – 36 degrees Fahrenheit). The insulating effect of snow cover offers extended periods when such temperatures are maintained at the turf surface. Gray snow mold is not common in Indiana, but I have found plenty of it where snow piles have remained all winter. The gray snow mold pathogen produces survival structures called sclerotia (Fig. B) that are about the size of a period printed on this page.

Pink snow mold is much more common in the lower Midwest because infection occurs under a wide range of temperatures (32F – 50F). Symptoms that develop after snow melts, during cold wet weather in spring are attributed to the Microdochium patch phase of the disease. The pathogen produces spores (called conidia) at the edge of circular patches. The conidia may be washed down slope to create new infections, especially on putting greens. Juvenile (less than one year old) creeping bentgrass is unusually susceptible to snow mold damage.

At this time of year, controlling gray snow mold is all about hastening recovery of the patches. Because of the narrow range of temperatures required for infection, the disease will not spread any more this year. Disturbing (raking) the matted turf and perhaps a light application of N will accelerate turf growth as temperatures rise and mitigate the effects of the disease.

We treat pink snow mold differently because it remains a threat through April and May. I do not think fungicides are warranted for fairways, but I would consider an application on tees and putting greens if numerous patches developed over the winter. Turf within the patches are thinned by disease progress and therefore are vulnerable to colonization by Poa annua. It is likely that only a contact fungicide (chlorothalonil) will limit spread while turf remains dormant. Once turf is actively growing, a penetrant fungicide (such as a DMI) may provide more effective control.

For more details about snow mold diseases check out our Turfgrass Disease Profiles on the Turf Program Website--- www.agry.purdue.edu/turf/pubs/index.htm

Rick Latin, Turfgrass Pathologist
Aaron Patton, Turf Extension Specialist
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Rejuvenating Turf in 2011: Part II

Part II: Preemergence and postemergence herbicides for crabgrass control in newly seeded areas
This turf tip is part of a three part series on spring seeding.

Early spring preemergence herbicides are often necessary in Indiana to prevent troublesome annual grassy weeds such as crabgrass and goosegrass. Additionally, these applications help to prevent the emergence of some broadleaf weeds. Most preemergence herbicides work to kill weeds by preventing cell division causing death to weed seedlings shortly after they germinate. All preemergence herbicides (except Tupersan) work to prevent the emergence of turfgrass seeds as well as weed seeds, so do not reseed areas treated with a preemergence herbicide this spring or do not apply a preemergence herbicide if you plan on seeding.

How to control crabgrass in lawns this spring

There are five potential options.

Control crabgrass as normal with a preemergence herbicide (dithiopyr, prodiamine, or pendimethalin) because the turf is not severely damaged and thin areas will fill-in from Kentucky bluegrass rhizomes. NOTE: If the lawn is tall fescue or perennial ryegrass it will not fill-in thin areas without additional seeding.

Tupersan (siduron) may be used for preemerg­ence control of annual grassy weeds in newly seeded cool-season turf and zoysia­grass. Check the label for rates and use directions. This herbicide is more expensive and short-lived, but it is the only safe preemergence herbicide to apply at the time of seeding.

Another strategy is to use a postemergence herbicide instead of a preemergence herbicide to control crabgrass in late May and June that is safe to use on seedling turf. Options include Drive (quinclorac), Tenacity (mesotrione), and SquareOne (quinclorac + carfentrazone). These products can be most safely used very soon after seeding to control crabgrass (see label for exact details on each turf species). If the seedlings are more mature (have been mown 2-3 times following their emergence) then other products such as Q4 Plus (quinclorac + sulfentrazone + 2,4-D + dicamba), Onetime (quinclorac + MCPP + dicamba), or Solitare (quinclorac + sulfentrazone) can also be used. For homeowners, there are now several products that contain quinclorac which can be used. Look for quinclorac in the list of ingredients on the label. NOTE: Tenacity (mesotrione) mentioned above can be used on all turf areas except residential home lawns at the time of this writing; however, a residential lawn label is anticipated for this product in the spring of 2011.

A fourth option is to use Dimension (dithiopyr) in May after a spring seeding to control newly germinated crabgrass that has emerged and is still at the 1-2 leaf stage or just started tillering. Dimension is the only preemergence herbicide which has good postemergence activity on newly germinated crabgrass. This application would also prevent future crabgrass germination through the rest of the summer in newly seeded areas. Another modification of this strategy would be to tank mix Barricade (Prodiamine) or Pendulum (Pendimethalin) with a post-emergence crabgrass product like Acclaim Extra (fenoxaprop), Drive (quinclorac), other quinclorac containing products, or Tenacity (mesotrione) in order to get both preemergence and postemergence control of crabgrass in a newly seeded area. The assumption with all of these herbicide options in this scenario is that the seedlings were planted in early spring and that they have developed enough of a root system to tolerate an application of a preemergence herbicide in May.

The last option is to go ahead and apply a preemergence herbicide to control crabgrass despite the fact that the lawn may be thin and in need of seeding. Since establishing turf in the spring is not as optimal as establishing turf in the late summer (mid-August to mid-September), you might likely have better long term results if you wait to seed in the fall as opposed to seeding this spring. This will only be an option for those patient enough to wait until they get their lawn back into shape.

Aaron Patton, Assistant Professor/Turfgrass Extension Specialist
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Check out these new and improved tools!

We have been working hard this winter trying to help you be more efficient…..

These tools/calculators are now available on our Purdue Turf Science web-site to help you answer various turf-related questions.

  1. An updated Turf Fertilizer Calculator. It still allows you to calculate granular fertilizer needs based on target nutrient rate and product analysis. It has been enhanced to help applicators interpret a fertilizer label and offers a new calculator to help determine liquid product needs. http://www.agry.purdue.edu/turf/fertilizerCalculator/index.html
  2. A NEW seed calculator: This tool allows you to understand a seed label, calculate seed needs, and compare products. http://www.agry.purdue.edu/turf/seedCalculator/index.html
  3. A NEW sand needs calculator: This new tool helps turfgrass managers determine sand needs for topdressing, filling core aeration holes and sand bunkers. It was designed in response to the numerous questions regarding how much sand to use. Users input various criteria such as how large their area is, what depth they intend to apply the sand, provides information regarding the importance of core cultivation and sand topdressing and the potential golfer’s response to core aeration spacing/depth. http://www.agry.purdue.edu/turf/sandCalc/index.html
  4. A NEW lawn species selection tool. This new tool was created in response to the numerous questions related to the “what is the BEST species” to plant in lawns throughout the state. This tool allows the user to first identify the site criteria: user’s must select their turf intended turf use (lawn or utility turf), environmental conditions (shade vs. sun), desired appearance/intended visual quality (low, medium, high), and the specific county where the turf will be cultivated. The tool then provides a list of potential species that could be planted and successfully cultured on the site. In addition a color photo of the turfgrass and brief description of the species are provided. Additionally a printable copy of this description is also offered. It also provides a link to important cultural and pest information for the North Central Region at the “Lawn Problem Solver” as well as our own Extension publications. http://www.agry.purdue.edu/turf/turfgrassSelectionTool/index.html

As always we are open to your feedback and suggestions for potential improvement. If something does not seem to be working properly, PLEASE let me know…

Cale A. Bigelow (email:cbigelow@purdue.edu)

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New GDDTracker site is live!

The GDDTracker Team (Michigan, Indiana, Illinois, and Ohio) is proud to launch the latest version of our turf pest tracking web site (http://www.gddtracker.net/). We have been very hard at work to bring you an even better product in 2011. You can now drop a star on the map to mark your location and with the new Google Maps interface, you can zoom in for a closer look. Another major change for 2011 is the addition of Ohio to the GDDTracker network; joining Michigan, Indiana and Illinois. Significant upgrades to the network include the addition of daily max/min air and soil temperatures and improved (12 km) resolution across the entire GDDTracker user region.

This website is useful for the tracking of the following:

  • Primo/Proxy application timing for annual bluegrass seedhead suppression

  • Embark application timing for annual bluegrass seedhead suppression

  • Annual bluegrass flowering

  • Broadleaf weed control timings

  • Broadleaf wed flowering

  • Crabgrass germination dates

  • Crabgrass preemergence herbicide application timings

  • Japanese beetle activity/life cycle

  • Bluegrass billbug activity/life cycle

  • Black turfgrass ataenius activity/life cycle

To help make this easier for you to use, you can sign up for email alerts to let you know when these events are about to occur or are occurring. Thanks to Dr. Ron Calhoun at Michigan State University for all of his hard work in putting this site together.

Aaron Patton, Assistant Professor/Turfgrass Extension Specialist

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Rejuvenating Turf in 2011: Part I

Part I: Spring seeding options

(This turf tip is part of a three part series on spring seeding.)

Seeding in spring is difficult and often unsuccessful. However, there are circumstances that warrant a spring seeding:

  • Thin turf due to winter damage

  • Poor turf density due to poor recovery from previous year’s problems, i.e., grub damage, drought damage, etc. This is the case in 2011 due to heat and drought in 2010.

  • Construction of a new home or business.

If a spring seeding is necessary, consider doing it before the ground thaws from winter. Although it is not necessary to seed before the ground thaws it may make seeding more easy as soils are often soft and moist in the spring which may make it more difficult to seed certain areas, especially with heavier equipment.

Seed planted now will lie dormant until the soil temperatures warm in late March, April or possibly May. Depending on your location in Indiana, dormant seeding can be done as early as Thanksgiving and as late as March. The benefit of dormant seeding is that as the soil heaves and cracks during the winter, crevices are created for the seeds which provide ideal germination conditions. Additionally, dormant seeding is easier to schedule than spring seeding, because spring rains make it difficult to find the right time to seed after March in Indiana. Seed can also be planted in April and May, but a March seeding date will allow more time for root development before summer.

Although any cool-season grass can be seeded in the spring, spring seedings are more successful with tall fescue and perennial ryegrass than with Kentucky bluegrass due to the faster germination rate and better seedling vigor of perennial ryegrass and tall fescue compared to Kentucky bluegrass (Fig. 1). If Kentucky bluegrass is seeded in the spring consider using a mixture of tall fescue: Kentucky bluegrass (90:10, weight: weight) or a mixture of Kentucky bluegrass:perennial ryegrass (such as 80:20, weight: weight)(Table 1). Seeding Kentucky bluegrass alone will result in marginal bluegrass establishment due to the slow germination and vigor of the seedlings and increased competition from crabgrass.

Fig. 1. Germination of perennial ryegrass (left, PR) will be followed by tall fescue (center, TF) and then Kentucky bluegrass (right, KBG).

Table 1. Recommended seeding rates for lawns in Indiana.


rate lbs/1,000 ft2

Days to

Kentucky bluegrass

1.0 to 2.0


Kentucky bluegrass + perennial ryegrass

3.0 to 6.0


Tall fescue

8.0 to 10.0

6 to 10

Tall fescue + Kentucky bluegrass

5.0 to 7.0

6 to 21

New turfgrass seedlings have poorly developed root systems and thus they cannot affectively take up the nutrients from the soil. Therefore, it is important to fertilize frequently after seeding to encourage establishment. To help the turf establish, apply a “starter fertilizer” to enhance seed germination and development. Starter fertilizer is high in phosphorus which is listed as the second number in the analysis on the fertilizer bag. For instance, a 16-22-8 fertilizer contains 22% P2O5. Apply the fertilizer according to the label directions would should supply at least 1.0 lb. P2O5 /1000 ft2. This application will likely include nitrogen (first number in the fertilizer analysis), which will also help the turf develop an extensive fibrous root system that is better able to take up nutrients and obtain water.

Aaron Patton, Assistant Professor/Turfgrass Extension Specialist

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Purdue Turf Bowl Teams Place in Top Third of Field

Purdue students continue to protect their “turf” among the rise of new competitors at the 17th Annual Collegiate Turf Bowl Competition hosted during the 2011 Golf Course Superintendents Association of America (GCSAA) Conference and Show in Orlando, FL.

The three-hour competition this year challenged student’s knowledge of more practical concepts of turfgrass management including disease, insect, seed, weed, and turfgrass identification. The competition covers mathematics, plant physiology, plant growth and development, human resource and financial management. Purdue’s performance in the competition over the last nine years has helped to bring additional recognition to the university, college and department. The students placed 2nd, 23rd, 28th, and 33rd out of 88 teams from across the nation. Agronomy student’s Matt Sumpter, Kurt Hockemeyer, Cody Whitis, Chris Sandels, Tony Feitz, C.J. Coy, John Thackery, Peter Kilanowski, Quin Stilwell, Ben Baumer, Lucas Braun, Matt Sliepka, Jeremy Eckes, Jon Conatser, and Kyle Imel represented Purdue at the competition. Despite weekly practices, with two hour-long study sessions starting in September students fell shy of their goal of finishing first but were extremely excited about their strong finish. Purdue once again solidifies its reputation as one of the top schools in the nation.

Students are already looking forward to next year’s competition at the GCSAA Show in Las Vegas, NV and the STMA competition in Long Beach, CA. They have set their sights on placing first and are committed to achieving that goal. The teams would like to acknowledge the financial support they received this year from the Agronomy Department and the Midwest Regional Turf Foundation. The teams would also like to thank Dr. Doug Richmond, Ryan Baldwin, Jon Trappe, Tracy Tudor, and their advisor Dr. Cale Bigelow for contributing their time to help educate and prepare the students. Please congratulate the 2011 Turf Bowl Teams on their performance and hard work the next time you see them.

Turf Bowl 2nd Place Team (left to right): Gregg Brenningmeyer (John Deere), Dr. Cale Bigelow, Chris Sandels, Matt Sumpter, Cody Whitis, Kurt Hockemeyer, Tracy Tudor, and James Fitzroy (GCSAA President)

2011 Purdue Collegiate Turf Bowl Participants (front row, left to right): Lucas Braun, Jeremy Eckes, Matt Sliepka, Matt Sumpter, Cody Whitis, Ben Baumer, and Kyle Imel. (Back row, left to right): Chris Sandels, C.J. Coy, Quin Stilwell, Kurt Hockemeyer, John Thackery, Peter Kilanowski, Jon Conatser, and Tony Feitz.

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