European Chafer Causing Serious Damage in Northeastern Indiana

Although reports of spring white grub damage have been relatively uncommon in Indiana in recent years, there have been a growing number of cases in the northeastern part of the state.
The European chafer Rhizotrogus majalis Razoumowsky is apparently at the root of several reports of large scale and severe damage to turfgrass this spring. This insect is a slightly different beast than our more familiar white grub species. It is significantly more cold-hardy which allows it to feed later into the fall and start feeding earlier in the spring compared to Japanese beetle and masked chafer grubs. It also shows up in areas with no previous history of white grub damage, including low maintenance areas.

Folks in Michigan have been dealing with this insect for many years now, but it is relatively new to Indiana; adults of this species were first detected in Porter, Kosciusko and Allen counties during 2007. With the help of several diligent individuals in the green industry, we have now linked several reports of serious spring white grub damage in LaGrange, Noble and Elkhart counties to this insect meaning that populations are now established in these areas and are likely established throughout the northern third of the state (see Figure 1 and 2).

Figure 1. Home Lawn in Nobel County showing extensive damage from European chafer grubs.

Figure 2. Low maintenance turf area showing patchy damage from European chafer.

Spring grub control can be difficult to achieve and the only realistic chemical options are trichlorfon or carbaryl. Even then, repeated application may be necessary and damage is not likely to be reversed at this late time. A more proactive approach aimed at preventing infestation this summer is more likely to provide a reasonable solution. Recommended products and application timings for white grub control can be found here: European chafers may also cause damage to a variety of field, forage and grain crops (see Figure 3).

Figure 3. Extensive, but patchy damage to winter wheat caused by European chafer grubs.

If you notice grub damage this time of year, take a closer look and try to find the larvae in the soil. European chafer larvae can easily be identified using a 10X hand lens to inspect the raster pattern (Figure 4). Once established these insects may require some special attention going forward as they tend to be more damaging and somewhat less vulnerable to traditional insecticide treatments. The best control is achieved using a preventive approach with applications of imidacloprid, thiamethoxam, clothianidin or chlorantraniliprole applied June through mid-July. Keep records of any European chafer infestation in order to identify areas to keep an eye on going forward.

Figure 4. Location (A) and form (B) of the raster pattern in European chafer grubs.

Doug Richmond, Turfgrass Entomologist and Extension Specialist

Follow me on Twitter @doctorDRich

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Hunting Billbug Larvae Overwintering in Indiana

We recently discovered that the hunting billbug is capable of successfully overwintering in the larval stage as far north as West Lafayette Indiana. This insect is mainly a pest of warm-season turfgrasses such as Bermudagrass and zoysiagrass and has become a perennial problem in parts of the state where these grasses are cultured. Although we’ve known for several years that this insect overwinters as an adult and produces two generations per year in this part of the country, its ability to overwinter here in the larval stage was previously unknown. Overwintered adults have been the primary management target, but insecticide applications targeting adults may have little impact on the soil-dwelling larvae. Instead of just 2 generations to think about, managers should be aware that 2 separate cohorts may occur.

Figure 1. Hunting billbug larvae found in soil during March 2015.

Figure 2. Hunting billbug adult (actual size = approximately 1 cm).

Figure 3. High- (top) and low- (bottom) cut zoysiagrass damaged by hunting billbug.

This means is that both larvae and adults may be active and present over much of the growing season. This fact could complicate insecticide timing, narrow the spectrum of useful management options and spread damage over a larger portion of the growing season. The following table contains chemical management recommendations based on my experience and those of our colleagues in North Carolina who have been dealing with this exact issue for some time.

Table 1. Chemical management options for hunting billbug based on target stage of the insect.

Target Stage(s)
Active Ingredients Timing
Adults bifenthrin, deltamethrin, lambda-cyhalothrin, zeta-cypermethrin As soon as adults become active (late April – early May)
Larvae clothianidin, thiamethoxam, imidacloprid, chlorantraniliprole When larvae are inside stems or crowns or present in soil
Adults &
clothianidin + bifenthrin (Aloft), imidacloprid + bifenthrin (Allectus)
bifenthrin + zeta cypermethrin + imidacloprid (Triple Crown)
When adults and larvae are present or after adults have been active for several weeks
Always follow label directions and recommended application rates

by Doug Richmond and Alexandra Duffy, Department of Entomology, Purdue University
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Weed of the month for April 2015 is Smooth Crabgrass

Smooth Crabgrass  

Biology: Smooth crabgrass (Digitaria ischaemum), is a summer annual grassy weed that is found throughout the Midwestern United states. Closely related to large crabgrass (Digitaria sanguinalis) and southern crabgrass (Digitaria ciliaris), these three species are often considered to be the most problematic weeds in lawns due to their ability to survive extremely low mowing heights, poor quality soils, and dry/hot climates.

Identification: Smooth crabgrass is a summer annual grassy weed that is commonly found in home lawns throughout the US. Smooth crabgrass can tolerate very dry, poor quality soils and is found in multiple cropping systems ranging from agronomics, to landscape, to horticulture, to vegetable gardens, along with both cool and warm season lawns in Indiana. Crabgrass plants are very opportunistic, so look for it to germinate in areas of bare soil like walkways, gardens, newly seeded turf areas, as well as a very open, thin turfgrass canopy.

Germination typically occurs from mid- to late-spring (late March-early May) in Indiana. If germination occurs while the temperatures are still slightly cooler, the plant will remain small for an extended amount of time. As the temperatures warm, more leaves will start to develop and the plant will begin tillering by early- to mid-summer (June). The young leaves of smooth crabgrass will have very little hairs, while large and southern crabgrasses have a dense covering of very fine hairs. All three crabgrass varieties will have a membranous ligule that has a torn or ‘shredded’ appearance.

Smooth crabgrass leaf emerging from coleoptile.

1-leaf size smooth crabgrass.

2-leaf size smooth crabgrass.

3-leaf size smooth crabgrass.

Usually some hairs are present on smooth crabgrass but many fewer than on large crabgrass.

Photo shows membranous ligule and few hairs on leaf sheath or leaf blade.

The development of multiple tillers can contribute to the clumpy appearance of a crabgrass plant, though smooth crabgrass is generally smaller in size than large crabgrass. Once mature, smooth crabgrass produces seedheads in the form of 3-5 spikes that are clustered at the top of long, erect stems. Seedheads mature at the end of summer prior to fall/autumn. As crabgrass dies with the first killing frost, the plant can appear as unsightly brown patches surrounded by green cool-season turf in lawns.

Prostrate growth of smooth crabgrass in short cut turfgrass.

Dense turf keeps out crabgrass. Here a patch of creeping bentgrass in a lawn is keeping out the crabgrass.

Chilling injury to crabgrass in cool fall months prior to the first frost.

Brown, dead crabgrass plants in a lawn following the first hard frost.

Cultural control: Maintaining a high quality lawn through higher mowing heights, proper fertilization (some fertilization is always better than none), and supplemental irrigation during drought will help the desired turf to outcompete crabgrass.

Biological control: None known specifically for control of smooth crabgrass in home lawns.

Chemical control: For more information about crabgrass control, see our recent post, Common Questions About Crabgrass Germination and Preemergence Herbicides Answered.

Both smooth and large crabgrass can be controlled using preemergence and postemergence herbicides.

There are multiple options for preemergence herbicides that are available for purchase by homeowners, including dithiopyr (Dimension), pendimethalin (Pendulum), and prodiamine (Barricade). These herbicides prevent the crabgrass from successfully germinating. For adequate control, these products must be applied before the crabgrass starts to germinate. One exception is dithiopyr, which has the ability to control crabgrass after it germinates until it reaches 1- to 2-tillers in size.

Once the crabgrass has already emerged, another option for control is the use of postemergence herbicides. Products that include active ingredients like dithiopyr (smaller than 1- to 2-tiller in size), quinclorac (Drive), mesotrione (Tenacity), fenoxaprop (Acclaim Extra) can be used to adequately control crabgrass that has already emerged. Each of these individual fertilizers provide a slightly different spectrum of control and works well on specific sizes (based on number of tillers) of crabgrass. Homeowners can choose a product based on the size of their crabgrass as well as its ability to control other weeds that you might have present.

For more information on weed control, search this blog and check out our Turfgrass Weed Control for Professionals Publication.

For archives of past weed of the month postings, visit our Weed of the Month Archive.

Aaron Patton, Turfgrass Extension Specialist, Purdue University
Leslie Beck, Weed Extension Specialist, New Mexico State University
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How to Keep Turf Areas Around Sidewalks From Failing

Last year I posted a turf tip on why it is so difficult to manage turf around sidewalks and driveways. I encourage you to read that post (Weed Management Next to Sidewalks and Driveways) as it provides recommendations for weed control, etc. in these areas as well as how to prevent weeds and encourage healthier turf in these spots.

Today's post is a little different. With the pictures below, I want to provide some of my common-sense suggestions on repairing/designing sidewalk areas around turf to help reduce long-term maintenance needs of these areas as well as increasing aesthetics. You might not agree with all of my recommendations, which is fine. However, I hope that you can agree that in most of the below scenarios there is a relatively simple solution (either now or to consider during construction) to reduce long-term maintenance costs.

Aaron Patton, Turfgrass Extension Specialist
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Weed of the month for March 2015 is Tall Fescue

Tall Fescue  

Biology: Tall Fescue (Festuca arundinacea) is perennial grass that can be both desirable as a lawn species when using improved cultivars or undesirable when forage-type (wide-bladed) tall fescue plants a contaminant other primary species in a lawn.

For all of you nerds out there like me, you might be interested in know that there has been much recent debate about the scientific name of tall fescue. While tall fescue has used the above scientific name consistently for over 60 years, it is now being classified by scientists formally as Schedonorus arundinaceus (Schreb.) Dumort. (also = Lolium arundinaceum (Schreb.) S.J. Darbyshire; formerly = Festuca arundinacea Schreb.). I know, very confusing even for me. Remember that there are many grasses called “fescues”. I wrote about this in a previous turf tip that I would encourage you to read (click here).

Identification: Tall fescue is a coarse-textured (wide-bladed), bunch-type grass. Improvements in tall fescue leaf texture have resulted in more fine-bladed varieties/cultivars that have helped to increase the turf quality and use of this drought-tolerant turf in Indiana. We often recommend improved turf-type varieties of tall fescue as the primary species for lawns, but older, wider-bladed, forage-type varieties of tall fescue such as Kentucky 31 (KY-31) still exist, and can be problematic weeds in lawns. This forage-type tall fescue can be easily spotted in lawns in early spring when they green-up faster than Kentucky bluegrass and by its bunch-type growth habit, which results in a clump of turf when present as a weed. Also, forage-type tall fescue can be easily spotted in lawns during drought as tall fescue stays green and actively growing during drought whereas Kentucky bluegrass will often enter a drought-induced summer dormancy.  

Kentucky 31 (KY-31) tall fescue makes a poor lawn.

Improved "turf-type" tall fescue

Sometimes tall fescue blends well into your lawn. Notice tall fescue clump in center of photo.

Weedy, forage tall fescue clumps are easily visible in Kentucky bluegrass turf in early spring.

Tall fescue in bermudagrass turf in the spring during green-up.

Tall fescue (green clumps) in a Kentucky bluegrass turf during a summer drought.

Tall fescue will often lack a ligule or possibly have a short membranous ligule. 

A very short ligule is barely visible.

Auricles are usually short and blunt but some can also be classified as short-clasping meaning that the auricle may wrap-around the stem but may not fully clasp or cross one another. You may also see small hairs protruding from the auricle. 

See the short auricle and small hairs?

The vernation (how the leaf is oriented inside the stem) is rolled on tall fescue and the collar is conspicuous (obvious) and usually wide.

Broad collar is easily visible.

Broad collar is easily visible.

The leaf blade is wide but variable in length with a pointed leaf tip. In some cases you can actually feel little barbs along the leaf margin when you run your fingers from the leaf tip down the leaf blade.One last helpful identification is the prominent veins in tall fescue compared to Kentucky bluegrass (only midrib is clearly visible).

For more on tall fescue identification, see this page in our turfgrass identification tool (click here, requires flash player).

Cultural control: When there are few weedy patches of bunch-type grasses like tall fescue, it is best to cut them out with a shovel or knife. Be sure to cut down a couple of inches into the soil to get all the stems. Refill the holes with soil and seed immediately with the desirable turf species similar to the existing turf.

Biological control: None known.

Chemical control: If the area has a large number of tall fescue plants, chemical control will be more efficient. A nonselective herbicide such as glyphosate (Roundup and others) can be spot-applied. These herbicides will also kill the surrounding desired turf species, so be careful to treat only the clump of tall fescue. Two applications may be needed for complete control and the area should be reseeded 7 to 14-days after the final application. Thoroughly rake the area to be seeded to remove dead plant material and ensure good seed-soil contact. For more information about complete renovation, refer to Turfgrass Renovation (Purdue Extension publication AY-13-W).

Chlorsulfuron (Corsair) was a selective herbicide registered for the control of tall fescue in many turf species. Some quantities of Corsair (labeled for most major turf areas) may still exist but this herbicide is no longer sold. Telar XP and Chlorsulfuron 75DF contain the same ingredient as Corsiar and can be used on turf in industrial sites and roadsides but not in managed turf areas like golf courses, lawns, and athletic fields. Spot apply chlorsulfuron according to label instructions. The tall fescue will slowly thin and die, allowing the desired species to fill in. Reseeding should not be needed if Kentucky bluegrass is present. Chlorsulfuron will kill perennial ryegrass, so do not apply it to perennial ryegrass.

To control tall fescue in warm-season lawns and athletic fields, apply a nonselective herbicide like glyphosate in late winter while bermudagrass is dormant. Alternatively, many sulfonylurea herbicides are labeled for the selective removal of cool-season grasses such as tall fescue from bermudagrass and zoysiagrass.

For more information on weed control, search this blog and check out our Turfgrass Weed Control for Professionals Publication.

For archives of past weed of the month postings, visit our Weed of the Month Archive.

Aaron Patton, Turfgrass Extension Specialist
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Common Questions About Crabgrass Germination and Preemergence Herbicides Answered

This time of year many have questions about crabgrass germination and control. Below are several previous Purdue turf tips that answer the most commonly asked questions about crabgrass control.
  1. When will crabgrass germinate?
  2. When should I apply my preemergence herbicide (crabgrass preventer)?
  3. Which preemergence herbicide should I use? - Professionals
  4. How to Select a Crabgrass Preventer from the Store – Homeowners 
  5. How do I control crabgrass in spring seeded turf?
  6. Do split applications provide better control than a single application?
  7. How to identify crabgrass?
  8. How will the cool spring affect crabgrass control? Originally posted April 22, 2011
  9. How might a late frost affect crabgrass?
Forsythia blooms are an indicator that crabgrass germination is just around the corner. See the link above "When will crabgrass germinate?"

Newly germinated large crabgrass plant. Photo taken in spring of 2012.
For more information on weed control, search this blog (search box in upper left corner of page) and archived turf tip postings and check out our Turfgrass Weed Control for Professionals Publication

Aaron Patton, Turf Extension Specialist
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How to Select a Crabgrass Preventer from the Store – Homeowners

Crabgrass is a summer annual weed that germinates in lawns each spring (click here for crabgrass identification information). Preemergence herbicides prevent emergence of crabgrass plants from the soil. These products must be applied prior to crabgrass germination which could occur as early as April 1 in southern Indiana and three or more weeks later in northern Indiana in an average year (there don’t seem to be many average years these days). Purdue research has shown that these herbicides can be applied in late winter (February or later) and still be effective all season. It is essential to apply these products early in spring prior to crabgrass germination or they will not be effective and you’ll have crabgrass.

Often, preemergence herbicides are combined with fertilizers. Since fertilization should be minimized in the spring, purchase products with most of the nitrogen in slow release forms such as methylene ureas or sulfur or polymer coated ureas. Avoid products with mostly (>70% of total nitrogen) quick-release nitrogen such as urea or ammonical nitrogen. For more information on fertilizing your lawn, see Fertilizing Established Cool-season Lawns.

Do not use preemergence herbicides on newly seeded lawns or before seeding your lawn – except products that contain siduron (see below images). To be most effective, preemergence herbicides need to be watered-in after application which usually means rainfall in the spring since most irrigation systems aren't yet operational. Refer to the label for specific instructions for each product.

Common Names (Ingredients) of Preemergence Herbicide Ingredients for Home Lawns
  • Benefin/Trifluralin
  • Pendimethalin
  • Dithiopyr – product of choice if you wait to apply until after crabgrass germinates
  • Prodiamine
I listed several ingredients above as our research has shown that all of these ingredients provide similar and effective crabgrass control in Indiana and the greater Midwest.

By maintaining a dense lawn, you can limit the amount of crabgrass. Proper fertility, mowing, and irrigation is essential for crabgrass control; consider herbicidal control only if necessary.
For more information on crabgrass germination and preemergence crabgrass control, see this posting (Common Questions About Crabgrass Germination and Preemergence Herbicides Answered) with multiple articles on this topic linked.

Here are some examples of products that you might encounter at your local store that will work well as a preemergence herbicide to prevent crabgrass emergence. For each I show the picture of the product as well as the “zoomed” in image showing you the ingredient in each.

Close-up of above picture. Same ingredient as the professional product Barricade.

No fertilizer in this product, just the herbicide on an inert carrier.

Close-up of above picture. Same ingredient as the professional product Pendulum.

Similar to Halts Crabgrass Preventer but with the fertilizer (Turf Builder).

Close-up of above picture. Same ingredient as the professional product Pendulum.

Close-up of above picture. Same ingredient as the professional product Pendulum.

Close-up of above picture. Same ingredient as the professional product Dimension. Useful ingredient if you apply after crabgrass germination as it will control crabgrass prior to tillering.

Only preemergence products with siduron are safe to use in the spring  when seeding cool-season turf.

The ingredient in this product is siduron which allows cool-season grasses to germinate but prevents crabgrass from emerging. It is good for seeding but doesn't last as long as other preemergence herbicides so it is not a good season-long preemergence herbicide. This ingredient is sold as Tupersan in the professional market.

Aaron Patton, Turfgrass Extension Specialist
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