Japanese Beetle Emergence Begins

Japanese Beetle Emergence Begins

We captured the first Japanese beetle adults of the year last week in our traps on the Purdue Campus. These traps are located in an area where emergence tends to take place much earlier than at most locations, so don’t expect to see any significant wide-scale emergence for another 2-3 weeks. We monitor this particular site in order to be able to provide turf and landscape managers with an early heads-up so they can prepare as necessary. For turfgrass managers concerned about controlling the larvae (white grubs) of this insect, the chart below provides guidance on product selection and timing in relation to expected efficacy.

Doug Richmond

Turfgrass Entomologist

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Spring Diseases in the Midwest

Spring Diseases in the Midwest

Spring has finally arrived and it is accompanied by the usual compliment of infectious turf diseases.  There should be no confusion between two “rhizoctonia” diseases.  Yellow patch (aka cool season brown patch) prevails during early spring, when rainy weather is combined with cool nights.  It also affects al turf species and the circular patches are most prominent on shorter mown turf (putting greens and surrounds).  Brown ring patch (aka Waitea patch) visits later in the spring evening temperature increases.  It is largely restricted to annual bluegrass.

Melting out on perennial ryegrass and Kentucky bluegrass is flourishing in some stands of taller mown turf (golf course roughs, municipal athletic fields and residential turf).  Red thread and pink patch are bloom, and the solar spot pathogen has awakened and will make its presence known shortly (in my opinion).   

Here in West Lafayette, soil temperature has increased to the point where the summer patch pathogen is emerging from dormancy.  Our soil temperature monitor suggests that we are entering a period when applications of effective fungicides may limit infection.

For more information, including color images of these and other infectious diseases of turf, go to our Purdue Turf Program Website (www.agry.purdue.edu/turf/). 

For more information on weather and turf diseases, go to http://btny.agriculture.purdue.edu/turfcast/

Rick Latin
Turfgrass Pathologist

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April's Weed of the Month is Purple Deadnettle

April's Weed of the Month is Purple Deadnettle

Purple Deadnettle 

Biology: Purple deadnettle (Lamium purpureum) is a common winter annual broadleaf weed found throughout the US. It is closely related to another winter annual broadleaf, henbit (Lamium amplexicaule). Both have vibrant purple flowers that can been seen now in lawns, landscapes, and fields.

Identification: Purple deadnettle is a winter annual meaning that it germinates in the fall, survives the winter as a plant, then flowers, develops seeds, and then dies when temperatures rise in late spring and early summer. Purple deadnettle blooms are mainly visible in April although you can find it blooming earlier and later depending on the area it is growing and the temperatures. Purple deadnettle is a member of the mint family and has a characteristic square stem. Purple deadnettle flowers are light purple in color and are small and tubular in shape.  

Purple deadnettle leaves are triangular in shape with shallow lobes. Typically, the upper leaves are more purple-red in color than the lower leaves.  

Cultural control: Purple deadnettle mainly occurs in turf and soils that are disturbed during the fall when it germinates. Proper mowing (higher mowing heights), proper fertilization (some rather than none to improve turf density), irrigation to prevent summer dormancy during drought, and aerification of compacted areas to improve turf health are all cultural practices that can be used to reduce purple deadnettle. If you only have a few purple deadnettle plants, you can usually pull them by hand.

Biological control: Some organic herbicides are available. Among the postemergence organic herbicides, the most common are pelargonic acid (Scythe) and acetic acid (5 percent or greater solutions). Other products that contain medium-length fatty acids and clove oil (eugenol) show some promise; however, these organic postemergence herbicides are nonselective and can injure actively growing desirable plants in the lawn and landscape, so their use should be limited to directed spot treatments. The bottom line is that most organic postemergence herbicides have limited use in turf and are better suited to weed control in parking lots, fence rows, and other bare ground applications. Many new organic products contain the active ingredient iron HEDTA (FeHEDTA). Multiple applications of this product are required for control. FeHEDTA containing products injure turf less (can actually make turf darker green), but their efficacy for weed control is yet to be well documented.

Chemical control: Purple deadnettle can be controlled using preemergence or postemergence products, but I will mainly discuss postemergence control as preemergence control is more limited to bermudagrass and zoysiagrass lawns.

The more common approach to controlling purple deadnettle in cool-season turf is to use postemergence herbicides after it has already emerged. Most postemergence herbicides including those containing 2,4-D, dicamba, fluroxypyr, and others will control purple deadnettle. As plants get bigger, herbicides will be less effective at controlling this weed. Additionally, since it is a winter annual, it will naturally die in the summer so late spring herbicide applications aren’t necessarily warranted. You can tell that purple deadnettle is beginning to die from summer heat stress when the leaves start to turn yellow in color.

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, Turfgrass Extension Specialist

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Weather and Turf Diseases

Weather and Turf Diseases

From a temperature perspective, weather patterns in the Midwest have returned to normal this spring.  I recall the 80 F days in March 2012, and all of the concerns about scheduling fungicide sprays.  Hopefully most turf managers have resisted the temptation (regardless of who or what is doing the tempting) to apply fungicides for early season dollar spot control this year.  Fungicides will be effective only if the pathogen is active, and Sclerotinia homoeocarpa becomes active when mild weather prevails—not yet, but we’re getting close!

I also think it is too early for a summer patch spray.  The decision rule suggests that applications targeted towards summer patch should be initiated when soil temperature (2” depth) is 65 F or greater for several days.  There is so much “fudge factor” there.  Little or no hard science went into developing the rule—it’s all empirical.  Keep in mind that the pathogen comes out of dormancy more like a dimmer switch than an “on-off” switch, so it will take a while to ramp up to speed.  We intend to conduct some summer patch trials this summer, so I hope to have something useful to report next year.   

I suspect that symptoms of yellow patch (aka, cool season brown patch) are apparent on bent/poa greens and surrounds.  The heavy rains during the week of April 12 will have aggravated the situation.  Last April, we established a fungicide trial in an area where a yellow patch outbreak was severe—as bad as I have seen it in 15 years or so.  The fungicides included Prostar, Heritage (representing QOI products), Banner Maxx (representing DMI products), Cleary 3336, a chlorothalonil, and an untreated check.  The plots were monitored closely for 4 weeks.  In terms of symptom reduction, there were no differences among treatments, including the unsprayed check.  However, as daily temperatures increased, and the superintendent applied supplemental N, symptoms in ALL plots disappeared within a week.  By June 1, there was no recognizable damage, cosmetic or otherwise, to the turf.

Rick Latin
Turfgrass Pathologist

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Black Cutworms Making Their Annual Migration North

Black Cutworms Making Their Annual Migration North

Black Cutworms have started showing up in light traps around Indiana. This means they will soon laying eggs, if they haven’t already.  Superintendents should be on the lookout for evidence of feeding damage on greens and tees. Also, remember that a soap flush of vulnerable, short-cut areas will often reveal the presence of black cutworms before damage is evident. One gallon of soapy water solutions consisting of 15 ml of lemon scented liquid dish detergent (Lemon Joyâ) poured over a 0.25 m area at several locations on each green or tee will quickly disclose these larvae which may be very small at this point in the season. Black cutworms are easy to control and there are a number of products that will do an excellent job, but remember to treat the target areas and at least a 15 ft. perimeter. Higher cut areas are not usually damaged, but they do serve as a potential reservoir of cutworms when they are located around more sensitive low-cut areas.

Some recommended active ingredients include:

Bifenthrin

Deltamethrin

Lambda – cyhalothrin

Cyfluthrin

Permethrin

Spinosad

Chlorantraniliprole

Chlothianidin

Stienernema carpocapsae (insect parasitic nematode)

Bacillus thuringeinsis (kurstaki strain)

As always, follow label directions for proper rates and do not irrigate for at least 24 hours after making a liquid application.

Doug Richmond
Turfgrass Entomologist

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Annual Ryegrass Showing Up in Lawns

Annual Ryegrass Showing Up in Lawns

I have had several emails and weed samples submitted recently of an unknown grass. In each case, the sample was annual ryegrass (Lolium multiflorum).

Annual ryegrass is a common ingredient in low quality seed mixtures. It appears in the spring time in lawns seeded the previous year either from some annual ryegrass in the seed mixture or from some seed in the soil. Annual ryegrass is a winter annual and it should die later this summer when it gets hot. Before dying, it produces a seedhead and its seed can mature quickly and drop to the soil where it can germinate the following fall. No control is recommended as it is an annual grass.

To reduce the likelihood of this weed being problematic in the future choose a seed mixture that does not contain annual ryegrass, Italian ryegrass or intermediate ryegrass and one that has no weed seed. If you have this problematic weed each spring, make sure to mow the grass before it can produce a seedhead to help reduce the likelihood that it will return.

For more information on differentiating annual ryegrass from winter wheat, a similar looking weed that also shows up this time of year in lawns seeded last fall, see this turf tip posted last year: Grassy Weeds in Turf Planted Last Fall.

Dr. Aaron Patton, Turfgrass Extension Specialist

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