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Update (6/13/2012)

Time to Hunt for the Hunting Billbug


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Weather

Mid-Missouri finally received some much needed rainfall on Monday, with areas getting scattered 0.5 – 1.0” totals.  At the turf farm, we received 0.65” in the morning event and could’ve used a bit more considering the 7-day forecast isn’t holding a lot of promise for another sustained rain event.  Even with the relatively small amount of rain, it is amazing how turf, trees, and shrubs have recovered from drought dormancy and are somewhat green again. 

Temperatures have also been mild, which means many of our summer turf diseases are lying in wait.  Nighttime temperatures have consistently been in the 50s, meaning brown patch on tall fescue has not been active even in irrigated lawns over the last few weeks.  A burst of summer is forecasted for the end of this week, and low temperatures are forecasted to be upper 60s and low 70s.  With this spark, I expect summer disease issues to begin in earnest over the next 5 days.  


Quick Hit
s

  • Scouting Alert for the next 5 days 
    • Tall fescue – Brown Patch
    • Kentucky bluegrass – Pythium blight (irrigated), Summer Patch
    • Creeping bentgrass -  Anthracnose on susceptible varieties (i.e. Penncross, Pennlinks, SR1020, Dominant), Pythium root diseases

  • Dollar Spot: While not conducive to summer diseases, this recent weather pattern has been perfect for dollar spot activity on creeping bentgrass.  Considerable mycelium and new infections were noted this morning on the bentgrass greens at the turf farm.   No dollar spot on Kentucky bluegrass has yet to come in the lab or is being observed at the research farm, presumably due to our recent dry conditions and relative infrequency of watering compared to our putting greens.  .   
      
  • Japanese beetle catches: Japanese beetle catch counts are starting to peak now in mid-Missouri.  Rolling masses of beetles having (ahem) fun are being observed on shorter mown athletic fields and turf surfaces.     I anticipate annual white grub outbreaks to occur 3-4 weeks earlier to coincide with these early beetle flight peaks.  Insecticide applications targeted for annual white grubs should be made shortly to coincide with the adult peak.  This application may also effectively control the newly emerging problem discussed below.  

Dig Dug to Find a Billbug Grub


Billbug damage is occurring throughout Missouri

Although the title of this section is born from fun memories of playing an addicting 1980’s video game called “Dig-Dug”, a serious insect issue is newly emerging in Missouri’s turfgrass landscape.  Over the last 6 days, I have identified billbug grubs in samples from zoysiagrass, bermudagrass and Kentucky bluegrass lawns and athletic fields.  Sample locations included St. Louis, Rolla, and Columbia so the problem appears to be widespread. 

There are four types of billbugs: bluegrass, Denver, Phoenician, and hunting.  The bluegrass billbug is well established in the Midwest and northern states, and is one of the top three pests on Kentucky bluegrass.  Denver and the Phoenician billbug, as the names imply, are not located in the region and are limited to western states.   This leaves the hunting billbug, a species thought to reside primarily in the Southeast.  Because most of these finds have been in warm season turf species, I suspect most, if not all, of these recent samples have been larvae of hunting billbugs… and this is not great news.   Evidently, we are now officially part of the SEC!   

The hunting billbug (Sphenophorus venatus vestitus) is primarily a pest of zoysiagrass and bermudagrass, but may also feed on Kentucky bluegrass and field crops such as corn and wheat.  Adults are ~ ½” long, black to dark reddish brown, have a pronounced curved snout, and reside in the thatch layer.  Larvae (grubs) are very small, 1/8 –3/8“ long, and unlike annual white grubs have no legs. 

Research is still ongoing to determine the complete life cycle, but it’s thought the hunting billbug survives as a dormant adult during the winter and emerges in early spring.  It begins to feed and lay eggs in mid-late spring in the leaf sheath.  Eggs hatch in 3-10 days and the small larvae start to find inside the leaf stem and migrate down into stolons.  The larvae soon outgrow the stems and fall out into the thatch layer where they continue to eat stolons and roots.  After several weeks of feeding, the larvae dig 2-4” into the soil and pupate into new billbug adults.  In our region, we can expect two generations of the hunting billbug, and judging from the size of recent finds (see above) I estimate larvae are starting to dive down in the soil to pupate.  Since another generation is coming, control of active infestations now is crucial to limiting further damage later this summer and fall.   

Hunting billbug damage may be the most often misdiagnosed problem in warm- season turfgrass, appearing similar to damage from diseases, drought, chinch bugs or delayed spring greening.  The adults are reclusive, only come out at night, and are well camouflaged.  Also, for a good portion of their larval stage, the billbug grub is inside the plant, making detection difficult.  Oftentimes, the only diagnostic symptom of billbug damage is the hollowed out stolons and leaf stems apparent after the larvae emerge from their turfgrass hatchery and feeding chamber.  A number of declining zoysia lawns were reported in eastern MO this past spring, and the hunting billbug may have been one of the factors contributing to these cases.      

Now is the time for hunting billbug scouting as all life stages may now be active and the larger grubs are emerging from the plant.  In zoysia and bermudagrass turf areas that aren’t greening up or are not responding to irrigation, play “Dig Dug” and break out the shovel.  Dig out a 3-4 inch square of turf and break it apart, sifting through the top 1-2” of soil and thatch.  The small white grubs should be apparent in the next week or two, but their time is fleeting.  Another way of monitoring is to target the adults with pitfall traps.  Using a small plastic cup or similar, dig out a few areas in the area and place the cup inside with the lip just even with the soil surface.  As the adult billbugs crawl around at night, they will fall into the cup and can be observed.  Another good use of the “red solo cup”.

If hunting billbug larvae or adults are found and associated with declining turf, an insecticide treatment is necessary.  For adult control in early spring, bifenthrin (Talstar), deltamethrin (Deltagard), imidacloprid (Merit), or lambda-cyhalothrin (Scimitar or Battle) are recommended.  For larvae control, clothianidin (Arena) or thiamethoxam (Meridian).  If both larvae and adult control are necessary (like NOW) applications of chlorantraniliprole (Acelepryn), or the combination products clothianidin +  bifenthrin (Aloft), or imidacloprid + bifenthrin (Allectus) are needed. To target the hunting billbug larvae, it is crucial to water in the insecticide with 1/8- 1/4” of irrigation.    

The Entomology team at North Carolina State University is currently conducting research on this issue, and below are a few fact sheets with more information.

http://www.turffiles.ncsu.edu/insects/Hunting_Billbug.aspx

http://entnemdept.ufl.edu/creatures/orn/turf/hunting_billbug.htm

http://ohioline.osu.edu/hyg-fact/2000/pdf/2502.pdf

       

Save The Date: July 10th
University of Missouri Turf & Ornamental Field Day

-  Want to see Dr. Starbuck discuss trees for the last time before his retirement? 
-  Want to hear more about the Poa annua control? 
-  Want to find out about the latest and greatest methods for turf and ornamental management?
-  Want to meet local vendors interested in providing management solutions?
-  Or, do you just want to eat a great lunch among your colleagues and research scientists?

Well then, come on over to the research farm on July 10th for all kinds of interesting lessons and information on how to effectively manage turf and ornamentals in Missouri.  Our outstanding lineup of presentations and displays is set, and our research teams look forward to meeting and discussing your plant management practices.  Look forward to seeing you there!!

Click here to see the full schedule.

Click here to register.

 

Lee Miller
Follow on Twitter!  @muturfpath
Extension Turfgrass Pathologist
University of Missouri