Posted 28 May 2015. PMN Crop News.
Entomology Update From the Turfgrass Entomology Lab at PSU
Source: Penn State University Press Release. agsci.psu.edu
University Park, Pennsylvania (May 21, 2015)--Annual bluegrass weevil update: We have had a rapid change in the development of our ABW populations in PA since my last blog entry (though it appears we are in a slight cool down at the moment). Early instar larvae were abundant in samples from across the state mid-week last week (May 13th). Our plant indicators that signal optimal larvicide timing (Rhododendron catawbiense – which I have been misspelling for a long time) have gone into full bloom in a relatively short time frame. If you are intending on putting down a larvicide, now would be a good time, as the population of larvae residing in the plant are beginning to appear in the soil.
It is hard to gauge what will happen over the next couple of weeks with ABW populations. I have visited a lot of sites where it has been very difficult to find adults or larvae. It is my thinking that many people scouted intensively and made well-timed adult applications. If you are having a hard time finding larvae in your “hot-spot” areas, you may not need a larvicide (*This is entirely dependent on past population sizes, damage, sampling intensity, and how much risk you are willing to take on).
Conversely, I have observed courses with damage appearing much, much earlier than anticipated. The unusually dry Spring may have stressed the turf to the point where damage is appearing weeks ahead of schedule. Make sure you provide adequate irrigation to areas where you have had a history of damage. It may not help you avoid ABW damage, but it will certainly increase your safety net.
Ants have ramped up mounding in the last week. The dry conditions seemed to have exploded populations. Controlling ant mounding at this point is going to be rather challenging. You may need to start thinking about interventions in the Fall, as many treatments made in early summer will provide only temporary relief.
Our earthworm activity is running opposite to the activity of ants. The unusually dry spring has reduced soil moisture, and in turn, earthworm activity. We failed to expel worms with seed meal extract this week (earlier in the Spring it was Wormageddon -to coin a phrase from Doug Middleton of Ocean Organics). So what gives? Earthworms are adverse to dry soils. When soils dry they either burrow deeper in the soil or aestivate (essentially hibernate) in a “mucus chamber”, enter a non-feeding state, or by curling up in a knot-like ball. But dont worry: they’ll be back! Fall is another big season for earthworm casting. We will keep you up to date on this project’s progress.