They’re out there, just not causing their usual damage…yet.
Observations from around the heart of corn country in Illinois indicate that corn rootworm larvae, though present and beginning to emerge into adulthood, are behind schedule with their potential root damage this summer for a couple of reasons, says University of Illinois crop scientist Michael Gray.
“Reasons for the delayed feeding and emergence this season likely relate to the deeper egg laying during last year’s drought and the heavy precipitation this spring and early summer across much of Illinois,” Gray says in a university report. “Saturated soils do not warm up as rapidly as dry soils and heat unit accumulations, key to the timing of corn rootworm development, have not accrued as fast this growing season.”
In his area of central Illinois, Gray says emergence and ultimate potential economic damage will likely begin about a week late. Normally, the bug’s out inflicting crop damage by this time. Gray still recommends staying on the lookout for damage now, collecting samples comprising 10 roots and consulting crop consultants or university experts before making a treatment decision.
(Source – http://www.agriculture.com/news/crops/cn-rootwm-damage-slow-to-arrive_2-ar32501)