Cover St ory day length is shorter and nighttime temperatures are cooler, adult billbug feeding damage becomes much more obvious simply because the plant has less capacity to tolerate feeding.
So, what now? All of this brings us around to the big questions. Exactly what do the record warm temperatures we observed in December and the near-normal temperatures of January mean for insect pest populations in May, June, July and August? The honest answer is that we don’t know, but I would speculate that they won’t mean too much. Yes, December was indeed a record warm month — not by a small amount, but rather by double digits. No recent previous-year temperatures have even come close. In December, plants were blooming, skunks were out running around, frogs were croaking, and it felt like our region had been moved further south to Florida. Without a doubt, some insects took advantage of the situation and were active. However, many turf insects were already in their “overwintering stage,” and that meant those insects were not going anywhere by the time December rolled around, regardless of temperature. Specifically, I don’t think the warm December will make any difference in the lifecycle or timing of soil insects such as mole crickets or white grubs. Fire ants did take advantage of the weather and were quite active, and I am confident the queen was laying eggs, more ants were Photo
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hatched, and the colony was very happy. But since these mounds are relatively active for much of the year, I don’t see much real impact for 2016. Hunting billbugs, sugarcane beetles and annual bluegrass weevils (Photo 3) overwinter as adults (mature larvae also for billbugs), and it is possible that they used the warmer temperatures in December to continue to mate and lay some additional eggs. However, I do not believe this slight potential increase in activity will have much of an impact on overall populations for these pests. Fall armyworms had already succumbed to mid-fall’s frosts and freezes, so there was no impact on their populations. Cutworms, which can survive cold weather, were very happy and active during December. A few golf courses actually had damage to putting greens from cutworms in December, but the overall impact on cutworm populations for 2016 will be minimal. My prediction for 2016? Will it be a record year for insects due to the record warm weather we saw in December? No! 2016 could be a record year for some turf insect(s), but I do not think it will be due to the previous warm winter. December did not allow any insect that normally doesn’t overwinter in the transition zone to survive since January temperatures quickly brought us back to reality. The warm December did not allow any insects to complete extra generations and thus start out 2016 with larger initial populations. It was warm — it was record warm,
Annual bluegrass weevil adult.
TENNESSEE TURFGRASS April/May 2016 Email TTA at: tnturfgrassassn@aol.com
indeed a novel event — but I really doubt that we’ll see anything of significance relative to insect pests in turf due to this phenomenon. There are times when strange weather significantly impacts insect populations, especially the timing of their occurrence. My experience, however, has not been that temperatures in the winter months have much impact on the timing of insect populations, but rather the spring temperatures in late March, April and May have the greatest effect. Warm temperatures in the winter, even the extreme record warmth of December 2015, are still relatively “cold” temperatures to insects. Therefore, not much will happen in December that really contributes to the overall timing of an insect population. However, unusually warm temperatures in April CAN and DO push insect populations forward. So, as we move into the spring and summer of 2016, keep that in mind. No matter how warm it was in December, if it is unusually cold and dry in April, insect populations will most likely be delayed, and the opposite will be true if April is warm and wet. The spring weather is a big factor in our insect issues for the rest of the year. That being said, December was a warm month of epic proportions so we all need to be vigilant and not assume that 2016 will be a “normal” year because it may not be. We have never seen a winter month this warm in history, so we can’t let our guard down. After near normal weather in January and February, March has chosen to be a repeat of December, with very warm temperatures through the middle of the month. These are the conditions more likely to cause an early emergence of pest problems. But, with that said, below-normal temperatures in April or a late freeze or frost can reset all of those forecasts. The only accurate prediction is the one you develop by being vigilant about scouting and staying on top of pest issues. We will continue to provide regular updates and reports throughout the season on turf insect issues this spring and summer on Turffiles (www.turffiles. ncsu.edu) and on Facebook “Turf, Bugs, and Rock n Roll.” T