Another Armyworm Year?

Last year's armyworm outbreak in Ontario was quite something. The large number of acres and high infestations across several counties was unprecedented. No other states or provinces reported anything like it. And the only signs that indicated that we could have a problem came from the high trap catch reports coming from Kentucky. Storm fronts brought the moths up to Ontario, while skipping over many of the other states in between. And unfortunately this year, Kentucky and Missouri have both reported catching true armyworm moths at reasonable numbers again this year. Other states are starting to see a trickling of moths in their traps too. Our blacklight trap at Ridgetown has been up since the beginning of April and started to catch our first armyworm moths on April 20th, though numbers have been quite low with only a total of 4 moths captured so far.

What does this all mean? There is a risk of armyworm being an issue this year, especially given all of the storm fronts that are moving up from the southern states this spring. How much of a risk is hard to tell yet. But we need to stay alert. Moths are going to be attracted to whatever wheat is still surviving as well as any fields with mats of weeds, which are plenty this year given that the rain and wind have not been cooperating with us this spring. We could see larval activity by the third or fourth week of May and through the month of June, first showing up in the more southern counties of Essex, Chatham-Kent and Lambton. Again, the important word being "could" but we should stay alert. Scout wheat fields in the next few weeks, and continue every 3-4 days until at least the end of June. Don't forget to check both the field boundaries and randomly within the fields too. Once corn starts to pop out of the ground those fields too are at risk, especially if they are neighbouring winter wheat fields or didn't get a decent burndown by mid April.

We will report moth catches and any larval sighting as soon as we are made aware of them

Figure 1. True Armyworm

.