- Author: Luis Espino
Finally, the armyworm season seems to be over. Moth trapping shows that the numbers are decreasing to the lowest levels of the season. Additionally, most fields are ripening and therefore less susceptible to armyworm injury.
Overall, armyworm infestations were not as severe as last year. At the beginning of the season there were some very early infestations; however, those infestations may have been detected early because growers and PCAs were scouting closely after last year's outbreak. In most cases, the early infestations that were brought to my attention consisted of small worms, which usually go unnoticed until a few weeks later in the season.
In late August, a second infestation peak occurred. However, this infestation was similar to what we see in normal years. Nevertheless, I saw some injury that might have been approaching treatment levels.
The armyworm moth trapping conducted this year started a little later than I wanted. Next year I hope to start trapping in late May or early June so the first armyworm peak can be detected timely. Number of moths trapped remained low until August, when they started to increase and reached a peak in all locations in the Sacramento Valley. The moth peak observed in early to mid August corresponds to the increased injury observed in late August, when eggs laid by those moths reached the 3rd and 4th instars.