There is much concern relative to “worms” feeding on brome and the prospect of those worms moving to wheat when it germinates. Infestations currently consist of either fall armyworms or armyworms. At this point, both seem to be mature larvae; thus, feeding damage is about finished for at least a couple of weeks. Fall armyworms do not usually overwinter in Kansas. Thus, after these larvae (worms) pupate in the soil and emerge as adult moths, hopefully, they will not oviposit in Kansas but head south for overwintering. Armyworms, however, can overwinter in Kansas. After they pupate in the soil, they may mate and search for actively growing plants to deposit their eggs. In agriculture, this is often brome or wheat. Late-planted wheat, however, often avoids this armyworm infestation. Plus, if there is no volunteer wheat available for these moths, that also helps tremendously to mitigate damage.
KSRE Crop Production Extension Agent Jay Wisbey provided a good example of a brome field affected by armyworm/fall armyworm feeding, plus some grasshoppers, coupled with dry conditions. The photo was taken near Gypsum in Saline County (Figure 1).
For more information about fall armyworms and/or armyworm management, please refer to the KSRE Wheat Insect Management Guide 2024 at https://bookstore.ksre.ksu.edu/item/wheat-insect-pest-management-2024_MF745. For recent insecticide efficacy results, see Table 1 below.
Figure 1. Damaged brome field near Gypsum, KS, on September 10, 2024. Photo by Jay Wisbey, K-State Research and Extension.
Table 1. Efficacy trials to control armyworms in brome. DAT=days after treatment.
|
|
|
Total worms/sq. ft |
|
|
Treatment |
Rate |
9/19/2021 (7 DAT) |
9/26/2021 (14 DAT) |
|
Fastac CS |
2.4 fl. oz/a |
0 |
1 |
|
Besiege XL |
8.0 fl. oz/a |
0 |
2 |
|
Stallion |
6.0 fl. oz/a |
0 |
2 |
|
Grizzly Z |
2.5 fl. oz/a |
0 |
0 |
|
Lorsban 4E |
1.5 pint/a |
3 |
3 |
|
Check (control) |
- |
25 |
26 |
|
Check (control) |
- |
18 |
20 |
Jeff Whitworth, Extension Entomologist
jwhitwor@ksu.edu