Insect Pests Threaten Grass Fields
Posted in General by Curtis Williams
Oregon State University has notified the Oregon Seed Industry with concerns about insect pest pressure occurring in Willamette Valley grass seed fields, especially tall fescue and orchardgrass. OSU personnel have identified both true armyworm (Mythimna unipuncta formerly Pseudaletia unipuncta) and clear-winged grasshopper (Camnula pellucida) populations over the past two weeks.
Damage in some fields is serious and we suspect that the problem, especially true armyworm, has started to move from South to North. Field damage from true armyworm looks very similar to what was seen last year with the winter cutworm with leaf chewing and decline of crowns.
Armyworms and cutworms both die from natural causes. In the last week, we have observed fungal diseases, tachinid flies, a wasp parasitoid, and ground beetles in local fields. These are the key factors for larvae mortality and help keep the armyworm in check. There are a few pesticides available but efficacy is dubious.