By Tom Royer, OSU Extension Entomologist
I received several reports of treatable greenbug infestations in winter wheat in Major County. This means it is important to scout your fields for greenbugs. I encourage you to use the “Glance n’ Go system, as it is easy to use.
There are several things that make Glance ‘n Go sampling a desirable way to make such a decision. You only have to “Glance” at a tiller to see if it has greenbugs (no counting greenbug numbers). You can make a decision to treat “on the Go” because you stop sampling once a decision is reached (no set number of samples). Finally, you can account for the activity of the greenbug’s most important natural enemy, Lysiphlebus testaceipes. Aphid Mummies
The Glance ‘n Go system be accessed in two ways. One is to set up an account with the myFields platform: http://myFields.info and sign up for a personal account. This system will allow you to sample a field with a smart phone in the field. To use it, you must have cell phone connectivity. You can then select the Glance n’ Go tool, plug in your cost inputs, and start sampling. Once you sign up, you can scout multiple fields and myFields will keep track of all your sampling information.
The second way is to access the Cereal Aphids Decision Support Tool on your computer http://entoplp.okstate.edu/gbweb/index3.htm . You can customize the threshold and selecting the Greenbug Calculator. Put your inputs in and it will select a threshold for your field. You can then download a paper Glance n’ Go form; take it to the field and start scouting.
By answering a few simple questions, you can determine an economic threshold for controlling greenbugs. This threshold is based on the estimated cost of treating the field and the estimated price of wheat. Once a threshold is calculated, you can print a Glance ‘n Go scouting form, take it to a field and record your sampling results. The form will help you to decide if the field needs to be treatment for greenbugs.
When scouting with the Glance ‘n Go system, keep a running count of tillers that have one or more aphid mummies and a running count of tillers that are infested with one or more greenbugs. The Glance ‘n Go form directs you to look at your total number of infested tillers and tillers with mummies after 5 stops. You will be directed to treat, not treat, or continue sampling. If there is enough parasitoid (mummy) activity, you will be directed to stop sampling and DON’T TREAT, even if you have exceeded the treatment threshold for greenbugs! Why? Because research showed that at that level of parasitism, almost all of the healthy-looking greenbugs have been “sentenced to death” and will be ghosts within 3-5 days. If they have received their “sentence” you can save the cost of an unnecessary insecticide application.
I accessed the Glance n’ Go tool to determine a “general” threshold that you can use for a Spring infestation, based on a wheat price of $5.50 per bushel and an application cost of either $4, $6, and $8 per acre. You can go directly to the website and download a paper form (Greenbug Spring Infestation) directly. The threshold is 3 greenbugs per tiller if your application costs are $4 per acre or 2 greenbugs per tiller for application costs of $6 or $8 per acre.
Contact your local County Extension Agricultural Educator for more information. If a field needs to be treated, check with Current Report CR-7194, “Management of Insect and Mite Pests in Small Grains”.