Scouting for greenbugs can be frustrating, but researchers in Oklahoma have developed an alternative method of sampling that might bring some relief to wheat producers.
“If you’ve ever had to scout for greenbugs, you know what a pain it can be because you go out there, you pick up the plants and try to count the number of bugs on a particular plant to see if you’re at threshold,” says Oklahoma Cooperative Extension Service small grains specialist Jeff Edwards. “It’s aggravating. The things are small, it’s tough to count the number of greenbugs per plant, and unless you’re keeping really good notes, it’s hard to remember how many greenbugs you found in one area of the field as opposed to another.”
The “Glance ‘n Go” sampling system is a presence or absence technique that is designed to be rapid and accurate. Based on data collected in more than 100 wheat fields in Oklahoma over a two-year period, Glance ‘n Go requires that the scout keep track of the number of tillers infested with greenbugs as opposed to counting the actual number of insects.
“There’s one card for the fall sampling and one card for spring sampling. And these are really easy to use, you can either print them off the Web and use a marker, or if you want to use one card over and over again, you can see your local county office and get a laminated card that you can use a dry erase pen on,” Edwards says.
Sampling begins with walking out into the field and making six initial stops.
“You want to have about 30 feet in between stops, so I normally take about 15 steps between each stop. At each stop, you’ll pick up three tillers and you’ll just look to see if greenbugs are there or not. So you don’t have to count the number of greenbugs, it’s either they are there, or they’re not,” Edwards says. “If you have greenbugs on a tiller, you make a mark on your sheet. If you don’t have greenbugs on a tiller, you leave it blank. After six stops, you add up the total number of tillers you have that are infested.”
After adding up the infested tillers, producers can refer to the recommendations sheet to see what steps to take next.
For instance, in the fall, if you have two or fewer tillers infested, you’re done with that field. No greenbugs, its not justified to spray that field. If between three and seven out of the 18 tillers are infested, you’ll want to keep sampling — do 6 more sites take another look at that field,” Edwards says. “If you have more than eight tillers infested out of the 18 that you’re going to look at, it’s a no-brainer, you need to spray that field.”
It’s important to note that the treatment threshold for Glance ‘n Go is only applicable for wheat after it reaches the 4-leaf stage, and also that Glance ‘n Go is designed only for the greenbug.
For more information on the system, go to http://entoplp.okstate.edu, click on “Hosted Websites” on the left, then click on “Cereal Aphids Pest Management” under “Agriculture Models.”