Tom Jordan says that burcucumber is not widespread across all of Indiana. It occurs more in pockets. Typically, it's in river bottom ground and may be more prevalent in northwest Indiana. At the same time, the Purdue University weed control specialist notes that if you have it in even one field, you'll remember it.
"It has continuous flushes even late into the season," says Tom Bauman, another Purdue weed control specialist. "If it isn't controlled, it can grow quickly up on top of soybeans and corn and pull them down. It's very difficult to deal with where you have it."
In the early days of weed control when several pounds per acre of atrazine could be applied, burcucumber stayed in check. But at today's allowable rates, atrazine won't stop burcucumber.
It's an annual weed which grows from hard seed, not a perennial, which means the seeds must germinate every year. But that doesn't keep it from being a tough competitor, the weed scientists agree.
A new product, Peak from Syngenta, is available this year. It does not contain a new active ingredient, but in this formulation it can be applied postemergence in corn. It has residual activity, so if it's applied with other postemergence products, Peak should help work against some of the late flushes of the weed, Bauman says.
Up until now, the choices were 2,4-D, which isn't particularly effective against it, and Banvel, which works OK until a new flush arrives. Neither of these products have residual activity.
The problem with letting it grow, Bauman says, is that it can produce so much canopy over the crop that it encourages moist conditions, which encourages crop diseases to develop in the crop. And even with today's equipment, burcucumber can be frustrating at harvest. Even once it's killed; it's slow to dry down, the weed specialists note.
Glyphosate is effective in Roundup Ready crops, but only against what's emerged when the application is made. One application of Roundup timed to get the rest of the weeds you're after won't stop burcucumber in fields where it is a problem.
"Every time it rains you're going to get another flush emerging," Bauman says.
This is one of those where it pays to scout and know where the patches are, or which fields it's in. Then you can plan your herbicide attack accordingly, Bauman notes. It's not one you want to ignore. Even though it's an annual, it can spread quickly if it's allowed to go to seed.