Mark VanGessel, Extension Weed Specialist; firstname.lastname@example.org
I have gotten a few questions about burcucumber over the winter. Like many things, weeds seem to be cyclical. They are a problem for a few years, then we get them under control and then sometime later we start to get questions about them again. Burcucumber has a large seed, which means it can emerge when the seeds are buried 3 to 4 inches deep. The seed buried that deep is often not controlled with soil-applied herbicides. It continues to germinate throughout the season, so “season-long” control is essential. It grows rapidly in warm weather and has tendrils that allow it to grow up and across the tops of a grain crop.
For most consistent control, it will require at least a two-pass herbicide program, but sometimes an additional application may be required. Effective management must include both preemergence and postemergence (foliar-applied) herbicides. POST herbicides provide the best Burcucumber control. POST programs that include effective foliar and residual herbicides will enhance season-long control by killing later emerging Burcucumber ﬂushes. Below are some suggestions for optimal control during the growing season.
Control in corn
Several corn herbicides provide good control of Burcucumber.
Effective preemergence herbicides include:
- Corvus + atrazine
- Balance Flexx + atrazine
Glyphosate, Liberty or dicamba/Status will stop Burcucumber before they begin to vine (max height 6 to 8 inches tall). However, none of them will provide residual control so treatment should include a residual herbicide.
Tankmix options for residual control with a POST application include Peak, Callisto, and atrazine. Penn State trials have shown very good results with Peak, but be aware it has some rotational issues (refer to label).
Control in soybeans
Generally, Burcucumber control in soybeans may be easier and less costly than it is in corn.
Planting soybeans in 30-inch rows can allow for cultivation and for later postemergence herbicide applications; however, the quicker canopy closure that occurs in narrower rows also can help to reduce later emerging weeds, including Burcucumber. Preemergence followed by postemergence of herbicides typically are needed for full-season control of Burcucumber.
In general, products that contain chlorimuron and/or metribuzin provide the best initial early season suppression of Burcucumber. These soil-applied products include:
- Authority MTZ 45DF (sulfentrazone + metribuzin)
- Authority XL 70WG (sulfentrazone + chlorimuron)
- Canopy 75DF (chlorimuron + metribuzin)
- Envive 41.3WG (chlorimuron + ﬂumioxazin + thifensulfuron)
- Fierce XLT 62.41WG (pyroxasulfone + ﬂumioxazin + chlorimuron)
- Trivence 61.3WG (chlorimuron + metribuzin + ﬂumioxazin)
- Valor XLT 40.3WG (ﬂumioxazin + chlorimuron)
- The most consistent postemergence options include chlorimuron (Classic). Chlorimuron provides both foliar and residual activity on Burcucumber (however chlorimuron is typically tankmixed with glyphosate for improved postemergence control). If using Synchrony (which contains chlorimuron), be sure to use STS soybeans to avoid crop injury.
- In Xtend soybean systems, Xtendimax or Engenia can be used, but it will not provide residual control.
- Glyphosate or glufosinate (Liberty) will kill emerged Burcucumber but will not provide residual control.