By Scout Nelson
As winter transitions into spring, many fields, especially those planted with winter wheat or left untilled, might exhibit substantial growth of field pennycress or shepherd’s purse. These weeds often thrive due to mild winter conditions coupled with early moisture that aids their germination and growth.
Identifying these weeds early is crucial as they can be easily mistaken for each other. Field pennycress is recognized by its long, rounded leaves with rounded, toothed edges. Shepherd’s purse, on the other hand, features oblong leaves with deeply lobed margins.
Both species typically germinate in fall or early spring and initially form a low rosette. As they mature, the stem elongates—a process known as "bolting." Although seed heads, which are round and notched for field pennycress and heart-shaped for shepherd’s purse, can help with identification, it is preferable to identify and manage these weeds before they reach this stage to prevent seed production.
Effective management should be implemented early. Both species respond well to tillage when small. In terms of chemical control, applying glyphosate (such as Roundup) as a preplant burndown is effective, especially when combined with 2,4-D to broaden the spectrum of weed control.
Other herbicides like bromoxynil and tribenuron can also be effective, particularly when dealing with infestations within wheat crops.
While these weeds are generally not dense enough to cause significant yield losses, they are known secondary hosts for soybean cyst nematode, which poses a considerable risk if fields are to be rotated into soybeans.
Effective early management of these weeds is crucial, not only for the immediate crop but also to prevent the future spread of nematodes in fields slated for soybean planting.
Photo Credit -gettyimages-dleonis
Categories: South Dakota, Crops