Direct seeders must be on the lookout for Stork's Bill. If it isn't already a problem weed for you it has the potential to become one very rapidly! Understanding its characteristics and control options are important to keeping an infestation from developing.
Data from G. Thomas's Saskatchewan Weed Survey indicate that Stork's Bill showed up in 0.8% of the Saskatchewan fields surveyed. However, the concern is that in fields where it occurred 44 % of the locations per field had an average density of 20.7 plants per m2. This density ranged as high as 59 plants per m 2. The survey also identifies three areas where Stork's Bill is a significant weed problem. These are southeast of St. Walberg, southeast of Big River, and north of Humboldt. The concern for other farmers is that it could spread.
Stork's Bill has a flexible life cycle that is particularly adapted to reduced tillage grain production systems. It can survive as an annual, winter annual, or biennial. It can only reproduce from seed but there can be several flushes per season. Emergence is optimal in moist soil so rainfall tends to bring on another flush. Individual plants can produce 200 - 600 seeds which do not have any dormancy unless placed deep in the soil. Once established the plants are drought tolerant so in dry years they can take over knolls and significantly reduce yields.
One of Stork's Bills competitive advantages is that it can emerge and thrive under low soil and air temperatures. This adaptation along with the winter annual form means that it can be quite advanced when other weeds are at the burn down stage. The seed also has a burial mechanism that gives it an advantage in reduced till systems because it can wiggle through residue layers. A long awn attached to the seed twists when dry and uncoils when wet. This action is significant enough to tend to corkscrew the seed toward the soil surface.
As seedlings a distinguishing feature of Stork's Bill is the three lobed cotyledons. It has finely divided leaves very similar to Flixweed and Scentless Chamomile. At maturity Stork's Bill can be a large low plant 2-3 feet in diameter. It produces seed stalks about 1.5 feet tall that produce small pink to purple flowers. From the center of the flower a long pointed capsule forms that resembles a stork's bill. At maturity this capsule contains 5 seeds and splits somewhat explosively throwing the seed up to 1.5 feet from the plant.
With these competitive advantages it is evident that direct seeders must reduce the chances of this weed infesting their farms. Probably the first advice is to be on the lookout for the weed in your neighbourhood. Explore all the options for control. Because Stork's Bill is not a common weed problem very few herbicide companies have pursued registration. As for in-crop control, there are certainly more options in cereal crops. So be sure to use products that give suppression or control as soon as you see any sign of Stork's Bill. Mowing ditches and other sanitation measures might also be considered if you see plants coming in from the edges of fields.
It will be well worth your time to avoid the problem of Stork's Bill on your farm now rather than fight it after it is an infestation!