What is in this article?:
- 2011: year of the pigweed?
- Step in right direction
- Soil-applied herbicides are not as reliable as glyphosate once was over the top.
- Ignite will not kill as large a pigweed as glyphosate once did.
- New technology coming down the pipe will not be as effective as glyphosate once was.
- Herbicide programs available in cotton and soybeans do not offer the flexibility glyphosate once offered.
We have had enough calamities this year to leave an impression on our minds for a long time and we are still a ways from harvest. Judging from the number of pigweeds sticking up above the crops and the number of hoe crews in the fields, no doubt, this pest has thrived among the other disasters that have been occupying our time.
Some have indicated that they feel pigweed will eventually put them out of business, while others have attacked the problem with a renewed vengeance and determination to keep this aggressive pest at bay.
As I travel around the state, it is interesting to note the large number of fields with pigweeds sticking up above the crops. These catch my eye and are much more noticeable than the extremely large number of very clean fields. Certainly, there are more pigweed escapes this year than in any of the past 10 years, but we have also suffered a more severe spring than in any of the past 10 years. It only takes a blink of the eye or a few bad weather days to get behind and create difficulty in catching up with pigweed.
Judging from the calls coming in, it appears that most farmers have realized the importance of not allowing additional weeds to produce seed this year. Managing the soil seedbank is the only chance we have to get in front of pigweed.
Several have told me there is no such thing as Zero Tolerance on large acreage, and I fully agree. But that does not mean we should not strive to reduce the soil seedbank. We have made a real effort to insure that no weeds produced seed last year in the “Zero Tolerance” demonstration fields.
We sampled the soil seedbank last spring and again this spring to monitor our progress. Careful sampling with a sub-inch GPS unit showed a 65 percent reduction in seed over one field and we found no seed in our samples in the other field, but a 90 percent reduction in the number of weeds germinating.
Our sampling technique was to pull 4-inch cores from numerous locations throughout the fields. Even in the field with 65 percent reduction, all samples showed near 90 percent reduction in the number of seed except two cores. These two cores showed a slight increase in the number of seed from last spring. No doubt this was caused by a weed that matured enough to produce seed prior to being chopped.
In some recent research by Jason Norsworthy, it appears that mature seed can be produced in as little as 14 days after the seedhead appears on a pigweed. The fact we saw a slight increase in the number of seed in a couple of samples indicates there were not a large number of seed produced in this area, but yet too many to realize the 80-90 percent reduction we were expecting.