Growers pleased with grass control Last week I discussed some growers' reports about Command and rice injury and yields. Most of the responses I have received in writing or by e-mail have focused on weed control. Most growers have been extremely pleased with the level of grass control and the reduction in input costs.
A couple of growers said it worked better on smooth seedbeds than on cloddy seedbeds. Others reported weed control was much better where fields had good moisture than where fields were dry. There were a couple of comments about missing sprangletop in stale seedbed situations.
The advantage of a pre-emergence herbicide, when it works, is you get the weeds before they emerge, or they emerge and die. You never have a chance to miss the timing on a postemergence treatment - the primary cause of failure with post-applied herbicides.
Pre-emergence herbicides perform much better on smooth, firm seedbeds than on loose cloddy ones.
Although our research studies comparing different ways to apply Command relative to planting and rolling really do not always show it an advantage, I like to apply Command behind a smooth roller on silt loam soils. If you are going to use Command and don't have a smooth roller, put one on your Christmas wish list.
On the clay soils where clods are inevitable, apply the Command and flush immediately to melt the clods.
Another thing it takes to make a pre-emergence herbicide work is moisture for activation. Command doesn't require as much moisture for activation as some other herbicides, but it does need some. Flushing silt loam soils to activate herbicides before rice emergence often leads to packing that requires more flushing.
In my experience with Command on silt loam soils, if I have good moisture at planting and roll behind the drill to seal it in, almost any shower will activate it. Again, maybe Santa will bring the roller.
I am not sure what is happening with sprangletop in the no-till situations. I don't have any sprangletop in my stale seedbed rice area, but we have had quite a bit of sprangletop in our conventional seedbed rice. Command has been outstanding on sprangletop on the silt loam soil at Lonoke, Ark., and also in Ken Smith's work in the clay soil at Rohwer, Ark.
I believe some of the problem is the burndown herbicide misses the weeds in the no-till situations. Some of it could be tank-mix antagonism. Some of it could be the tiny sprangletop plants are sheltered by vegetation residue and the soil surface.
All the sprangletop data we have is on the tight-head species. We will keep looking at sprangletop in no-till.
Several growers commented on length of control, which varies with rate, grass species and environmental conditions. I am surprised by the number of farmers who said no other grass control measures were needed. I say always plan on having to treat for late-emerging grasses. If you don't have to, it is a bonus. Next week I'll write the aerial application story I promised for this week.