#Grow15: Weed Control Practices

02 Jun #Grow15: Weed Control Practices

Reference: http://www.agriculture.com/crops/pesticides/herbicides/grow15-weed-control-practices_179-ar49807

Incorporating new weed control tactics is not as simple as altering herbicide programs. But when faced with herbicide-resistant weeds, you’ll want to use every tool available.

The first step when you choose a weed control program is to use multiple effective herbicide groups, says Bob Hartzler, Iowa State Extension weed specialist. Be sure to consider the species, weed density, and known resistances.
Some farmers get into trouble when they let weed densities build up, says Hartzler.

“Small changes can make significant differences in selection pressure and prolong herbicide effectiveness,” says Hartzler.
Along with altering your herbicide program each year, Hartzler recommends adding mechanical tactics to your weed control program.
“Even the best herbicide program still places selection pressure on weeds for herbicide resistance,” says Hartzler. “That’s why alternative tactics are so important. What works for some farms won’t work for others. That’s where it’s going to get difficult.”
Mechanical tactics

1. Consider preplant tillage
   “There’s no doubt that tillage provides benefits in managing weeds,” says Hartzler. “Any seedbed tillage you do is going to bury a significant amount of seeds at a depth where they can’t germinate.”
   But it has its drawbacks. You’re putting the seeds into deep storage, and the next round of tillage will bring them back to the surface.
   “In most situations, I wouldn’t recommend preplant tillage just for the sake of managing weeds, unless it’s a total control failure,” says Hartzler.
2. Incorporate cultivation
   Cultivation will allow you to target problem areas in specific fields.
   “What we like to remind farmers is that you don’t have to do all of your acres,” says Hartzler. “You don’t even need to do all of your field. Resistance problems are patchy in nature.”
3. Consider the planting date
   If you have a problem field with a significant weed infestation, hold off on the planting that field, says Hartzler.
   Waiting will reduce the time that the herbicide needs to work, explains Hartzler.
4. Narrow the row spacing
   “As long as we are at 30-inch rows, waterhemp is going to be a big problem,” says Hartzler.
   Narrow-row soybean spacing will reduce the time until canopy closure. It should be a consideration if you have the ability to make it work, says Hartzler.
   Other tips from Hartzler include stopping weeds from entering your field. Do a better job controlling the weeds in the ditch and waterways, he says. And if you have resistant weeds in certain fields, take the time to clean your equipment.