Eliminating Weed Competition

Eliminating Weeds
Weed management isn’t as simple as it once was. You could make one pass over the field with a herbicide application and maybe make a second pass later in the season to catch stragglers and hold weeds back until canopy, scouting for weeds in wheat until it’s nearly time for harvest. While weed resistance seems to get most of the attention as one of the biggest weed management challenges, it’s just one factor that is making weeds tougher to control.

Consider that a single velvetleaf seed can remain viable in soil for up to 50 years and the likes of waterhemp or Palmer amaranth can produce hundreds of thousands of seeds — per plant. Small weeds can no longer be overlooked as though they might not affect the overall crop.  

Yields Take a Hit

Take, for example, a 2009 to 2011 study of weeds competing with corn, conducted by University of Minnesota Extension. Once weed height reaches 3 to 4 inches — usually when corn is around the V3-V4 growth stage — the crop loses nearly 12 to 13 bu/A within the first week and 27 to 29 bu/A within the second week.

When it comes to wheat harvest, though, success isn’t measured by yield alone. Weed competition can be as detrimental to grain quality as it is to overall yield. Competition for nutrients can reduce protein; spoilage can result if green weeds are harvested; and if the weeds go to seed, those seeds can be difficult to remove when cleaning grain.

Five Factors

These reductions in yield and grain quality are due largely to the crop competing with weeds over five factors, explained in detail by the University of Illinois Extension:
  1. Light: This is especially critical when weeds grow taller than the crop.
  2. Moisture: After removing a dense population of weeds, the amount of water a crop can access is an essential factor in how well the crop recovers.
  3. Nutrients: Particularly in coarse-textured soils and soils with low fertility, weeds can exhibit a “luxury consumption” of certain nutrients, such as nitrogen.
  4. Space: Dense infestations of weeds lead to allelopathy — the suppression of plant growth due to release of natural plant-derived substances — which contributes to yield loss due to additional competition.
  5. Environmental: More than any other factors, soil and air temperature and soil moisture and rainfall before, during and after initiation of competition affect weed emergence and growth, herbicide effectiveness, the competitive interaction between crop and weed, and the ability of the crop to recover from early weed competition once weeds have been removed.


Solutions

When it comes to eliminating weed competition in wheat, Huskie® Complete herbicide is a solid choice for controlling grass and broadleaf weeds, including resistant biotypes. It also has a wide window of application, helping you extend your weed control until closer to wheat harvest.

In corn, Capreno® herbicide is the longest-lasting postemergence product available, meaning it helps keep your fields clean until the corn canopies. It also has multiple modes of action, so you get a weed resistance management tool in addition to very effective weed control.

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Corn & Soybean Digest outlines five practices for maximizing weed control.

North Dakota State University identifies the three most important weed management goals.
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