Eberle: Stand and plant assessment can help pinpoint issues in forage fields

In understanding forage production, University of Wyoming (UW) Extension’s Carrie Eberle said assessing plant health and forage stands is very important. 

“Assessing our plants is an important tool for understanding forage and production,” Eberle told producers during 2019’s WESTI Ag Days, noting diagnosing issues in forages starts with assessment of stands and plants.

Stand assessment

Assessing the stand enables producers to determine whether they need to change management strategies. 

“Stand assessment looks at stands and stem counts,” Eberle said. “We may have plants, but if we’re not getting enough stems to produce tonnage or we don’t have plant stems, we need to start over.”
Increasing stems increases dry matter, and there are several ways to increase the number of stems in an alfalfa stand, she noted. 

In general, Eberle said production at 55 stems per square foot levels off. Between 40 and 55 stems per square foot results in yield reductions, and stand density below 39 stems per square food results in significant yield reduction.

“At that point, farmers will probably want to re-establish their fields,” Eberle said.

She added, “Assessing our stands will help us to figure out whether we have a population issue or a management issue in our fields.” 

Plants

If producers see good stands, they should next look at the plants themselves. 

“We want to see a dark green color and a nice, dense plant with full, whole leaves,” Eberle said. “As we look across our fields, we don’t want to see a lot of soil, and we don’t want to see wilting or weeds.”

At the same time, plants should also not be short or stunted.

“If we find a field with bad-looking plants – however we qualify that – there are a number of likely culprits,” she said. 

First, the environment may be a factor in plant health. If fields are too hot, cold, wet or dry, plants will suffer. 

In addition, soil fertility can negatively impact plants.

“We could have toxicity issue or a problem with chemical damage. There are also pathogens that affect plants,” Eberle noted. “There is a whole suite of things that can cause our plants to get sick and not perform well.” 

Indicators

As an example, Eberle suggested looking at the leaves on a plant to assess the health of the plant.

Plant discoloration, spotting or mottling can be an indication of plant health.

“The location of the discoloration is also important in diagnosing nutrient deficiencies in particular, because nutrients move differently throughout plants,” she said.

Additionally, damage to the plant, such as holes in the leaves or lesions on the stems, can indicate pathogen or pest challenges.

The roots can also provide insight on plant health. 

“If one of our fields looks bad, we can pull a plant out of the ground and look at the root to help inform what’s going on,” Eberle said.

The area of the field that is affected can be important, as well. If one particular spot has poor-performing plants year after year, Eberle noted it is probably not being affected by disease, pathogens or insects. Rather, the problem is likely related to soils. 

“Soil tests and management to specific areas of our fields can help, as well,” she said.

“We have a number of tools in our toolbox when looking at the health of our forages,” Eberle said. “Hopefully, we can use these tools to build a strong management system for our fields.”

Saige Albert is managing editor of the Wyoming Livestock Roundup. Send comments on this article to roundup@wylr.net.