BMR corn: Love it or leave it

By Mike Rankin

In my many years spent as a county extension agronomist in one of the largest dairy counties in Wisconsin, I heard a lot of reasons to grow brown midrib (BMR) corn and a lot of reasons not to. Similar to the current slate of potential presidential nominees, people either loved or hated BMR corn. Interestingly, both opinions were often formulated after a year or two of growing the crop.

“You have to treat BMR corn like a specialty crop,” said Dan Wiersma, alfalfa business manager for DuPont Pioneer. “Before you start growing BMR corn, there needs to be a team discussion between you, your nutritionist and your agronomist. If your nutritionist hasn’t had a lot of experience with BMR, you might want to invite a dairy manager who has. Expectations for the crop need to be clearly understood.”

In his comments at the Midwest Forage Symposium held in Wisconsin Dells last month, Wiersma discussed both the advantages and disadvantages of planting BMR corn. He started his presentation by asking the audience for reasons why they didn’t like to plant BMR hybrids. Not surprisingly, yield drag, lodging and lack of disease resistance were immediately volunteered by several attendees. Wiersma proceeded to tackle all three concerns.

“There’s still a yield drag for BMR hybrids but plant breeders continue to close the gap,” said Wiersma. “We generally see more yield loss with BMR under stressful conditions than with conventional hybrids. Plant stress can also lower starch content. The other thing to keep in mind is that feed consumption goes up with BMRs; hence, more acres are needed to meet your silage inventory goals."

To minimize the yield drag aspects of BMR, Wiersma first suggested doing your homework on hybrid selection. “There are yield differences among BMR hybrids just as there are for conventional hybrids. Look for yield information from multiple locations and sources. At the same time, also consider differences in fiber digestibility and starch content,” he noted.

Wiersma suggested planting BMR hybrids on your best fields to minimize stresses from factors such as poor drainage and low soil fertility. If possible, he also recommended taking advantage of rotation effect by planting BMR hybrids where the previous crop wasn’t corn. Finally, ensure that nitrogen and potassium fertility meet the needs of the crop.

“Potential yield is highest on the day you plant,” said Wiersma. “Doing everything you can during the first four to six weeks of plant growth to hold that potential is really important.”

To minimize plant lodging, once again Wiersma suggested evaluating hybrid data carefully and targeting genetics with proven standability performance. He emphasized the importance of potassium fertility for maximum stalk strength.

“Keep in mind, we’re dealing with a stalk that contains less lignin,” explained Wiersma. “From research trials, we know that the growing environment can impact the amount of lignin in the plant — even for BMRs. As such, the degree of plant lodging may also vary from year to year or field to field."

Just as with conventional hybrids, planting rates also influence the standability of BMRs. Wiersma suggested talking to your seed company representative to confirm best planting rates for specific hybrids. He also noted that excessive planting rates could lower silage starch content.

To maintain yield potential, eliminating stresses from insect and disease pressure is especially important when growing BMR corn.

“Today, many BMR hybrids are triple stacked,” noted Wiersma. “There are also differences in hybrids for disease resistance. The yield and quality benefits of foliar fungicide applications have been somewhat mixed but that remains an option where field disease pressure is high.”

To get the greatest return from planting and feeding BMR hybrids, Wiersma suggested storing the product separately from conventional hybrids and then targeting the feed to the highest producing animals. “We’ve also seen the most success where dairies are feeding a high-forage diet,” he added.

The advantages of feeding BMR corn to high-producing cows are well documented. BMR corn does, however, need to be treated differently than conventional corn hybrids. This is true from both an agronomic and also a feeding perspective. “To be successful, advanced planning with your agronomist and nutritionist will pay big dividends,” said Wiersma.