Heat Stressing Some Alfalfa

By Cheryl Anderson
DTN Staff Reporter

OMAHA (DTN) — The recent extreme heat spell is putting stress on alfalfa — especially dryland stands — growing in already-arid regions such as western South Dakota. However, irrigated alfalfa in other areas is holding up well in the heat, according to reports.

Some alfalfa growers in the western part of the South Dakota have not been able to even get a first cutting yet, according to Karla Hernandez, Extension forages field specialist at the South Dakota State University Extension, Watertown Regional Center.

Hernandez said she was out inspecting fields on Thursday, and she said that with such little moisture, the alfalfa fields have not grown very much.

"It’s not even worth taking a cutting right now," Hernandez said. She added that without rain, growers in western South Dakota may only get one cutting for the whole season.

Alfalfa planted in western South Dakota has very little growth, forcing some growers to wait until late July or early August for a first cutting.

Dan Undersander, research and Extension forage agronomist for the University of Wisconsin at Madison, said stressed or damaged alfalfa in dry areas is really more a matter of drought stress.

"Alfalfa can grow in hot weather up to 120 to 130 degrees (Fahrenheit)," Undersander said. "But it does need water to grow. When moisture is short and temperatures are high, it makes drought stress worse, as plants use more water at higher temperatures."

On weather maps, spots in the western Dakotas and a little south have been short on rain and have had above-average temperatures. However, Undersander said that is isolated to those areas.

The remainder of the summer is likely to be characterized by huge differences between dry and wet areas, according to Bryce Anderson, senior ag meteorologist for DTN/The Progressive Farmer.

"Western Plains areas will continue to be drier while central and eastern Plains sectors will have additional chances for moisture. The areas of western South Dakota, eastern Wyoming and northwestern Nebraska that are in beginning stages of drought will likely continue having problems getting rain during the majority of the season," Anderson said. "This, along with above-normal temperatures, will keep the hay crop below average in those areas."

Most of the western portions of both Nebraska and Kansas are dry, but alfalfa stands are doing well because most fields are irrigated.

Mitch Stephenson, assistant professor/range and forage specialist for the University of Nebraska-Lincoln’s Panhandle Research and Extension Center, said that while April was a fairly wet month, conditions have been dry in May and June. Dryland alfalfa is still in fairly good condition, but could be at risk if dry conditions prevail. He added there have been some issues with weevils as well. Weevils were also reported in north-central Nebraska.

Western Kansas is also in a dry spell; however, most alfalfa stands in that area are irrigated, according to A.J. Foster, Extension specialist of agronomy – crops and soils.

Undersander reported that growers in Wisconsin are still having some stand problems from the cool weather early in the season.

"After alfalfa was planted in the middle of April, we had some really cool weather that did not get much above 40 degrees," Undersander said. "The alfalfa came up, but it doesn’t grow if the temperature is less than 46. So it just sat for two weeks. Some died, some got diseases and we have some poor stands."

Probably about 20% of seedlings planted in the Wisconsin area this spring were affected, he said.


– Douglas G. Zillinger (north-central Kansas):

"To date, no heat stress due to an inch of rain on Friday night. This could change fast as we are averaging in the high 100s with wind every day now."

– Clayton and Jackie Kline (northern Missouri):

"I’m in the northeast corner of Missouri, and in my immediate area, there is little irrigation and I’m not aware of any irrigation of alfalfa. It has been hot and dry here also. It appears that most growers got their first cutting off in good shape, but there has been little regrowth because of the lack of moisture. It has been 90 to 95 degrees on many days, but I would say there has been little damage to the alfalfa that couldn’t be straightened out with some good rain. Around here there is usually more damage done to the alfalfa by too much moisture than by too little."

– Karen and Bill Johnson (southwest Iowa):

"We finally got a half-inch of much-needed rain today in southern Shelby County, which the alfalfa should love! It hadn’t rained here since June 4."

– Crawford McFetridge (Finger Lakes area of New York state):

"Well, up to about three or four days ago, things were fairly green. Now the lawns are burning off and corn in places is turning blue-gray. If it doesn’t rain today, I would say that alfalfa here is going to take a hit. It won’t ruin the crop, but it will cut the yield. If it doesn’t rain, it is going to be a game changer all across the board."

– Keith Landis (northern Illinois):

"Northern Illinois looks good as far as alfalfa crop. A number of farmers are on their second cut and have either chopped or wrapped it. Timely rains and low humidity in between has helped."

Cheryl Anderson can be reached at cheryl.anderson@dtn.com

Follow Cheryl Anderson on Twitter @CherylADTN