WEST LAFAYETTE, Ind. - Forage producers need to get out into their fields to assess the health of plants as they begin to break dormancy after a particularly harsh winter, a Purdue Extension forage specialist says.
Forages growing in areas affected by below-zero temperatures during periods of no snow cover are the most at risk for damage because snow serves as insulation for the plants and protects them from bitter cold. Low-lying parts of fields where snow accumulated and then iced over also are at risk for loss from suffocation.
"The lesson here is to get out there and observe those fields," Keith Johnson said. "Now is the time. As the crop breaks dormancy, producers need to check to see if plant green-up is occurring. If that's not happening after several days with temperatures in the 50s and 60s, it's time for concern."
Green-up usually happens around the third week of March in southern Indiana, then 10 or more days later in the northernmost part of the state.
Although soils have stayed frozen for most of the winter, Johnson said alfalfa growers still should pay attention to root heaving. When some soils, especially those that are saturated and with some clay, go through multiple freeze and thaw cycles, it can push the alfalfa plant up out of the ground.
Other areas of plants that should be inspected include the crown and taproot.
"Growers should take a tool along with them as they scout so they can slice into the crown of a few plants to see if the bud tissue is cream-colored and green," Johnson said. "They also can inspect the root for cream-colored tissue. If they find dark brown tissue, that's not a good sign."
Farmers who find problems in their fields have a few options to remedy them.
If the problem is severe enough, Johnson said it might mean using land previously intended for another crop to instead start a new forage stand. But if the problem area is limited to one large section of a field, it might be possible to start over just in that area.
"Farmers do have the option to patchwork in new seed in areas of loss, but they need to be aware that it will be a little bit tricky to manage for the first season because forages will need to be harvested at different times," Johnson said.
For fields where the stand might be thin, producers can consider over-seeding. Using a broadcast seeder on an all-terrain vehicle is typically a preferred method to avoid taking tractors and drills into soggy fields.
But before growers over-seed, Johnson said they need to look carefully at soil fertility and residual overgrowth and develop a plan to fix any problems.
"Growers need to look for underlying issues that would cause seedling failure," he said. "Some of those issues include low soil pH and poor fertility. They need to make sure that residual growth from 2013 is no more than 4 inches tall so that the seed can reach the soil surface.
"Also, overseeding alfalfa seed into a field that currently has alfalfa is risky because the currently established alfalfa produces a chemical that hampers the establishment of new alfalfa seedlings."
The timing of over-seeding also is crucial. Johnson said broadcast seeding should be done at green-up because seedlings will have to compete with perennial plants breaking winter dormancy.
Finally, growers need to make careful seed selections, partially based on field history. For example, the weed history of a field would have an effect on seed selection because herbicides used to control broadleaf weeds also kill perennial broadleaf forages. It's also important to choose a seed that mixes well with the forages already growing.