Tackling Toxic Weeds

An equal opportunity problem, weeds can show up in grass hay just as easily as in alfalfa.

By Becky Mills

The first step to control weeds is identification. “Get someone local, a county agent or specialist, to help you identify weeds,” says Texas AgriLife Extension Forage Specialist Vanessa Corriher-Olson. “There is variability from region to region.

“Scout early in the spring so you can identify them before they get a chance to grow and spread. After you identify them, you can determine if they are toxic and you can control or eliminate them before you bale hay.”

She says identification is also a key part of getting rid of them. Annual weeds may need a herbicide application or mowing at a different time of year than perennial weeds. Corriher-Olson says Texas growers should be on the look out for Carolina horse nettle, black nightshade, silver leaf nightshade and parilla mint.

Along with scouting and timely control, she says, “If we maintain the soil fertility and pH, we can reduce the weed population.”

Purdue University Forage Specialist Keith Johnson agrees with Corriher-Olson on the importance of proper identification. “In the past 15 to 20 years, we’ve had a problem with the misidentification of cress leaf groundsel. We’re seeing more and more of it with no-till. There is some toxicity associated with it. But like many weeds in the spring, its flowers are yellow and it is being misidentified as yellow rocket.”

He also warns, “We are seeing a poison hemlock explosion in Indiana. It is commonly found on the edge of fields, but it is beginning to creep into fields. We also occasionally see eastern black nightshade in new fields of alfalfa. In grass hay, the Purdue specialist says horse nettle can be a problem, but is often rejected because of the spines on the plant.

Johnson echoes Corriher-Olson on timely scouting, though. “Don’t just go in with the mower conditioner and bale. Once the weeds are in the bales they are hard to identify. Scout fields and do it often.”

Rotation, Rotation, Rotation

Jim Batte and Derek Dupuis, partners in Chloemeadows Dairy Farm, have an efficient way to keep toxic weeds out of their hay. They use an aggressive rotation program to make sure they aren’t in their fields in the first place.

After two years of baling alfalfa/timothy hay, the Teeswater, Ontario, producers kill the legume/grass mix in the fall with glyphosate, then plant corn in the spring. “The ploughed down alfalfa sod enhances the corn crop by aerating the soil and adding nitrogen,” says Batte.

Next, soybeans are planted in the corn stubble. After the beans are harvested, winter wheat is planted, then corn follows again. The following spring, oats and barley, seeded with alfalfa, are planted. In July, the mix is harvested in 3 x 3 x 6 bales, wrapped in plastic and fed as baleage to their dairy heifers. The following two years, the alfalfa is baled as dry hay.

While the two partners use herbicides as needed for the other crops, Batte says, “From the time we plant our alfalfa until we kill the crop down, we use no chemicals on that particular crop.”

Batte and Dupuis also partner with Gary Whitlock of Bruce Square Baling Ltd. They purchase and bale about 1,800 3 x 4 x 7 bales of alfalfa/timothy dry hay for dairy and beef customers. They also bale an additional 50,000 3 x 3 and 3 x 4 bales of hay and straw for sale and custom work.

Bruce Square Baling Ltd. has three Massey Ferguson 2150 balers and a Hesston 7433 baler to produce the 3 x 3 bales. They also own an MF2170 baler, as well as an MF2170 XD baler they purchased this year, for the 3 x 4 bales. “The 2170 XD puts a higher percentage of straw in the bale, which the brokers like, especially for exporting purposes,” says Batte.

Their equipment is purchased and serviced by Connect Equipment Corporation in Chepstow, Ontario.

For more information see:
Alfalfa: Irrigation, Harvest Scheduling and Rotation Timing

Blister Beetles in Forage Crops
Colorado State University

Guide to Toxic Plants in Forages
Purdue University

For information on another toxic threat to livestock, see “Blister Beetles.”