Johnsongrass, sorghum grasses and sorghum-sudan hybrids can be toxic to livestock after a frost. The frost injury causes the release of prussic acid, or cyanide in the plant.
As a result, grazing these forages after a frost can be deadly to cattle.
To minimize the potential for prussic acid poisoning caused from sorghums or johnsongrass, follow these management practices:
1) Do not graze pastures with Johnsongrass for two weeks after a killing frost.
2) Utilize sorghum-sudan hybrids only as hay after frost, (do not feed this hay for at least 2 weeks)
3) Do not feed silage cut from a frosted field for 6 weeks following ensiling.
Prussic acid usually dissipates in 10 to 14 days following a frost. Extra care should be taken to avoid potential poisoning if cattle are grazing fields with johnsongrass after a frost. Many times the first frost injury does not totally kill all of the johnsongrass in a field.
Lower elevations in a field may be killed initially with upland sites remaining green. As a result the time to leave animals out of a field will need to be extended beyond the first killing frost if partial frost damage occurs in a field. By checking fields for wilted plants after a frost you can determine when the majority of the sorghum or johnsongrass is killed and keep cattle out of the field until the prussic acid has dissipated from the plants.
Preparing grain bins and equipment for harvest
Grain crops that are stored on the farm have a limited storage life due to molds, insects, rodents and other pests. If you haven't already done so, now is the time to prepare grain bins and harvesting equipment to help ensure that grain going into storage will remain in good condition.
A pre-harvest checklist for grain bins should include the following:
- Removing old grain from combines, truck beds, grain carts, augers and any other equipment that is used to for harvesting, transporting or handling grain. Even small amounts of insect-infested or moldy grain left over from a previous harvest can contaminate a new bin of grain.
- Adjusting combines according to the manufacturer's specifications to minimize grain damage and to maximize the removal of trash and fines.
- Removing any spilled grain, weeds, tall grass or other vegetation around bins to reduce the likelihood of insect or rodent infestations.
- Inspecting grain bins, inside and out, for cracks, loose or missing bolts and rust and corrosion. To help make inspecting the bin easier, place a light inside the bin after dark and inspect from the outside for any cracks or holes. Small gaps can usually be filled with a high quality caulking material.
- Cleaning grain bins thoroughly before filling to eliminate any existing mold or insect infestations. Remove all old grain, sweep the walls, floors and ledges and remove and clean augers and boots.
- Removing all debris from fans, ducts and exhaust vents. If possible, clean under perforated floors to remove any accumulation of dust and fine materials that can harbor insects and rodents.
- Inspecting the wiring for fans and other electrical components for loose connections, and cracked, frayed or broken insulation. All exposed wiring should be run through waterproof, dust-tight conduit.
After cleaning and making all repairs to the floor, walls and around the outside of the bin should be sprayed with an approved residual spray. Pesticide applications without adequate cleaning are generally a waste of time and money.
For more information on grain bin sanitation, see UT Extension publication PB 1395, Insects in Farm-Stored Grain - Prevention and Control. You can find this and other UT Extension publications on online: https://utextension.tennessee.edu/publications/
A bin full of grain represents a major investment. Following this simple checklist before the harvest season begins can pay you huge dividends down the road by helping to assure that grain quality is maintained during storage.
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