A very promising north Alabama wheat crop was quickly turned into a disaster on Easter weekend, when sub-freezing temperatures moved into the region. Now, many growers are assessing their options for the crop.
“Much of the crop was heading when the cold temperatures occurred,” says Charlie Burmester, Auburn University Extension agronomist. “This wheat now has almost no yield potential.”
Seed formation has been stopped and the heads are turning yellow and drying down, he said in late April. Wheat that was in the boot stage or earlier seems to have less damage, he added.
“However, in many of these fields, we are seeing freeze damage on the stem which also could greatly affect yields. The extent of this freeze damage will not be known until this wheat is heading,” he says.
Farmers were being advised to check with their insurance providers before they make any management decisions concerning the wheat crop. Options appear to be using the wheat as a cover crop and planting either soybeans or cotton.
“Some farmers may want to graze or cut the wheat for hay,” says Burmester. “Check wheat herbicide labels for possible restrictions on grazing or cutting the wheat for hay. Also, take a sample of the wheat for nitrate testing. At this time we are unsure if nitrate toxicity will be a problem with the wheat or not.”
Researchers at Auburn University have made the following recommendations concerning freeze-damaged wheat:
•Assess the situation carefully: It is difficult to predict how much damage cold weather may have done to wheat because numerous factors can come into play, including stage of growth, variety, how cold it became, how long it stayed cold and fertility. Different fields on a farm or even parts of a given field may have been affected differently due to differences in elevation and/or exposure. Thus, careful inspection and evaluation on a field-by-field basis is required. The growth stage of wheat is a particularly important factor influencing the impact of cold weather on grain yield
• Do not rush the decision: It makes sense to wait at least a week before deciding what to do. This will make the damage easier to detect because dead, frozen tissue will turn brown and other indications of damage will be easier to identify. There is still plenty of time to harvest cold damaged wheat for forage and obtain good forage quality.
• Consider all options: If it is determined the grain yield potential of a field has been severely reduced, it makes sense to consider all the options. No doubt a wide variety of situations exist on various farms and in different fields. In some cases, there may be some damage, but perhaps not enough to preclude grain harvest.
There may be some producers who want to graze their freeze-damaged wheat. Given the growth stage of wheat at present, this would need to be done within the next two to four weeks in order to provide good quality pasture forage. Hoof damage may be excessive in fields that are wet. Strip grazing would be the best way to obtain a good level of forage utilization. Continuous grazing, especially at low stocking rates, would be particularly wasteful.
Some producers will want to harvest wheat for hay, which is certainly an option. However, the long period of time required to cure high-moisture hay at this time of year makes rain damage a substantial risk. Wheat hay is porous and needs to be stored inside. For producers who have the option of storing damaged wheat as silage, this is probably a better choice than making hay. Still other producers may decide that they will simply chemically burn down their damaged wheat and plant another crop — soybeans or cotton — that promises to provide more profit than grain wheat.
• Growth stage at which to harvest wheat for forage: Wheat may be harvested for forage from the boot stage (just before heading), or the milk stage (when the head releases a milky liquid if sliced open), to the mid-dough stage (when the grain has a “dough-like” consistency inside). As the plant matures, plant moisture content, digestible dry matter, and crude protein levels decline. Most beef cattle producers who intentionally grow wheat for forage harvest at the mid-dough stage, as this maximizes dry matter yield while still producing forage suitable for most classes of beef cattle. Producers who have animals with higher nutritional requirements — such as dairy animals — may wish to harvest at the boot or milk stages.
• Moisture content for wheat silage: If forage harvested for silage is too dry, it will not pack easily or well, resulting in poor fermentation. If it is too high in moisture, there will be undesirable fermentation and excessive seepage. In bunker silos, a moisture content of 65 percent to 70 percent (30 percent to 35 percent dry matter) is advisable. Oxygen-limiting structures can be used to store lower moisture silage. In addition, some producers may have the option of wrapping low moisture forage in plastic as baleage if they have access to bale wrapping equipment.
The only way to know the moisture content of forage, say the researchers, is to sample and test for moisture. The direct harvest of wheat at the mid-dough stage of maturity may be possible. However, less mature wheat likely will need to be cut and wilted in order to have a low enough moisture content to be properly ensiled.
• Packing of silage: A key to making good silage from any forage crop is to exclude air from the silage. Packing of small grains is more difficult than many other types of forage because of the hollow stems. Thus, fine chopping (theoretically one half inch) and thorough packing are essential.
• Probable yield: Healthy wheat planted for forage and harvested at the mid-dough stage often produces about 2 tons of dry matter per acre, which is the equivalent of about 2.25 tons of hay or 7 tons of 65-percent moisture silage. Wheat harvested at earlier stages of maturity and/or that has been severely damaged by cold will produce less dry matter and fewer tons of hay or silage.
• Feed value/animal performance: The stage of growth at harvest has a profound impact on forage quality. The crude protein content of wheat silage harvested at the mid-dough stage is usually in the range of 9 to 11 percent on a dry-matter basis, which is better than corn. However, the energy level of mid-dough stage wheat silage is only about 80 percent of that of corn silage, so animal performance is correspondingly lower unless an energy supplement is provided along with the silage. The quality of unweathered wheat hay should be close to that of silage harvested at the same stage of growth and exposed to the same environmental conditions.
• Nitrates: It is possible for freeze-damaged wheat to contain toxic levels of nitrates, especially before heading. The ensiling process usually results in a substantial (at least 25 percent) reduction in nitrate levels, which is an added reason to consider harvesting damaged wheat forage for silage rather than hay. However, the only way to know for certain if forage contains potentially toxic nitrate levels is to have it tested. The Auburn University Soil Testing Laboratory will test forage samples for nitrates at a cost of $6 per sample.
• Pesticides: Some wheat fields receive treatments with pesticides for which there are grazing or harvest restrictions. Such restrictions should be strictly observed.
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