NEWS for North Dakotans
Agriculture Communication, North Dakota State
University
7 Morrill Hall, Fargo, ND 58105-5665
May 21, 1998
Farmers with crusting problems in their fields need to act quickly to prevent crop loss, according to Mike Peel, agronomist for the North Dakota State University Extension Service. Should crusting or other problems lead to significant crop loss, they'll need to determine whether it will pay to replant.
"Crusting will be most noticeable in fields with low organic matter and little surface residue, following heavy rain, and especially in fields that have been tilled excessively," he says. "When the crust is not broken the developing seedling will not get any sunlight, so it will quickly deplete the seed's nutrient stores and the plant will die.
"A light harrow, double disc drill set very shallow or a rotary hoe can be used to gently break the soil crust and solve the problem."
If crusting, frost, disease, hail or other stresses have caused significant crop damage, a farmer may be faced with the decision whether to replant.
"Comparing estimated return from the replanted crop, minus replanting costs, with expected return from the damaged crop," says Peel, "most often indicates the crop stand should be left."
The optimum plant population for maximum yield in both barley and wheat is about 30 plants per square foot, according to North Dakota seeding rate trials. Any reduction in the plant population will reduce yield, but not proportionally. For instance, a 60-percent reduction in a plant population may result in a yield loss of only 20 percent when growing conditions are good. Good yields have been obtained with plant populations well below 10 plants per square foot.
Replanting small grains should not be considered, says Peel, when populations are at 10 plants per square foot or greater.
Probably more important than plant population is planting date. In North Dakota, delaying the planting of small grains past May 15 will typically result in yield reductions on the order of 0.5 to 1.5 percent of total yield for every day of delay.
"While it is difficult to make yield comparisons between an early-planted crop with a less than desirable stand, and a much later planted crop with an optimum stand, it is safe to say," says Peel, "that when the original crop is planted well before mid-May, its yield potential may be better than that of a replant. The availability of soil moisture must be considered, as it may be depleted by the current crop—and will be further reduced during replanting."
In trying to decide how badly a crop is injured, here are two things to consider:
nThe growing point of a small grain plant is below the soil surface during early development, making it less susceptible to injury. In this early stage, plants can suffer complete loss of above-ground vegetation without being killed. After leaf damage at this stage, wait several days before making an appraisal of stand reduction.
nThe growing point is a good indicator of plant health. The growing point should be white or cream-colored. Darkening or softening of the growing point usually precedes the death of the plant.
If plant damage warrants abandoning the crop and replanting a new one, says Peel, it may be wise to consider switching to a crop that can be planted late, such as millet, dry beans or buckwheat. Before switching crops, producers need to consider the potential for previously applied herbicides to damage a different crop.
"The final decision whether to replant should be an economic one, based on sound agronomic information. If the cost of replanting is equal to or greater than any profit gains, then exercise is the only thing gained by replanting," says Peel. "The critical factors in making a decision to replant are the yield potential of the damaged crop compared to that of a replant, the difference in returns based on those yields, and the cost of replanting."
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Source: Mike Peel (701) 231-8037
Editor: Barry Brissman (701) 231-7866
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