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Issue No. 3, Article 7/April 11, 2008

Issues in Illinois Wheat

The Illinois wheat crop has mostly survived the winter, and the most recent rating put the crop at 61% good and 27% fair, with the rest equally divided between poor and excellent. After watching over the winter as excessive rain fell in some areas, followed by standing water and ice, we are fortunate to have a crop in as good a shape as this one is. It was helped by the fact that the weather stayed relatively cold most of the winter, with few warm-cold cycles to damage the crop.

Wheat has been relatively slow to resume growth this spring due to cool temperatures. Growth in southern Illinois has been better, but here at Urbana wheat is still less than 6 inches tall, and though tillering appears to be adequate, lack of sunshine and continued cool temperatures are delaying development. This will change quickly once it warms up, but we can already expect some delay in heading unless it gets warmer than usual later in April. That would speed up the crop but would not likely improve yield potential much. Sunshine and average temperatures over the next month will do a great deal of good.

One exception to the generally good condition of the winter wheat crop is the damage in some northern Illinois fields where water stood or ice covered the crop for a period of time. There were several bouts of such weather over the winter, and it could have been any of these events--or perhaps more than one--that caused the damage. In affected areas, which usually occur in patches rather than across entire fields, most to all of the leaf tissue is dead, and the plants are probably dead in some cases. It has been cold enough to delay regrowth in that part of the state, and it's possible that some of the plants with no surviving leaf area might still manage some new leaf growth. Even if that happens, tiller and head counts will likely be reduced, and we can expect lower yields in these parts of the field even if plants survive and grow back.

The pattern of dead plants tends to be in streaks and patches, not necessarily all in low areas where water might have stood. Such a pattern indicates that snow cover and ice formation might have interacted to cause or prevent such damage, perhaps more than once. Photos sent by Lyle Paul of the variety trial at DeKalb suggest there might be some variety differences, but differences due to location in the field are also likely. Prospects for having that trial make it to harvest remain uncertain.

Damage to winter wheat in the UI variety trial at the Research Center near DeKalb. Photo by Lyle Paul.

Such damage, plus the very high wheat prices this year, brings questions about the prospects for using spring wheat, either to fill in damaged winter wheat or to plant in whole fields. The short answer about growing spring wheat in Illinois: It can do well, yielding as much as two thirds to three fourths as much as winter wheat, but only if we end up having a relatively cool spring and early summer, with enough moisture to get the crop through to harvest in mid-July. Spring wheat varieties are not developed for, or tested under, Illinois conditions, so we would have to take what we can get from states like Minnesota, North Dakota, and Montana. Because all spring wheat planted in those areas is hard wheat used for milling and baking, quality, including protein content, is a primary consideration. Getting high-grain protein and acceptable flour quality from spring wheat grown in Illinois is challenging, and we can expect lower prices than farmers in more northern areas will receive.

Because of our climatic limitations, growing spring wheat in Illinois is risky, and there is little we can do to reduce the risk. In fact, it's already getting late to plant spring wheat, just as it is to plant spring oats. To have much chance of producing good yields (40 to 50 bushels per acre), spring wheat needs to be planted by mid-April. The same is true for spring oats, though we expect yields of 100 bushels or more for oats (on a weight basis, equivalent to a wheat yield of 53 bushels) if they are planted on time and we get reasonable growing conditions. The two crops share many of the same limitations, though grain quality, which is usually a primary concern in spring wheat, is less problematic for oats. If the primary need or market is for straw, spring wheat should produce quantities similar to that from spring oats, but perhaps of higher quality as straw.

Finally, nitrogen fertilizer on wheat remains an issue and a concern, both for those not yet able to apply N and those who applied it before heavy rain and are wondering how much is still there. Concern about the amount of loss is best managed by watching the crop carefully and being ready to apply more N if the crop starts to lose the dark green color it should develop as the weather turns warmer with more sunshine. There might be some advantage to applying 40 or 50 lb of N fertilizer (lawn N fertilizer will work, using about a pound of N, or 4 lb of material, per 1,000 square feet) by hand to a small area (maybe 20 by 20 feet) of a field now to serve as a color reference over the next month. If the rest of the field remains the same color as the added-fertilizer area, then applying more N is unnecessary.

If N has not yet been applied to wheat this spring, it will pay to apply it even as late as heading, though yields will often be reduced by the delay. How much they are reduced depends on how much N the crop has been able to take up by now. If tiller numbers are good and crop color is reasonably good, then there is little deficiency yet and there may be little yield loss if N can be applied within the next week. If the crop is already pale green and tiller number is low, then yield has been reduced, and it will be reduced further the later N is applied. Steve Ebelhar showed in southern Illinois that the crop may lose a bushel or more per day of delay in N application from jointing to heading, though this is expected to vary a lot over years. --Emerson Nafziger

Emerson Nafziger

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