Issue No. 18, Article 10/July 24, 2009
Illinois Wheat in 2009
The 2009 wheat season in Illinois will go down in the books as a rather average one, with the July yield estimate from NASS standing at 59 bushels per acre. Yields in northern Illinois averaged about 70, while in central Illinois they ranged widely, from only 46 in the west to 83 in the east. Yields were consistent across southern Illinois, averaging in the mid- to upper 50s in the four southern crop reporting districts.
The low yields in western Illinois are somewhat surprising, but acreage was down by nearly half there, and it's likely that much of the problem was related to late planting and planting into wet soils. The response of wheat to late planting varies a lot among years, and the penalty in 2008-09 was larger than it is in many years. Planting into wet soils didn't help. The winter and early spring conditions were not too stressful, though late-planted wheat needed more recovery time than the spring provided. Wet weather in the spring contributed to N loss and to problems with disease, especially Fusarium head blight, or scab.
The story in southern Illinois was more focused on grain quality than on yields, though the two were related. Yields were not particularly high in many fields, but they were better than in some poor years in the past. Test weights were as low as we have seen, and dockage due to low test weights was common. Some elevators tested for vomitoxin (DON) that is produced in grain by Fusarium, and docked according to level.
With constant rainfall during the flowering period, application of fungicides for scab control was either not feasible or not particularly effective. Many fields showed high levels of head blight early, and in many of those fields, kernels were very light, and many were likely blown out of the combine. This helped improve quality but couldn't cure all problems. At least some of the low test weight came, as it often does, from the crop's having gotten rainfall after maturity, with kernels swelling as they took on moisture and then drying again, but with lower density. It was not as wet when the wheat flowered in central and northern Illinois, so quality there was much better.
The wheat variety trials that we conduct at six locations in Illinois have been harvested, and regional results are now posted at vt.cropsci.illinois.edu/wheat.html. Yields were better than we had expected, with trial averages (bushels per acre) as follows: Dixon Springs, 75; Belleville, 87; Perry, 80; Urbana, 92; DeKalb, 99. We had some water damage problems at Brownstown and so are not including those results in the southern regional average. They will be available as an individual location soon, but the variability was high and the yields relatively low for that location, so results will need to be used with caution.
As in the previous year, we allowed the entry of insecticide-treated seed as long as untreated seed of the same variety was also entered in the trials. Seed treatment insecticide increased yields modestly in 2009, even in the northern region, where we have not normally seen much response. The effect was not consistent among varieties. We continue to think that response to seed-applied insecticide is likely to be greater in southern than in northern Illinois, due to the greater likelihood of viral disease transmission by aphids in southern Illinois.--Emerson Nafziger