High-Yield Wheat: A Strong Finish

February 8, 2011 06:20 AM

A final boost for wheat yields and quality frequently comes from the use of well-timed and properly applied foliar fungicides. The use of disease forecasting models really helps fine-tune fungicide decision making in addition to helping you learn how the varieties you raise are affected by
different diseases.

Yield benefit. How much payback a grower is likely to receive from a foliar fungicide is obviously determined by variety, the product used, the disease he is going after and how well the product is applied. I have seen as much as 40 bu. per acre yield responses from the application of a late-season foliar fungicide, in addition to 5 lb. to 7 lb. per bushel increases in test weight. While such high-yield responses are possible within susceptible varieties and high-disease-pressure environments, yield increases in the 10% to 20% range are common, especially if the fungicides are timed correctly.

Nozzle specs. When it comes to optimal fungicide application strategies, producers need to select a set of nozzles specifically designed to apply foliar fungicides. While the air induction nozzles many farmers use for corn and soybean herbicide applications will obviously apply fungicides, they generally won’t provide the standards of coverage required by most fungicide products. Ideally, nozzles should deliver droplets within the 300 to 350 micron range to achieve a good standard of canopy penetration and coverage. Producers who are targeting fusarium head blight (scab) should apply a product specifically for scab suppression with forward and backward angled nozzles. Keeping the water volume at 15 gal. per acre has also been found
to improve scab suppression, especially within a high-disease-pressure environment.

Tissue testing. Tissue testing and a sound soil testing program go hand in hand. I use tissue tests as a long-term tool to help make better nutrient management decisions for the current crop, as well as for future fertility planning.

Tissue tests can be pulled at the fourth to fifth leaf, jointing or early heading stages. Clean leaf samples (new growth not contaminated with soil) should be submitted from GPS-marked regions of the fields, so a history of nutrient levels specific to those areas can be assembled.

While you will frequently see annual highs and lows depending on the growing season and moisture, consistently low levels of nutrients should be quickly addressed. Most tissue tests find at least one nutrient is deficient.

A good lab should be able to turn a sample around in 24 to 48 hours and notify you of the results via e-mail or fax. Corrective action needs to be made, if necessary, as soon as possible.

Just because soil nutrients are available within the soil profile doesn’t mean the proper nutrient uptake is taking place during the different stages of the growing season.

Dry conditions, wet conditions, high pH, low pH and high or low soil phosphate levels are all factors that can directly or indirectly affect plant growth, as well as how other nutrients interact within the different productivity regions of the field.

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