Pierce Paul, Jorge David Salgado
Current wheat growth stage range from Feekes 7 to Feekes 10. At Feekes 7, two nodes are visible, one about 2 inches above the soil line and the other about 3-4 inches above the first; at Feekes 8, in addition to the two nodes seen at Feekes 7, the tip of the flag leaf, the fourth leaf above the first node, is visible; and at Feekes 9, the flag leaf is fully emerged. Feekes 8 marks the beginning of the period during which we recommend that field be scouted to determine which disease is present and at what level. Septoria blotch is usually one of the first to show up, and it already has been reported in some fields.This disease is favored by cool (50-68F), rainy conditions, and although it usually develops early in the season, it really does not cause yield loss unless it reaches and damages the flag leaf before grain fill is complete.
If the weather conditions continue to be rainy and favorable for foliar disease to develop, spores will continue to be produced and new infections will occur. Results from previous studies have shown that the greatest benefits from foliar fungicide applications were obtained when applications were made between Feekes 8 and 10 and cultivars are susceptible. This is largely because most of our major foliar diseases usually develop and reach the flag leaf after Feekes 8-9. However, before making a fungicide application, scout fields and look for the presence of diseases, particularly Septoria and powdery mildew, on the lower leaves. Septoria blotch will appear as dark irregularly-shaped lesions with black dots in the center. At this early stage, powdery mildew appears a fluffy white powdery growththe surface of the leaves and lower stems. There are several different fungicides available for use on wheat. Obtain current pricing of fungicides to determine the most economical control option. Use 15-20 gal water/A with ground equipment and 5 gal water/A if applying by airplane. Using less water will lower effectiveness. Check labels for application timing restrictions.
Source : osu.edu