Within the last two weeks Rex Herrington and I have traveled most of the state and have looked at a considerable amount of wheat. Across most of the state the wheat crop has thinner than normal stands, which can be mostly attributed to a very dry fall and late emergence in many fields. Fortunately, rainfall across most of the state within the past 4-6 weeks has really turned the crop around. According to the crop weather report (3-21-2004), the wheat crop is 4 percent excellent, 19 percent good, 38 percent fair, 27 percent poor, and 12 percent very poor.
Powdery mildew has plagued most of the Backlands and Northeast Texas since early February and continues to persist and many fields. From my conversation with CEAs and IPM agents, this is probably one on the worst incidence of powdery mildew in a long time. The HRW wheat varieties are more susceptible to powdery mildew than SRW wheat. Some of the varieties that appear the most susceptible include Jagalene, Thunderbolt, Cutter, Stanton, and Ogallala. Typically, the wheat plants can withstand higher infestation of powdery mildew than of leaf or stripe rust; however, weak wheat stems and lodging may result from heavy powdery mildew infestations. Management of powdery mildew is seldom justified if a variety has moderate resistance; however, fungicide applications to susceptible varieties may be economically justified and numerous fields have been treated in Central Texas.
Numerous fungicides are labeled to control powdery mildew and include, Headline (6-9 oz/A), Quadris (6.2 oz/A), Quilt (14 oz/A), Propimax (4 oz/A), Stratego (10oz/A), and Tilt (4 oz/A).
Rusts: Very little stripe rust has been observed within the last few weeks; however, the stripe rust pressure on susceptible varieties (Coronado and 2174) have approached a concerning level in McGregor. Based on reports from South Texas and the current weather patterns, leaf rust will likely be a much bigger problem in 2004 than 2003. South Texas is experiencing very heavy leaf rust pressure and the inoculum will likely be moving northward into the Northern Blacklands and Rolling Plains of Texas.
It appears that a different race of leaf rust may be present this year, in addition to old races of leaf rust. In the South Texas wheat nursery, wheat varieties that were rated as totally resistant in 2003 have been infected with leaf rust, including Agri-Pro Cutter and Jagalene. Moderate leaf rust infection was also observed in McGregor on the Agri-Pro Cutter field. Trace levels of leaf rust were observed in the Abilene wheat nursery on susceptible varieties.