All wheat in Thomas County is heading and most if not all has been sprayed with fungicide. We want to protect the head and the flag leaf for disease, especially rust. Our wheat is in the Feekes 11.0 growth stage where the kernel is ripening. The grain fill period can last from 30 – 50 days depending on stress of environment. A low stress and high yield environment, it will take closer to 50 days.
Fusarium Head Blight
Last year was a bad year for Fusarium Head Blight. It infects during the flower stage, and we had wet conditions during that time last year. Wheat flowers 4 – 5 days after heading and lasts a few days. We are past flower stage now so possibility of head blight may only be for later planted or later blooming wheat. However, we are having the weather conditions that favor it, which you can see at the Fusarium Head Blight Prediction Center.
UGA Plant Pathologist Dr. Alfredo Martinez says about the use of chemical control:
“Control using fungicides can be difficult due to the specific time the fungicides need to be deployed and because selection of fungicides labeled for FHB is limited. Timing of fungicide applications is crucial for the control of FHB. Foliar sprays must be applied at the first sign of anthers extruding from the wheat (anthesis). Triazoles work best when applied right before or at early flowering on the main stem heads. The use of nozzles that provide good coverage of the spike is essential for proper disease management. The fungicides labeled for FHB disease-suppression only are listed in Table 3.″
Leaf And Glume Blotch
This is another disease wheat can have during grain development. I wanted to share some pictures from Terrell County Ag Agent Nick McGhee he has seen on the Alabama line. Here is an excerpt from the UGA Wheat Production Guide:
Lesions (spots) are initially water-soaked and then become dry, yellow, and finally brown. Lesions are generally oblong, sometimes containing small black spore producing structures called pycnidia. The lesions are often surrounded by a yellow halo. Lower leaves are generally more heavily infected, with lesions joining together to cause entire leaves to turn brown and die. If pycnidia are present on lower leaves when the uppermost leaf and the head begin to emerge, infective spores will move to the top of the plant in splashing rain even after a brief shower. Symptoms may not appear for 10-15 days on the top leaves or glumes on the head. By the time lesions are seen on the head, it is too late for effective fungicide use. Therefore, it is important to examine the lower leaves for lesions when making decisions about fungicide application, not just the top leaves. Lesions are first tan or brown on the upper portion of the glume while the lower part remains green. As the head matures, it becomes purplish to black in appearance from glume blotch. Leaf and glume blotch can reduce yield as much as 20% and reduce test weight due to grain shriveling even when disease severity is low.