There were a few more reports of stripe rust from Oklahoma this week and a Twitter report of the disease in southeast Kansas bordering Missouri. Several colleagues made visits to research sites in south central Texas and reported severe leaf rust on varieties known to be susceptible to that disease. To date, Extension agents, crop consultants and growers all indicate that rust is not widely active in Kansas.
With the wheat crop in south central and southeast Kansas approaching or already at the flag leaf emergence stages of growth, growers are encouraged to be on the lookout for diseases. When people think of stripe rust, they often visualize the characteristic bright yellowish-orange lesions on adult plants. Symptoms of stripe rust on younger leaves are often less rectangular because the fungal growth within the plant is not limited by the veins of younger leaves.
When scouting wheat, it is important to look down within middle layers of the crop canopy for symptoms of disease. Wheat puts out new leaves rapidly during the vegetative growth prior to heading. In some cases, plants may add a new leaf every seven to 10 days. These new leaves at the top of the canopy are less likely to express disease symptoms simply because it takes time (10-14 days) for the disease to develop. Focus on leaves that where present over the last two weeks. These leaves have a higher probability of infection than the new leaves at the top of the canopy.
— Ryan Flaming is a Kansas State Research and Extension agent for Harvey County. Agriculture is his specialty.