Source: Purdue University
Head scab damaged much of southern Indiana's wheat in 2009, so farmers should take time to monitor their crops for the disease this year, a Purdue University agronomist says.
Wheat is now at a critical growth stage to scout for the development of head scab. Most plants acquire this disease anytime from the flowering stage through the early dough stage, said Purdue crop disease expert Kiersten Wise.
Head scab is caused by the fungus Fusarium graminearum, which produces mycotoxins that are often harmful to livestock and humans. Seeds infected with the disease will be slow to emerge and will tiller poorly.
Symptoms of head scab include bleaching of the spikelets, along with pink or orange masses of spores on spikelets.
"Head scab will probably not hit southern Indiana as hard as it did last year, but we have started seeing early symptoms of the disease in fields throughout the state," Wise said. "We are keeping our eye on the situation since the weather we have been having is favorable for scab development of infected spikes."
Favorable weather conditions for the disease include high humidity and frequent rainfall. It takes only 2-3 days of light rainfall, with optimum temperatures between 75 degrees and 85 degrees at early flowering, for a field to be more vulnerable to head scab. Most wheat in Indiana is past the early growth stage at this point. If infection did occur, however, symptoms will be visible over the coming weeks. It is still important to monitor wheat fields now to know if steps need to be taken at harvest to manage scabby spikes, Wise said.
To help prevent wheat head scab, it is important to apply the correct fungicides as soon as flowering occurs. Wise said farmers should select a variety of wheat that has some level of resistance to the disease.
For more detailed information about head scab, see the Purdue Extension publication, "Fusarum Head Blight (Head Scab)" here.