MISSISSIPPI STATE -- Mississippi's corn is battling for decent yields as cool, wet weather hampers growth and triggers common rust disease throughout much of the state.

"Corn is in its critical pollination period which is the most sensitive time for any stresses," said Dr. Erick Larson, extension corn specialist at Mississippi State University. "The weather conditions since Memorial weekend have caused an unusually heavy outbreak of common rust in corn fields."

Initial symptoms of rust are small bleached spots which are readily visible when holding leaves up to light. After five or six days, golden to cinnamon-brown colored pustules develop.

"Rust will reduce photosynthetic energy production," Larson said. "Developing corn kernels are very dependent on this energy production during pollination and early grain fill."

Larson said the disease has arrived earlier and more severe than normal for the state. Fields are impacted throughout most of the corn-growing counties, primarily in the Delta and East Central region.

Weather has delayed the crop in Northeast Mississippi, and the corn is not developed enough for rust to be a significant problem.

"Some areas near Tupelo have had around 25 inches of rain since Memorial weekend," Larson said. "Some of these fields may be abandoned if they dry out enough for growers to plant alternative crops."

Hybrids differ in their resistant abilities to common rust, making the type of hybrid an important component in management and scouting decisions. County extension agents can inform growers which hybrids are resistant to rust.

"This year's severe outbreak will make farmers look for more resistant hybrids next year," Larson said.

Dr. Dennis Reginelli, Noxubee County agricultural agent, said certain corn hybrids have been hit harder and will have reduced yields.

"Scouting from field to field is essential because timing treatments is important," Reginelli said. "The crop's stage of development impacts control decisions. Some fields need preventive efforts, others need treatments to stop further damage. In some cases, the disease or the crop is too far along to apply any chemicals."

Reginelli said the crop's high yield potential is influencing farmers to do their best to protect their fields.

"Farmers have very good yield potentials and that's why they are working so hard to control the rust," Reginelli said. "When they look at yield potential, they know it won't take long to repay for control efforts. It will pay for itself."

Reginelli said wheat also had rust damage this year.

"1997 has just been a year for rust. The cool temperatures, rain and humidity have amounted to triple trouble," Reginelli said.