Forage producers in southwestern Missouri should be on the lookout for rust in tall fescue fields, warns Brie Menjoulet, University of Missouri Extension agronomist.

"Sparse and relatively minor cases of rust are common in Missouri,” she says. “However, the heavy dews that we have experienced the last few weeks, coupled with the minor winter, seem to have increased the severity and range of the outbreaks.”

Rust doesn’t necessarily affect the overall quality of hay or pasture. But it can reduce yield and make the fescue harder for cattle to digest. With cattle, normal grazing routines can be followed. But producers should use caution when allowing horses to feed on infected pasture or hay. “Horses could be more sensitive to inhalation of the spores,” Menjoulet says.

Fescue seed yields can be reduced by as much as 40% when the grass is severely infected with rust due to lowered photosynthesis. “Some producers may consider skipping fescue seed harvest altogether and using these fields for hay or pasture,” the agronomist says.

Cutting fescue for hay as soon as possible to avoid increased yield loss is another strategy worth considering. “Fungicide applications can be made, but the results may be unsatisfactory at this stage on maturing fescue stands. If fungicides are applied, pregrazing and preharvest intervals must be followed as indicated on the label.”