Stripe rust has been found in Arkansas and Louisiana wheat crops. Discovered in southwest Arkansas the second week of March, the rust hasn't been as aggressive as some first feared. Warm, dry weather is helping keep it in check.
“Temperatures have been fairly warm, even at night,” says Jason Kelley, Arkansas Extension wheat and corn specialist. “Stripe rust likes cooler weather.
When nighttime temperatures are at 60, or above, the rust isn't as quick to develop. We've had lows around 60 at night and into the 70s during the day, so that's helped hold the stripe rust back.
“Also a factor is the majority of the state is pretty dry. There hasn't been a lot of dew or cool, rainy weather.”
In Louisiana, the story is much the same. “Stripe rust isn't a big problem yet,” says Steve Harrison, LSU AgCenter wheat breeder. “It certainly could get to be one, though.
“Most of the stripe rust is on varieties we knew were susceptible. Most fields are free of rust although a few are being sprayed.”
Some Louisiana wheat is also being sprayed for leaf rust. “That disease seems to be moving a little but, like stripe rust, isn't severe at this point.
“Our biggest problems currently are weedy fields where growers couldn't get into the fields until it was too late. That's because it was so wet in January.”
There are estimates that Louisiana has over 250,000 acres wheat this year. “I don't have a problem with that number. It may be a little higher.
“There's certainly much more wheat than there was last year.”
Generally, Louisiana wheat “looks good. There are exceptions but the dry, sunny weather we've had for the last month has been beneficial.”
Mississippi had 85,000 acres of wheat in 2006. With around 275,000 acres of wheat this year, the state has its largest wheat acreage since 1982. Those acres are mostly concentrated in the delta part of the state.
“We haven't seen a lot of stripe rust in our wheat yet,” says Erick Larson, Mississippi Extension wheat specialist. “I suspect there's Mississippi wheat that's been exposed to it but most wheat in grower fields is largely made up of varieties fairly resistant to stripe rust.”
Many varieties that performed poorly against stripe rust “have been purged over the last several years,” says Larson. “Stripe rust has been a serious disease for us and, until this year, we saw a steady trend away from wheat. So purging those varieties was a good thing.”
While conditions in Arkansas are currently favorable to wheat “we're not past the danger stage with stripe rust,” warns Kelley. “There's still a ways to go. Most of our wheat, even with earlier varieties, isn't nearly out of the woods. The earlier varieties may have heads popping out here and there along the field edges.
“I hope it doesn't happen, but next week the weather may change and be more conducive to rust. We need to watch out for it.”
As for corn, Kelley says planting is “wall-to-wall. We've had a good stretch of planting over the last couple of weeks. A lot of corn has gone in.
“The southeast corner of the state — Chicot County, Ashley County — is probably 75 percent to 95 percent planted. Even as far north as Marianna, Ark., corn acreage is around 50 percent planted.”
In Mississippi, another problem has recently surfaced. “We've had a lot of calls about aphids popping up,” says Larson. “Growers want to know about treating for them.”
Once wheat begins the jointing stages, “it should be stout enough to handle aphid damage. But the aphid populations being reported in some fields are extraordinarily high.”