Few things are business as usual amidst the COVID-19 pandemic and yet, Oklahoma State Extension managed to maintain the integrity of the experience of one of the state’s longest standing wheat field days despite utter chaos.
The field day no doubt took countless planning and accommodations to deliver a similar event online via Facebook as it would have in the flesh, but the end result was an experience in line with the original made accessible to more people than ever before, with upwards of 700 views on many of the day’s scheduled speakers. With a host of expert presenters, the Lahoma Field Day helped set the standard and create a template for virtual field days in the future.
Plant pathologist Bob Hunger updated producers on the disease load observed in the variety plots at Lahoma. The plots in these trials were untreated for insects or disease and can provide a good barometer for diseases coming into the state.
“We had a late planting date this year so we saw very little of the wheat streak mosaic virus or any of the mite transmitted viruses,” Hunger said. “We have seen most all of our other diseases present.”
Hunger said leaf spot diseases have been prevalent among the plots and among fields scouted throughout Oklahoma.
“Septoria leaf blotch has been very common and has moved up pretty high in the canopy as the season has progressed,” Hunger said. “It started early and continued even now as this cool, moist weather we’ve had has moved it along.”
Stripe rust presented challenges for wheat producers across the southern states this season and Oklahoma was impacted later as the disease drifted north. Cases ranged from severe to light across the state with some areas hit harder than others.
“More recently, leaf rust has moved in to replace the stripe rust,” Hunger said. “Leaf rust tends to like warmer temperatures… but as the season progresses we’ll see more leaf rust come into the state.”
Stripe rust, leaf rust and stem rust are three of the most prevalent types of rust diseases plaguing Oklahoma wheat, and while stem rust is rarer to see in the field, several fields witnessed instances of stem rust this year, Hunger said.
In addition to rusts and blotches, Hunger said powdery mildew did not pose too much of a problem, while the incidence and prevalence of loose smut has been surprisingly more than normal. Loose smut can be handled by treating seed and Hunger said it is important to avoid planting seed from fields that had loose smut this year in order to control it in future fields.
Wheat breeding specialist Brett Carver was on hand to discuss Oklahoma State’s variety performance in the trials, specifically in the case of newly released beardless variety OK Corral.
“I’m happy to say that OSU is back in the beardless wheat shootout and we have the perfect name for that variety — OK Corral, a 2019 release,” Carver said. “Planted right next to OK Corral is Deliver, it’s not part of the parentage of OK Corral but they do have similar maturities.”
Deliver, a variety produced in 2004 was an essential piece in improving yield for the OK Corral variety. Carver was quick to clarify that while OK Corral is a beardless variety and good for grazing, it is also a grain producing wheat.
“We do not produce forage only wheat varieties in the breeding program,” Carver said. “Yes, we focus on forage production but it’s also got to be part of the bigger package and that bigger package has to include grain quality that can be delivered to the elevator, delivered to the mill and used to make bread.”
Agronomically speaking, Carver said OK Corral establishes quickly, builds and closes canopy quickly and comes with some Hessian fly resistance. The disease package included in OK Corral is thanks, in part, to its breeding including a soft wheat and an OSU experimental line with Ukrainian germplasm from an eastern European grazing grain pipeline.
Overall, Carver said he’s been satisfied with OK Corral’s performance in the trial, especially given the conditions the Lahoma variety trial plots have been under.
“We don’t treat this wheat ideally, we give it the usual conditions,” Carver said. “We plant around the middle of October — the sixteenth would have been our planting date here — and we do not use treated seed, fungicide or provide any help.”
Tank Mixing Nitrogen and Insecticide
Integrated pest management specialist Tom Royer spent the last three years researching a common practice among Oklahoma’s continuous wheat producers and found a surprising amount of economic impact in a simple, practical change in topdress applications.
“As topdress nitrogen applications became more popular and widespread around the state in continuous wheat, I started hearing that producers were also adding a pyrethroid insecticide in with their winter topdress nitrogen application,” Royer said. “I wondered if it was really paying for itself and I had an idea that they were probably avoiding two trips across the field when they could make one.”
Royer addressed the practice with retail supplies, asking how common the practice was and through their feedback found the practice to be widespread but he was still unsure of any true economic benefit.
While it is an inexpensive treatment to add on to a topdress, especially using a generic pyrethroid he was unsure of the viability of mixing the two for one-pass applications and established some plots alongside the Lahoma variety trials as well as at experiment stations in Chickasha and Stillwater.
The research focused on a commonly grown variety, Oklahoma State’s Gallagher, and worked with four treatments — one with no topdress, topdress only, pyrethroid only, one with both topdress nitrogen and the pyrethroid. In order to take a closer look at insect response, the researchers took a count before and two weeks after applications.
“At the time, we found out there was really very little insect activity when we were actually putting out these treatments,” Royer said. “We didn’t see a lot of change in insect activity one way or the other.”
When Royer reviewed the resulting data from the trials over the three years of the study, he was surprised to find a conclusive benefit to the combined topdress practices.
“What we found is that the combination of topdress nitrogen with the pyrethroid, on average over all of the trails we did, provided a benefit of about five bushels per acre increase in yield over the untreated plots,” Royer said. “The combination would be the most economical because when we looked at either one of the treatments themselves, the increase in yield itself using both would have been the same as the combination except you would have had an extra trip across the field.”
Royer is continuing to research what phenomenon makes the practices so conclusively beneficial, but he has a hunch that the results work well in continuous wheat production fields because they tend to favor mite buildup. The reduction in mite loads alongside the available nitrogen could be the source of the yield bump.