Fungicide Sense

12:26AM Jan 04, 2014
Peter Pistorius
( Rhonda Brooks )

Scouting reveals scenarios that warrant treatment

Low corn prices might cause some farmers to eliminate any potential plans they have for using a foliar fungicide in 2014, but that’s not the case for Pete Pistorius. The Blue Mound, Ill., farmer says fungicides will factor into his management decisions this coming season, particularly in fields planted to continuous corn, late-maturing hybrids or hybrids susceptible to foliar disease.

"I’ll spray them where I think they’ll give me an economic return, whether we have $3 corn or $6 corn," says Pistorius, a sixth-generation farmer.

He adds that scouting corn in-season is the only way to know whether and when to pull the application trigger.

The past two years offer prime examples of why Pistorius says scouting is critical, but for different reasons. In 2013, he sprayed a foliar fungicide on 80% of his corn crop post-tassel, at the brown-silk stage (R2). He says the decision to spray was an easy one.

"We had a late planting and a cool summer with ample rainfall, conditions that are conducive to disease pressure," he explains. "Plus we had a pretty big crop and wanted to protect our investment. We didn’t want to lose any yield to disease or standability problems."

Those factors were far different from the situation Pistorius and most Midwest producers faced in 2012. Still, Pistorius sprayed a foliar fungicide on a handful of corn acres that year, hoping to protect the plants from what ended up being a historic drought.

"We thought maybe we could slow those plants down a bit growth-wise so they weren’t taking in as much heat," Pistorius recalls, adding that he is unsure whether the crop actually benefited from the application.

Brianne Reeves, BASF technical market specialist, acknowledges drought conditions in 2012 hammered much of the Midwest corn crop beyond help. However, she says a crop performance payoff in less-intense drought conditions can occur because fungicides help keep plant stomata open and functioning. Stomata are the micro­scopic pores on plant leaves that allow the exchange of gases and water.

"Providing corn plants relief from heat can help root systems through the stress so they can tap into any available soil moisture," Reeves says.

BASF, as well as Bayer CropScience and Syngenta, promote fungicide applications in corn crops for so-called plant health benefits.

"Fungicides physiologically impact the health of corn plants and contribute to higher photosynthetic rates," says Randy Myers, Bayer fungicide products manager. "They also help corn plants use nitrogen more efficiently and develop stronger cell walls, which makes plants less prone to lodging."

Reeves recommends corn farmers make a sequential application of Priaxor at the vegetative stage followed by Headline AMP at tassel to get the biggest payoff. She says BASF research shows corn yields an additional 12 bu. to 17 bu. per acre with tassel applications, as well as incremental increases in disease control, plant health and yield benefits from sequential applications.

Tough choices. However, foliar fungicide use, apart from disease pressure or a high level of risk, finds little support among academic plant scientists.

Kiersten Wise, Purdue University Extension plant pathologist, tells farmers to weigh fungicide treatments against the price of corn. If corn is $4 per bushel and a fungicide application costs $24 (including product and application method), she says farmers need to recoup at least 6 bu. to break even.

While Pistorius takes university agro­nomic research into consideration, he says farmers need to look beyond weigh-wagon results.

"A foliar fungicide can make a significant difference in how corn dries so it stays green on top and brown toward the ground," he explains. "When you see this, you know your corn is dying down the proper way, hopefully adding a longer period of time to absorb moisture and nutrients, which contributes to test weight and yield."

Pistorius will not determine his final application strategy this summer until he scouts fields, but he has prepaid for his fungicide so he can quickly take action, if need be.

"I have to do everything I can to manage risk," he says. "Fungicides aren’t silver bullets, but they are a good tool in a comprehensive management approach." 

You can e-mail Rhonda Brooks at [email protected].