Since 2005, more than 400 Iowa farmers working with the Iowa Soybean Association's On-Farm Network have conducted more than 1,000 replicated strip trials testing fungicides on soybeans and corn.

PARTICIPATE IN IOWA TRIALS: Foliar fungicides are applied to corn and soybeans in summer to help manage diseases. It will most likely pay to spray them in wet years, when foliar diseases are most evident and could impact the yield of corn and beans if they aren't sprayed. You can still participate in Iowa fungicide trials for corn and soybeans this summer.

Most of these trials compared yields from a foliar fungicide versus an untreated check. But some directly compared several fungicides, or fungicides with other products (herbicides, insecticides and foliar fertilizers), or two passes of fungicides, or fungicides applied in-furrow. "Over the years, the use of fungicides in our On-Farm Network strip trials have had the highest return on investment among the many crop input products we've tested for both corn and soybeans," says Mick Lane, communications director for the network. 

In 2013, with the wet spring drawing out the planting period for so long, Iowa's corn and soybean crops are at several different growth stages right now. Some of the earlier planted corn is at or approaching the V5 growth stage. The later planted corn is a lot smaller.  

A journal article recently authored by Peter Kyveryga, who is the On-Farm Network's senior research associate, and Daren Mueller, an Iowa State University Extension plant pathologist, reports on the network's trial results with fungicides. Soybean yield responses to Headline fungicide were greater with a higher amount of spring rainfall. Also, in a recent ISU Integrated Pest Management newsletter article Mueller says "…the greatest responses to foliar fungicides we have seen over the past five years in Iowa have been when disease could impact yield of corn or soybeans."

Soybean yield response to fungicides tends to go up as spring rainfall increases.

"Guess what … this spring has been wet," says Tristan Mueller, On-Farm Network program manager. "Cool, wet soils, followed by hot, humid air could make this a banner year for crop diseases in the state." ~~~PAGE_BREAK_HERE~~~

Summarizing the past fungicide trials and results, the following information is reported in the journal article authored by Mueller and Kyveryga.

Results of corn fungicide trials over the past five years in Iowa

Headline fungicide on corn. A single application of Headline fungicide produced an average yield response of 4.6 bushels per acre. In 2009, two applications of Headline (first application at V5 and second application at Vt-R2) produced an average yield response of 7.8 bushels per acre.

Stratego YLD, applied at V5, was tested in replicated strip trials during 2011 and 2012. Average yield response for treated strips was about 1 bushel per acre, which is about the cost for the fungicide. Both of these years were drier than normal, so the larger yield response we'd seen in previous years was not expected. Bayer CropScience recommends applying Stratego YLD with postemergence herbicides to avoid extra application costs.

ProAct + propiconazole vs. Headline or Headline AMP vs. untreated. In 2011 and 2012, these products were tested in head-to-head comparisons. The ProAct + propiconazole had very similar yield responses to both Headline and Headline Amp, with all treatments yielding more than the untreated strips.

Results of soybean fungicide trial over the past five years in Iowa

Headline on soybeans: Nearly 300 trials were completed from 2005 through 2012. The average yield response across eight years was 2.3 bushels per acre. For more, check the updated soybean fungicide calculator. Be sure to plug in spring rainfall to get a better idea of what fungicides could do for your soybean yields this year.

ProAct + propiconazole vs. Headline on soybeans was tested in 2012. Even though it was a very dry year, the ProAct treatments had yielded 0.5 bushels per acre higher than Headline and 0.9 bushels per acre higher than the untreated.~~~PAGE_BREAK_HERE~~~

2013 trials -- you can still participate in this year's On-Farm Network trials

Several fungicides and other products are still available for farmers to test this year in On-Farm Network replicated strip trials. For more information on foliar trials for this summer, visit the On-Farm Network online.

Corn fungicide trials for 2013:

* Arysta LifeScience: ProAct + propiconazole fungicide vs. Headline fungicide vs. untreated applied at V5.

* BASF: Priaxor fungicide vs. untreated applied between V8-V10 

* MANA: Custodia fungicide vs. untreated applied between VT-R2

* Syngenta: Quilt Xcel fungicide and Halex GT herbicide applied between V4-V8

* Quantum VSC/Light is a soil amendment that should be applied between V4 and V10

Soybeans fungicide trials for 2013:

* Arysta LifeScience: ProAct + propiconazole fungicide vs. Headline fungicide vs. untreated applied at R3

* BASF: Priaxor fungicide vs. Priaxor + Fastac insecticide vs. untreated applied at R3 

* MANA: Custodia fungicide vs. Headline fungicide applied at R3

* Novozymes: Ratchet LCO promoter applied at vegetative stages

* Quantum VSC/Light is a soil amendment that should be applied at vegetative stages.

Scouting On-Farm Network Trials

Iowa State University crop scouts and ISA On-Farm Network staff are continuing to collect data in as many of the 2013 replicated strip trial fields as possible. ScoutPro, a new application for iPhone and iPad, will allow you to easily identify pest and collect your own geo-referenced scouting data in a format than can be easily transferred to your computer. The app is available free to ISA members and On-Farm Network participants at the App Store. Contact Tristan Mueller for an activation code in order to download it. Again, it's free. (Sorry, Android users. Your version of the app is not yet available.)