b'ON LOCATION: TAR SPOT SUMMITA SYSTEMS APPROACH ISNEEDED FOR TAR SPOTAt the AgReliant Genetics Tar Spot Summit, growers talk about agronomic management strategies to combat the new disease.Alex MartinSINCE FIRST BEINGspotted inWhen it comes to management strate- to plant health, says Rod Jurgens, a 2015 in the Midwestand becominggies, two pieces come into focus: hybridgrower based out of Hopkinton, Iowa. more of a nuisance from 2018 onward selection and fungicide management.Were not happy with 240 bushels per tar spot is a newer disease threateningFor us, it comes down to geneticacreI want 280.corn crops throughout the season.potential in our areaand theres a lotSylling believes in 2023, fungicide is Caused by the fungus Phyllachoraof different factors you can go into,going to be used 100% on his operation, maydis, tar spot is commonly identified bysays Jon Bauman, a grower based out ofbut for his battle against tar spot, its all black, circular discolorations on the leaves,Kendallville, Ind. Those good racehorsebased on the return on investment.husks and stalks of corn plants, accordinghybrids have worked well in our area.Its going to be used, but Im going to a release from the USDA ARS in WestBetween 2021 and 2022, we had a dev- to continue to do checksat the point Lafayette, Ind. Sometimes, a tan halo sur- astating time with tar spot, and it reallywhere that ROI is flat or Im not making rounds the spore-filled spots, causing acame into the field late this year. If tarmoney doing it, its gone, he says. But fish-eyed lesion. By the time those char- spot is managed well, those racehorsesIm worried that its going to take a while acteristics appear, typically, growers willcan keep up. for breeding to get to that point.SWexperience a loss of yield from the disease. When it comes to disease pressure, In 2021, [tar spot] affected us prettygrowers are prioritizing plant health in significantly on one or two farms, saystheir varieties. Thats just as true when it Myron Sylling, a grower from Spring Grove,comes to variety selection for tar spot.Minn. It affected all hybrids that year, andDisease pressure has been high on we lost 20 bushels per acre on that farm our list for a long time, Unger says. the harvest stability was terrible. Plant health has been paramount, Sylling wasnt the only grower whoand its remained that way. had difficulty battling tar spot when it firstWe still plant a racehorse emerged on his farm. Three other grow- hybrid there, but a majority of ers joined him on a panel at the AgReliantour hybrids are what Id call a Genetics Tar Spot Summit from Nov.workhorse.28-29each faced different issues andInstead of focusing on found different solutions to combat thethe racehorses that gener-disease, but none have managed to com- ate high, high yields, Unger pletely eradicate it from the farm.finds value in varieties Solutions are focused on a systemswith more stability and approach of managing, the four agree. overall disease resistance. This year, we adopted a two passBy focusing on overall deal, and that worked very well for us,disease resistance, Unger says Del Unger, a grower from Carlisle,finds that hes still able to Ind. This year was better, and were prob- achieve high yields. ably one of the few in our area that canIn addition to hybrid say that. Well continuing to do the twoselection, fungicide use passesbut the concerning part aboutand timing is a need for all this for us is were still making two passdealing with tar spot. application. Its not a silver bulletwereFungicides and different still seeing some infection. modes of action are paramount 44/ SEEDWORLD.COMFEBRUARY 2023'