Those first conditions may vary from farm to farm, but the last one is available to everyone, especially in the early application timing around V5 corn (give or take a couple leaves). At this stage, you can still run your ground rig over the field, and you may be doing so to apply a herbicide treatment already. If that’s the case, then the fungicide could be getting a “free ride” over the field. This greatly lowers the amount of yield gain you need to get a great ROI.
This year, the price of fungicides has come down, as well. Some companies like BASF have just straight up lowered the prices on great products like Priaxor. In other cases like the Bayer Plus program, excellent products like Stratego YLD may be as low as $2-3 per acre if this is your fourth or fifth Bayer product for the year. Find more rebate details on their website or by visiting with your agronomist.
At this spray timing the plants are still relatively small. The recommended use rates are roughly half what the rates are at tassel, so that helps keep the costs down, too. For example, Priaxor is often used at 2 ounces and Stratego YLD at 2.5 ounces around V5. There are many different, effective, multiple mode of action fungicides out there. These are just a couple well-known examples.
Focus on ROI
If application is free or a minimal cost ($2-3/acre to run your own sprayer), and high quality fungicide could be sourced for as little as $2-3/acre after rebates, even if the corn price is not great (let’s use $3 as an example) you’d only need 1 to 2 bushels to break even on the treatment and 3 to 6 bushels to triple your money!