Test plots can look rather gnarly this time of year, especially this year. Many plants are firing. Some plants are flat-out drying up.. Nevertheless, whether it's at a field day or whether you just stop by a nearby plot on your own, Bob Nielsen says you can still learn form plots if you take certain factors into account.
One tip the Purdue University Extension corn specialist offers, and we don't think he's kidding, is to watch out for green garden spiders in webs extending across the row, hung to corn plants. Apparently he's so phobic about these that he considers it akin to running into a tarantula.
On the more agronomic side, before you make conclusions on plant health between one hybrid and another, you need to know whether the plot was sprayed with a fungicide. If so, what was used and when was it sprayed? Most fungicides applications are not 100% effective, but it could mask a weakness of a highly-susceptible hybrid to key diseases, such as gray lead spot.
There are differences in how hybrids stand up to/and or resist stalk rot diseases. This should be a good time to pick up those variations, he notes. Again, the comparisons won't be fair if the plot was sprayed with fungicides. Foliar diseases, that would assumedly be more rampant where the field was not sprayed, will tend to set up plants for stalk rot diseases later, partially because it's simply another stress on the plant.
One thing to look for that may not seem obvious is whether a hybrid you're considering cannibalizes it's own stalk to fill the ear in times of stress. There is a large difference in the degree to which a particular hybrid will cannibalize the stalk to produce an ear. It's something you should know about a hybrid before you make final seed selection details for next year. If cannibalization has occurred, don't be afraid to do your own push test- pushing stalks to see if they snap back. Stalk rot will be more common if the plant has moved nutrients from the stalk to kernels on the cob to ensure that it can develop as many kernels as possible.
If you go to a field day, be on the front row of the ring of people around the speaker, not in the back. Be aggressive about asking questions, not passive, he notes. Ask the tough questions about root strength and standability. See if what you're told matches up with what you see while viewing those hybrids in the plot later in the program.