For the second year in a row, the concept of waiting until corn is taller to come into herbicide-resistant corn with a broad spectrum herbicide has resulted in weedy corn. The reason is the same as a year ago- too much rain after planting. The Throckmorton Farm operated by Purdue University near Romney has been hit with considerable rainfall over the past two months.
Jeff Phillips, Tippecanoe Extension ag educator, who helps with the plots, says corn planted May 21 was approaching his height by July 7, and he's not short! The corn planted June 10 was about knee-high, the same as corn in many other places that was planted at about the same time frame.
One year ago weeds were rank when corn was sprayed at this time, or slightly earlier. One year ago there was one planting date, during the last week of May. The weed control from Ignite on Liberty Link corn was incredible. However, Pete Illingworth, the member of the farm crew who handles herbicide applications, notes that he added several other ingredients to take down big weeds.
Whether he can repeat his miracle performance for a second year in a row remains to be seen. We reported how well it turned out last year- we'll report it this year whether it turns out well or not. When interviewed during the winter about how to control big weeds in very late corn, Bill Johnson, Purdue University wed control specialist, responded that you need to pray a lot and be lucky!
Early weed competition takes away from yield, especially on corn, according to published university trial data. Last year's corn still averaged 196 bushels per acre, with some plots yielding well over 200 bushels per acre. The problem last year and this year, however, because the problem wasn't anticipated either year, is that there were no plots where weeds were controlled early to compare for yield loss that might have been caused by early season competition with weeds.
As a result of the weeds, counts that might reveal differences in planter performance at various planting depths, speeds and pressure settings have not been made yet. However, they will be made. The plots will also be taken to harvest for yield. The results will be analyzed using statistics to see if there are any differences amongst these factors that carried over to the edge of the season.