Last night’s storms that rolled through central Iowa and into east central Iowa produced some tremendous winds. And with tremendous wind comes damage to a very good looking corn crop. To the best of my knowledge wind damage to corn started north of Woodward and moved east through Slater, Huxley, State Center, Marshalltown and eastward. I’ve heard reports that the damage was 8 miles wide in several areas. From what I’ve seen at this early stage is mostly lodged corn to within a foot of the ground and some slight green snap.
From here it is mostly a waiting game. The corn is between 3 and 7 days from tasseling and in some field the first tassels become visible over the weekend. The rule of thumb that I follow is that more than 10 days from tassel, lodged corn will ‘goose neck’ to form reasonable rows. Ten days prior to tasseling the amount of corn that will gain vertical orientation again decreases. And after tasseling very little lodged corn will regain vertical orientation.
One of the questions that always comes up is how much yield loss can be associated with lodging. There is very little data available but I have no doubt that some yield loss will occur compared to unaffected fields. The straighter the corn stand the better the odds. If there was green snap the rule of thumb is 1% yield loss for each 1% of stand loss. This is not completely true since neighboring plants can compensate with increased grain fill, but 1% yield loss per 1% stand loss is an easy rule to follow.
True crop damage will take several weeks to assess the amount of yield loss, but some beginning assessments can be made in about three to five days.