Head Scab of Wheat.
The wheat looks fairly clean of any leaf diseases at this point. In wheat fields that I have walked recently, the critical flag leaf (leaf extending above the boot) is green and healthy. The cool weather has probably helped suppress most of the diseases. If the weather warms up and we continue in this rainy pattern however, then we could be set up for some head scab problems. Head scab, or Fusarium Head Blight, is probably the most yield-robbing wheat disease across IN and IL. Like most diseases, infection is dependent on the right weather conditions (cloudy, rainy, and warm during flowering). Wheat following corn is more susceptible to head scab because the head scab pathogen is the same one that causes Gibberella ear and stalk rot of corn. Farmers can use fungicides to help suppress/control head scab. Apply the following fungicides at early flowering (Feekes 10.51) stage; heads fully emerged and beginning to flower: Folicur, Caramba, Proline or Tilt. The strobilurin fungicides such as Headline and Quadris should not be used for head scab. Apparently these fungicides have caused higher levels of DON (grain toxin) in research trials and therefore are not recommended for this use.
Multi-colored Corn.
Certainly the cool/wet weather has a lot to do with the sickly, yellow appearance of our corn crop. Some hybrids (none from Heritage) will turn a purple color during cool weather conditions – mostly a genetic response. If warm/dry weather ever returns, this crop will green up and grow normally. However, there are some subtle differences between hybrids when it comes to "greenness". Evaluating test plots this week (and last season), we’ve noticed these differences in appearance – and they are mostly the result of their genetic background. For example, Heritage 4686 VT3 has a dark green color, while 4616 RR2/YGPL is more apple-green and 4716 RR2/YGPL is a pale green. This difference in color will follow through much of the season and can be very noticeable when a field is planted in alternating blocks of different hybrids.
Corn Replants and Hybrid Selection.
"It’s been in the ground close to three weeks now and no sign of emergence", is a familiar quote voiced by a number of frustrated farmers around the region. Some areas in the field have an adequate stand while the lower, poorly-drained areas show no signs of life. It’s just been too wet and cold for too long. Replanting has begun in some areas of the states. A reminder that hybrids replanted late in the spring should contain all the insect and herbicide traits, i.e. triple-stack or VT3 products, except where the 20% refuge corn is required. Late-planted corn can come under attack from corn borer and earworm later in the season if not protected by the trait. A few years ago when we had to replant corn in early June, many farmers opted not to include a rootworm insecticide for the replants (or the label prohibited a second in-season application). That year the young, replanted corn seedlings were devastated by rootworm larvae feeding in several fields that I scouted. Lesson learned – use insect traits for replanted corn.
Have a great Memorial weekend!
Dan Childs, Agronomist
