The lack of rain and hot temperatures has allowed grasshoppers to start moving from field borders and grassy waterways to the edges of both corn and soybean fields.Grasshoppers can defoliate plants, which may result in yield loss. As these grasshoppers get bigger, they will move from the field edge to border rows, and then expand farther into the field. The first thing we would recommend is to scout the outer field edges to determine if an insecticide is warranted.
Targeting field borders with an insecticide application might be quite effective instead of spraying the entire field. But, it also depends on the number of grasshoppers present and how much damage they are causing. More information on grasshopper damage and control options, including insecticides, is here: http://cropwatch.unl.edu/2017/scout-field-borders-grasshoppers.
I have heard some reports of Western Bean Cutworm egg masses on corn leaves in western Dawson County.
Western Bean Cutworm moths lays egg masses on the upper leaf surface in the upper canopy. The eggs are white, but as they mature, they turn a dark purple color. After hatching, the larvae will crawl up the corn stalk to feed on the tassel. They will then travel down to the silks where they will start to feed on the developing ear.
Once this occurs, management becomes very difficult. Insecticides are a viable option to manage Western Bean Cutworm larvae, especially before they travel down to the silks where they are more protected for insecticide applications.
For more information and scouting recommendations, please see: http://cropwatch.unl.edu/2017/using-degree-day-models-predict-western-bean-cutworm-flights.
Japanese beetles (Popillia japonica Newman) have been steadily increasing the last several years in Nebraska. An article released on June 19 through CropWatch shows the latest distribution map on a per-county basis (http://cropwatch.unl.edu/2017/japanese-beetles).
From a statewide survey conducted in 2016, Dawson, Buffalo and Hall counties were infested with Japanese beetles. We have already seen adult beetles in central Nebraska. Japanese beetle adults are about ½ inch long with a metallic green head and thorax.
They have a series of characteristic white tufts of hair on each side of their abdomen. In home gardens and landscapes, they typically feed in clusters on ornamental plants like roses, lindens, and grapes where the foliage, flowers, and fruits can all be affected. Feeding is distinguished by leaf scraping or skeletonizing the leaf completely.
In corn fields, adult beetles feed on silks. There is only one generation per year and adult beetles begin to emerge in late June.
If your field is not tasseling or silking yet, it’s a good idea to watch for them, especially once silks have emerged.
Adults are found on field margins first where population density will be the highest. However, make sure to scout the entire field before making any management decisions. The University of Illinois Extension program recommends using an insecticide during silking if there are:
1) three or more adult beetles per ear,
2) silks clipped to less than ½ inch long,
3) corn pollination less than 50% complete.
If you see Japanese beetles in corn during silking, and all three criteria are met for applying an insecticide, products containing pyrethroids may be helpful.
Insecticide active ingredients that end in ‘—thrin’ (i.e. cyhalothrin, cypermethrin, etc.) are in the pyrethroid class. Make sure to scout and read the label before making any insecticide applications.
I received a phone call about replanting after a farmer’s corn field sustained severe hail damage a couple weeks ago.
Hail can be frustrating at any time of the growing season, but it’s especially cumbersome the later we get into the growing season. Replanting is a viable option the smaller the crop is and during the early part of the growing season. If damage is sustained now, farmers are looking for other options and crops to plant.
If this is the case, be sure to check any planting restrictions from herbicide applications already made. This includes planting a crop that can be used for cattle feed.
It’s a stressful situation for any farmer after their crop gets hailed out. If you have crop insurance, contact them first.
Then, consider all your options. If you want to rotate to another crop and herbicides were applied, check the label to determine any planting, grazing, or forage restrictions.
If you are in this situation, I would encourage you to look at these articles on CropWatch before replanting http://cropwatch.unl.edu/2017/crop-hail-damage-resources.