Over the past few days I have received several reports of large grasshopper populations in several soybean fields.

Initially, grasshoppers tend to occur along field edges and areas near drainage ditches. No economic damage has been reported due to grasshoppers yet, but consider this an early warning to scout fields. There are no good thresholds established for grasshoppers in corn or soybeans. Generally, consider treatment in pre-bloom soybeans if grasshoppers are present and 40% or more defoliation is encountered. When in the pod forming and pod filling stages treatment is recommended with 20% or more defoliation.

Wheat is being harvested, or is ready to be harvested, in a good portion of the state, but high temperatures, high humidity and predicted rain showers daily for the next week have the potential to cause problems.

Where large amounts of rain fall, getting combines into the field may be difficult. Where fields are passable, grain may be mature but high in moisture. It is important to get wheat out of the field quickly after the kernals have matured to avoid loss of yield, reduced quality and ultimately sprouting in the heads. Combines operate most efficiently and with less kernal damage when grain moisture is between 13-20%. If wheat is harvested much above 14% it needs to be dried relatively quickly to prevent sprouting in storage. Wheat is harder to dry than corn because of the high humidity this time of the year and because it packs tighter than corn thus grain depths in the bin need to shallower or fan speeds/volumes greater.

The following links to publications from Purdue University and the University of Missouri may be useful if the current weather conditions persist and problems are encountered.

• Drying Wheat to Prevent Spoilage and Sprouting
• Wheat Harvest, Drying and Storage

We spent a fair amount of time scouting wheat fields for cereal leaf beetles earlier in the season. Now it is time to focus attention on adjacent corn fields.

The adult cereal leaf beetles can now be found in adjacent corn fields. They are primarily found on the perimeter of the corn fields. Though I have encountered them throughout some corn fields. Adult cereal leaf beetle damage appears as longitudinal slits between the leaf veins. Corn plants usually outgrow the injury. Unlike larval damage in wheat, there are no firm thresholds for adult damage in corn. One threshold suggests treatment when 10 or more adults are found per plant and 50% of plants show feeding damage.

While some growers are still trying to plant or replant first crop beans, double crop opportunities will likely be occurring in about 2-3 weeks. Courtesy of your soybean checkoff dollars, a webcast is availble to view with tips on various management practices. Although originating out of Virginia, many of the tips are helpful here in NJ.

Increasing Double-Cropped Soybean Yield
http://www.plantmanagementnetwork.org/edcenter/seminars/soybean/DoubleCropped/
This 20-minute webcast is open access. Viewers can also opt to see a 5-minute executive summary version. This shorter executive summary version is permanently open access courtesy of the United Soybean Board. [Read more…]

Many corn fields have been repeatedly saturated by recent successive rainfalls. Numerous fields, particularly no-till fields, are yellowing.

While this could be due to several factors, one may be the lack or loss of Nitrogen. On sandy soils, N has probably leached below the root zone and on heavier textured soils some may have also leached but more than likely some denitrification has occurred where N is lost to the atmosphere.

Regardless, some supplemental N applications may be necessary. Sidedressing N is the best option but soils are so wet that it may be a week or so before growers can get in. In other cases, growers may not have such equipment. Fertilizer suppliers may have equipment to apply such products as UAN solutions or Urea(preferably with a urease inhibitor if not incorporated). If surface applied, N losses can occur if rain doesnot follow application within a day or two.

How much N to apply is also a question. If a good amount of N was applied before or at planting then 50 lbs/A of actual N is probably appropriate. If growers put little or no N down in hopes of sidedressing, then a good portion of their planned amounts will be needed.

The ideal time to apply sidedress N is between corn stage V6 and V8 (12-18 inches tall). If the growers have early and late planted corn that is yellow, then the early planted, taller fields should be fertilized first.

Mark VanGessel, Extension Weed Specialist; mjv@udel.edu
I have seen Palmer amaranth seedlings emerging in corn fields that had no preemergence herbicides applied.

There are Palmer amaranth plants in DE and MD that are resistant to glyphosate. So fields with Palmer amaranth present, or fields where you suspect it is present, need to be treated with an effective herbicide (or herbicide combination) that will provide postemergence control as well as residual control. Some considerations include atrazine, Callisto, Capreno, Impact, Permit Plus, Halex, Realm Q, Resolve Q. Other products such as Status or Liberty provide effective postemergence control, but will not provide residual control.

Palmer amaranth plants look very similar to smooth and redroot pigweed. However, Palmer amaranth leaves, stems, and petioles do not have hairs (smooth and redroot pigweed do have fine hairs). Palmer amaranth’s leaves have long petioles that are often as long, or longer, than the leaf blade. As a result, the leaves often droop. Occasionally, leaves will have a variegated “V” mark or watermark across the leaf blade. On-line photos can be found at http://extension.udel.edu/ag/files/2013/05/AMAPA_images_lg.pdf

Source: Read More from Weekly Crop Update