Foliar Feeders in Oklahoma Soybean Fields

We are starting to see an increase in defoliation from insects in some soybean fields around the state. Basically these insects can be broken down into two distinct groups; “foliar feeders” and “pod feeders”. Fall army worm has been observed in some fields. The distinct identifying characteristic of fall armyworm is the inverted “Y” on the head capsule. Fall armyworm can quickly do damage that results in yield loss. The general rule of thumb for fall armyworm and other foliar feeders is the following:

Treatment is recommended when foliage loss is around 15-20% during pod fill. However, if pods are filled defoliation losses can be 35-40% before the treatment threshold is reached.

The other insect that has been observed in some fields is corn earworm, which can feed directly on pods and greatly reduce yield potential. Control of corn earworms is suggested if you find two or more per row-foot.

With the high yield potential we still have in some of our soybean fields and the price of soybean make sure you continue to scout for pest problems.

Treatment information can be found at the following link:
http://pods.dasnr.okstate.edu/docushare/dsweb/Get/Document-2347/EPP-7167web.pdf

Relying on glyphosate only applications is not good

Over the last 6 months I have been in several soybean fields around the state and more often than not we see developing weed control problems. These problems seem to be centered on the continual use of glyphosate with no other tank mix partners. I’m not saying we have glyphosate resistant weeds but with continual applications of glyphosate only we may not be far from developing resistant populations. In some cases, 3 to 4 applications of glyphosate only have been made within a single cropping season. This is simply not a good practice, I realize it may be the most economical in a single year but long-term the economics of controlling glyphosate resistant weeds will not look so good.

Combining herbicide chemistries is very important to ward off resistance, especially rotations that are dominated by glyphosate resistant crops. Using pre-emerge products can reduce the number of glyphosate applications in season to as few as one. Plenty of good herbicide options are available for RR soybean production, non-RR soybean production, and Liberty Link beans. All of these require careful attention to detail and a well thought out plan. A well thought out herbicide program will pay long-term.

Do we rely on glyphosate too much for weed control?

Is the era of glyphosate only weed control over?

Double cropping decisions

As we move into the first part of July, producers possibly need to re-think double-cropping decisions. In the case of soybean, it is not recommended planting past July 10. Planting after this date greatly reduces yield potential.

Grain sorghum can be planted until July 15-19 in most areas. Planting after this date reduces the chances of properly maturing before the first frost.

The only grain crops that can be planted after this date is sunflower and sesame. Both of these crops can be planted until July 25 and even as late as Aug. 1 in the southern part of the state.

What drives the decisions for double cropping, is it soil moisture, time of year, crop rotation, or some combination of these? I realize it varies in different parts of the state and some areas simply to not get enough precipitation to double crop. I would like to hear what drives the decision making process.

In my opinion if you have the moisture available after wheat harvest you should use it because soil water retention during summer fallow periods in Oklahoma is not efficient in storing water. Only about 20% of water is stored during a summer fallow period.