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Monday, April 1, 2013

Greenbug Update

As recently as Wednesday last week I had announced that the predators should be able to handle the greenbug population I currently find in our area wheat. What a difference a few days make. Starting Thursday, March 28th I began receiving phone calls in earnest about possible heavy greenbug infestations in wheat north of Tulia in Swisher County that were already severe and on the increase. Since that time I have been able to confirm all reports with several on-site inspections.

In these areas, I find very few predators to control an already economic and growing population of greenbugs. Upon occasion, I also found some pockets of Russian Wheat Aphids, and some spotty but heavy populations of Brown Wheat Mites intermixed with the greenbugs. The Brown Wheat Mites are very small, but rarely an economic concern.

What is alarming is that this population of aphid species is still on the increase and has begun dispersing. A very high percentage of these aphids found were of the winged biotype. Myself and multiple entomologist and Texas A&M AgriLife Extension Agents from Tulia north to at least Amarillo, have now noted heavy greenbug flight and movement. During the heat of the day, these winged aphids are dispersing and moving, being carried by winds in huge numbers. Personally, I have not witnessed these greenbug ‘clouds’ near Plainview in Hale County, but they are now quite notable just to the north of Kress in southern Swisher. I strongly suggest that all area wheat producers and consultants be on the lookout for aphid pests as you evaluate your wheat this week for frost damage, mosaics, etc. Even proactive wheat producers that made insecticide applications just two to three weeks ago in conjunction with herbicide applications could be looking at a re-infestation problem here in April.

On March 28, Dr. Ed Bynum, Texas A&M AgriLife Extension Entomologist, Amarillo, released the latest issue of
Panhandle Pest Update. In this issue Dr. Bynum reported some possible area problems with these aphid pests, gave identifying characteristics of these pests, discussed economic thresholds, and listed relevant insecticide products. Most wheat producers should find this issue very helpful. A link to that newsletter is provided here.

I do urge wheat producers to take into account the full economic picture when making decisions about this spring’s wheat aphid pest treatment options. Soil water availability, irrigation costs, and cost return on investment can easily become an issue for area wheat producers this season, as can some possible freeze damage from recent weather events. Another factor to consider is the presence or absence of plant disease. As I scouted area fields these past two weeks I noted a higher than expected and consistent amount of mosaic present in the majority of wheat fields. There are four differing types of wheat mosaic that can infect or area wheat, but identifying which type is actually present in your field requires samples to be sent to a lab. Many times, identification of which type of mosaic that is present in your field is a moot point once disease symptoms are noticeable. These mosaics are normally transmitted to wheat by the Wheat Curl Mite in the fall from green native grass, summer growing volunteer wheat, or corn. Early spring virus transfer might also be possible by other aphid species. All management options for spring control of these mosaics are: few known and none that have proven to work on a severe and widely dispersed infection of these viruses across a full wheat field.

If all of these factors, insect, drought, and mosaic combined in one wheat field, it can be difficult to justify spending much capital with little hope of return on investment. Unfortunately, several area wheat fields might be in this situation. In many cases, other options, such as grazing, utilizing the wheat as cover, or possibly hay are all options is necessary.

If I can help you identify a problem, or for more information, please give me a call anytime.


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