Wheat Pest Status March 27, 2015

Wheat Pest Status March 27, 2015

Over the past few days I have been making spot checks in some of our Hale, Swisher, and Floyd County area wheat fields on the way to the office.  All but the latest planted fields are now jointing, in decent shape, and will be looking for some moisture soon.  There is still quite a bit of insect activity in these fields and some potential for pest problems to keep a close eye on.  The greenbugs seem to be the largest threat at this time but there are plenty of other aphid species in this wheat.  I still have not found any Russian wheat aphids but, in speaking with a few area crop consultants, there are a very few in the area.  Dr. Ed Bynum, District 1 Entomologist, is consistently finding them and greenbugs in a little heavier population than us in his area to our north.

To me, our greenbug population seems to be trying to increase during the warm weather we have been having.  The aphid will typically move up the plant to more tender and sensitive areas during better weather and becomes very active in feeding.  Once that happens, the aphid is also more likely to begin reproducing heavily.  In the fields I have been watching, the predator and parasitoid population is holding the greenbugs in check.  The potential and conditions are certainly right for a pest outbreak area wide.  It is more likely that in a fair number of area fields the greenbugs could outpace the beneficial insects.  Our area crop consultants have also made me aware of a few fields that have reached economic levels for greenbugs that have been treated already this week.  The only way to determine if your field is nearing pest problems is thorough and educated scouting.  

    Action Threshold Table for Greenbugs

Plant Height (inches)                      Number of Greenbugs / linear foot

                3 – 6                                                           100 – 300

                4 – 8                                                           200 -  400

                6 – 16                                                         300 – 800

Good Luck,

Blayne

Wheat Pest Status

Wheat Pest Status February 2, 2015

 

                It has been a lagging end to the 2014 season.  Luckily pests have been fairly quiet in our area wheat allowing us to focus on finishing our cotton, corn, and sorghum harvest on the days the weather permitted us to work in the field.  I received word mid-week last week that some greenbugs were heavy in wheat and were being treated in Castro and Randle County.  This prompted me to make a swinging loop through Swisher, Hale, and Floyd wheat fields late last week and early this week for a general pest check.  I found a healthy greenbug population that ranged from moderate in the Happy to Tulia area, light to moderate in a Plainview to Lockney line, and very light to light from Hale Center to Cotton Center.  In all general areas the pest population was lower if the wheat was being grazed.  There was no field that I checked in any situation this week that was near an economic level.  Predators, predominantly lady beetles, were also on the increase helping to keep tabs on the pests.  This is not to say that there are not some fields in the area with economic greenbug issues.  Each field needs to be evaluated for its own pest population and economic situation.

                Our wheat is certainly turning and flourishing behind our recent moisture events, as are the winter weeds.  If they are not already, producers will be heading to the fields to address these weed problems soon.  It is very tempting, especially in the current economic situation, to mix an additional pest control application to this weed control pass trying to eliminate a need for a future pest treatment.  I would urge producers to get a good handle on their specific pest situation in the field before choosing this option.  Making a pesticide application when one is not required at the time often creates more problems in the near and upcoming future than they ever save.

                Our wheat is currently in some of its last stages before setting its head size and jointing.  I estimate most fields that I checked are 3 to 7 weeks from that critical stage.  While still in this immature stage, wheat can tolerate quite a bit of damage, both from weather and pests, before any damage becomes economic.  Spraying for a sub-economic level of greenbugs today will not eliminate the problem, but rather reduce the greenbug population for a few weeks while killing out the predator population.  The result is usually a recovering population of greenbugs, and whatever else decides to invade the field, that does become economic without predator determent at a much more critical and damage sensitive crop development stage.  It has been my experience that this potential preemptive spray applied now so that a second application will not have to be made later actually causes either that second, more costly application later or, if the field is left untreated, causes the loss of profitability for the field.  At the same time we do not want to miss an economic pest situation that needs to be addressed when we are making an application now anyway. 

                Again, I urge producers to scout their wheat fields this week to have all the information at hand before making a final decision about their near future applications.

 

Thanks,

Blayne Reed

Transform Section 18 Extended

2014 Section 18 for Transform on Sugarcane Aphids in Sorghum Extension

                Unfortunately many of us are still dealing with the sugarcane aphid in sorghum fields:    

This week I received two phone calls from independent crop consultants in Floyd County describing a handful of field situations with the aphid well over the expressed action threshold for this aphid with aphids infesting heads, panicles, and green leaf coverage in the thousands with harvest still several weeks away.  In our Hale & Swisher scouting program, I also have several fields nearing, but not quite at, this level.  While convincing producers to actually make the additional inputs of a Transform application this late in the growing season remains a tough sale and most of our producers with sugarcane aphid problems are currently opting to harvest early or apply sorghum harvest aids without major incident yet, having the option to chemically control this aphid should remain a vital option for our area producers.  

With a little petitioning through the sugarcane aphid task force, we were able to have the deadline of the section 18 extended until December 10, 2014.  Hopefully this will be post killing freeze date when we can hopefully (and finally) put this invasive pest to bed for the season.

I still urge producers and consultants to keep good tabs on this pest until harvest or freeze.  If treatment looks like the best option for any field, at least now we still have that option.

Blayne

Novermber, 2014 Wheat Status and Questions

Wheat Status November, 2014

The following is a re-print of an e-mailed update regarding some of the things we (Texas A&M AgriLife Personnel) have been seeing in wheat this fall.  It is written by Dr. Ron French, Extension Plant Pathologist Amarillo, and sums a few things up very well.

Leaf rust of wheat in the Texas Panhandle (26 counties) area during fall 2014.

I have received phone calls regarding leaf rust, samples have been submitted, and I have visited fields that have had leaf rust (no stripe rust, no stem rust).  Leaf rust is as far north as Hansford County and as far south as Hale County, so far. Leaf rust has been present since at least October 14.   This is very similar to what occurred in fall 2007 and fall 2008.  

Here is a link to a factsheet that was done in fall 2008 titled “Leaf Rust of Wheat in the Texas Panhandle, Texas South Plains, and Texas Rolling Plains (Fall 2008)”. http://amarillo.tamu.edu/files/2010/11/LeafRustFall2008PSR.pdf

I was not able to find any leaf rust in parts of the Rolling Plains (Wichita Falls, Elektra) during a drive back from Wichita Falls that I did last week on Wednesday, October 29, 2014. I have made some calls and there are no reports yet. (NOTE: the wheat was recently planted)

In summary, a warm and wet year (plus dew) for the Texas Panhandle (based on the 26 counties) will allow for leaf rust to be present as late as the end of November.  In 2008, we were as high as the low 80s Fahrenheit  during some days in November and as late as Thanksgiving week for Amarillo (week of November 23). We also had snow as well during late November that year.  In 2007, leaf rust of wheat was present through early December in the Rolling Plains.

Although theoretically inoculum could potentially survive a mild winter, a normal winter will not allow for that.  Since spring 2008, I have been monitoring a few fields and I have not been able to track any survival of inoculum. From the Texas High Plains to Wichita Falls. In fact, one year, there were trace levels of leaf rust in mid-March, but after a cold spell and snow, that field was clean for the rest of the season.

Wheat rusts (Puccinia spp.) are not good soil and leaf survivors (dry out, freeze dry, loose viability quickly, can be microbially degraded) but there “edge” comes from producing billions of small spores.  Although most desiccate while wind-blown, it only takes a viable spore to initiate infection. The spore inoculum follows the so-called “Puccinia pathway” from South to North (i.e. warmer areas such as South Texas, Louisiana, and Mexico may/will send spores to northern locations.

If the pathogen produced a hard tissue survival structures like sclerotia or chlamydospores,  survival would take place. Or if there was vascular infection in the stem.  Or if it infected roots (like Fusarium spp.)

Therefore, there is no need to spray and any leaf loss is nowhere near that to a field being grazed.

Fields with leaf rust are showing new leaf growth with minimal or no leaf rust present. And with low temperatures between 28° and 46° F in the Texas High Plains in the next few days, leaf rust activity will keep on decreasing as the pathogen is most active between 59°-72°F. Currently, only certain hours of the day are still providing ideal conditions for leaf rust development.

Wheat viruses:

Blayne has been recommending samples be sent to the Texas Plant Diagnostic Clinic in Amarillo (http://plantdiagnostics.tamu.edu) lab by consultants, producers, and others for diagnosis of diseases, including those caused by viruses.  Wheat viruses such Wheat streak mosaic virus and/or Triticum mosaic virus have been found in some samples from Swisher County as well as other counties.

Most samples brought in due to yellowing of the leaves, are found to be infected with Fusarium sp., especially if the seed was not treated with a fungicide.  Some yellowing of the leaves are due to leaves touching the soil, getting wet, not drying as fast, and therefore are attacked by secondary fungi such as Alternaria sp.). These are samples that my group (French lab) processes for all disease except for viruses. Virus diagnosis is done by the Rush lab via Jacob Price.

For more information, go to: http://sickcrops.tamu.edu

Best regards

Ron French

Ronald D. French, Ph.D.

Assistant Professor and Extension Plant Pathologist

Coordinator, Texas Plant Diagnostic Clinic

Department of Plant Pathology & Microbiology

Texas A&M AgriLife Extension Service

6500 Amarillo Blvd. W.

Amarillo, TX 79106

Main Office: 806-677-5600

Office Phone: 806-677-5616

rdfrench@ag.tamu.edu

Thank You Dr. French.  I would like to add that our usual wheat pest populations have been running fairly low, but we are finding several arthropod species that are known to be vectors of wheat diseases. The recent rains were just the fuel this wheat needed to recover from these noted ailments and carry it down the road a bit.

Blayne