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Thursday, November 6, 2014

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


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

Friday, September 12, 2014

"White" Sugarcane Aphid Arrives on the Souther High Plains



The sugarcane aphid arrives on the southern High Plains

Blayne Reed, Patrick Porter and Ed Bynum

We have been watching for the possible arrival of the sugarcane aphid, Melanaphis sacchari, on the High Plains, and we must now report that it has been found.  Clay Golden, an independent crop consultant serving the area, discovered a small pocket of the aphids on soft dough stage sorghum in an extreme northwestern portion of Floyd County on September 9, 2014.  Upon his find Clay enlisted the aid of Blayne Reed, EA-IPM Hale & Swisher counties, who supported Clay’s identification of the aphid.  Dr. Pat Porter and Dr. Ed Bynum were then presented with aphid samples and confirm the identification. 

Given the proximity of this aphid population to neighboring counties; ½ mile from Briscoe, 2 miles from Swisher, and 7 ½ miles from Hale, combined with some possible smaller and un-confirmable sugarcane aphid hits in nearby sorghum in Swisher and Hale and that this aphid is often dispersed by prevailing winds, it is logical to assume that it is present over a wider area encompassing small portions of all four counties. Many of the aphids in Clay’s sample were at the developmental stage just prior to becoming winged adults, so we expect that further dispersal is happening now.

After Clay’s discovery, we asked for some help and perspective from our downstate colleagues who have been dealing with this pest since last year. Here is a summary of information from Raul Villanueva, Robert Bowling, Stephen Biles and Mike Brewer.

1) It takes ten days to two weeks for isolated aphids to establish significant colonies on sorghum. So scouting should be concentrated on finding the first few infesting aphids in the field on lower leaves.

2) Stephen Biles, Extension Agent IPM in Victoria, has done some very recent work on an action threshold in sorghum in the reproductive stage. Stephen’s work suggests that a good action threshold for treating is an average of 100 aphids per leaf. He suggests sampling 10 plants per location within a field (several locations) and picking the leaf below the flag leaf and an additional leaf from the middle of the plant. If there are an average of 100 aphids per leaf (2,000 total on all 20 leaves), then come back in two days and re-sample to see if the population is increasing. If the numbers are going up then consider treating. If the numbers are not going up then don’t treat but continue to monitor. Observations of this aphid from downstate have shown that some populations can crash very quickly. We don’t know how to predict which populations will crash and which will increase.

3) Transform (available under a Section 18 exemption) is the most effective insecticide. It can be used at a rate of 0.75 to 1.5 ounces per acre. Our downstate colleagues have had good results at the 0.75 ounce rate, but good coverage is essential at this rate. They strongly recommend 10 gallons of carrier volume per acre by ground and, if this can’t be achieved with aerial application, they recommend a bare minimum of 5 gallons per acre and a minimum rate of Transform of 1.0 ounces per acre. (Which is to say the 0.75 oz rate of Transform may not work by air at 5 gallons per acre.) We do not know if a 1.0 oz rate can be put out at less than 5 gallons per acre. Our colleagues have also said that Dimethoate is not a good option because it is not a consistent performer.

This aphid is not going to be Atilla the Hun on the High Plains. Invasive species often do the most damage in their first year or two of invasion before natural enemies can respond to the new pest.  For this year at least, the aphid is arriving late in the season and will not be infesting whorl stage plants which will be limiting the aphid in time to build into an economic problem. We also have products that have proven to control this aphid. This, combined with the implementation of good scouting techniques, give us confidence that this aphid can be effectively controlled if necessary. The Section 18 allows for two applications of Transform (1.5 oz maximum per application), with the total application for the season not exceeding 3.0 ounces. There is also a mandatory 14-day waiting period between the first and second application. So this gives us six weeks of good control, assuming 14 days of activity from each application. This should be sufficient to carry us through harvest.

It is not known whether the sugarcane aphid can overwinter on the southern High Plains; it is a subtropical species and overwintering survival is very much in doubt. We also do not know how fast the sugarcane aphid can reproduce given the predicted cooler temperatures in this week’s weather forecast.  We will have to watch for it next year when our sorghum is in the whorl stage, but for this year we can handle the problem if it arises.

The sugarcane aphid is fairly easy to recognize and distinguish from our other common aphids. Look for black-tipped antennae and legs. Dr. Ed Bynum recently posted an article on identifying the sugarcane aphid: http://amarillo.tamu.edu/files/2010/11/PPU-V6i6-5-23-2014.pdf . Our publication Sugarcane Aphid: A New Pest of Sorghum is available here: http://www.agrilifebookstore.org/product-p/ento-035.htm . We will of course keep you informed of new developments.


            I should also note, particularly to this audience, a few details.  Today the sugarcane aphid is only officially confirmed in Floyd County.  This confirmation comes from a currently very small pocket population that remains hard to find within that field, even for Clay who has walked this field all season long and visited the exact spot several times now.  I have not found any pockets of the sugarcane aphid in our program fields.  Whorl stage sorghum type hay crops could be at the highest risk.  I would also like to doubly stress that it is very late in the season and we have a proven product in our pest control toolbox if need be.  While the history and proven damage of this aphid makes it worth a closer than normal check in area sorghum for this late in the season I would personally like to sum it up this way: These guys are mean and nasty, but they came wearing Bermuda shorts, they did not pack a coat, and the ‘wanted dead not alive’ posters are hot off the press.
Blayne Reed