Monday, July 9, 2018

Sugarcane Aphid Arrives on Texas Southern High Plains

Kerry Siders, EA-IPM in Hockley, Cochran and Lamb counties, just reported that Danny Quisenberry, a crop consultant, found sugarcane aphids on older grain sorghum four miles north of Earth in northern Lamb County.

Additionally, Greg Cronholm, a private crop consultant, just reported sugarcane aphids on sorghum in southern Castro County.

Neither of these populations is at a treatable level, just small colonies on isolated plants at present. If this year's infestation pattern follows those of 2014-2017, then it is likely the aphids are already present in Hale, Floyd and Lubbock counties, although we have had no reports of this as yet.

Tuesday, April 24, 2018

Extension Entomology List of Sugarcane Resistant Sorghum Hybrids

Extension Entomologist Dr. Allen Knutson has released a list of sugarcane aphid resistant sorghum hybrids. The entries are based on multiple years of replicated field trials by AgriLife personnel Robert Bowling, John Gordy, Danielle Sekula, Mike Brewer and Allen Knutson. It should be noted that none of these trials are from the High Plains.

The remainder of this article is quoted directly from Dr. Knutson's document.

"Soon after sugarcane aphid emerged as a pest of sorghum in 2013, growers, consultants and seed company representatives observed that some hybrids were not as heavily infested with sugarcane aphids as were other hybrids. These observations led to field research studies that confirmed that some hybrids were resistant to sugarcane aphid due to their genetic makeup.  As a result, many seed companies now market hybrids with some resistance or “tolerance” to sugarcane aphid. 

Beginning in 2014, Texas A&M AgriLife Extension and Research evaluated some of these hybrids in replicated field trials. Trials were conducted in the Rio Grande Valley, Gulf Coast and north Texas and compared the number of sugarcane aphids and leaf damage to hybrids known to be susceptible to sugarcane aphid.  

These trials confirmed resistance in 14 hybrids from seven different seed companies ( seeTable).  This list is not complete and these and other seed companies may have other hybrids with resistance to sugarcane aphid.  Also, seed companies are releasing new hybrids with sugarcane aphid resistance each year, and growers are encouraged to visit with their seed representatives regarding current hybrids.

In these trials, sugarcane aphid populations increased more slowly, and plants exhibited less leaf damage compared to susceptible hybrids.  As a result, resistant hybrids were less likely to require an insecticide treatment for sugarcane aphid. However, resistant hybrids are not immune, they must be monitored for sugarcane aphid infestations, and treatment with insecticides may still be warranted to prevent yield loss or honeydew contamination at harvest.

The level or expression of resistance may vary by geographic region, and field trials are needed to evaluate resistance of these hybrids ( see Table) and others under growing conditions in the Texas High Plains and other production regions.

In addition to sugarcane aphid resistance, yield and other agronomic qualities must also be considered in selecting hybrids for planting.  Hybrids that are high yielding and well adapted, yet   susceptible to sugarcane aphid, may be more profitable, and if so, can be protected from sugarcane aphid damage by frequent scouting and a well- timed application of an insecticide if needed.

While resistant varieties can reduce the risk of sugarcane aphid, they should be part of an overall pest management plan that includes early planting, weekly field scouting, use of thresholds and efficient use of insecticides, if needed, selection of insecticides applied for midge and headworms that help preserve natural enemies of sugarcane aphid, and control of Johnsongrass, an important host of sugarcane aphid."


Friday, September 29, 2017

SCA After the Rains: Now What?

We are now concluding five straight days of rain on the southern High Plains, but sugarcane aphids are still with us. I spent some time today collecting infested leaves and examining the aphids under a microscope, and I have to report that I can't find any evidence of the fungi that hammered populations on the Gulf Coast. (Although I will keep monitoring the situation.) Most of the aphid colonies I observed looked just fine, and there were some beneficial insects like syrphid fly and lady beetle larvae feeding on them. Dr. Katelyn Kesheimer, IPM Agent in Lubbock and Crosby counties, took 7 Day After Treatment data in a sugarcane aphid efficacy trial yesterday between rain events, and she reported that there was a slight decrease in aphid numbers on the untreated plots, but nothing to write home about.

So the rains did not really reduce the number of aphids, but, significantly, the cooler temperatures slowed them down. Aphid development and reproduction is slower in cooler temperatures, so the explosive population growth potential is not going to be here until we get significantly warmer. The practical effect of this is that fields that still require treatment, or will require treatment, do not have to be sprayed as quickly as they would be in hotter conditions. This is good for a few reasons, one of which is that it will pay to wait a few days.

We know that our insecticides do not work as well when it is cold, or, put another way, they work better when it is warm. Current predictions put the warmest days next week as Sunday - Tuesday, and then Friday - Sunday. If an application needs to be made, make it during the window of warmest days. Given that we don't really have hot weather in the forecast, it would not be a good idea to cut insecticide rates in the face of these moderate temperatures.

Dr. Kesheimer included a generic formulation of imidacloprid in her efficacy trial because growers are using it due mostly to its relatively low cost and a marketing push. We already have older data that this off-label insecticide does not provide good sugarcane aphid control, and her 7DAT data are reinforcing what we already know. Transform and Sivanto remain the effective sugarcane aphid insecticides.


Friday, September 8, 2017

It Is Not Over for the High Plains

Even though it is getting late in the season, sorghum is still at risk from sugarcane aphid, especially later planted sorghum. In Lubbock we are seeing leaves with thousands of aphids, and for the last two weeks many of these have been winged. These aphids have and will continue to ride the winds as they do each year. If this year is like the past three years, the aphids will spread westward and northward. Dr. Ed Bynum in Amarillo is reporting treatable populations in his area. The rains did not stop the aphids, and there is no reason to think they will stop before the first or second hard freeze. Last year we harvested sorghum at the Halfway Experiment Station after first freeze and still had plenty of aphids on the plants and in the heads.

What I am trying to say is that if you have grain or forage sorghum in the field, this is no time to get complacent. The photos below were taken at the Lubbock Research Center this morning before sunrise.

Leaves being killed by aphids, and honeydew darkening the soil where it dripped. 

Leaves on late planted sorghum completely covered by honeydew from the thousands of aphids feeding on the undersides of leaves above. All of the sorghum in this field looked this way. 

Mid-June planted sorghum. The untreated row is on the left, obviously. The row on the right was sprayed with 5 oz. of Sivanto. 



Tuesday, August 15, 2017

One more Texas Panhandle County with Sugarcane Aphids

After reporting yesterday of sugarcane aphids in Moore and Sherman Counties, we received an email from Stephen Cox, crop consultant. He is finding sugarcane aphids in Hansford County. We appreciate everyones help letting us know about new findings of sugarcane aphids.

Monday, August 14, 2017

New counties added to the Texas Panhandle

I received a text today from Kaj Overstreet, crop consultant, that he has been finding sugarcane aphids in fields in Moore County. Then I received another text that he found sugarcane aphids in fields in Sherman County.

Also, last Friday, August 11th, I received a call for Mr. J. R. Sprague, County Extension Agent for Lipscomb County, that crop consultants found sugarcane aphids in a cotton field. I contact Dr. David Kerns, Texas A&M AgriLife Extension Cotton Entomologist, to determine if we should be concerned about sugarcane aphid in cotton. Besides Dr. Kerns being a cotton entomologist he worked on sugarcane aphids in sorghum while with LSU the past few years before coming back to Texas. He stated that sugarcane aphids could be found in cotton, but aphids were not able to survive to cause damage. The sugarcane aphid is indiscriminate as to where or what crops the alate (winged) aphids may land on. After a female aphid lands on a plant she will begin giving birth to live immature aphids.  Since cotton is not a sorghum related plant the aphids are unable to live very long. Therefore, sugarcane aphids should not be a threat to cotton, but other aphids do live and reproduce on cotton.

Wednesday, August 9, 2017

Sugarcane Aphids Found in Glasscock and Reagan Counties

Sugarcane Aphids Found in Glasscock and Reagan Counties

 

After first being detected in neighboring Tom Green County nearly 7 weeks ago, SCA has now finally shown up in both Glasscock and Reagan Counties. The timing is quite nice as most all of the sorghum in Glasscock, Reagan and Upton Counties is drying down and anywhere from days to a week or so away from harvest. There is a little late planted grain sorghum as well as haygrazer that will have to contend with the aphid, but for the most part St. Lawrence area sorghum will be harvested before economic damage can be inflicted on the crop.

 

 

Brad Easterling

EA-IPM

Glasscock, Reagan, Upton Counties

PO Box 299

Garden City, TX  79739

432-354-2381 (o)

940-256-1524 (m)

http://glasscock.agrilife.org/

https://www.facebook.com/stlawrenceipm/