Friday, September 29, 2017
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
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.
Tuesday, August 15, 2017
Monday, August 14, 2017
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
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.
Glasscock, Reagan, Upton Counties
PO Box 299
Garden City, TX 79739
Thursday, August 3, 2017
We have been monitoring several fields in Crosby and Lubbock counties for some time, and this week the aphid numbers are higher than last week - considerably higher in some places. At the Lubbock Research and Extension Center where we have had almost 2 inches of rain in a week over two events, the aphids have now exceeded the treatment threshold on pre-boot through soft dough sorghum.
There is still a chance that rain and high humidity will kick off the fungi that kill sugarcane aphids, but as yet there is no evidence this is happening. Even with the more humid days we have experienced of late, our average humidity is well below that in South Texas where the fungi were given credit for reducing aphid numbers.
The good news is that there are relatively fewer aphids coming in now than in past years, so fields are building toward treatment thresholds in a softer manner. The larger colonies on High Plains plants are beginning to generate winged aphids.
Brent Bean, Agronomist for Sorghum Checkoff, reported sugarcane aphids on sorghum in Parmer County today. Deaf Smith County was also added to the map today. DeBaca County in east central New Mexico also has confirmed sugarcane aphids. The official map has been updated to reflect these discoveries.
Friday, July 28, 2017
Tuesday, July 25, 2017
For the southern High Plains we now have sugarcane aphid confirmed in Crosby, Lubbock, Hale and Floyd counties.
The less than good news is that fairly high numbers of headworms (corn earworm + fall armyworm) are being found in panicles. I was in a field in northeastern Crosby county last week that had 1-3 medium to large worms per head, and this field was later treated. Katelyn Kesheimer, IPM Agent in Lubbock and Crosby counties, just reported a field near Shallowater in Lubbock County that had a large number of worms. Stan Carroll, the Research Technician who runs the cotton bollworm/corn earworm traps at the Lubbock Center, told me this morning that he emptied the traps Tuesday night and had a high number of moths in them when he checked them Wednesday morning. We are therefore experiencing a big flight of cotton bollworms/corn earworms. The good news, if you can call it that, is that the fall armyworm trap captures are still well below average.
Insecticide selection for headworms is complicated now that we have sugarcane aphid or the threat of sugarcane aphid in the system. Most of our older insecticides like pyrethroids, Sevin, Lannate etc. will provide control, but they will also eliminate the beneficial insects from the field and leave it more open to damage by the sugarcane aphid. Newer insecticides like Blackhawk and Prevathon will preserve the beneficial insects, but they are more expensive than the older products. Besiege is a combination product; it has the same active ingredient as Prevathon but with a pyrethroid as well. Besiege will not preserve beneficial insects. If a headworm treatment is needed then the risk of sugarcane aphid will have to be factored into the choice of insecticides. As an additional complication, we think our corn earworm is still susceptible to pyrethroids in spite of some slippage downstate, but we know that fall armyworm is less susceptible to pyrethroids, especially the larger worms. One good thing is that headworms do not require the high gallons per acre of spray that sugarcane aphids do, so applications can be made with 3-5 GPA - but check the label for the specific product you intend to use.
Treatment thresholds are based on the size of the worms, number of worms per acre, heads per acre, control cost and value of the crop. For example, in the table below a treatment would be justified at 14,000 large worms (longer than 1/2 inch) per acre when the cost of control was $10/acre and the grain value was $7.00/cwt. To put this in perspective, if the field had 28,000 plants per acre, this would be one large worm per two plants. The online headworm threshold calculator is here.
Friday, July 21, 2017
Thursday, July 20, 2017
Sunday, June 25, 2017
|Lubbock Co sugarcane aphids on sorghum|
Friday, June 23, 2017