Updated October 24: Added Cullman County to the list.
Updated September 25: Add Marengo County to the list of counties where sugarcane aphid has been reported.
Updated September 15: Sorghum producers are still battling the sugarcane aphid. It was reported last week from fairly young sorghum in Houston County and from sugarcane in Cleburne Co. Kim Wilkins reported it in north Baldwin Co. a week or so ago and I forgot to add Baldwin to the map. It is important to scout any young sorghum and apply an insecticide (chlorpyrifos) if needed. If high rates of this insecticide are applied, there is a 60 day preharvest interval. Do not apply this insecticide to sweet sorghum. How many aphids are too many? Advice from entomologists in Lousiana and Mississippi: treat if more than 30% of the plants have at least one aphid AND there are an average 100-250 aphids per leaf.
Updated August 25: Sugarcane aphid was found in sorghum in Lowndes County last week.
Updated August 15: AU and Agribusiness personnel have also found it in Autauga, Coffee, Lee and Macon counties. In some fields the aphids are widespread throughout, and in others they seem to be confined to small patches.
Updated August 13, 2014: Sugarcane aphid reported from two more Alabama counties by Dow AgroSciences personnel: Tallapoosa and Tuscaloosa.
Updated August 4: Ron Smith reports that this aphid has been found in sorghum in the Wiregrass Region (Geneva and Henry Counties).
Updated July 31: Rudy Yates reports finding these aphids in several sorghum fields in Dallas County. He sent the image posted here.
Updated July 26, 2014: Dr. Hagan reports Sugarcane aphids from his plots on Clanton, AL (Chilton Co,). Drs. Catchott, Gore, and Cook provide an update on how to manage the pest: http://www.mississippi-crops.com/2014/07/25/white-sugarcane-aphid-update-7252014/
Original post from July 18:
This week Dr. Austin Hagan from Auburn University and the Alabama Cooperative Extension System found sugarcane aphid, Melanaphis sacchari, on sorghum in his variety tests in Brewton, AL. Thanks to Dr. Charles Ray from Auburn University for confirming the identification. There were not enough aphids to cause damage to the sorghum in the variety tests at this time.
Sorghum growers in Alabama should scout their sorghum as soon as possible for this aphid. There are various aphids that feed on sorghum, but this one looks different and causes more damage. White sugarcane aphid is a light colored aphid with no obvious markings except for black tailpipes and black feet. Other aphids on sorghum have spots, a green stripe down the back, or have a black head, black legs and black tailpipes. This publication from Texas A&M AgriLife Extension has pictures of the various aphids, as well as important life history information on white sugarcane aphid: http://nueces.agrilife.org/files/2014/05/Sugarcane-Aphid-Publication.pdf.
Important: do not spray an insecticide unles there are enough aphids to cause damage. Dr. David Kerns and Dr. Sebe Brown from Louisiana State University have developed the following threshold for treatment. Treat if more than 30% of the plants have at least one aphid AND there are an average 100-250 aphids per leaf. See these blog posts for their advice on what to do when you find white sugarcane aphid: http://louisianacrops.com/2014/06/20/white-sugarcane-aphid-considerations-and-status-in-louisiana-grain-sorghum/ and http://louisianacrops.com/2014/07/17/sorghum-midge-and-white-sugarcane-aphid-concerns/. Dr. Michael Brewer, Texas A&M AgriLife Research, provides more information on how to look for and decide when to treat white sugarcane aphid here: http://ccag.tamu.edu/files/2014/07/Compilation_sorghum-aphid_IPM4.pdf
Also very important: There is no Section 18 label for applying Transform to sorghum in Alabama. Growers will need to use insecticides containing dimethoate or chlorpyrifos (see the above LSU blog posts for a discussion of rates and efficacy).
Perhaps even more important: If this aphid is present do not spray the grain sorghum field with a pyrethroid. Dr. Jeffrey Gore, Mississippi State University, explains: “One thing that this aphid has done is change how we manage grain sorghum in Mississippi. Even very low population densities will explode to treatable levels within one week after a pyrethroid application. We are first trying to get people to scout for midge rather than making an automatic application because of that. The other thing we are trying to do is get them to use dimethoate for midge instead of a pyrethroid because we feel that dimethoate is less likely to flare white sugarcane aphid. Also, Gus [Lorenz] said that some white sugarcane aphids were sprayed with dimethoate in Arkansas and control was not acceptable. Because of that, we are only recommending Lorsban and Transform.”
If you are concerned about what you find on your sorghum, contact your Regional Agronomic Crops Extension Agent, or me at email@example.com.
Kathy Flanders, Extension Specialist and Professor, Entomology and Plant Pathology, firstname.lastname@example.org
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