The sugarcane aphid arrived to KY a month earlier in 2016 than in 2015

Raul Villanueva, University of Kentucky Extension Entomologist

Insect description and damage
The invasive sugarcane aphid (SCA) Melanaphis sacchari has arrived to Kentucky almost a month ahead in 2016 compared to 2015 (https://kentuckypestnews.wordpress.com/2016/02/16/sugarcane-aphid-losses-with-sweet-sorghum/). Sugarcane aphids have caused yield losses going from 30% to

Figure 1.  An adult SCA (pink arrow) and first 
instar nymphs (blue arrow) detected on a sweet 
sorghum  field in Trigg County, KY on 07/15/16. 

(Photo credit Raul T. Villanueva)

100% to sorghum grower since 2013 on many states of the US. Sugarcane aphids affected severely grain and sweet sorghum fields last year in GA, SC, MO, and TN and KY. Last Friday (7/15/16), a small numbers of sugarcane aphids were detected in a field of sweet sorghum in Trigg County (Fig. 1). Although the numbers are still low in this field, populations may pick up sooner. So far in the U.S all SCA populations are composed by female individuals. Each female can produce 6 to 12 nymphs per day, and in less than one week they can complete its life cycle. This rapid life cycle can cause quick outbreak of SCA populations.

Armyworm Moth Captures are Abnormally Large.

Doug Johnson, Extension Entomologist, University of Kentucky

Armyworm moth.

Recent moth flight of armyworm (AW), in western Kentucky has been much larger than is normal for this time of year. It is not terribly unusual to see problems with this insect on pasture and forage grasses in late June and July, especially in central Kentucky This year’s much larger AW flight during late July and August in western Kentucky is truly unusual. It is difficult to know what to make of this because it has no precedence in our data set. Nevertheless, the fact is they are here.

Generally, I would expect to be looking for fall armyworm (FAW), Spodoptera fugiperda,at this time of year, but our moth captures for this insect in both central and western KY have been quite low, perhaps because the cold winter and spring pushed their overwintering locations farther south, and/or they were later beginning their annual northward migration. Even so we have seen some localized but significant populations in south-central KY.

  The data we see on the armyworm moth flight of course, describes the movement of adults, which are not the damaging stages. It is the juvenile, caterpillar stage that will appear in September that might pose the threat. Moth flights in the earlier portion of the season followed a relatively normal pattern. Our most common problem with AW comes in May on small grains and that is what we saw this year. Also, there is often a small bump in flight in June and July that usually doesn’t amount to much. Those events were relatively normal this year. What is different this year is that following that relatively normal flight in June and July we have another and much larger flight in July and August that will produce caterpillars in September.

Armyworm Caterpillar

AW has a very broad host range; it eats on many plants but really prefers grasses. On the whole, corn and grain sorghum should be too close to maturity for much damage. However, late planted soybeans and forage crops, most especially newly seeded forage crops could be in some danger.

Producers are advised to keep an eye on very late planted / late developing soybeans, along with forage crops, particularly grasses and most especially newly planted grasses, and grass-alfalfa mixes. There is no established threshold for this pest in these circumstances, but populations around 4-6 worms per sq.ft. probably require treatment.

US-EPA Grants Section 18 Emergency Exemption Label for Use of Transform™ WG for Control of Sugarcane Aphid on Grain Sorghum in Kentucky.

Doug Johnson, Extension Entomologist, University of Kentucky

The United States Environmental Protection Agency (US-EPA) has granted the use of Transform™ WG for control of the sugarcane aphid, (Melanaphis saccahri) on sorghum.

Sugarcane Aphid Collected in Kentucky

Doug Johnson, Extension Entomologist, University of Kentucky

Sugarcane aphid (SCA) has been collected in two western Kentucky (KY) Counties. County Extension Agents Ben Rudy in Fulton Co. and Trent Murdock in Graves Co. have collected SCA from grain and sweet sorghum respectively. Identity was confirmed by Dr. Lee Townsend, Extension Entomologist, with the University of Kentucky (UK) in Lexington. Thus far, only the two infestations have been reported. The infestation in Fulton Co. is below treatment threshold, but the infestation in Graves Co. is much larger. Regardless of size, this does confirm that this new sorghum pest which likely migrates in from the Deep South can reach Kentucky during, if late, in the production season. Sugarcane aphid is a threat to all forms of sorghum (grain, forage, sweet) and will infest many other grasses including Johnson grass, which can act as a host for reproduction and a source of infestation.

Sugarcane Aphid Reported in Tennessee

Doug Johnson, Extension Entomologist, University of Kentucky @DrDougStinkBugs

Dr.Scott Stewart (@BugStewart) has tweeted the first discovery of sugarcane aphid (SCA) in Tennessee (07/07/15) at the AgriCenter in Memphis. The aphids were found and photographed by Drew Ellis. Numbers are low, but this does indicate that the pest is moving up the Mississippi River valley.

Several of our colleagues to the mid-south have commented on the large number of  lady beetles  & larvae that are feeding on these aphids, helping to keep the pest in check. A single insecticide application will stop all that help. Do not apply until absolutely necessary!

Kentucky producers in counties along the Mississippi River and / or counties contiguous with western Tennessee counties are most likely to see this pest.

SCA was not reported in Kentucky in 2014 but was collected in western Tennessee counties and in counties in the Missouri boot-heel. It is not a foregone conclusion that SCA will reach Kentucky, but it is an important enough pest to keep on your watch list.

Grain Sorghum producers / consultants / scouts, that are Twitter followers are encouraged to follow Dr. Scott Stewart, Univ TN, (@BugStewart) along with Dr. Gus Lorenz, Univ. AR , (@guslor77) and Dr. Angus Catchot, MS. St. Univ. (@acatchot). They will be working to manage this problem in their states before the pest gets to Kentucky; if it gets to Kentucky.

KNOWLEDGE IS MONEY!

Sugarcane Aphid Active in Mississippi…..Not close to Kentucky Yet

Doug Johnson, Extension Entomologist

Several locations in Mississippi (MS) have been identified as having grain sorghum infested with sugarcane aphid. Though it is important to keep up with what is happening, it is also quite important

New Aphid Pest on Grain Sorghum – Sugarcane Aphid

Doug Johnson, Extension Entomologist, University of Kentucky

Figure 1. Sugarcane aphid on
sweet sorghum; Shelby Co. TN
2014. Univ. TN.

Over the past two growing seasons a difficult new insect pest of grain sorghum has been found across the mid-south. This new pest is an aphid called the sugarcane aphid, Melanaphis sacchari. Be sure not to confuse this with the yellow sugarcane aphid, Sipha flava, which has been around the lower Mississippi river valley for several years. These are two completely different insects. Before we go any further, it is important that you understand that at present, NEITHER of these aphids have been found in Kentucky. My concern is one of preparation, as both of these aphids are found in western Tennessee and southeastern Missouri.

Watch for worms in grain sorghum heads

Doug Johnson, Extension Entomologist

Fig. 1. Corn earworm on Corn

Fig. 2. Sorghum webworm
 on sorghum

It is about the time of year for problems with corn earworm (Fig.1.) to begin in grain sorghum. Though I have not seen or heard of any local problems my colleague in VA, Dr. Ames Herbert, is beginning to see some problems. In Kentucky we generally see these problems in the area west of the Pennyrile Parkway and more importantly in LATE planted fields. You are also likely to see a mixture of worm species including the sorghum webworm (Fig. 2.)