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Extension Entomology

Author: kansasbugs

Sugarcane aphid expanding to new counties in Kansas

New detections of sugarcane aphid (click here for identification and management information) have been reported this week for Kansas counties: Kearney, Pawnee, Scott, Finney, Comanche, Reno, Barton and Saline.

Several fields in Finney, Ford, Meade, and Pratt have reached threshold levels and have been treated. However populations reported from the other counties remain low and were found on only a few hot spots within a field. Remember that hot weather can increase SCA numbers rapidly! See current map here.

Note that the economic threshold is 20% of pre-boot plants infested with established colonies (>100 aphids), or 30% of plants infested post-boot.

Treatment options are either Transform (1 oz per acre) or Sivanto (4 oz per acre). For earlier stage plants, Sivanto will provide a longer period of protection, but is about 40% more expensive. For plants that have headed out, Transform will be a more economic option, as a long period of residual activity will be less important, and it is also safer for the beneficial species. For a list of products and labels, visit the myFiels.info Insecticide Selector.

DO NOT mix these products with any organophosphates or pyrethroids or any combinations thereof – it will actually reduce their efficacy.

If there is a need to control headworms, these products can be mixed with either Prevathon or Blackhawk, but nothing else.

For help with scouting and identification, click here to see instructions and pictures.

To see local management information, click here.

For more help, contact your local Extension office. Find yours by clicking here.

 

Sugarcane aphids still hanging on!

–The KSRE Field Crop Entomologists Team

Sugarcane aphid populations continue to persist in sorghum across much of Kansas, but cooler temperatures are slowing them down considerably. However, monitoring populations is still strongly encouraged as infestations can grow quickly if temperatures warm up. Winged aphids are moving from early planted sorghum fields to late planted fields, so pay close attention to whether infestations are winged or wingless. Wingless aphids have the potential to increase rapidly, but several factors, including presence of natural enemies, can help slow population growth. In all cases, be sure to monitor populations closely. Bottom line: scout often.

photo-sep-20-12-28-09-pm
Winged aphids (alates).

Yield loss due to aphid feeding can occur up through black layer. However, most losses caused by sugarcane aphid occur between boot stage and up through soft-dough (50% dry weight in the seed) stage; more data is needed to understand losses between hard dough and black layer, but seed weight (grain quality) and total yield may be reduced. Further details about sorghum growth and development can be found here (MF3234.pdf).

photo-aug-30-12-18-10-pm
Lady beetle eggs in a sorghum head.

Harvest of early-planted sorghum is underway, and late-planted fields are only a couple of more weeks from being ready (depending on weather conditions). Most decisions to spray for sugarcane aphid this time of year are aimed at avoiding mechanical issues associated with high aphid numbers and honeydew coating leaves and heads. Although buildup of honeydew can cause significant harvest problems, this is not an inevitable outcome. Weathering can reduce honeydew stickiness, so once grain is fully ripe, delaying harvest for a week or two may be an option, provided there is no indication of lodging. As lower leaves senesce or die off, aphids migrate to the upper leaves and eventually into the heads. We have observed this behavior in several fields this fall. However, colder overnight temperatures will significantly retard aphid growth and reproduction, and significant aphid mortality may occur before freezing.

Aside from honeydew and potential mechanical issues, lodging can also be associated with high aphid populations. It is important to understand that sugarcane aphid is not the only pest in sorghum this fall. We have observed high levels of 2nd generation chinch bugs feeding behind panicle leaf sheaths, which can also weaken stalks and cause lodging. In addition, from a plant physiology standpoint, during the last weeks of grain filling sorghum stems tend to shrink due to natural plant remobilization process, affecting final stalk strength.

When making a decision to treat so close to harvest, growers should consider four main factors: 1) overnight temperatures, 2) stage of crop maturity and potential yield, 3) aphid density, and 4) and the preharvest interval for registered insecticides. If the aphids have been heavy, but your grain has turned color, you may want to wait until the honeydew weathers to become less sticky before trying to harvest it. Read and follow the insecticide labels. For Sivanto and Transform, the preharvest interval is 2 weeks. Follow forecasted temperatures for upcoming weeks. Cooler nights will slow populations. We’ve observed aphids killed by 10 hours at 46F in a small lab study, but more data are needed to understand what low temperatures, for what period, will kill them under field conditions.

photo-sep-28-4-36-32-pm
Sugarcane aphids after exposure to freezing temperatures.

Again, monitoring fields and relying on more than a single sampling event will provide additional information for making a treatment decision. The only reason to treat aphids past black layer is to avoid potential harvest issues. Killing aphids this fall will not impact aphid populations next year in Kansas. This is a migratory pest and will not overwinter in Kansas.

Sugarcane aphid expanding to other counties in Kansas

Sugarcane aphid has been confirmed in the following counties in Kansas: Marion, Sedgwick, Sumner, Cowley, Labette, Meade, Haskell, and Ford. Populations first reported in Sumner and Cowley counties have reached threshold levels (30% of plants infested with visible signs of honeydew on leaves) and are being treated with insecticides. Scouting fields early will help determine the need for an insecticide application before losses occur. Treating too soon may increase the need for additional insecticide treatments later, as populations can rebound based on immigration events. Scout often, as densities can change quickly. Report any infestations in new counties to your local agent or using http://myFields.info.

SCA counties KS 2 Aug 2016

Figure 1. Current counties in Kansas confirmed with sugarcane aphid in green.

Recommended treatment options for SCA control are either Transform (Dow AgroSciences) at 1 oz per acre, or Sivanto prime (Bayer CropScience) at 4 oz per acre, applied in 15 – 20 gal of water from a ground rig. Application from the air will be more costly and less effective, as it will not permit application of these materials in sufficient volume to obtain the coverage necessary for good efficacy. The cost per acre is lower for Transform, and this material is also the least toxic alternative for aphid natural enemies. If headworms are present in damaging numbers (1-2 per head or more, the majority still less than 1 inch long), Blackhawk (Dow AgroSciences), Prevathon (Dupont) or Belt (Bayer CropScience) are alternatives that can be considered for controlling them. Note that Belt registration has just been revoked by the EPA, but existing stores may be used. Of the materials labelled for headworm control, these are the ones likely to have the lowest impact on beneficial species assisting with aphid control. We have found Prevathon to be compatible with Transform in a tank mix; all other combinations should be tested first for compatibility by mixing small amounts in a jar to ensure no precipitate forms. Read the label carefully before you spray.

First report of sugarcane aphid in Kansas sorghum for 2016

—by the KSRE Field Crop Extension Entomology Team

Our team has been actively scouting sorghum fields the past few weeks for any infestations of sugarcane aphid, which is a relatively new pest affecting Kansas sorghum. We received a report from Jill Zimmerman (KSRE Extension Agent, Cowley County, KS) on July 18, 2016 of a potential infestation in a commercial field near the Sumner/Cowley County border; the report was confirmed in two fields this morning by a state specialist. Based on the size of the aphid populations observed, which included several plants that were producing winged aphids (i.e., alates), this field was first infested approximately 3-4 weeks ago. A significant number of natural enemies were observed feeding on aphids, which can help to slow aphid growth.

Photo Jul 19, 12 53 01 PM

Sugarcane aphid populations have been slow to build in Texas and Oklahoma this growing season. This record is approximately 10 days sooner than when we found aphids in 2015. Aphid densities are well below threshold, but those with sorghum fields are encouraged to scout fields now.

Photo Jul 19, 11 41 42 AM

Report all new infestations by contacting your county extension agent. For myFields.info users, submit reports using the Pest Sampler module (https://www.myfields.info/pest_sampler). To receive pest alerts about sugarcane aphid, create an account (https://www.myfields.info/user/register) and include your state and county information to receive notifications specific to your area.

For more information on sampling procedures, action thresholds, or effective insecticides, visit https://www.myfields.info/sca.

Scout early, scout often, and know before you spray.

Transform approved for use in Kansas to control sugarcane aphid

—by the KSRE Field Crop Extension Entomology Team

This week, Kansas received a section 18 approval for the use of Transform (sulfoxaflor) against sugarcane aphid for 2016, which will give sorghum growers two effective materials to manage aphid infestations. Note, there are differences in price between these two products, which should be factored into any treatment decisions, especially when multiple applications may be necessary.

Recent reports have sorghum receiving insecticide treatments for relatively light populations of sugarcane in south Texas, but the aphid is beginning to slowly move north, so the potential exists for much earlier infestation of Kansas sorghum this year. There are also confirmed reports that the aphid overwintered on Johnsongrass rhizomes just north of Lubbock, TX. This is about about 80 miles further north than in 2015. Reports from Texas indicate some of the cultivars rated as resistant seem to be holding up well, probably with the assistance of good natural enemy populations.

The Sorghum Checkoff has a list of ‘tolerant’ (= resistant) hybrids, but it does not indicate any regional adaptations for the hybrids. We have not yet ranked Kansas-adapted hybrids for resistance to sugarcane aphid, but efforts are underway to evaluate hybrids this summer. We strongly recommend that growers and extension agents contact their local entomology specialists for advice, as management recommendations will vary regionally.

Scout early, scout often, and know before you spray!

 

And Still Talking About Ash Trees – Brownheaded Ash Sawflies

—by Dr. Bob Bauernfeind

Based on reports posted by Department of Entomology Diagnostician regarding her having received specimens of adult brownheaded ash sawfly, I went out to a site where ash trees have been heavily infested the past couple of years. And, they are back. Though from a distance all appears normal, upon closer look, “pinhole feeding” is underway. By enlarging the image, the still-wee-larvae responsible for the “nibble holes” can be easily seen.

To treat or no-to-treat becomes an individual’s decision. Should trees become defoliated, they will rapidly recover, producing a flush of new foliage.

Brownheaded Ash Sawflies

Update on the status of Emerald Ash Borer (EAB) in Kansas

—by Dr. Bob Bauernfeind

The KDA has recently issued a brief news release on the 2015 deployment of traps for the detection of Emerald ash borers in Kansas. This is a cooperative effort between two regulatory agencies: Federal United States Department of Agriculture APHIS-PPQ, and the Kansas Department of Agriculture’s Division of Plant Protection and weed Control.

Lindgren funnel trap map for 2015

The majority of traps will be the familiar purple prism traps. Additionally in 2015, Lindgren Funnel Traps (LFTs — inserted image, left side of above map) will also be used —- those traps will be green-in-color as opposed to the pictured black LFT.

Within Kansas: Emerald ash borers have been documented in 3 (currently quarantined) counties: Leavenworth, Wyandotte and Johnson. EAB are relatively restricted within those contiguous counties.

2014 EAB quarantined counties

 

Ash/Lilac Borers (ALB)

—by Dr. Bob Bauernfeind

In last week’s edition of the Kansas Insect Newsletter, Dr. Cloyd presented information on Ash/Lilac borers including the use of pheromone traps to determine the onset of current-season ALB moth activities. Coincidentally on the date that the newsletter went out (April 16), I recorded first-of-the-year catches (in the Manhattan area). The latest catch was April 21.

ALB traps

It would appear that temperatures regulate moth activities as seen on the following table:

temperature and moth activity

Sad note: Yesterday, April 14, 67 oF —- 0 ALB, 1 house wren

Now is the ideal time to initiate insecticide applications for controlling ash/lilac borer. As suggested by Dr. Cloyd, “Insecticides containing the active ingredients, permethrin or bifenthrin may be applied to the bark at least up to six feet from the base…….”. Also, treat larger limbs within reach.

Eastern Tent Caterpillar (ETC) and European Pine Sawfly (EPS) Update

—by Dr. Bob Bauernfeind

While recent cool temperatures have had people wondering when warmer temperatures will prevail, both ETC and EPS have thrived —– not surprising because these are cool-season insects.

Currently, Eastern Tent Caterpillar “tents” are of sufficient size that they can be easily detected. If people object to the presence of webbing and caterpillars, and if within hands-reach, the easiest remedy is to use your fingers to “rake-out” the web. Preferably do this during daylight hours when most (if not all) caterpillars are “resting” within. Do not fret if several caterpillars fall to the ground —- individually, the few escapees are of no concern. If a person is skittish about touching web masses (and the caterpillars and frass within), that portion of the branch can be pruned and disposed of.

Eastern Tent Caterpillars

European pine sawflies require a different approach because it is impractical to prune out each infested terminal. Fortunately, EPS are highly susceptible to insecticides. There are numerous products registered for use in Kansas against EPS. Horticultural oils and soaps are very effective against the “soft-bodied” larvae. A single thorough application will eliminate EPS larvae. But do so NOW before they become thoroughly destructive.

European pine sawfly

 

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