Insect Strip

Insect Strip

Thursday, July 20, 2017

Sugarcane aphids in the Panhandle

Yesterday, Brent Bean received a call from Justin McGee, Independent Agronomist, that he had found sugarcane aphids in a field that is located in the very Northwest corner of Donley County. Justin sent me the gps coordinates to the field and I went today, July 20th, and I too found the aphids. I did not doubt Justin’s finding, but I wanted to see for myself before sending out a newsletter with the bad news. From what I found there were very few winged and non winged aphids, one to 4 aphids on a single leaf on a plant, and the percentage of plants infested were less than 10%. 
Also, yesterday afternoon Blayne Reed posted to his blog that sugarcane aphids were found in Floyd County by Clay Golden, Independent Crop Consultant, https://halecountyipm.blogspot.com/2017/07/sugarcane-aphid-arrives-in-floyd-county.html. The field was located in Southwestern Floyd County near the community of McCoy. We can hope the sugarcane aphids will be just as slow to build up in the Panhandle as they have been in Lubbock County and in Tom Green County. However, with these findings, scouting for SCAs will, unfortunately, need to be intensified across the Panhandle and the Central Plains.

If you do find sugarcane aphids, please send samples or photos of the aphids to your County Extension Agent, IPM Extension Agent or to Dr. Pat Porter (Extension Entomologist -Lubbock) or me, Ed Bynum. This will allow us to better inform everyone where the sugarcane are and the movement of the aphids. We greatly appreciate Justin McGee and Clay Golden for telling us what they found so we can now keep you informed about the movement and activity of the sugarcane aphid.

Friday, July 14, 2017

Western Bean Cutworm Increasing Activity

Western bean cutworm (WBC) moth activity has continued to increase across the Panhandle the past couple of weeks. John Quillin, Independent Crop Advisor, texted me a couple of photos of western bean cutworm egg masses that he found while scouting.
Western Bean Cutworm Egg Masses
Photo: John Quillin

Western Bean Cutworm Hatched Egg Mass
Photo: John Quillin
 It has been noted in other states and also here on the Texas High Plains that most Bt traits no longer provide adequate control of WBC, except for hybrids containing the Vip3A toxic protein that is in Viptera, Leptra, or Agrisure Duracade 5522 E-Z Refuge hybrids. This means the majority of corn on the Texas High Plains could be susceptible to western bean cutworm feeding if field infestations reach damaging levels. Therefore, Bt fields should be scouted and sprayed like they were non Bt fields. The following links provide information about which Bt corn traits are in different seed companies corn products, http://amarillo.tamu.edu/files/2010/11/BtTraitTableJan20171.pdf, and WBC scouting and management practices, http://msuent.com/assets/pdf/08WBCMngemntCorn.pdf. If there are signs of unexpected damage in corn with the Vip trait, report such damage to your seed dealer or Texas A&M AgriLife Extension so fields can be checked.
Based on past years of moth trapping data (2012 to 2016) we should have from two to three more weeks of high western bean cutworm moth activity before numbers begin to drop off, http://amarillo.tamu.edu/facultystaff/ed-bynum/insect-surveys/. Therefore, there will be an extended period for egg laying. Eggs when freshly laid are pearly white, gradually turn purple and will hatch in 5 to 7 days.

Newly hatched larvae will feed on the egg shell and then move to the developing tassels within the flag leaf before the tassel emerges from the whorl. If the the tassel has emerged the larvae will feed from the tassel to the silks for about 10 days after hatching (DAH). Field studies showed that 80% of WBC larvae move to the ear zone by 10 DAH with 89% being 2nd or 11% 3rd instar larvae. These two tables can be used as a guide to determine the time frame from when larvae hatch to when the majority of larvae begin to move into the ear tip. This provides a short window for making applications when infestations reach treatable level.
Western Bean Cutworm Larval Development*
Instar
1 DAH
5 DAH
10 DAH
14 DAH
21 DAH
28 DAH
1st
100%
33%




2nd

67%
89%
14%


3rd


11%
29%
3%

4th



57%
39%

5th




58%
64%
6th





36%
* DAH = Days after hatched, based on Antonelli, 1974 Phd thesis, University of Idaho


Western Bean Cutworm Larval Movement after Hatching*
Location
1 DAH
5 DAH
10 DAH
14 DAH
21 DAH
28 DAH
Tassel/ Tassel Leaf
57%
47%
1%



Leaf axils
26%
41%
19%



Silks
17%
12%
73%
34%


Between ear/silk


7%
33%
33%

Ear tip



33%
67%
54%
Ear side





46%
* DAH = Days after hatching, Dr. Chris DiFonzo - Michigan State University, WBC Biology Study - 2009
Our Texas A&M AgriLife Extension guide,”Managing Insect and Mite Pests of Texas Corn”, Ento-040 states that insecticides should be applied when 14% of the plants are infested with eggs or larvae and the corn is 95 percent tasseled. Colorado State University states it should be economical to spray if eight percent of the plants have egg masses or small larvae. And, if most eggs are hatched then treat when corn is at least 95% tasseled and before larvae start feeding on silks. However, if most eggs have not hatched and the corn is completely tasseled, then treat when most eggs have reached the purple stage. Both of these are good guidelines for helping to make decisions for when to treat. 
The next decision is which insecticide to use to get good control. Our list of insecticides labelled for WBC control is predominately limited to numerous pyrethroid products. All of these products should be inexpensive and provide good control, BUT for us on the Texas High Plains the pyrethroids will flare spider mites. Thus, making it harder and more expensive to prevent yield losses from spider mite infestations. Our other insecticide options are Prevathon, carbaryl products (Sevin etc.), chlorpyrifos products, spinosad products (Blackhawk, Entrust, Spintor 2SC, Tracer), methoxyfenozide products (Intrepid 2F, Troubadour 2F), Radiant SC, and Besiege which has a pyrethroid mixed in the product. Belt was banned by EPA last year, but distributors and retailers can still sell any remaining stocks for grower use. Lannate is not labelled for WBC, but it is labelled on corn for fall armywom and corn rootworm beetles. 
Carbaryl and chlorpyrifos products are older insecticide chemistries that probably have not be used in years. Looking at old efficacy trials carbaryl provided up to 80% control at a 2 lb ai/A rate from two applications. Chlorpyrifos at 1 qt/A was ineffective with a single application. A laboratory trial showed chlorpyrifos provided 100% mortality 1 day after spraying, but mortality of exposed larvae at 8 days after spraying was 60%. For the other insecticides I have only been able to find corn efficacy data for Prevathon. In a trial from Nebraska using Prevathon at 20 fl oz/A rate there were 0% of the ears infested with WBC larvae 27 days after treatment. This is only one trial but it illustrates the effectiveness of Prevathon for WBC control. Prevathon will not flare spider mites, but it is an expensive product to use. Unfortunately, I do not have any information on the performance of the other products labelled for WBC control.

Friday, June 30, 2017

Western Bean Cutworm and Fall Armyworm Moth Trapping across the Texas High Plains

Overall, the moth trapping numbers have increased for Western bean cutworm (WBC) in the north Panhandle. There was a big increase of WBC in Hartley, Hansford, Hutchinson, Moore, and Ochiltree counties. This increase in WBC moth activity is greater at this time of the growing season than the WBC moth activity was in 2016. Since this activity is earlier than last year there may be WBC eggs being laid on vegetative corn and  earlier planted corn fields will be more attractive for egg laying than delayed planted corn fields. 





Fall armyworm numbers have also increased across several counties. There was a noticeable increase in Lipscomb, Moore, Ochiltree, and Swisher counties. Dr. Pat Porter has also noted a large increase in FAWs the past couple of weeks in his traps at Lubbock, http://focusonagriculture.blogspot.com/2017/06/fall-armyworm-2x-normal-and-may-be-on.html?utm_source=feedburner&utm_medium=email&utm_campaign=Feed%3A+FocusOnSouthPlainsAgriculture+%28FOCUS+on+South+Plains+Agriculture%29. The subsequent egg laying and larval development may be of concern in non-Bt corn and sorghum.


Data graph from Dr. Pat Porter, Texas A&M AgriLife Extension - Lubbock, TX


Monday, June 26, 2017

Sugarcane Aphids found in Lubbock County, Texas

Yesterday, Katelyn Kesheimer, EA-IPM for Lubbock and Crosby Counties, and Adam Kesheimer found a colony and a few individual Sugarcane Aphid, Melanaphis sacchari, in a sorghum field in southern Lubbock County. This is the first detection of sugarcane aphids this far north in the Texas High Plains. Also, Katelyn reports finding yellow sugarcane aphids at low levels. Last Friday, I emailed and posted a newsletter on the different aphids that infest both grain and forage sorghums as a review on how to identify the different aphids. This information can be found at the Texas Panhandle Pest News blog, http://txppipm.blogspot.com. Other specific information regarding the sugarcane aphid on treatment thresholds, insecticides, and yield losses can be located at the Texas Sugarcane Aphid News blog, http://txscan.blogspot.com/2017/06/preparing-for-sugarcane-aphid-part-ii.html.

Treatment threshold:
Pre-boot: 20% of plants with aphids.
Boot: 20% of plants infested with 50 aphids per leaf.
Flowering to Milk: 30% of plants infested with 50 aphids per leaf.
Soft dough through dough: 30% of plants infested, localized areas with heavy honeydew, and established aphid colonies.
Black layer: Heavy honeydew and established aphid colonies with treatment only for preventing harvest problems.

Aphid Control
Yellow sugarcane aphids - Field experience has shown that foliar applications of chlorpyrifos 4E at 12 fl oz/A mixed with dimethoate 4E at 12 floz/A provides good control. However, do not apply dimethoate after head formation.
Greenbugs - The primary insecticide for greenbug control is still chlorpyrifos at 1 to 1.5 pints/A.
Corn leaf aphids - rarely a need to treat for the corn leaf aphid.
Sugarcane aphids - EPA has granted another Section 18 emergency use exemption for Transform WG for 2017. The preferred use rate for the Texas High Plains is 1.25 -1.5 oz/A.
Sivanto Prime continues to be labeled for sugarcane aphids under a 24(c) special local need label. The preferred rate for the Texas High Plains is ≥ 5.0 fl oz/A.

Both Transform and Sivanto will control yellow sugarcane aphids and greenbugs when populations are mixed.

These are suggestions based on research and experience, but other conditions may cause unforeseen or unexpected poor performance. The Texas A&M AgriLife Extension Service will not assume responsibility for risks when using insecticides. Read and Follow the label.

Friday, June 23, 2017

Aphids to Scout for in Grain and Forage Sorghums

Now that early planted fields are growing well and later planted fields are emerging, it may be a good time to  review some of the aphids that need to be scouted. First, we have several aphid species that are pests of sorghum and may be mistakenly identified by some individuals. 


An aphid that can be a pest of seedling sorghum through grain development is the Yellow sugarcane aphid, Sipha flava (Forbes). This aphid is usually lemon yellow, but may be pale green. The body has rows of small spines (hairs), the cornices are very small and difficult to see. The tips of the feet and antennae are not black. While feeding on the underside of a leaf the  aphids inject a potent toxin that cause seedling leaves to turn reddish/purplish and older leaves yellow. Very few aphids are needed to cause a leaf to die. They do not produce honeydew. Economic injury levels have been established for seedling plants up to the three true-leaf stages and can be found in the the Texas AgriLifepublication, B-1220, “Managing Insect and Mite Pests of Texas Sorghum”. No economic injury levels have been established for vegetative plants after the third true-leaf stage and during head development, but damaging infestations can develop and cause yield losses. However, the following greenbug action threshold can be used for yellow sugarcane aphid to prevent excessive yield losses in older sorghum. Yellow sugarcane aphids have already been found this spring.














Action threshold levels for greenbug (yellow sugarcane aphid) on sorghum at different growth stages
Plant size
When to treat
Larger plant  greater than 6 inches to boot 
Colonies causing red spotting or yellowing of leaves and before any entire normal-sized leaves on 20% of plants are killed
Boot to heading
At death of one functional normal-sized leaf on 20% of plants
Head to hard dough
When colonies are sufficient to cause death of two normal-sized leaves on 20% of plants


Greenbugs, Schizaphis graminum, is another pest of sorghum if the sorghum is not a greenbug resistant hybrid.  The majority of commercially available sorghum hybrids are resistant to biotype C and E greenbugs. Some sorghum hybrids have resistance to the biotype I greenbugs. In very general terms an aphid biotype is when aphids are able to survive and reproduce on a host that it could not survive on previously. For example, greenbugs were first a pest on small grains and then in the 1960’s greenbugs were able to survive and damage grain sorghum. The greenbugs that were able to survive on sorghum were designated as biotype C. Sorghum breeders were able to identify genes in sorghum that were resistant to the biotype C greenbugs. Then greenbugs were able to survive on the sorghums containing the genes for the biotype C greenbugs. These new greenbugs were labeled as biotype E greenbugs. Researchers have now identified four biotypes (C,E, I and K) that are able to infest sorghum. All greenbugs, regardless of the biotype, are identical in appearance. Greenbug biotypes E and I are most common greenbugs in our sorghum fields and may occur together in some sorghum-growing areas. Therefore, the use of sorghum hybrids with resistance to the greenbug biotypes in our area will provide protection and prevent damaging infestations. 

The greenbug is a light green colored aphid with a darker green stripe down the back. The tips of the cornicles, antennae and the tarsi (feet) are black. This aphid also injects a toxin into the plants when feeding that causes reddish spots on the leaves and aphids produce honeydew. Feeding on a susceptible hybrid will cause leaves to begin to die, turning yellow and then brown from the outer edges. Populations on a susceptible hybrid can develop to extremely high numbers on the underside of the leaves. Greenbug populations can increase twenty-fold per week and cause extensive loss in yields in a short period of time. The action threshold can be used in making decisions on when to treat.   




Corn leaf aphids,  Rhopalosiphum maidis, is an aphid that infest the whorl of the sorghum plant. They do not inject a toxin when feeding and rarely cause economic yield losses. When populations are establishing one may have to pull out the whorl and unfurl the leaves to find aphids on pre-boot sorghum. However, when populations are abundant aphids can be easily seen in the whorl. The aphid is dark bluish-green to gray-green in color. The entire parts of the legs, antennae, and cornices are black. Beneficial insects, such as lady beetles, are attracted to and feed on the corn leaf aphids. Therefore, the corn leaf aphids are an important source for building up beneficial insects to help control other aphid pests, such as yellow sugarcane aphids, greenbug, and sugarcane aphids. Since the corn leaf aphid primarily lives in the sorghum whorls, their populations rapidly declines when the sorghum boot extends out of the whorl and heads exerts from the boot. 




Sugarcane Aphid, Melanaphis sacchari, has been an extremely damaging pest of sorghum since 2015 on the Texas High Plains. These aphids have diverse coloration from pale yellow, grayish, or tan. The distal half of the antennae, cornicles, and tips of the legs (feet) are black. They excrete large amounts of honeydew that covers the upper side of the lower leaves making them sticky and shiny. They infest  all leaves from the top of the plant to the leaves down into the canopy. They do not inject a toxin, but feeding damage from the sheer numbers of aphids on a leaf will cause leaves to turn yellow and will kill leaves. Infestations on pre-boot sorghum can cause significant yield losses. The threshold for treating sugarcane aphids on the Texas High Plains is based on the growth stage of the sorghum plants and a percentage of plants infested for that growth stage. 

Treatment threshold:
Pre-boot: 20% of plants with aphids.
Boot: 20% of plants infested with 50 aphids per leaf.
Flowering to Milk: 30% of plants infested with 50 aphids per leaf.
Soft dough through dough: 30% of plants infested, localized areas with heavy honeydew, and established aphid colonies.
Black layer: Heavy honeydew and established aphid colonies with treatment only for preventing harvest problems.

Sugarcane aphids are becoming closer to the Texas High Plains. On June 1st, sugarcane aphids were reported on sorghum in Kiowa County, OK, about 200 miles east of Amarillo and Canyon. Yesterday, sugarcane aphids were reported on sorghum in Tom Green County, 3 miles east of San Angelo, by Josh Blanek, CEA - Ag, and confirmed by Joel Webb, EA-IPM. 





Aphid Control
Yellow sugarcane aphids - Field experience has shown that foliar applications of chlorpyrifos 4E at 12 fl oz/A mixed with dimethoate 4E at 12 floz/A provides good control. But do not apply dimethoate after sorghum heading.
Greenbugs - The primary insecticide for greenbug control is still chlorpyrifos at 1 to 1.5 pints/A.
Corn leaf aphids - rarely a need to treat for the corn leaf aphid.
Sugarcane aphids - EPA has granted another Section 18 emergency use exemption for Transform WG for 2017. The preferred use rate for the Texas High Plains is 1.25 -1.5 oz/A.
Sivanto Prime continues to be labeled for sugarcane aphids under a 24(c) special local need label. The preferred rate for the Texas High Plains is ≥ 5.0 fl oz/A.
Both Transform and Sivanto will control yellow sugarcane aphids and greenbugs when populations are mixed.
These are suggestions based on research and experience, but other conditions may cause unforeseen or unexpected poor performance. The Texas A&M AgriLife Extension Service will not assume responsibility for risks when using insecticides. Read and Follow the label.