Sulfoxaflor (Transform), Federal Courts and The March of Folly

Sometimes a regional decision with national implications can have dire unexpected consequences half a nation away. The Ninth Circuit Court of Appeals in California handed out a ruling in early September that EPA should withdraw the Federal registration for sulfoxaflor insecticide. The logic for the decision was that sulfoxaflor was a neonicotinoid insecticide (according to press coverage) and EPA should not have registered it without more honeybee safety studies. Indeed, EPA did ask the Registrant, Dow AgroSciences, for additional bee safety data but registered the insecticide for national use without those additional studies. (Neonicotinoids are getting some of the blame for the decline in honeybee numbers, but the science on the issue shows it is a very complicated problem and insecticides might only play a minor part. The companies that manufacture and sell neonicotioids are making enormous (and expensive) strides in limiting bee exposure when valid science says there is a real risk.)

The initial dataset submitted by Dow AgroSciences to EPA did show some sufloxaflor toxicity to bees, and that is why EPA wanted further studies. However, in spite of the fact that every press release I could find on the court decision labeled sulfoxaflor as a neonicotinoid, the truth is that it is not a neonicotinoid according to the Insecticide Resistance Action Committee (IRAC), an authority on pesticide mode of action. IRAC lists Class 4 as Nicotinic Acetylcholine Receptor (NACHR) Competitive Modulators, but the subclasses are not the same. Neonicotinoids are in Class 4A (neonicotinoids). Sulfoxaflor in Class 4C (sulfoxaflor). (http://www.irac-online.org/modes-of-action/). While sulfoxaflor and the neonicotinoids target the same site they apparently differ the way they affect the site, and that is why IRAC has them in different subclasses.

EPA, which is not known to be friendly to insecticides, explains bee safety in their  sulfoxafor registration, and note the label restrictions on using it on pollinating crops. “The EPA does not allow sulfoxaflor application to plants that are attractive to bees for three days before bloom, during bloom, or until petal fall for the majority of crops. For the remaining bee-attractive crops, we also added advisory language to the labels to notify known beekeepers of scheduled application and to apply these products in early morning or late evening. Since bees are typically only present when plants are in bloom, and the toxicity of sulfoxaflor residue is primarily a concern when the residue is freshly applied (the residue generally dissipates within three days), we expect that the application restrictions we put in place will protect bee colonies from harmful exposure.” (http://pesticides.supportportal.com/link/portal/23002/23008/Article/35618/Why-did-EPA-register-sulfoxaflor-I-heard-it-harms-bees) [Link seems to have been removed 10/16/15 or before.]

By now your eyes might be glazing over, but it was necessary to establish these facts before pointing out a looming disaster that might occur if sulfoxaflor is not returned to the market for use on sorghum in 2016. The sugarcane aphid (Melanaphis sacchari) underwent some type of genetic shift a few years ago, adapted to sorghum, and has been decimating sorghum crops in the southern U.S.A. since 2013. It is fair to say this has been a crisis for sorghum growers; typical yield losses are 60 – 100% if the aphid is not controlled. This pest has rapidly expanded its range and can now be found as far north as Colorado and Illinois. The latest distribution map is here: http://txscan.blogspot.com/2015/10/new-map-17-states-and-417-counties.html .

Presently there are only two insecticides effective against sugarcane aphid; sulfoxaflor (sold as Transform) and Flupyradifurone (sold as Sivanto). Our traditional, older aphid insecticides provide only mediocre control, and in fact they kill beneficial insects that help control sugarcane aphids and this makes the aphid outbreaks even worse than if no insecticide had been applied. (These older insecticides are also extremely toxic to honeybees.)

The Federal court system has taken away one of two effective sugarcane aphid insecticides, so most people would think that since there is one left it is no big deal. But it is a big deal, and a very scary big deal. Aphids are renowned for developing resistance to insecticides. There is very little sexual reproduction (resulting in mixing of genes) in aphids and females are born pregnant and give birth to live young that are genetically identical clones of the mother. If a female has genes for resistance to an insecticide then all of her progeny will have those genes.

Sivanto is an IRAC Class 4D insecticide (Butenolide) and different from the Class 4C Transform. The foundation of insecticide resistance management has always been that if an insecticide must be used, then any additional insecticide use in the same season should be with a product with a different mode of action.  It is likely that resistance that develops to Sivanto will not protect sugarcane aphid from Transform applications, and the reverse is true as well. But now we have only one effective insecticide for sugarcane aphid, Sivanto, and it will be used on the vast majority of sorghum acres grown in the U.S. in 2016. The very best way to get resistance to an insecticide is to use it over a large area on multiple generations of a pest, and that is precisely what we are going to do with Sivanto in 2016 if Transform (sulfoxaflor) is not restored for use on sorghum.

So thanks to a Federal Court Ruling in California we now stand a very good chance of blowing out (developing resistance to) Sivanto, the sole remaining insecticide effective against sugarcane aphid and the last insecticide that makes sorghum an economically viable crop when sugarcane aphids are present. Right now, and until we get good sources of host plant resistance and/or an improbable new insecticide, all that stands between sorghum and disaster is Sivanto. I’m sure the Federal Court in California made its decision on the narrow scope of the case before it, but it is imperative that an exemption to allow sulfoxaflor to be used on sorghum in 2016 be granted. If we don’t have that exemption and Sivanto begins to fail then we will resort to the older, less effective but more bee-toxic insecticides and people will really get an idea of what bee toxicity means.

Fall Armyworm Trap Captures Very High

As we start to wind down the season there has been a late surge of fall armyworm moths captured in the Lubbock traps. This puts late sorghum at risk of headworms. It also puts very late planted corn at risk of fall armyworm infestations in the ear.

Rumors of Sugarcane Aphid Resistance and Adaptation to Corn Are Unsubstantiated

Dr. Ed Bynum has addressed some unsubstantiated rumors flying around the High Plains; 1) that sugarcane aphid has become resistant to insecticides in Mexico and 2) that it is now able to develop on corn and is damaging corn in Mexico. I tried to address this last topic in my post last week, but Dr. Bynum has provided more detail on both issues in his newsletter post today.

The bottom line is that there is no evidence of insecticide resistance and no evidence that the aphid can damage corn.

Corn, Cotton and Sugarcane Aphids

Many people on the High Plains are finding what looks like sugarcane aphids on corn and to a lesser extent cotton, and the question we are receiving is whether the aphid will get on these crops and, if so, will it become a problem.

The answer to the first part is a definite YES; they will get on all of our plant species. In the past few weeks we have had billions of winged adults flying from sorghum fields and all of them need to land somewhere. They are basically like flakes of ash from a giant volcanic eruption and will settle out over the landscape.

The answer to the second part of the question is that neither corn or cotton is a good host for the aphid. Small aphid colonies are being found on these crops but they are not expanding rapidly and will not get anywhere near pest status, at least if our aphids behave like sugarcane aphids do in Mexico and south Texas. Sandy Endicott from DuPont Pioneer monitors the sugarcane aphid situation in Mexico and the southern U.S. and provided some perspective to us earlier in the week. In Central Mexico there are four counties where the sorghum crop is a complete loss. The report went on to state that DuPont Pioneer people were finding small colonies on corn, but that there was no concern at this point but they will continue to watch closely. The situation on sorghum in Mexico seems to be extreme yet only small colonies are being found on corn. This matches what our Extension Entomology colleagues Danielle Sekula-Ortiz and Raul Villanueva have reported from the Valley; small colonies only and these do not persist. Corn, being a grass, is much more closely related to sorghum than is cotton, a dicot. The sugarcane aphid has adapted to sorghum and its relatives (including millet) but not to corn, and certainly not to cotton. (Cotton aphids, which look quite similar to sugarcane aphids, are currently being found on southern High Plains cotton.)

Having said all of this, aphids are good at adaptation if they have the genetics to do it. As far as we know, and based on a lot of credible information, none of our crops that are not in the sorghum group are at risk. We would appreciate reports of healthy looking and expanding colonies of sugarcane aphids on any of our non-sorghum crops. Our contact information is here. We don't expect any phone calls but it never hurts to be vigilant.

Headworms Up; New Invasive Aphid Found in Panhandle

Headworms and Late Corn Fall Armyworm

Corn earworm and fall armyworm adult trap captures are up significantly in the last week and this means headed sorghum should be scouted for headworms. It also means that late planted non-Bt corn should be scouted for fall armyworm. Corn earworm is not an economic problem in corn, but fall armyworm can do a lot of damage to ears if it infests them prior to hard dough stage. Prevathon and Belt are good choices for control of fall armyworm in corn and they will not flare spider mites (which are also being found readily in corn and sorghum). As headworm insecticides they will not flare sugarcane aphids in sorghum. 

New Invasive Aphid Pest

Sipha maydis, which we are choosing to call the hedgehog aphid after Colorado State University's lead, was found in Lipscomb and Hockley counties on sorghum on the same day last week. Given the distance between discoveries it is likely that the aphid is widely distributed on the High Plains and we would appreciate reports of new discoveries. 

The aphid is easy to recognize; it is shiny black with white spines.

Dr. Ed Bynum has written an excellent summary of what is known about S. maydis in his newsletter. This pest of small grains has the potential to be a serious threat to wheat and other crops. 

High Plains Sugarcane Aphid Thresholds Lowered

Experience with the sugarcane aphid in the last few weeks has prompted us to lower our treatment thresholds. The new thresholds can be found on our Sugarcane Aphid News website. The article concludes with suggestions for tank additives for sugarcane aphid control. 

Spider Mites in Sorghum

Dr. Ed Bynum, Extension Entomologist in Amarillo, has published a good summary of the spider mite situation in sorghum this year. I have seen some fairly heavy infestations in fields but don't have time to write. And Dr. Bynum's article is better than I could do anyway.

Spider Mites in Sorghum, Texas Panhandle Pest News, August 11, 2015. 

Multiple Aphid Species in Sorghum, What a Year

Some area sorghum fields are experiencing significant numbers of aphids, but not just sugarcane aphid the recently arrived pest from the south. We also have high numbers of yellow sugarcane aphid, greenbug and corn leaf aphid. Of these, the corn leaf aphid is the only one that is not a threat.

Blayne Reed, Ed Bynum and I put out the first sugarcane aphid control experiment today just east of Hale Center. The pre-treatment count averages were something like 70 sugarcane aphids per leaf, 60 yellow sugarcane aphids and 30 greenbugs. (I have not formally tallied the numbers yet, but these are best guesses from my tired brain.)

Dr. Bynum wrote an excellent article on the practical and important differences between sugarcane aphid and yellow sugarcane aphid, and it can be found here. He discusses biology, damage and thresholds.

As you scout fields be sure to note the number of sugarcane aphids, yellow sugarcane aphids and greenbugs separately. As Dr. Bynum notes in his article, we don't have any thresholds for yellow sugarcane aphids on older sorghum so we recommend spraying them on the greenbug damage thresholds. However, if there are a significant number of sugarcane aphids in the field then it would be a good idea to treat the field with an insecticide that took out sugarcane aphids. These insecticides, Transform and Sivanto, are also effective on yellow sugarcane aphid and greenbug. However, the reverse is not true; our traditional insecticides for yellow sugarcane aphid and greenbug are not very effective on sugarcane aphid. So spray to kill all three species - don't leave sugarcane aphid in the field.

Good News: Fall Armyworm Not Numerous

It has been a very strange summer; early indications pointed to a bad fall armyworm year, but trap captures in that last two weeks suggest that we might get a break. As the graph above shows, fall armyworm trap captures at Lubbock are well below the three year average. Kendra Bilbrey, Cochran County Extension Agent, has also been operating fall armyworm traps and her data agree with the very low fall armyworm moth numbers found at Lubbock. 

Kendra Bilbrey's fall armyworm trap data from Cochran County. 

This is great news for sorghum because fall armyworm is part of the headworm complex. Corn earworm (cotton bollworm) is the other part. I don't have trap data for corn earworm, but my field sampling tells me that the numbers are around normal. Additionally, late planted corn that is entering green silk stage will draw corn earworm and fall armyworm away from sorghum. Green silk corn is highly attractive to these insects and neither of these pests can tell whether the corn on which they are laying eggs is Bt or non-Bt. In essence the late planted corn will act as a trap crop and provide partial protection for nearby sorghum. This is not necessarily bad news for corn; Bt will kill many of the caterpillars. 

However, late planted non-Bt corn might be in for a rough time; it will attract these late summer fall armyworms and corn earworms. This is one of the reasons that non-Bt corn should not be planted late on the Southern High Plains, and it is one of the reasons that, in an earlier post, I hinted that late planted corn should forego the required non-Bt refuge this year. The real worry in corn is fall armyworm rather than corn earworm, and the fact that fall armyworm numbers are well below average right now is a good thing for all of the late planted corn in the area. 

So, at least for right now, the indications are for a relatively light headworm year in sorghum. And this is the year we really need it! Headworm insecticide applications with the usual products could flare sugarcane aphid. (There are two headworm products that won't flare sugarcane aphids; Prevathon and Belt.) A three axis threat to sorghum; sugarcane aphid, sorghum midge and headworms, could be an expensive proposition. But at least for right now it looks like the headworm part of the equation won't amount to a serious problem in the next few weeks. Of course I don't have a crystal ball and am not going to make any assumptions about late planted sorghum; corn will not be attractive for egg laying past green silk stage and thus sorghum might get heavier infestations. But for now I will take a little good news and we will keep tabs on what happens in the next few weeks. 

Getting Ready for Sorghum Midge

In the July 8th edition of FOCUS I promised to write more detailed information on sorghum midge. This year a lot of sorghum was planted earlier than normal in order to avoid the potential worst problems associated with sugarcane aphid. (Congratulations if you employed this IPM practice! It seems to be paying off now that sugarcane aphid is firmly established in Southern High Plains counties.) In general, sorghum that completes bloom before August 4th or so in our part of the Southern High Plains will escape economic midge damage. However, some of this early sorghum and the abundant Johnsongrass can serve as early hosts for midge and give later populations a head start. It is too soon to know what midge populations will be like this year, but on balance we have plenty of egg-laying hosts in the system.

As I started this article I saw an excellent summary from Angus Catchot and Jeff Gore at Mississippi State University. This article is so good that I am going to link to it as most of what I would have written about sorghum midge: it contains recognition, biology, scouting information and control suggestions: http://www.mississippi-crops.com/2015/07/18/scouting-for-sorghum-midge-with-confidence/ .

One key point about sorghum midge is that it lays eggs in blooming sorghum only on the day the anthers are visible. However, it takes several days for a sorghum plant to flower from the top of the panicle to the bottom and, due to uneven flowering across the field, it may take a week to ten days for the field to complete pollination. Adult midges (tiny flies) live about one day, but there is continual re-infestation of the field each day, so low midge numbers on the first day of flowering might be high midge numbers in subsequent days. And overall midge numbers in the system increase as August progresses.

Sampling should be done in mid-morning, or after temperatures have reached 85 degrees. The treatment threshold depends on sorghum panicles per acre, midges per panicle and cost of control. The threshold calculations can be found in Managing Insect and Mite Pests of Texas Sorghum on page 19 - 20.

Insecticide selection has changed because sugarcane aphid is present in many area sorghum fields. Our management recommendations prior to sugarcane aphid were pyrethroids, Lannate, Malathion and Lorsban. Unfortunately, all of these insecticides kill beneficial insects, the same insects that help slow down the sugarcane aphid. And, to make matters worse, they don't do a good job of killing sugarcane aphids. So the net result of using them might be to help sugarcane aphids rapidly increase in the field. However, it is important to treat midge if it reaches threshold; do not forsake a needed midge treatment out of fear of what might happen with sugarcane aphid.

As a practical matter, scout the field carefully to determine whether there are sugarcane aphids present. If so then you can still use the insecticides listed above, but consider adding Transform or Sivanto for sugarcane aphid if you think you need to. Or be prepared to come back with Transform or Sivanto later. Not all midge insecticides will risk flaring sugarcane aphid; Blackhawk has just received a 2ee label on sorghum for midge control and should be used at 1.5 - 3.0 oz per acre. I do not have direct experience with this spinosad product, and in fact have not seen the new label, but Dow says is will work and they stand behind its performance for full control.

I am not sure that we will have an increased midge problem this year, especially since all bets are off due to the very wet spring and early summer. However, I wanted to provide some information on making midge control decisions in light of sugarcane aphid.

Sorghum midge: Patrick Porter

Sugarcane Aphid at Treatment Threshold in Southern High Plains Counties

At a minimum, Floyd, Crosby and Lubbock counties now have sorghum fields at the economic threshold of 50 to 125 sugarcane aphids per leaf and insecticide applications started over the weekend. Blayne Reed, Extension Agent - IPM in Hale, Swisher and Floyd counties said that private consultants called in the first Floyd County applications today. Monti Vandiver, Syngenta Crop Protection and former Extension Agent - IPM, said that the aphids in Crosby and Lubbock counties are now at treatable levels. 

This is in no way meant to imply that the other infested counties don't have fields at threshold level, so it is imperative that all sorghum fields on the Southern High Plains be scouted. This aphid can go from barely noticeable to exceeding the economic threshold in as little as 5 days. All of the scouting procedures, treatment threshold and insecticide information is presented here: http://www.texasinsects.org/sorghum.html . 

This is a reprint of a news article I just posted on the Sugarcane Aphid News Site at http://txscan.blogspot.com . The SCA news website is the best place to stay current on Texas sugarcane information news and view the latest distribution maps. 

Fall Armyworms in Corn and Sorghum, Early Midge Warning

Fall armyworm in corn and sorghum

Fall armyworm trap captures at Lubbock are up this week and we are on course to approximate the high numbers experienced in 2014.

FAW trap capture as of 7/8/15. Click for a larger view. 

Larvae feed on corn ears and ear shanks and behind leaf collars. Our recent research at Lubbock has shown that one fall armyworm larva, when boring through the side of an ear, causes an average of 0.20 lbs. of yield loss per ear through direct kernel injury and damage by associated fungi. In our experiments the mycotoxin (fumonisin) levels in grain greatly increased in ears damaged by fall armyworm side entry damage. Heavy infestations may result in substantial yield losses because larvae feed directly on the ear. Additional losses can occur when shank feeding causes ears to drop and when stalks lodge as a result of feeding damage to the nodes. 

Non-Bt corn and single toxin Bt corn (Cry1F Herculex) should be scouted carefully as it approaches silking and for at least two weeks thereafter. Scouting for fall armyworms can be difficult. Check corn leaves and grasses in the furrow for egg masses. There may be 50 to 100 eggs per mass. Also check for small larvae behind leaf collars and at the bases of primary and secondary ears. Small larvae differ from late instar larvae in that they are pale tan in color and have a small black spot on each side toward the head. Larger fall armyworm larvae tend to be brown in color while corn earworm is more brightly colored in yellow, red, pink or beige. 

Unfortunately, we do not have a treatment threshold for fall armyworms on reproductive stage corn. Our research trials at Lubbock have shown that if an insecticide is needed applications should optimally occur in a five day window starting at or just prior to silking. Applications made 7 days after silking were less effective at control because many of the larvae were protected inside ears. 

Larvae hatching from a fall armyworm egg mass.

On larger fall armyworm larvae the "inverted Y" on the head capsule is thicker and more pronounced than on the corn earworm.

Posterior ends of fall armyworm (top) and corn earworm (bottom) larvae. Fall armyworm has 4 relatively equally spaced dots on the second to last segment. Corn earworm has more and longer "hairs". 

Fall armyworm (top) and corn earworm (bottom).

All photos by Pat Porter.

Suggested insecticides for fall armyworm in corn. Click for a larger view. 

Sorghum

Fall armyworm infests whorl stage, boot stage and headed sorghum. Whorl stage sorghum can withstand significant damage. Sorghum in the boot stage through grain fill should be scouted for headworms (fall armyworm + corn earworm). Prior to the arrival of sugarcane aphid in sorghum we would have said to determine which caterpillar species was predominate in a field and then choose either a pyrethroid (if corn earworm) or a non-pyrethroid (if fall armyworm). This distinction is because pyrethroids are not very effective on larger fall armyworm but are good at controlling corn earworm.  However, things change when sugarcane aphid is present in a field; pyrethroids and organophosphates should be avoided because they destroy the beneficial insects that suppress sugarcane aphid populations. Insecticide considerations for "other" pests when sugarcane aphid is present are covered in our special publication here. 

Treatment thresholds for headworms are based on the size of the larvae, the value of the crop per acre and the cost of control. The following table refers to corn earworms, but action levels are really caterpillar numbers whether they are corn earworms or fall armyworms. Note that there are two separate thresholds, one for large larvae and one for medium-sized larvae. Full details are presented in Managing Insect and Mite Pests of Texas Sorghum.

Sorghum midge

A future article will cover sorghum midge in more detail, but it is possible that midge problems may be worse than normal this year because of the abundance of Johnsongrass, an early season host of sorghum midge. It is generally true that fields that bloom before August 4th in the Plainview area will not have economic midge damage. However, Greg Cronholm, Independent Crop Consultant and Extension Agent - IPM (retired) has found midge on sorghum as early as July 25th. If we start out with abundant midge numbers coming from Johnsongrass then the August 4th assumption may not hold up this year. 

Sugarcane aphid and whorl stage sorghum on the Southern High Plains

By Tommy Doederlein, Pat Porter, Blayne Reed and Kerry Siders

Sugarcane aphid arrived early in south Texas this year but its northward expansion was apparently slowed by the record rainfall. However, in the last two weeks it has made a rapid advance and was found in Lubbock County on June 29^th.  This is two months earlier than the August 27^th, 2014 first detection by Blayne Reed in Floyd County. Last year’s late arrival allowed us to avoid making insecticide applications. While it is still too early to guess how severe the problem might be this year, we would like to provide some information on management practices prior to boot stage.

When on whorl stage sorghum, economic populations of sugarcane aphids can result in near total yield loss because it destroys leaf cells that provide nutrition to keep the plant growing, exert the panicle and fill the grain. The worst case is a heavy sugarcane aphid infestation on whorl stage plants. Later infestations on headed sorghum are somewhat less of a problem and may only result in minor yield losses and harvest difficulties due to honeydew accumulation.

Early detection is the key to successful sugarcane aphid management. All fields should be scouted weekly from shortly after emergence until one week before harvest. If sugarcane aphids are not found in a field then the weekly scouting should continue. If light populations of sugarcane aphids are found then the scouting should occur twice per week. The doubling of the scouting interval is because of the rapid reproduction of the aphid. As Angus Catchot, Entomologist at Mississippi State University, put it, “This is the first pest I have seen that can go from ‘barely there’ to ‘Oh my God’ in five days.

Sugarcane aphids are easy to differentiate from the other aphid pests of sorghum and there is a recognition guide posted here: http://txscan.blogspot.com/2015/02/recognizing-sugarcane-aphid.html .

The treatment threshold is an average of 50 – 125 aphids per leaf on whorl stage plants. Research in Texas has shown that an average of 250 aphids per leaf is around the break point where yield declines equal the cost of control, but this many aphids can cause a honeydew and sooty mold problem. The goal is to apply the insecticide soon enough to keep the aphid numbers below 250 per leaf. Quick action is needed when fields reach the economic threshold, so don’t delay in pulling the trigger. The treatment threshold is the same for susceptible sorghum and the “resistant” or “tolerant” sorghum hybrids; once threshold is reached then insecticides should be applied as soon as possible. Blayne Reed, Extension Agent in Hale, Swisher and Floyd counties, with support from all our regional IPM specialists, is leading our 2015 research on how the “resistant” hybrids withstand sugarcane aphid. It is far too early to say anything other than, from a management perspective in 2015, expect resistant hybrids to perform in line with susceptible hybrids. The so-called resistant hybrids should be scouted like susceptible hybrids and sprayed like susceptible hybrids with the yet field-unproven hope there will be fewer aphids or better performance from the “resistant” lines.

There are two good insecticides available; Sivanto and Transform. Expect each product to provide around 10 days of control. Be sure to visit the field 3 – 4 days after the application to make sure the insecticide is working. If a follow-up application is needed after 10 days then rotate to the other insecticide. Insecticide rotation is critical for resistance management; aphids are extremely dangerous as far as resistance because they are genetic clones (no sexual reproduction and mixing of resistance and susceptibility alleles). If the mother has resistance alleles then the offspring will have the same resistance alleles; if the mother survives the dose then the progeny will survive the dose, and so will all of their progeny and their progeny across generations and growing seasons. The only way to kill these resistant insects is with the other insecticide. Insecticide rotation is the key to preventing resistance, and aphids are exceptionally adept at becoming resistant.

It is important to preserve beneficial insects – they won’t prevent sugarcane aphid from reaching threshold on the High Plains (yet), but they will slow the aphid down. There is evidence from the Gulf Coast that, after three seasons of the aphid and the beneficial insects coexisting, the beneficial insects are starting the season in high enough numbers to exert a significant amount of control on the aphids. This is not the case in the High Plains; our beneficial insects have not had the chance to arm up against the aphids and we don’t have enough of them to keep aphid populations under control. But we do have enough of them to slow the aphids down and perhaps avoid an additional insecticide spray later in the season. The best way to help the beneficials is to avoid pyrethroid and organophosphate insecticide applications; use Sivanto or Transform and let the beneficials live.  We have a new publication called InsecticideSelection for Sorghum at Risk to Sugarcane Aphid Infestations, 2015. This publication discusses insecticide choice for sugarcane aphid control and insecticides to use on other pests in fields that have sugarcane aphids in them. Other sugarcane aphid resources available at http://www.texasinsects.org/sorghum.html. We have established a statewide sugarcane aphid news website at http://txscan.blogspot.com.

We don’t know what to expect in 2015 as far as sugarcane aphid. All we know for sure is that it has arrived two months earlier than last year and is now threatening whorl stage plants. We encourage weekly field scouting until the aphids are found and then twice-weekly scouting thereafter. Apply insecticides when there are 50 – 125 aphids per leaf and use either Transform or Sivanto. Check to make sure the insecticide worked and, if an additional application is needed later, be sure to rotate insecticides in order to prevent resistance.

Update on Fall Armyworm

Things have been quiet on the fall armyworm front since the large trap captures earlier in the season. However, Greg Cronholm, Independent Crop Consultant and Extension Agent - IPM (retired), called earlier in the week to report finding very heavy egg deposition on small corn in Hale County. Greg said that the eggs were from a species in the armyworm group but he did not think they were fall armyworm. Yellowstriped and beet armyworms are a possibility as is a different armyworm species. We will try to rear out some larvae to determine the species.

Sugarcane aphid found in Lubbock County

I found a colony of sugarcane aphids on Johnsongrass near the Lubbock airport on Monday, June 29th after only 10 minutes of looking for the insects. An additional 30 minutes of looking resulted in no additional colonies being found. The aphid identification was confirmed by other Extension IPM personnel via digital photo.

Sugarcane aphid is on the southern High Plains for 2015, but the good news is that it appears to be in low numbers so far. Blayne Reed, Extension Agent IPM in Hale, Swisher and Floyd counties, and his scouts sampled two dozen sorghum fields on June 29th in Hale and Swisher counties and did not find any sugarcane aphids. Floyd county was not sampled. Kerry Siders, Extension Agent IPM in Hockley, Cochran and Lamb counties, spent time this week sampling Johnsongrass in Hockley and Cochran counties and did not find any sugarcane aphids.

Many of the aphids found in the Abilene area and southward last week were winged, and it is likely they are on their way north.

The Extension Entomology group on the southern High Plains; Blayne Reed, Tommy Doederlein, Kerry Siders and Pat Porter are putting together a two page guide on dealing with the sugarcane aphid on whorl stage sorghum. This guide will appear here in the next day or two and will include identification, scouting, treatment thresholds and insecticide suggestions.

Planting Sorghum or Corn in “Yellowed” Pre-Plant Treated Fields

Blayne Reed, Extension Agent IPM, has just published an excellent article on considerations for planting corn or sorghum in ground treated with yellow herbicides in anticipation of cotton planting.

The full article is here: http://halecountyipm.blogspot.com/2015/05/planting-sorghum-or-corn-in-yellowed.html

Here is the first paragraph:

It is no secret that we have had a devil of a time with weed control these past few seasons.  In response we have been getting better and more aggressive in our use of pre-plant herbicides in our primary row crop, cotton.  This is making for an interesting dilemma with such a long (yet welcome) period of wet weather delaying most cotton plantings.  Any more delays in cotton planting and many of us will be outside our window for our full potential of profitable cotton crop.  This leads many of us to consider alternate crops that do not require as large a production window such as corn or sorghum planted slightly later.  So, what can we do about our fields that were aggressively treated with pre-plant residual cotton herbicides?

View the answers. 

Corn or Sorghum in Place of Cotton in 2015: Insect Considerations

Some cotton growers are considering planting corn or sorghum if they can’t get all of the cotton acres planted by the insurance cutoff date. This article is meant to provide a few insect considerations when thinking about corn and sorghum. Dr. Dana Porter, Ag Irrigation Engineer at Lubbock, is preparing an article on irrigation considerations for release here in a few days.

Corn

The three biggest pest threats to late-planted corn on the southern High Plains are fall armyworms, spider mites and mycotoxins (which are affected by fall armyworm and corn earworm).

Any corn planted in June is considered to be “late corn” from an insect perspective. There is still time to reach maturity with some of the less-than-full-season hybrids, so by late I mean only as applied to insects. The first and perhaps most important suggestion is to plant a good Bt hybrid; fall armyworm numbers increase as the season progresses and this insect can cause significant yield loss to non-Bt corn and Bt corn that does not have at least two toxins in it. There are very good hybrids available with two or more toxins and a list can be found here: http://www.texasinsects.org/uploads/4/9/3/0/49304017/traittable2015april6south.pdf). Your seed dealer will be able to make specific hybrid recommendations. I would avoid one toxin corn (Herculex and Yieldgard) because it won’t stand up well to high fall armyworm numbers. Here are my rankings for the efficacy of Bt hybrid types against corn earworm and fall armyworm:

Caterpillar Pest	Bt toxin combination in commercial hybrids
	Cry1F	Cry1Ab	Cry1Ab+ Cry1F	Cry1Ab+ Vip3A	Cry1Ab+ Cry1F+ Vip3A	Cry1A.105+ Cry2Ab2	Cry1A.105+ Cry2Ab2+ Cry1F
Corn earworm	F-P	F-P	F-G	VG	E	G	G-VG
Fall armyworm	F-P	F-P	F-G	VG-E	E	G	VG

P=Poor, F=Fair, G=Good, VG=Very good, E=Excellent
Click here for commercial names of these products. 

Fall armyworm is a major threat. How bad can it be? Our research at Lubbock has shown an average of 0.2 pounds of yield loss per ear when fall armyworm punctures the side of an ear and feeds on kernels. The losses come both from direct ear feeding and from the fungi that come along with the insects and through the wounds they cause. In or trials 52% of the yield loss was from fungi and 48% was from direct kernel damage by the insect. These same research trials showed drastically higher levels of mycotoxins in ears with side puncture FAW damage than ears with only tip damage. Fall armyworm larvae can also damage the ear shank and cause ears to drop to the ground.

Pay particular attention to the Bt corn refuge planting. All Bt corn with two or more toxins planted in the “cotton zone” (basically south of Amarillo) is supposed to have a 20% non-Bt block planted in the field or in a closely adjacent field. Strip refuges of four or more rows are also allowed. Single toxin corn is supposed to have a 50% refuge. Even though our recent research makes us confident that strip refuges have less fall armyworm damage than block refuges (from the toxic Bt pollen falling in the strips and creating toxic kernels), this protection is adequate with only low to moderate populations of fall armyworm. Late planted corn should expect heavier populations of fall armyworm, so a refuge, if it is to be planted, should be a block refuge that can be sprayed if things get bad. Also, even though seed blends are not supposed to be planted in the “cotton zone”, some fields are planted to seed blends. None of the non-Bt seed in a seed blend counts toward refuge in the cotton zone, so a correct refuge, if it is planted, should be calculated as if there was no refuge seed in the seed blend.

We don’t worry about corn earworm (cotton bollworm) much since it is mostly a tip feeder, whereas fall armyworm is a tip feeder, punctures the sides of the ears and does shank damage. Fall armyworm is the biggest caterpillar threat so choose your Bt corn to protect against fall armyworm. 

The next threat, and one that is always present whether corn is Bt or not, is spider mites. Bt corn has no effect on spider mites. Mites can be a very serious problem and occasionally require more than one miticide application. The good news is that late-planted corn is somewhat less prone to reaching the economic threshold for spider mites than is corn planted earlier in the season. Late planted corn should still be scouted, but the spider mite threat is somewhat lower.

Mycotoxins are the next worry in corn. Research has shown that corn growing under too much drought stress is prone to developing high aflatoxin levels, and corn grown with too much water is prone to developing high fumonisin levels. The relationship between water stress and mycotoxins levels is not well understood. There is an insect component, too, because the insects wound the ears and allow points of entry for the fungi that make mycotoxins. If you are going to plant corn then be certain you have enough irrigation capacity to keep it around at least 75% ET during peak water demand; silking through grain fill. Mycotoxins at levels beyond the Federal standards can either cause a dock at the elevator or make the crop unmarketable. Dr. Dana Porter will write about irrigating corn later in the week.

Sorghum

Sorghum is an excellent crop for late planting and the biggest worry being voiced this year is sugarcane aphid. It is true that we have been surprised how quickly the sugarcane aphid moved north 2015, and it is possible it will be an early to mid-season arrival on the southern High Plains this year. (Last year we dealt with it as a late season problem.) However, we have two excellent insecticides to control the aphid and we have solid economic thresholds. If the aphid arrives early to mid-season then it is likely that 2-3 applications will be needed. If it arrives later, say in August, then one application might be sufficient if any treatment is needed at all. There are sorghum hybrids resistant to sugarcane aphid, but the resistance is not all that strong and these fields should be monitored as if they were planted to  susceptible hybrids. The resistant hybrids are Sorghum Partners (Chromatin): SP6929, KS310, NK5418, and K73-J6; Monsanto: DKS37-07 and Pulsar; and Pioneer: 83P56. The sugarcane aphid is not a reason to avoid planting sorghum on the southern High Plains; it is manageable. Statewide sugarcane aphid news can be found here: http://txscan.blogspot.com . 

Sorghum planted in June has a higher chance of needing sorghum midge control than earlier planted sorghum. While pyrethroids are often used for midge control, it should be noted that they can drastically enhance the risk from sugarcane aphid by removing the biological control agents from the field. Non-pyethroid insecticides should be used, and this is also the case if headworms need to be controlled. These complexities are explained in three videos posted here: http://www.texasinsects.org/sorghum-videos.html .