Friday, December 9, 2016

Sorghum Stalk Nutritional Quality and Sugarcane Aphid Damage

One of the questions as we end the season is what kind of affect does sugarcane aphid damage have on the nutritional quality of sorghum stalks that are used for stover. We conducted two experiments this season, and both were designed to look at leaf damage and its affect on grain yield. However, in conducting these experiments we ended up with many plots with discreet levels of leaf damage, and The United Sorghum Checkoff Program asked us to harvest stalks from the various plots and send them for nutritional analysis.

To be clear, the results that appear below are for grain sorghum, not forage sorghum. One experiment was conducted at the Lubbock Research and Extension Center using a sugarcane aphid-susceptible hybrid grown under moderate furrow irrigation, and the other was conducted at the Helms Farm near the Halfway Experiment Station. This experiment was conducted on a sugarcane aphid resistant hybrid grown under drip irrigation that supplied relatively more water than was available at Lubbock. Data from the two trials showed very similar trends, so they were combined to generate the following charts.

The Leaf Damage Rating System developed by Blayne Reed goes from 0 to 10, with 1 being very little damage on the lower leaves, to 10 being all the leaves on the plant with observable damage. Sugarcane aphid damages lower leaves first and then moves up the plant, so a leaf damage rating of 5 would suggest the leaves in the lower 50% of the canopy are damaged.

Each dot on a graph represents at least 4 stalks harvested from a plot at a given leaf damage rating. The nutritional analyses were performed at Servi-Tech Labs in Amarillo. A sample report from Servi-Tech is here.

Figure 1. There was a highly significant decrease in Total Digestible Nutrients with increasing levels of leaf damage.

Figure 2. Crude Protein was not significantly different between plots with different levels of leaf damage. 

Figure 3. There was a highly significant increase in Acid Detergent Fiber (non-digestible components) with increasing levels of leaf damage.

Figure 4. There was a highly significant decrease in Digestible Energy with increasing levels of leaf damage.

Figure 5. There was a highly significant decrease in Metabolic Energy, Beef with increasing levels of leaf damage.

Figure 6. There was a highly significant decrease in Net Energy, Lactating with increasing levels of leaf damage.

Friday, August 12, 2016

Consider the entire Texas High Plains Infested

In the last few days there have been reports of sugarcane aphids in many new counties on the Texas High Plains, and most of these recent reports are from fields at sub-economic levels. Fields in counties reported as infested ten days to two weeks ago are now exceeding the treatment threshold in many places.

As mentioned in this newsletter over the last few days, we have new confirmed infestations in Terry, Lamb and Parmer counties. Brent Bean from the United Sorghum Checkoff Program just wrote about fields he personally inspected, so we can add Castro, Deaf Smith, Randall, Oldham and Potter counties to the list. Dr. Ed Bynum in Amarillo has added Moore, Sherman and Lipscomb counties.

One purpose of posting counties known to have the aphid is to alert growers and consultants to start scouting. Last year the aphid hit hard in a relatively predictable band that we could track northwestward. This year the aphids are filtering in quietly and may be in all sorghum production areas without our knowledge. Given the widespread distribution of the aphids, albeit at low initial numbers on the periphery, for the purposes of scouting it is time to consider the entire Texas High Plains to be infested.

Thursday, August 11, 2016

Sugarcane Aphids moving further west on the Texas South Plains

Over the last few days I have received calls from Danny Quisenberry, crop consultant, confirming sugarcane aphid on the east side of Earth, in Lamb county; and Chris Locke, crop consultant, who also confirmed a find near Lazbuddie, in Bailey county. These infestations were not at treatable levels at the time of find. To date I have not found or received reports of SCA in Cochran county.

Tuesday, August 9, 2016

Terry County has Sugarcane Aphids

Tyler Mays, Extension Agent - IPM in Terry, Yoakum and Gaines counties, today found sugarcane aphids on 23% of plants in one sorghum field five miles west of Brownfield. The dryland field has uneven development and ranges from pre-boot stage to bloom. We have no other details at this time.

Our 2016 Sugarcane Aphid Management Guidelines are posted online. This publication includes recognition, scouting, treatment thresholds and effective insecticides.

Thursday, August 4, 2016

Conditions for use of Transform - Section 18 Emergency Exemption Label

The Section 18 Emergency Exemption label for Transform has some specific information regarding application use and application restrictions. A COPY OF THE LABEL MUST BE IN HAND WHEN APPLICATIONS ARE MADE.

Here are some of the specifics from the Texas Section 18 Label. However, be sure to read the label before applying.
Rate range: 0.75 to 1.5 oz. per acre.
Application by ground or air (no chemigation).
Wind speed not to exceed 10 mph.
Droplet Size: Use only medium to coarse spray nozzles (i.e., with median droplet size if 341 μm or greater) for ground and non-ULV aerial application according to ASABE (S 572.1) definition for standard nozzles. In conditions of low humidity and high temperatures, applicators should use a coarser droplet size except where indicated for specific crops.
Boom height for ground application: Not to exceed 4 feet.
Carrier volume for ground application: A minimum of 5 to 10 gallons per acre - to be increased with increasing crop size and/or pest density.
Carrier volume for aerial application: A minimum of 3 gallons per acre, but a minimum of 5 gallons per acre is recommended.
Preharvest Interval: Do not apply within 14 days of grain or straw harvest or within 7 days of grazing, or forage, fodder, or hay harvest.
A restricted entry interval (REI) of 24 hours must be observed.
Do not make more than two applications per acre per year.
Minimum Treatment Interval: Do not make applications less than 14 days apart.
Do not apply more than a total of 3.0 oz of Transform WG (0.09 lb ai of sulfoxaflor) per acre per year.
Do not apply product ≤ 3 days pre-bloom until after seed set.

Wednesday, August 3, 2016

Sugarcane Aphid found in Hockley County

On Tuesday, August 2, sugarcane aphids were found in Hockley county just west of Ropesville on flowering to dough stage grain sorghum. This area has a high concentration of grain sorghum production in the county this year. It would appear that the aphid had moved in over the last few days in a few fields. There are couple of fields with aphid numbers which are reaching threshold levels and will trigger an insecticide application. Grain sorghum producers are encouraged to intensify their scouting for the sugarcane aphid. Contact Kerry Siders at 806 638-5635 for more information.

Tuesday, August 2, 2016

Sugarcane Aphids moving into the Texas Panhandle

Yesterday Dr. Jourdan Bell found sugarcane aphids in her sorghum silage trial near Bushland, TX. Infestations on leaves of some plants were already into the hundreds. Also Scott Strawn, County Extension Agent - Ochiltree, reported yesterday a producer finding sugarcane aphids in a field in his county. The aphid could be anywhere in between these locations. So be diligent to be looking for the sugarcane aphid when scouting. A quick method when looking for the aphids on the underside of the leaf is to reach down into the canopy, using your arm or soil probe, to lift up the leaves. Also, look for honeydew droppings on the the upper surface of leaves. The sugarcane aphid should then be found on leaves above the leaves with the honeydew. Aphids that are just beginning to colonize on a leaf may be missed when using this method. So, a total plant method as described in the post yesterday, August 1st, will provide a more thorough method for examining a plant.

Photo: 8/1/2016 by Jourdan Bell

Photo. 8/1/2016 by Jourdan Bell

Monday, August 1, 2016

Sugarcane Aphids Have Reached Threshold in Lubbock County

Sugarcane aphids have reached treatment thresholds in sorghum in east Lubbock County. Last week we were optimistic that the beneficials were doing their jobs and preventing the aphids from exploding, but the aphid reproductive capabilities have proved too great. I was in a field today that had approximately 50% plants infested with aphid colonies, some as big as several thousand, with heavy honeydew in some areas. I am also seeing more winged adults. While beneficial activity is still high, they cannot compete with the exponential growth rate of the aphids once pest populations get this high.

Tommy Doederlein (EA-IPM, Dawson and Lynn Counties) reported today that SCA exploded over the weekend. Where there were 10-20 aphids late last week, there are now several hundred if not thousands, and honeydew is heavy. They are currently treating.

Greg Cronholm, independent crop consultant in Hale County, reported today seeing SCA colonies on the upper one third of the plant. Colonies are substantial with winged adults present.

Scouting for Aphids – Whole Plant Method
SCA will start colonies on the underside of leaves, so you must look there when scouting your fields. One method that is quick and easy is to cut the entire plant with your pocket knife and turn it upside down to inspect the bottom of each leaf individually. The smaller colonies will be harder to spot so examining the plant up-close will give you a better chance of spotting them.

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.

What to Spray
It is crucial that you preserve your beneficials while still getting high efficacy. Insecticide efficacy trials on the High Plains last year confirmed that there are only two good choices when it comes to SCA: Sivanto and Transform. (FYI – Both of these products will take out both SCA and Yellow SCA!).

The data below are from Dr. Ed Bynum and Dr. Pat Porter’s SCA trial in Bushland in 2015. The significant spikes in aphid numbers following treatments of Karate and Nufos (Chlorpyrifos, also sold as Lorsban) are because the treatment also killed the beneficials. Nufos (Chlorpyrifos) at one pint, and Karate at 1.92 oz provided poor control but, to make matters worse, any aphids that escaped the treatment were allowed to reproduce without any pressure from predators.

Chlorpyrifos can be effective at one quart per acre (while killing beneficials and allowing population resurgence), but at this rate has a preharvest interval (PHI) of 60 days. Transform has a PHI of only 14 days for grain or straw harvest and 7 days for grazing, or forage, fodder, or hay harvest. Sivanto has a PHI of 7 days for forage and 14 days for dried grain, stover, or straw. Always make sure to read your labels before using any chemical.

Tuesday, July 26, 2016

On July 21st, I received word that Eddie Meeks (crop consultant) found sugarcane aphids while scouting in a sorghum field near Black, TX. Black, TX is approximately halfway between Hereford, TX and Friona, TX on US Highway 60. This is the farthest northwestern location that the sugarcane aphid has been reported on the Texas High Plains.

Photo by Mr. Eddie Meeks

Thursday, July 14, 2016

Sugarcane Aphid in Crosby County

Sugarcane aphids have been found in sorghum in northeastern Crosby County, just west of McAdoo. There were mixed populations of SCA and yellow sugarcane aphids, both at low levels. Less than 5% of plants were infested, and colonies were small with 5-10 aphids each. Only one winged adult was found. Aphids were only on the north side of the field. 

Wednesday, July 13, 2016

Managing Sugarcane Aphid on the Texas High Plains

Now that sugarcane aphid has been found in Floyd County it is safe to assume that we will shortly find it in surrounding High Plains counties. We all went through the aphid invasion last year and there is no need to go in to great depth on scouting and management, so I will just hit the highlights from lessons learned last year. If you want to read our complete 2016 sugarcane aphid management publication it is here.

Early planting is going to pay off

The earlier the aphid arrives during crop development, the more damage it can do. Infestations prior to boot can cause sterile panicles and decrease yields to essentially zero. Infestations at or after flowering, while still very serious, are somewhat less potentially damaging. This is why our treatment thresholds vary by crop 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.

Our earlier planted sorghum has either finished flowering or is now flowering and has moved to the place it can withstand more aphids. In part this might matter because we have a relatively high number of beneficial insects in the system, and they have a better chance of keeping populations below treatment thresholds when those thresholds are higher. And even if one insecticide application is necessary, the need for a second application is far less likely in a much more mature crop.

Weekly scouting is a must

Under hot, dry conditions, the reproductive capacity of this aphid (which is born pregnant) is something approaching Shock And Awe, and everyone who went through the 2015 season will agree.  Missing a weekly scouting might mean missing populations low enough to be brought under control with insecticides. In 2015 we had many fields that were sprayed too late and adequate control was not achieved without a second application. Once the aphid has been found in a field, then twice-weekly scouting is important. Last year I would have linked to our guide to recognizing the sugarcane aphid, but this year I think we all know what the enemy looks like.

"Tolerant" hybrids are susceptible hybrids

There are a few hybrids with resistance to sugarcane aphids, although the seed industry chooses to call these "tolerant" hybrids because they rightly don't want to give the impression they are bulletproof. Our best resistant hybrids are what could be called moderately resistant, and this won't stop the aphids from reaching treatment thresholds. It may slow them down, and it may let the beneficial insects have more time to exert control, but all other things being equal it is merely a delaying action. Fields of "tolerant" hybrids should be scouted and sprayed based on the treatment threshold just like fields of completely susceptible hybrids.

Insecticide choice matters - a lot

Last year saw everything in the book, and some things not in the book, being thrown at sugarcane aphids. Many of these insecticide products were our old aphid standards, and what we found was that they were not very good at killing aphids, but they were very good at killing beneficial insects (the big guns in aphid control after an application). Our insecticide trials confirmed this; we had massive aphid resurgence where we killed the beneficial insects. There are only two good insecticide choices for sugarcane aphid: Sivanto and Transform. Both of these provide high efficacy with minimal impact on beneficial insects.

Make the first application count

Last year we observed insecticide applications of Sivanto and Transform made with high rates and plenty of carrier volume most often did such a good job of control that the few surviving aphids were cleaned up by beneficial insects. Conversely, we observed that fields sprayed with lower rates and/or insufficient carrier volumes frequently did not get control and required a second application.

Experience is a good teacher

This pest is manageable. Last year was a bit of trial and error, but after one growing season of intense aphid pressure we are much better equipped in 2016.

Sugarcane Aphid in Floyd County, Probably Other Counties

Post by Blayne Reed, Extension IPM Agent in Hale, Swisher and Floyd counties.

Independent crop consultants have found sugarcane aphids in Floyd County.  The populations are very light, hard to find, and as of this morning, only along the ‘waterways’ leading westward up the caprock or on the very few fields off the caprock farther east.  These draws cut a pretty good way westward into Floyd and Crosby counties.

One of the fields confirmed with SCA was actually in southwestern Floyd at the edge of one of these draws.  It is very likely we have SCA farther west right now than we realize, but at a level very difficult to find without a fleet of entomologist in every field.  At face value this looks like the same infestation pattern we have had for the two previous years with the aphids either flying on the easiest route or pushed by wind up these ‘funnels’ and drawn to the irrigated sorghum fields on the edges of the draws.  In terms of population today, the number of infested plants is well  below 1% with less than 10 aphids per colony.  We all know how fast this can change and all of our consultants involved with these finds have already re-visited these few infested fields with little change so far.  There are not many winged aphids yet.

This is a very quick and early find by several of our outstanding area independent crop consultants in the region.

Thursday, July 7, 2016

Reports of Sugarcane Aphid in Oklahoma

I received a call this morning from a County Extension Agent from Lipscomb County in the Texas Panhandle. He had seen on Facebook that sugarcane aphids were found near Clinton, OK. As a crow flies this about 175 miles east of Amarillo, TX on interstate 40. I contacted Dr. Tom Royer, Oklahoma State University entomologist, to see if this could be confirmed. He stated that low numbers of sugarcane aphids were beginning to be found in several Oklahoma counties. So, this is just another report of an increase in sugarcane aphid activity.

Aphids Found in Mills County, Reported in Comanche, Hamilton Counties and More

Tom Guthrie, County Extension Agent Ag, in Mills County is reporting building populations of sugarcane aphid on sorghum in Mills County. Some fields have exceeded the economic threshold. He has credible reports of sugarcane aphids in Comanche and Hamilton counties.  Additionally, a private consultant has reported finding aphids in Nolan, Fisher and Jones counties at treatable levels.

Sugarcane aphids on sorghum in Mills County. Photo credit: Tom Guthrie.

Aphids Found in Mills, Comanche, Hamilton Counties and More

Tom Guthrie, County Extension Agent Ag, in Mills County is reporting building populations of sugarcane aphid on sorghum in Mills, Comanche and Hamilton counties. Some fields have exceeded the economic threshold. Additionally, a private consultant has reported finding aphids in Nolan, Fisher and Jones counties at treatable levels.

Sugarcane aphids on sorghum in Mills County. Photo credit: Tom Guthrie.

Saturday, July 2, 2016

Sugarcane Aphid in Sorghum near San Angelo

Joel Webb, EA-IPM Runnels and Tom Green counties, today has identified sugarcane aphids in the San Angelo area.  This is the nearest confirmed growing season report of the sugarcane aphid to the High Plains area.

The aphid was confirmed as overwintering right here in Hale County and was found on native Johnson grass in Lubbock, Hale, & Swisher Counties earlier this spring, but since that time has fallen off the ‘radar’ with no more colonies found in our area.  We assume healthy populations of predators are to credit for the disappearance of the aphid from our area, but we cannot be certain.  With no native sugarcane aphids to monitor, we have been and will be watching the migration of the aphid from the south while anticipating and bracing for their arrival on the High Plains.  In the Valley, Coastal Bend, and Hill Country, the aphid has been an economic pest this year, but reduced in population compared to recent seasons.

(Text copied from Blayne Reed's 7/1/16 newsletter)
We have a concise guide to recognizing the sugarcane aphid.

Wednesday, June 29, 2016

Sugarcane Aphid on the Texas High Plains; So Far a No-show

Given that we know sugarcane aphid overwintered as far north as Plainview, and that it was found on Johnsongrass in Lubbock County in early May, the question we are most frequently asked lately is, "Why don't we have sugarcane aphids yet?"

That is a good question, and I wish I could be totally certain of the answer. I suspect that our beneficial insects wiped out the overwintering aphids. We had extremely high numbers of ladybugs, syrphid flies and the other predators that went in to overwintering last year after feasting on sugarcane aphids. In what should be considered to be good news, we also had fairly heavy aphid numbers in wheat this spring, but not enough to do significant economic harm. But these wheat aphids, which were not sugarcane aphids, provided food for our early season beneficial insects, which in turn were available to start munching on the overwintering sugarcane aphids in the area. This is just conjecture on my part, but it is the simplest explanation of why sugarcane aphid was here in the early season and is now gone.

The next most common question we are getting is, "When will the aphids arrive?" Of course no one knows the answer, but later is better, and growers who planted early are seeing a benefit from that practice. Last year the first sugarcane aphids found on the High Plains were discovered in Lubbock County on June 27th, and within three weeks we were scrambling to get fields sprayed. I think that last year we had some colonies beginning to build locally in late June, but, given the wide area infested a few weeks later, it is most probable that one or more flights of winged aphids came up from the south on wind or storm events. This year we probably do have some small pockets of sugarcane aphids locally. The good news is that aphids are not extremely numerous on the Gulf Coast and in the Hill Country. Our colleagues south and east of here are reporting that they have only light to moderate infestations (although some fields required treatment). They are also saying that beneficial insects are catching up to the aphid populations and decimating them. This is means there will be fewer aphids traveling on the winds and landing on our front door. If we have fewer aphids colonizing our plants then the beneficial insects we have in the system will have a better chance of suppressing those that do arrive.

I wish I could predict what will happen in the next few weeks, but of course I can't. If you find sugarcane aphids in your fields then please give us a call. The telephone numbers for your High Plains IPM Agents and Extension Entomologists are listed here. We sincerely appreciate people who take the time to call and report pest problems.

Tuesday, May 24, 2016

Blacklands Update

Sugarcane and Yellow Sugarcane aphids are slowly increasing in population, and individuals and small colonies (3-4 aphids) can be seen on the mid-upper leaves. Populations remain well below thresholds.
The pictures below (taken today) show SCA on sorghum in Hill County. Only a few populations this large have been seen in the fields, and these were isolated colonies (surrounding plants were clean). You can see larvae of the Scymnas ladybug preying on the aphids. Beneficial activity has been high.

Monday, May 9, 2016

SCA found on sorghum in Hill County

A few sugarcane aphids (SCA) have been found feeding on sorghum around Itasca as of Friday, May 6. Aphid numbers are very small, on less than 1% of plants with only one or two aphids per colony. SCA were found last year as early as May 29th.

Winged SCA and two nymphs.

One SCA in a colony of Yellow SCA.

Tuesday, May 3, 2016

Sugarcane Aphid Found in Lubbock County

Dr. Pat Porter and I found several sugarcane aphids this morning on Johnson grass about 6 miles east of New Deal. We found adults, several nymphs and even one alatoid (a nymph that will soon become a winged adult). We confirmed that these are in fact sugarcane aphids using a microscope and identifying their characteristic dark-tipped antennae, cornicles and feet. This finding on May 3 is almost a full eight weeks before the first sighting of SCA in Lubbock Co on June 27 last year.

SCA on Johnson grass. Photo by Pat Porter.