Thursday, March 23, 2017

First 2017 Texas SCA Discovery in Commercial Fields

Danielle Sekula, IPM Agent in Weslaco, is reporting finding small colonies of sugarcane aphids. She said, "My student Alma and I detected sugarcane aphids on commercial sorghum at about the V8 stage down by the river in Hidalgo County. That was on Tuesday, March 21, about 3 weeks earlier than we first found them in a commercial field in 2016. The colonies we found this week were small, containing one winged aphid (alate) and 3 to 5 small nymphs. Sugarcane aphids are barely starting to colonize. But with the current heat and strong winds, the sugarcane aphid may start to populate rapidly and migrate north quickly in our valley sorghum in the next few weeks.

Please start scouting your sorghum diligently and prepare for possible spray applications, if need be."


Thursday, March 2, 2017

Preparing for Sugarcane Aphid on the High Plains Part 1: Early Season

Sugarcane aphid will most likely return for another run at the High Plains sorghum crop in 2017, and this is the first in a series of articles to compile management suggestions based on what we learned from our 2015 and 2016 research and general field experiences. Contributors to this work include Dr. Ed Bynum, Extension Entomologist in Amarillo, Dr. Katelyn Kesheimer and Blayne Reed, Extension Agents IPM in Lubbock and Crosby counties and Hale, Swisher and Floyd counties, respectively, and Dr. Pat Porter, Extension Entomologist in Lubbock.

Beneficial insects cleaned up the overwintering aphids in 2016

In our 2015/2016 overwintering studies we found successful aphid survival as far north as Tulia. This was a bit of a surprise as our studies the previous year found survivorship only as far north as Hale Center. In 2016 we found SCA on Johnsongrass in Lubbock and Swisher counties in early May. At the time we were concerned that it would be a long aphid season, but fortunately there were abundant aphids in 2016 wheat. These served as food sources for the large number of beneficial insects that went in to overwintering in the fall of 2015 after feeding on sugarcane aphids. After the initial 2016 aphid finds on Johnsongrass we intensified our search, only to discover that the small sugarcane aphid populations were no longer to be found. It seems that the beneficial insects finished eating aphids in wheat and then moved over and wiped out the overwintering and colonizing sugarcane aphids on Johnsongrass.

Eventually sugarcane aphids began to arrive from the east in July, first along the cap in Crosby and Floyd counties. This time they trickled in little by little, and this was fortunately unlike the large clouds of winged aphids that hit the southern High Plains all at once in 2015. Last year's gradual westward movement of aphids meant that they were relatively predictable.

What about this year?

The abundance of beneficial insects early in the season this year will be important in protecting sorghum by preventing aphid movement from Johnsongrass to sorghum fields. Given that we had far less sorghum in 2016 than in 2015, it is the case that we had fewer beneficial insects going into overwintering in 2016. In effect we are starting 2017 with fewer beneficial insects in the system, but fewer sugarcane aphids as well. Katelyn Kesheimer checked some wheat fields today and found that some had high numbers of bird cherry-oat aphids and greenbugs, but there were high numbers of beneficials insects as well. Other wheat fields did not have many aphids or beneficial insects. Ultimately, aphid infestations on the High Plains will depend on overwintering and the earliness of arrival and severity and movement of sugarcane aphids from downstate. This causes a level of unpredictability for our 2017 sugarcane aphid situation. We will monitor populations and report our findings in this newsletter.

Early planting resulted in far less aphid pressure

Our primary recommendation for 2016 was to plant early so that the sorghum was as far along in growth stage as possible by the time aphids arrived. It is well documented that earlier growth stages can suffer more damage, so the idea was to outrun the aphid as much as possible. This strategy paid big dividends in 2016 for those who employed it.

However, to a lesser extent in 2015 we were also suggesting that late planted sorghum might suffer less damage because of all of the beneficial insects in the system that had developed on earlier planted crops. This definitely did not happen in 2016 and the standard and late planted crops were severely damaged by the aphid. So with two years of experience and data, our strongest recommendation is to plant early so as to outrun the aphid as much as possible.

Seed treatments are cheap insurance

We recommend that neonicotinoid seed treatments be used on all sorghum. In 2016, the early planted crop would not have benefitted from the 45 days of protection afforded by seed treatments. However, if we had not had abundant aphids in wheat to serve as food for the large number of beneficial insects that went in to overwintering, it might have been a different story and the early planted sorghum crop might have been infested in May or June. It is too early to tell whether we will have a similar high number of overwintered beneficials to provide protection in 2017. Fields planted in the normal window or late could expect significant aphid pressure within the 45 day window of seed treatment effectiveness. Also, even though seed treatments gradually play out, they still provide some sub-lethal effects on aphid reproduction beyond 45 days and, depending on chance, seed treatments might mean one insecticide application later rather than two. On balance it makes sense to use treated seed to protect against downside risk of infestations in pre-flowering and flowering growth stages. Even for standard and late planted sorghum the ability of seed treatments to provide protection depends largely on when the aphids infest the crop during the season. Therefore, even fields with treated seed need to be scouted for sugarcane aphid.

"Resistant or Tolerant" hybrids are still susceptible

None of the so-called resistant or tolerant hybrids on the High Plains have been shown to be able to keep aphid numbers below treatment thresholds. At best they slow the rate of aphid population increase; when the aphids arrive the threshold will most probably be exceeded and insecticides will be necessary. However, our research at Halfway showed that there is a significant economic benefit to using resistant hybrids even though they still need to be sprayed at the normal threshold. As yet we do not have a list of resistant or tolerant hybrids that we have confidence in, and it will take three years of replicated data from the High Plains before solid recommendations can be made. At present we recommend that growers consult their local seed company for suggestions on resistant or tolerant hybrids.

Coming in Part II

The next article will address treatment thresholds, insecticide rates and efficacy, and an economic threshold for a potential second insecticide application if the first application failed or could not be made.

Monday, February 20, 2017

Short High Plains SCA Management Videos Posted

We have just posted nine short videos that encompass our 2015 - 2016 research results and experiences as a primer as we enter the 2017 season. Presenters are Katelyn Kesheimer, IPM Agent in Lubbock and Crosby counties, Blayne Reed, IPM Agent in Hale, Swisher and Floyd counties, Dr. Ed Bynum, Extension Entomologist in Amarillo, and Dr. Patrick Porter, Extension Entomologist in Lubbock.

The videos present data from the Texas High Plains and may not be applicable elsewhere.

1. Aphid overwintering and seasonal abundance (3:41)
2. Early planting is a good idea (3:40)
3. "Resistant" sorghum hybrids and seed treatments (4:23)
4. First insecticide application threshold (3:03)
5. Insecticide application and product efficacy (8:46)
6. Timing of a second insecticide application (4:15)
7. Rate of damage with uncontrolled aphid populations (4:05)
8. Insecticides to prevent sticky harvest problems (5:56)
9. Aphid effects on stalk quality for grazing (3:43)

Sunday, February 12, 2017

Transform Insecticide Granted 2017 Sec. 18 Label

Dale R. Scott and his colleagues at the Texas Department of Agriculture have once again secured EPA's permission to use Transform WG (sulfoxaflor) on sorghum. The conditions are identical to last year; the product may not be used within three days of flowering until seed set, there can only be two applications, and the highest rate is 1.5 oz/acre. The pre-harvest interval is 14 days for grain or seven days for grazing, forage, fodder or hay harvest. The full EPA document is here.

We would like to thank Dale for his continued efforts on behalf of Texas sorghum producers; TDA has successfully garnered a Transform Section 18 each of the last four years.

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.