2015 Sugarcane Aphid Efficacy Trial – 7 DAT Counts

2015 Sugarcane Aphid Efficacy Trial – 7 DAT Counts

               

                The sugarcane aphid continues to amaze in a startling way across the region.  Today I recommended treatment on the last of our scouting program fields that had been thus far untreated.  That makes 100% of our participating grower’s sorghum fields across Hale, Swisher, & Floyd that has reached the action threshold for at least their first treatment.  The pattern of these fields seemed to go from 1-2 sugarcane aphids per leaf across the field to 48.9 – 128.9 aphids per leaf across the field in 10 to 14 days.  With so much unknown about this new aphid to the area and products untried in the region, all new information should be shared with consultants, industry, and producers as soon as possible.  Yesterday we made our 7 days after treatment in our trial field just east of Hale Center. 

                For this trial, we have teamed up our program with our district entomologist from district 1 and 2, Dr. Pat Porter and Dr. Ed Bynum, Syngenta, and Bayer Crop Science.  Shared with you today are varying rates of products currently recommended or labeled for sugarcane aphid control.  Unfortunately, we had a SNAFU and misunderstanding in dealing with unfamiliar partnering equipment, GPA output, and chemical calculations that through this trial off with a 16.7% lower rate than what was intended for each treatment.  Actual applied amounts are shared here. 

                Data consists of 5 randomly selected plants from each small plot where we counted all aphids on one lowermost green leaf and one upper leaf (second leaf below flag leaf) from each randomly selected plant for a total of 10 leaves per plot.  This trial is an RBD and has 4 replications.  Due to noted differences in control between the upper leaves and lower leaves, we have calculated differences in aphid numbers in terms of upper and lower leaves in addition to total aphids averaged per leaf. 

                The ineffectiveness of controlling the aphids on the lower leaves in this trial should be chalked up to coverage.  The row spacing in these plots is 32 inches.  These plots were treated with 16.5 GPA and all treatments were applied with 0.25% NIS as a surfactant and still we did not seem to penetrate the canopy enough to achieve control on the lower leaves.  This matches what we are seeing in treated fields also.  I have been in contact with several independent crop consultants indicating similar findings in their area fields.

                Russ Perkins, Bayer Crop Science, is recommending changing adjuvants to an COC, something with silicone or something heavier to help penetrate down into the canopy to get at those lower, aphid covered leaves.  Monti Vandivier, Syngenta, seems to agree, “It’s all about coverage right with this aphid right now.  We need to penetrate that canopy and cover the entire infested area.  In my trials, I have been using Dynamic and getting decent penetration… at least on 40 inch rows… Controlling this sugarcane aphid reminds me a lot about fighting heavy spider mites in corn.  We need a good MSO or something heavy to pull those treatments down.”

                Today Russ told me, “Adjuvant choice with Sivanto should not impact the product quality… We just need it as deep in the canopy as we can get it.”

               

Special thanks to Dr. Pat Porter for making these graphs while I was in the field today!!!

Blayne Reed

New Mexico and Top Tier of Texas Infested by Sugarcane Aphid

New Mexico and Top Tier of Texas Infested

Robert Bowling has updated the sugarcane aphid infestation map to, in part, reflect Jane Pierce's discovery of aphids near Clovis, New Mexico, and a confirmed report from Ochiltree County at the top of the Texas Panhandle. Dr. Pierce is an entomologist with New Mexico State University and her discovery in New Mexico is a first for the State.

The latest map does not yet reflect the reality that many southern High Plains counties are now applying insecticides to aphids at or over the threshold.

Sorghum Midge Threat While Under Sugarcane Aphid Watch

Sorghum Midge Threat While Under Sugarcane Aphid Watch

                 The following was written by Dr. Pat Porter, District 2 Entomologist, about the potential sorghum midge threat this season.

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.

Thanks Pat!!!

Blayne Reed