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