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Saturday, May 20, 2017

Plant Bugs and Aphids


  There are still cotton fleahoppers around this week. Treatments have been made for them in all three counties, and I was picking up more nymphs this week than I was last week. Threshold is 15 - 20% plants with fleahoppers. Cotton is beginning to bloom in all three counties. Fleahoppers will no longer be a pest of concern once a field reaches the first week of blooming. Once a field is blooming, we need to start watching out for other plant bug pests, like the verde plant bug, lygus bugs, and stink bugs. In the Rio Grande Valley, Dani has reported a few verde plant bugs moving into cotton as well as a few bollworms. I found a couple of lygus bug nymphs in a Matagorda county field this week.
  Prior to peak bloom it's recommended that a sweep net be used for sampling for lygus. Using a standard 15 inch sweep net, make 15 - 25 sweeps at a time, concentrating on a single row. The number of sweeps you will be able to make is dependent on the amount of foliage that accumulates in the net. Avoid letting the net accumulate too much debris, since it will prevent you from getting an accurate sample. Try to take at least 100 total sweeps from 4 - 6 locations in the field.

  We did receive approval for a section 18 for use of Transform in cotton for control of plant bugs. This section 18 expires October 31, 2017. When using Transform to control plant bugs the rate per application allows for 1.5-2.25 oz/acre, with no more than a total of 8.5 oz/acre per year. Remember not to apply within 14 days of harvest, make applications less than 5 days apart, or make more than two consecutive treatments per field. The full section 18 label can be found here.

Cotton Flower
Photo: Kate Harrell
  This week sugarcane aphid populations are on the rise. If you need the scouting guide, it can be found here. Threshold for these insects begins at 50 aphids per leaf if field conditions are warm and dry. The two products available to spray for the sugarcane aphids are Sivanto and Transform. Use Sivanto at 4-5 oz/acre, do not go lower than 4 oz for good residual. When applying with a ground rig use at least 10 gal per acre to get the chemical into the lower canopy. If the canopy cover is pretty dense, you may need to go to 15 gal. For Transform use at 1-1.5oz/ acre, and do not go lower than 1 oz for good residual.
Full Reference Material
   In the Rio Grande valley, Dani has been finding rice stink bugs and sorghum midge. We need to be watching for those pests as well. Midge is a problem in sorghum during bloom, the female midge lays eggs in the florets, where the maggots consume the developing fruit. To check for midge, beat the flowering grain head around inside a bucket or jar. Any midge will wind up smeared on the side of the container. Check at least 20 heads per 20 acres of field. If the fields are smaller than 20 acres, check 40 heads. The threshold for midge can be calculated by this calculator or:

Number of midges                  (cost of control in $ per acre x 33256)

per flowering head = (Value of grain in $ per cwt x number of flowering heads)

  I saw a few rice stink bugs starting to show up in fields in Matagorda county this week. Use the same bucket technique used for midge to check for rice stink bugs, but check at least 30 plants or 1 sample per acre in larger fields. This calculator will help determine threshold for rice stink bug.

  Keep in mind that treatments for rice stink bug or midge can knock back predator populations and flare aphids. That doesn't mean that you shouldn't treat if you find stink bugs or midge at threshold, but it does mean that you should check aphid populations after treatment and be ready to treat with Transform or Sivanto afterward if populations do flare.

Wasp Mantidfly
Photo: Kate Harrell
  This week's insect is the wasp mantidfly. The adults are predatory, and will hang out near flowers. They grab and eat whatever flies by with their raptorial forelegs. Their color pattern and shape mimics that of a paper wasp, which keeps things that would be predators away, since they are mistaken for something that stings. The larvae of this insect species are parasitoids of spiders, and eat their host from the inside out before pupating and emerging as adults.

  On Wednesday I got a call about some interesting feeding activity near the edge of a field in the Crescent area. The damage was beside a house with a couple of trees around it. The photos below show some cotton plants that appear to be gnawed off at the base of the plant. Leave a comment with what you think happened!

Have a great weekend everyone!



For more information check out:

Danielle Sekula's full Pest Cast

Texas Sugarcane Aphid News

Lygus bugs in the Cotton Insect Management Guide

Friday, May 12, 2017

Fleahoppers to Plant Bugs and Aphids to Midge


  This week the fleahopper numbers in cotton are mostly down. I know several folks have treated for them, and have had no trouble knocking populations back. The threshold for fleahoppers is 15-20% of plants with fleahoppers. Some of the cotton in Jackson and Matagorda county is starting to bloom. Cotton fleahoppers are no longer a concern after plants are blooming, but we will need to start looking out for stink bugs, lygus bugs, and verde plant bugs after bloom.

  Sugarcane aphids were reaching treatable levels in a few places in Jackson and Matagorda county this week. They tend to pop up on the edges of fields first, then move in to the rest of the field. This guide is a good tool to use when scouting for them. Keep in mind that sugarcane aphids have black cornicles (tailpipes), feet, and antennae ends. They tend to be pale yellow in color, and lack the opaque green stripe down the middle that greenbugs have. The aphid populations I've seen have been mixed with corn leaf aphids, greenbugs, and the sugarcane aphids.
Photo: Kate Harrell
Sugarcane Aphids
Photo: Kate Harrell

  Some sorghum is starting to boot or head out in all three counties. Once it begins to bloom, we need to keep and eye out for sorghum midge, and then for rice stink bug. The threshold calculator for sorghum midge can be found here, and the threshold calculator for rice stink bug can be found here.

  This week's bug is one a vegetable grower I get veggies from brought me last week. The photo below unfortunately doesn't show the full color of the insect. The body was black when looked at straight on, but iridescent blue from any other angle. This is an anchor bug nymph, and it is a type of predatory stink bug. It was a good challenge to identify, I had wrongly assumed it was a plant feeder (since it's a stink bug), and spent time looking over pest species. It's a predator! The adults of several species have white, orange, or yellow markings on the back that closely resemble the shape of an anchor, hence the name.

Anchor Bug
Photo: Kate Harrell
Let me know if you have any questions or concerns. Have a great weekend and happy mothers day!


Friday, May 5, 2017

Fleahoppers and Sugarcane Aphids


  The cotton in Wharton county ranges from cotyledon to half grown squares. In Jackson and Matagorda county all the cotton I have looked at is squaring nicely. Nearly everything has some wind damage. The nicest looking cotton I've looked at in Wharton county was near a tree line that blocked the wind. I'm hoping the wind will let up and we can catch a little rain soon. This week I saw more adult fleahoppers in cotton, but I've seen very few nymphs so far. There were a few fields at threshold this week in all three counties. Fleahopper feeding will cause squares to drop, and plants can recover for and compensate for some square loss. The threshold for fleahoppers is 15-20 per 100 plants.

Cotton Fleahopper
Photo: Kate Harrell
  I'd also like to note that Texas received approval for a Section 18 for use of Transform in cotton to control plant bugs. This label is good until the end of October. The rate for plant bug control with Transform is 1.5 - 2.5 oz/acre, with no more than a total of 8.5 oz/acre per year used, and no more than 2 consecutive applications per crop. Don't apply within 14 days of harvest, and don't make applications less than 5 days apart. The label can be found here.
  Dani Sekula, in the valley, reported seeing some tarnished plant bugs, and a few isolated fields with verde plant bugs and stinkbugs. She also had a few fields in her area treated for red spider mites. The aphid numbers have been crashing in the valley as the beneficials catch up with them.

Sugarcane Aphids
Photo: Kate Harrell
   Sugarcane aphid populations are present in sorghum fields in Wharton, Jackson and Matagorda counties. I heard of fields at threshold and being treated in Matagorda county. Populations in Wharton county seem to just be moving in to sorghum. The colonies I found were small, on the edges of the field, and contained a winged aphid. Check out techniques and timing recommendations for checking sugarcane aphids in the chart below. Transform and Sivanto are the two chemicals labelled for use on sugarcane aphids in sorghum.
  Stephen Biles has been seeing low numbers of sugarcane aphids in Calhoun, Refugio and Victoria counties. Everything so far has been along the edges of the fields, similar to what I have seen in Wharton county.

Lady Beetle Eggs
Photo: Kate Harrell

Sugarcane Aphids and Lacewing Larva
Photo: Kate Harrell
  I would like to mention that today I saw a few flags out marking the herbicide technologies. If you need flags to mark your herbicide tolerance, contact either your seed sales rep or your chemical retailer to get flags. It never hurts to double check a chemical label, either. It's always good to know the recommendations for any application. 

  The bug of the week this week was brought to me last week as a lovely caterpillar, and has now moved on to the pupal stage. It's a polyphemus caterpillar, and is one of our very large native silk moths. They eat a variety of broad leaf trees and shrubs. They are commonly found on oak trees, but this particular caterpillar was on (what was left of) an azalea. For size reference, the pink thing in the photo of the caterpillar is a pencil, the caterpillar was larger than my thumb. The cocoon is in the corner of a reusable grocery bag. I'll keep you updated on its progress! 

Polyphemus caterpillar, left

Polyphemus cocoon, right

Photo: Kate Harrell
Let me know if you have any questions or concerns, and have a great weekend.


Looking for more information? Check out the resources below.

Dr. Gaylon Morgan and Dr. Josh McGinty's most recent Texas row crop newsletter on the Varying Tolerances to Liberty Applications in Cotton Varieties can be found at the link below:

Danielle Sekula, the IPM agent in the valley, posted her most recent Pest Cast Newsletter at the link below:

Stephen Biles, the IPM agent in Calhoun, Refugio and Victoria counties most recent newsletters for sorghum and cotton can be found at the following websites: