Aphids and Thrips

Western Flower Thrips Adult
Photo: Kate Harrell

Howdy,

  I am currently keeping an eye out for thrips. This is a small (about 1/15") light tan or straw colored insect with a punch and suck type mouthpart and asymmetrical mandibles. They punch a hole with one side, then siphon the juice out with the other. They feed one plant cell at a time, and march along punching and sucking as they go. The adults are winged, can travel short distances on their own, and can be carried by a breeze for a fair distance. Larvae hide on the underside of the leaves, often close to the leaf veins. Feeding damage for this insect causes the leaves to crinkle and curl, and often looks silvery when examined. Thrips feeding can cause delays in plant maturity and eventual yield reduction.

Thrips Feeding Damage
Photo: Kate Harrell

  While the insects are visible to the naked eye and scouting can be done just by examining the plant, it is easy to miss some of the smaller larvae. Smacking a cotton plant around on the inside of a cup will knock them off and can make them easier to count. This video Blayne Reed put together has techniques for scouting thrips as well. Cotton with a neonicotinoid seed treatment is usually safe from thrips for about 2-3 weeks after emergence. Seedlings in a sandier soil will lose the effects of a seed treatment more quickly than those in heavier clay soils. Rainfall can also impact how long the seed treatments are effective, the more it rains the shorter the amount of time the seed treatment stays effective. Our weather has been particularly uncooperative up until most of this week, and we have a good deal of 1-2 leaf cotton that has already been in the ground long enough to have lost seed treatment protection.

  The economic threshold for thrips is one thrips per true leaf of the plant until the 5th true leaf stage. Once the plant reaches this stage, treatment for thrips is rarely justified. Check out the cotton insect guide at this website for more information.

Aphids on Cotton
Photo: Kate Harrell

The threshold for cotton aphids is 50 aphids per leaf, and if you see the aphid mummies in the field, that's a good thing. Parasitoid wasps lay eggs in the aphids, and the aphid forms a mummy while the wasp larvae pupates inside. These wasps, lady beetles, and lacewings all can make a dent in aphid numbers. Treatment for aphids is very rarely justified since the numbers need to be so high before they can cause an economic problem. If you do decide to treat for aphids, do not use a pyrethroid. Pyrethroids are non specific, and kill predatory insects as well, but aphids will bounce back quickly due to their high reproductive rate. 

Aphid Mummies on Cotton
Photo: Kate Harrell

  Lately I've heard some talk about spider mites in cotton, but those tend to prefer hot and dry weather. The humidity here normally keeps their numbers from getting too high. If you are concerned about a field, there is more information on this website.

  I've still been seeing sugarcane aphids on Johnson grass on the edges of fields. A&M is participating in a nation wide mapping project for the sugarcane aphid movement again, and I check very few sorghum locations. If you see sugarcane aphids moving into sorghum, I would greatly appreciate it if you would contact me. Your input will help a great deal with this mapping project.

  Please feel free to contact me if you have any questions or concerns, and check out the links below for more information.

Sincerely,

Kate Harrell

For More Information:

Aphids in Cotton

Cotton Growth and Development overview

Cotton Growth and Development

Plant Population Evaluation

Replant Decision Making

Wind Damage

Howdy,

  We have experienced entirely too much wind lately, and I've seen varied degrees of stressed cotton in all three of my counties. The wind damage along with the cooler temperatures have been rough on a lot of seedling cotton. If your plants have a live green growth point and the stem isn't crispy, it's likely the plant will recover. Research shows that fields can still be considered viable with stand counts as low as 13,000 to 26,000 plants per acre, as long as they are evenly spaced.

Wind Damaged Cotton
Photo: Kate Harrell

Wind Damaged Cotton
Photo: Kate Harrell

Wind Damaged Cotton Seedling with New Growth
Photo: Kate Harrell

Wind Killed Cotton Seedling
Photo: Kate Harrell

Wind Damaged Cotton Seedling
Photo: Kate Harrell

Wind Damaged Cotton Seedling with Viable Growth Point
Photo: Kate Harrell

Wind Damaged Cotton, Dead Seedling on Left, Two Viable Seedlings on Right
Photo: Kate Harrell

  Thrips are also a concern currently. Seed treatments have worn off after 3 weeks, even if the plants have been in the ground but haven't been up for that long. Thrips can add stress to our already stressed cotton. Our economic threshold for thrips is an average of at least one per true leaf, until the 5th true leaf stage.

  I have been picking up sugarcane aphids on Johnson grass on the edges of fields. A&M is participating in a nation wide mapping project for the sugarcane aphid movement, and I check very few sorghum locations. If you see sugarcane aphids moving into sorghum, I would greatly appreciate it if you would contact me. Your input will help a great deal with this mapping project.

  Feel free to contact me with any questions or concerns. I hope everyone has a great weekend and our weather gets a little more cooperative.

For more information check out:

Cotton Growth and Development overview

Cotton Growth and Development

Plant Population Evaluation

Replant Decision Making

Ag Symposium

  A web-based producer training, or webinar, is scheduled for April 17, 2018. It will be taking place at the Wharton, Jackson, and the Matagorda county office. The addresses and a phone number for each location are:

Wharton County Extension Office- (979)532-3310

315 East Milam Street, Suite 112

Wharton, TX 77488

Jackson County Services Building, Kitchen- (361)782-3312

411 North Wells Street

Edna, TX 77957

Matagorda County Extension Office- (979)245-4100

2200 7th Street

Bay City, TX 77414

1 CEU in the IPM category and 1 CEU in the general category will be offered to Texas Department of Agriculture Pesticide License Holders. There will also be an EPA Auxin Specific Training at the end of the program for those that still need to attend one. There is no fee to attend this program. Please check out the program schedule below:

2018 Corpus Christi Agriculture Symposium: Putting $ Back in Your Pocket

April 17, 2018

7:30 am-12:15 pm

7:30-8:00 am REGISTRATION

Marine

8:00: Baitfish as a Secondary Crop for Aquaculture Producers – Dr. Andrew Ropicki, Marine Economics Specialist

Live marine baitfish represents a potentially profitable new market for current Texas marine aquaculture (red drum and shrimp) producers. This presentation examines the economic feasibility of Texas red drum farms adding pigfish production to their operations. 

Range and Livestock

8:30: The Forgotten Goat – Dr. Joe Paschal, Extension Livestock Specialist

Since cattle are the main livestock enterprise in Texas, they are the typical focus for most educational programs.  Learn about the goat, another excellent meat animal, and considerations for managing a herd!

9:00: Alternative Ranching Operations – Dr. Megan Clayton, Extension Range Specialist

Review some options for adding to an existing conventional ranch or develop value-added programs to increase profitability.

9:30: Tips for Stretching your Dollar in Forage Production – Dr. Josh McGinty, Extension Agronomist (0.5 General CEU)

Highlighting ways to increase the efficiency of inputs in improved pasture and hay production, including species/variety selection, fertility management, and weed control.

10:00: Internal and External Parasites in Livestock – Dr. Joe Paschal, Extension Livestock Specialist (0.5 General CEU)

Review parasites that could decrease cattle productivity, how and when to treat them, and preventative measure to take.

10:30: Cost Saving Tips for Brush Control – Dr. Megan Clayton, Extension Range Specialist (0.5 IPM CEU)

Management of brush can be an expensive endeavor. This session will review a few ways you can reduce your cost through thoughtful follow-up treatments, equipment ideas, and chemical selection.

11:00 – COFFEE BREAK

Cropping Systems

11:15: Protecting your Investment in Cotton and Grain Production – Dr. Josh McGinty, Extension Agronomist (0.5 IPM CEU)

In light of the development and spread of herbicide-resistant weeds, economical weed management is becoming an increasingly complicated prospect.  This will be a discussion of the options for managing the most problematic weeds in cotton and grain with a combination of both older and new weed management technologies.

                                                                                                                                                 

11:45: Potential Profitability of No-till vs. Conventional Cotton & Grain Sorghum – Mac Young, Risk Management Specialist

An evaluation of potential yields and profitability of conventional vs. no-till cultivation practices in dryland cotton and grain sorghum in South Texas.

12:15: ADJOURN (for those who do not need the auxin training)

12:30-1:15 pm: Optional Auxin Applicator Training – Dr. Josh McGinty, Extension Agronomist (1 additional CEU)

This training is now required for anyone (pesticide license holders and workers making applications under the supervision of a licensed applicator) who will be applying the dicamba-containing products XtendiMax, Engenia, or FeXapan in 2018.  This training will cover the updated label requirements and best management practices for reducing the risk of off-target movement of these herbicides.  

Cotton Emergence, Heat Units, and an Ag Symposium

Howdy!

  This season has been off to a good start, I've been in the field planting a few variety trials and gearing up for this year. I know some folks were planting as early as the first week of March, and others are still planting now. The rain over the weekend was good for a lot of folks, and I hope the weather cooperates with us this season.

  Cotton growth is strongly influenced by temperature, and germination occurs quickest in warm (above 64 degrees Fahrenheit), moist soils with a high oxygen content. Seeds are in a state of suspended animation due to a lack of water and oxygen. Germination begins when the seed tissue absorbs water, activates metabolism and initiates growth. Inside the seed, the cotton embryo has a radicle at one end and a plumule at the other. The plumule will form the stem and leaves, while the radicle will form the roots. Temperatures below 50°F can kill the radical in the soil once the seed has begun to germinate. Cotton plants require more than 100 hours above 64°F to emerge. Germination can begin when the daily temperature is 60°F at the seedling's depth, but growth will be slow. Cotton needs about 50 heat units to reach emergence.

  Heat units (DD60s)are an estimation of the accumulated temperature effect during a day based on the average of the maximum and minimum daily temperatures in degrees Fahrenheit.

             (°Fmax + °Fmin)

DD60=                 2              - 60

  I calculated the heat units for this past week (Sunday to Friday) using online recorded high and low temperature information:

Wharton: 8.5; 15.5; 15; 4; 4; 8.5
Total for the last 6 days= 55.5

Bay City: 10.5; 16; 16.5; 5.5; 6.5; 14.5
Total for the last 6 days= 69.5

Edna: 12.5; 17.5; 14.5; 6; 5.5; 12.5

Total for the last 6 days= 68.5

  Emergence has been a little spotty in places with the cooler nighttime temperatures we've had. If you are worried about stand in a field, plant populations from 13,000 to 26,000 plants per acre with some spacing uniformity are considered viable stands.

  Below I have included a flyer for our upcoming Ag Symposium. This will be taking place in Wharton, Jackson, and Matagorda counties. Contact your local extension office to find out more for each location and to RSVP.

Feel free to contact me if you have any questions or comments, and have a great weekend!

Sincerely,

Kate

Sources:

http://cotton.tamu.edu/General%20Production/Georgia%20Cotton%20Growth%20and%20Development%20B1252-1.pdf

http://cotton.tamu.edu/General%20Production/scs-2005-17%20Soil%20Temp.pdf

https://cals.arizona.edu/crop/cotton/cropmgt/population_evaluation.html

Weather information from Weather Underground's Calendar

For more information check out:

Cotton Growth and Development overview

Cotton Growth and Development

Replant Decision Making

Soil Temperatures for Cotton Planting