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A few weeks ago I introduced the new IPM Audio Updates that we are producing. The IPM Agents strive to cover all the important news yet keep the broadcast under 10 minutes. The High Plains version features Blayne Reed, Kerry Siders, Dagan Teague and John Thobe. The Concho St. Lawrence version features Haley Kennedy and Brad Easterling. Pat Porter and Suhas Vyavhare will make cameo appearances as needed.

There are two separate broadcasts, one for the High Plains and one for the Concho St. Lawerence area. If you want both then sign up for each one separately. The signup page is here:  https://www.texasinsects.org/signup-texts.html. Once you are signed up, you will get a text message immediately after the weekly broadcast is completed and posted on our server.

There is not much fine print: We will never share your phone number or any other information with anyone. We don't ask your name, but we will ask whether you are a producer, consultant, ag industry, AgriLife or other. This so that we can get an idea of who is using the service. If you decide to stop getting the text messages, just text the word STOP to the number that is at the bottom of each text message. 

Join us for rapid updates on insects, weeds, diseases and growing conditions as we start the 2020 season. If you want to sample the broadcasts before signing up, the ones so far are here: https://www.texasinsects.org/southern-high-plains-pest-news.html. (Future recordings will be in stereo.)

Off Topic: COVID-19 Life in Lubbock and the Southern High Plains

The coronavirus restrictions have been in place for over one month now and there are 494 known cases in Lubbock County as of this writing, and relatively few in surrounding counties. When I look at how we as a people have handled this as compared to some other places I think it says a lot about us.

For example, a co-worker's mother was discharged from an assisted care facility three weeks ago, and on the way out the door the family was told a worker at the facility had tested positive for the virus. So what did the family do? They took their mother to their house where they could care for her and totally quarantined themselves for two weeks. They did not have to do it, they did it to protect others.

The great reopening will begin this week at the direction of our governor and local politicians. No one wants more virus cases, but many local businesses are on the brink and need to reopen, even if in a modified fashion. We are about to embark on a great experiment and the outcome is unknown. However, what I do know is that we are a unique people. The video linked below shows some of that. It contains some of my photos from over the years and was issued through 4th on Broadway, a group of volunteers that for 30 years has put on the 4th of July parade and largest free festival in the state with support from local businesses and individuals. The music is by Doug Smith, and his family graciously donated it when they learned about this project. I am deeply grateful for their gift, and to be living here on the southern high plains of Texas.

https://vimeo.com/406063736

Patrick Porter

Miller Moth Deluge Near

We had tons of army cutworm larvae in many of our wheat and alfalfa fields this spring. I have never used the word tons when trying to describe a quantity of insects, but here is some math. We recently conducted an insecticide efficacy trial on these larvae, and they averaged 7 per square foot. An acre would have 304,920, and a 50-acre field would have 15,246,000. We have many, many wheat fields that are infested this year. The larvae are now entering the pupal stage and will soon emerge as adults and invade our homes and structures. 

Army cutworm larvae from two plots in the efficacy trial.

They prefer to fly at night and seek shelter in the day, which is why you will get up one morning and find your porch covered, and more moths in the house if it is not sealed up well. Don’t leave your truck windows down either. Some people say that a bowl of water and a little dish soap can be left under a porch light. The moths come to the light and contact the water where the dish soap has eliminated the surface tension so the moths sink and drown. This is true, but it won’t really reduce the number of moths to any degree, although the revenge factor might make you feel better. Revenge might be on your mind because the two biggest complaints about the moths are that they keep people from sleeping because of all of that flying around in the bedroom while they are trying exit the house, and because the oils from their bodies stain draperies and furniture. 

An army cutworm moth.

“Miller moth” is a generic term that refers to several moth species that fly in large numbers and create a nuisance. Here on the High Plains the Millers are usually the army cutworm. The adults that fly in a few weeks will spend some time feeding on plant nectar, making us even crazier than we already are under this COVID-19 isolation, and then they will begin their long migration to the Rocky Mountains where they will spend the summer annoying people there. The bears won’t mind though because Miller moths are a delicious treat for them and they are known to eat up to 40,000 per day, which provides approximately 20,000 calories. (Our insectivorous bats and birds will have a good time in the next month or so as well.) 

As summer wanes the surviving moths will begin migrating back to Nebraska, Kansas, Oklahoma and the Texas Panhandle. Each female will lay as many as 1,000 eggs in the fall on wheat, alfalfa, various weeds and even turfgrass. The eggs will hatch and the resulting larvae will overwinter. Larval development in the spring is slow because it is cold, and insect metabolism is very slow when it is cold. Eventually though they will become fully grown, pupate, and next year’s moths will emerge. 

Pest News in About 10 Minutes Per Week

Extension IPM Agents on the southern High Plains and in the Concho Valley and St. Lawrence areas are now producing short audio recordings about what is being found in the field. The intent is to address current insect, weed and disease issues and look forward a bit to what might be coming next week.

For the Concho Valley and St. Lawrence areas, Brad Easterling and Haley Kennedy record and post their audio file on Tuesday afternoon. High Plains IPM Agents Kerry Siders, Blayne Reed, Dagan Teague and John Thobe record and post their audio file on Wednesday afternoon.

We will shortly start a service that will text subscribers when a new version is uploaded. For now you can go to the web page where these are posted. The photo below shows the types of topics that have been addressed in recent weeks.

Army cutworms damaging wheat

A researcher at the Lubbock Center asked us to tell her what was eating up her ryegrass plots. Suhas Vyavhare and I checked the plots and some wheat fields near Lubbock and found abundant army cutworm larvae. The growth stages are varied from small to about one-inch, so there is plenty of damage yet to come.

Nebraska has a nice 2017 army cutworm alert that states the treatment threshold is four larvae per square foot (for grain production).  Our publication Managing Insect and Mite Pests of Texas Small Grains (page 8) says, "In outbreak years, fields can have 10 - 20 cutworms per square foot." What we saw today was not to that point, but it is still early and many larvae were small and hard to find. Typical damage includes chewing on leaves, cut plants and severed stems.

The first thing you will see when scouting is the leaf damage. During the day, the cutworms will be beneath the soil surface near the plants.

Army cutworm larva.

Clipped stem on 6-inch wheat plant.

Know what you are buying in your Bt corn hybrids (including sweet corn)

The 2020 version of the Handy Bt Trait Table has just been published. This two-page quick reference guide lists the Bt and herbicide packages in all US field corn in an easy to follow manner. It also lists the pests the corn claims to control and those that have developed resistance to the trait packages. This year's changes include a discussion of finding European corn borer resistance to Cry1F corn in Canada. The table also now lists Bt toxins to which corn earworm (cotton bollworm) is resistant.

But wait, there's more! The first ever version of the Handy Bt Trait Table for Sweet Corn is now available as well. There are only a few Bt combinations available in sweet corn and the new table lists them all, including those for which resistance has been determined. Basically, only Vip3a sweet corn now provides good control of corn earworm in the south. The table lists all hybrids available in the US by company, hybrid and Bt type.

The Handy Bt Trait Tables for both field corn and sweet corn can be found here: https://www.texasinsects.org/bt-corn-trait-table.html

The following graph shows the number of corn earworm larvae per 25 ears of Bt and non-Bt sweet corn grown on the Experiment Station in Lubbock in 2019. It is easy to see that the older toxins are no longer working and in fact have many more larvae than the non-Bt types. (This is because the caterpillars are resistant to the older Bt toxins and also lose the behavioral tendency to cannibalize when on the Bts.) The graph also shows that Vip3a is doing a very good job of controlling corn earworm.

Some Bt Sweet Corn No Longer Effective

I received a few calls this summer from sweet corn growers who wondered why they had corn earworm larvae in their Bt sweet corn. The short answer is that corn earworm has now developed resistance to the older set of sweet corn toxins and only the newest toxin will provide good control.

I ran a sweet corn sentinel plot trial at Lubbock this summer to determine the ability of Bt sweet corn to control corn earworm (as compared to non-Bt sweet corn).

The bottom line was that I found roughly twice as many healthy corn earworm larvae in the older types of Bt corn than in the non-Bt corn. There are a few reasons for this; a) corn earworm is largely resistant to Cry1Ab and Cry1A.105+Cry2Ab2, toxins which worked well several years ago, and b) it has been shown in the scientific literature that resistant larvae on Bt sweet corn largely lose their cannibalistic drive. On non-Bt corn there is usually one big surviving larva per ear by the time the larvae are older. On Bt sweet corn where the insects are resistant or partially resistant to the toxin(s) they are not as prone to cannibalism and there are often multiple surviving older larvae.

Here are some data from this summer's trial at the AgriLife Research Center at Lubbock.

The two columns on the right give us an idea about the health of the larvae. Corn earworm has six instars, and those reaching third instar will probably not be killed by Bt and have a good chance of completing development. I did notice a slight developmental delay in resistant caterpillars on the older Bt toxins as compared to non-Bt corn, but it was minor, perhaps a setback of a couple of days in development.

Attribute II has the older Cry toxin from Attribute and the newer toxin, Vip3a. At least for the High Plains of Texas, if you are a commercial sweet corn grower and want to use a Bt hybrid, it would be worth sourcing seed with Vip3a as one of the toxins.