Monthly Archives: June 2020

Unlike cotton production areas in the Mid-South, tarnished plant bug is an uncommon and sporadic pest of Georgia cotton. However, tarnished plant bug populations must be scouted as economic infestations occur in some fields each and every year. Only treat tarnished plant bugs if threshold levels are exceeded. Tarnished plant bug sprays are disruptive to beneficial insect establishment. Our primary method for scouting plant bugs is square retention. Our goal is to retain 80 percent of all first positions as we enter bloom. The square retention technique works well in pre-bloom cotton but is not as a reliable technique in blooming cotton as physiological shed confounds counts. More scouts are using sweep nets to monitor plant bugs. Sweep nets are an excellent tool for
monitoring adult plant bug populations, but the drop cloth (especially a black drop cloth) is more effective for monitoring immature plant bugs.

Adult tarnished plant bug (left) and immature tarnished plant bug in bloom (right). Images by Russ Ottens, University of Georgia and Ron Smith, Auburn University, Bugwood.org.

Effective use of the sweep net becomes difficult after bloom due in part to plant size and more emphasis should be placed on use of a drop cloth. Also be observant for both adult and immature plant bugs when making visual plant inspections; examine terminals and inside the bracts of squares, blooms, and small bolls. Also be observant for “dirty blooms”, blooms in which many of the anthers are dried and brown. Dirty blooms are an indication that plant bug (especially nymphs) are feeding on larger squares which the plant did not shed. 

“Dirty Blooms”. Images by Ron Smith and Barry Freeman, Auburn University, Bugwood.org.

Clouded plant bug adult (left) and immature (right). Images by Ron Smith, Auburn University, Bugwood.org.

Tarnished plant bug thresholds can be used for clouded plant bugs, but clouded plant bugs should be counted 1.5 times when using a sweep net. Note that the threshold is higher during the third week squaring and bloom compared with the first two weeks of squaring.

Sweep Net and Drop Cloth Thresholds:

Third week of squaring through bloom: Drop Cloth: 3 plant bugs/6 row feet, Sweep Net: 15 plant bugs/100 sweeps

First 2 weeks of squaring: Drop Cloth: 1 plant bug/6 row feet, Sweep Net: 8 plant bugs/100 sweeps

As a result of great team work with the Georgia Department of Agriculture and BASF, Georgia cotton farmers have a new Liberty label allowing shortened intervals between sequential Liberty applications which can improve weed control.

Research has shown understanding the time interval between sequential post applications is one of many critical components for an effective weed management system. The figure below compares 6 inch Palmer amaranth response to sequential Liberty applications as influenced by interval between applications. Obviously, one needs to spray Liberty when the biggest pigweed in the field is 3” for complete control and in this event a follow up application can be made when the next flush of pigweed reaches 3”. With the challenging weather during 2020, spraying all weeds at 3” or less may not be practical for some fields; thus, when pigweed is too large to kill with the first application then the second application timing is important.

DO NOT MAKE MORE THAN TWO LIBERTY APPLICATIONS in a season for resistance management purposes; follow the second Liberty application 10-12 days later with a layby directed application including conventional chemistry such as Diuron + MSMA + Crop Oil or Roundup + Diuron (add Envoke with layby if morningglory or nutsedge is an issue; check carryover)!

Few critical points from the label: 1) One must have 24 (c) label in hand when making application; 2) Liberty may be applied twice over-the-top of glufosinate-tolerant cotton as long as there is at least a 5 day interval between applications; 3) Do not include tank mix partners when making two applications less than 10 days apart. 4) Do not apply more than 36 oz/A overtop of cotton per application.

Click the following link to view the Liberty 280 SL FIFRA Sec. 24(c) Special Local Need Label:  Liberty 280 SL NVA 2020-04-594-0079 shortened seq interval 04-14-2020b_24c GA-20003

Dicamba (A. S. Culpepper).  On June 8, 2020 the U.S. EPA released critical information on Engenia, Fexapan, and XtendiMax. The entire release can be found at https://www.epa.gov/newsreleases/epa-offers-clarity-farmers-light-recent-court-vacatur-dicamba-registrations

Please visit the website for details; however, below are the details of the order:

“Details of the Order

EPA’s order addresses sale, distribution, and use of existing stocks of the three affected dicamba products – XtendiMax with vapor grip technology, Engenia, and FeXapan.

1. Distribution or sale by any person is generally prohibited except for ensuring proper disposal or return to the registrant.
2. Growers and commercial applicators may use existing stocks that were in their possession on June 3, 2020, the effective date of the Court decision. Such use must be consistent with the product’s previously-approved label, and may not continue after July 31, 2020.”

Weed Control Thoughts (Use only labeled products and follow all labeled directions and restrictions):

Scenario One:  Large pigweed with enough in-crop dicamba for two applications:  Spray labeled Roundup + dicamba immediately, wait 7 to 10 days and then make a second application; 12 days later run the layby rig with either 1) Direx + MSMA + Crop Oil if grasses are not up or 2) Roundup + Direx if grasses are up (add Envoke with layby if morningglory or nutsedge is a problem).

Scenario Two:  Large pigweed with enough in-crop dicamba for one application:  Spray labeled Roundup + dicamba immediately, wait 7 to 10 days and then make a Liberty tank mix application; 12 days later run the layby rig with either 1) Direx + MSMA + Crop Oil if grasses are not up or 2) Roundup + Direx if grasses are up (add Envoke with layby if morningglory or nutsedge is a problem).

Scenario Three: Large pigweed with no dicamba available. Sequential Liberty applications will be best approach although less effective than either dicamba system above. We were able to obtain a new state label for Liberty shortening intervals between sequential applications which will improve control (sending information in blog tomorrow).

Other Thoughts:

1. Tavium registration was not revoked and therefore the herbicide is not impacted as of now.
2. The Enlist program of herbicides are following a similar path to that of Engenia, Fexapan, and XtendiMax in the court system. No one can predict the future.
3. In Georgia, we have all worked so hard to steward every pesticide and we should collectively be proud! However, this is a wake-up call in several ways. First, we must work together even harder generating sound science to preempt this type of situation in the future. Second, for those few growers who have down played the importance of using all pesticides wisely, what a wake-up call!!!!

Yesterday UGA ANR agents received this news yesterday from Dr. McCann:

Below is a link to an article which recaps what occurred in U.S. Court of Appeals for the Ninth Circuit the 9th District yesterday. The Federal Court overturned EPA’s approval of dicamba-based herbicides made by Bayer, BASF and Corteva Agrisciences. The ruling effectively makes it illegal for farmers to continue to use the product.

https://usrtk.org/pesticides/court-orders-epa-approvals-of-bayer-dicamba-herbicide-vacated-says-regulator-understated-the-risks/

The Georgia Department of Agriculture will explore what options are available to growers in this growing season. The registration for the products were going to end in December 2020.

Given the timing and our collective investment in the safe use of these products, this is a disappointing turn of events. More will be forthcoming in the near future from the companies and GDA.