Threading The Needle: A Weed Scientist s Perspective

Transcription

1 Threading The Needle: A Weed Scientist s Perspective Joseph T. Ikley Purdue University, West Lafayette, IN

2 Herbicide Resistance in Indiana Weed species Redroot pigweed PSIIinhibitor (group #5) C. lambsquarters X Jimsonweed ALSinhibitor (group #2) #2/#5 Kochia X X X X X C. ragweed X X Herbicide resistance glyphosate (group #9) #2/#9 Giant ragweed X X X Giant foxtail X PPOinhibitor (group #14) #2/#9/#14 Tall waterhemp X X X X X Horseweed X X X Johnsongrass Shattercane X X Palmer amaranth X X X X X (Heap 2017)

3 Adoption of Soybean Traits LL and Xtend soybean planted in 2017 Ø US LL 13.5 million (15%) Xtend 20 million (22%) Ø Indiana LL (estimate) 275,000 to 560,000 acres (5-10%) Xtend 1.3 million acres (23%) Soybean traits for 2018 Ø US LL 17 million (19%) Xtend million (44-55%) Ø Indiana Combined LL, Xtend, Enlist 2.8 to 3.7 million acres (50-65%)

4 Dicamba Use in Indiana Ø 1990 use in corn Applied on 14% of corn acres 1 application of 0.34 lb A -1 = 267,000 lbs Ø 2000 use in corn Applied on 13% of corn acres 1 application of 0.22 lb A -1 = 157,000 lbs Ø 2005 use in corn Applied 59,000 lbs in corn Ø 2017 use in Xtend soybean (estimate) 1.3 millions A of Xtend soybean planted 1 application of 0.5 lb A -1 = 650,000 lbs Ø 2018 Use in Xtend soybean? 2.6 million A planted 1,300,000 to 2,600,000 lbs?

5 Purdue Weed Science Dicamba What Happened in 2017?

6 Herbicide Drift in 2017 Indiana Ø It wasn t just dicamba Ø 257 official drift complaints (129 suspected dicamba) Sharpen Glyphosate HPPD-inhibitors Atrazine Other auxins 2,4-D burndown Right-of-way applications Brush control

7 2005 to 2017 Total Annual Drift Complaints

8 Recent Drift & Dicamba Data for Indiana Year Complaints Dicamba Percent

9 Vegetation Samples with Dicamba Symptoms Ø Majority of samples were non- Xtend soybean Ø Other samples included: Redbuds Oaks Watermelon Giant ragweed Cocklebur Velvetleaf

10 Central Indiana Weather in 2017 Ø May 8 th wettest on record Longest dry stretch 5 to 7 days depending on location Ø June 20 th wettest on record Longest dry stretch 7 to 12 days depending on location (early June through June 12) Very windy on many dry days Ø July 24 th wettest on record Longest dry stretch 4 to 6 days depending on location

11 Spray Hours in 2017 Ø All data compiled using weather station at the Agronomy Center for Research and Education (ACRE) Wind meter at 2 m Ø Calculated number of spray hours based on Xtendimax/FeXapan label in to 15 MPH winds Accounted for soil moisture conditions and rainfall Ø Recalculated spray hours based on 2018 rules 3 to 10 MPH (including wind gusts) Sunrise to sunset

12 Spray Hours with 2017 Label (Ignoring Gusts) 334 May 2017 June 2017 Jul 2017 Sun Mon Tue Wed Thu Fri Sat

13 Spray Hours with 2017 Label 184 Hours May 2017 June 2017 Jul 2017 Sun Mon Tue Wed Thu Fri Sat

14 Spray Hours with 2018 Label 44 Hours May 2017 June 2017 Jul 2017 Sun Mon Tue Wed Thu Fri Sat

15 Wind Speeds June 22 to :00 5:00 8:00 11:00 14:00 17:00 20:00 23:00 2:00 5:00 8:00 11:00 14:00 17:00 20:00 23:00 2:00 5:00 8:00 11:00 14:00 17:00 20:00 23:00 2:00 5:00 8:00 11:00 14:00 17:00 20:00 0:00 3:00 6:00 9:00 12:00 15:00 18:00 21:00 0:00 3:00 6:00 9:00 12:00 15:00 18:00 21:00 0:00 3:00 6:00 9:00 12:00 15:00 18:00 21:00 Wind Speed Wind Gust

16 July :00 5:00 8:00 11:00 14:00 17:00 20:00 23:00 2:00 5:00 8:00 11:00 14:00 17:00 20:00 23:00 2:00 5:00 8:00 11:00 14:00 17:00 20:00 23:00 2:00 5:00 8:00 11:00 14:00 17:00 20:00 23:00 2:00 5:00 8:00 11:00 14:00 17:00 20:00 23:00 2:00 5:00 8:00 11:00 14:00 17:00 20:00 23:00 2:00 5:00 8:00 11:00 14:00 17:00 20:00 23:00 Wind Speed Wind Gust

17 Spray Hours with 2017 Label 250 Hours Jun 2017 July 2017 Aug 2017 Sun Mon Tue Wed Thu Fri Sat

18 Spray Hours with 2018 Label 132 Hours Jun 2017 July 2017 Aug 2017 Sun Mon Tue Wed Thu Fri Sat

19 Wind Speeds in June at ACRE 19 Year Total Hours Gusts Total Hours Wind > 10 MPH < 3 MPH (58%) 93 (13%) (51%) 150 (21%) (53%) 121 (17%) (46%) 149 (21%) (59%) 91 (13%) 5-year Average 385 (53%) 121 (17%)

20 Spray Hours in June at ACRE with 2018 label 20 Year Spray Hours Sunrise to Sunset Hours Wind Gust > 10 MPH Sunrise to Sunset Hours Wind < 3 MPH (72%) 33 (7%) (61%) 60 (13%) (65%) 45 (9%) (60%) 53 (11%) (72%) 41 (9%) 5-year Average (66%) 46 (10%)

21 Spray Hours in May at ACRE with 2018 label 21 Year Spray Hours Sunrise to Sunset Hours Wind Gust > 10 MPH Sunrise to Sunset Hours Wind < 3 MPH (69%) 25 (5%) (81%) 33 (7%) (77%) 31 (7%) (73%) 32 (7%) (73%) 30 (6%) 5-year Average (75%) 30 (6%)

22 If the Weather Hasn t Changed, What Has? Ø Timing of applications Later application = more sensitive vegetation in landscape Higher temperatures = more volatility Ø Rate of dicamba per application Ø Total volume of dicamba applications Launched on 20 million acres Ø Removed some language regarding sensitive vegetation from labels? How to apply older dicamba POST in corn?

23 If the weather hasn t changed, what has? Ø Timing of applications Later application = more sensitive vegetation Higher temperatures = more volatility Rate of dicamba per application Ø Total volume of dicamba applications Ø More conservative labels? Ø How to apply older dicamba POST in corn?

24 Concluding Thoughts Ø Label is difficult to follow based on historic weather conditions Do we have enough sprayers to legally cover the acres? Ø Label can be confusing with regards to wind speed If average wind speed is >8 MPH, there are gusts over 10 MPH If average wind speed is 6 to 8 MPH, very risky ~20 to 30 hours in May and June in a given year Under 6 MPH is safest bet for no gusts over 10 MPH Ø Weather conditions are best in July and August Which part of label is applicator more willing to gamble on?

25 Questions?