Trends In Peanut Weed Control Dr. Eric P. Prostko Extension Weed Specialist University of Georgia Tifton December 2002

Trends In Peanut Weed Control

Dr. Eric P. Prostko

Extension Weed Specialist

University of Georgia

Tifton

December 2002

Trends in Peanut Weed ControlTopics for Discussion

tillage incorporation cultivation herbicide use reduced rates tank-mixes weed shifts resistance R & D



Trends in Peanut Weed ControlStrip-Tillage Production

27

1719

0

5

10

15

20

25

1995 1997 1999 2001

Year

Acr

es -

%

Source: UGA Peanut Production Surveys

Strip-Tillage Weed Control timing of burndown paraquat, glyphosate,

2,4-D, Valor yellow herbicides? Incorporation Florida pusley, evening

primrose, Texas millet perennial weeds?



Trends in Peanut Weed ControlHerbicide Incorporation

0102030405060

1993 1995 1997 1999 2001


Herbicide Incorporation

or

Equally as effectiveCenter-pivot irrigation is $2-7/A cheaper!



Trends in Peanut Weed ControlMechanical Cultivation

73 7263

47

35

0

20

40

60

80

100

1993 1995 1997 1999 2001

Year

Acr

es -

%


Why has mechanical cultivation declined?

disease management better herbicides time savings strip-tillage increases fuel prices



Trends in Peanut Weed ControlSoil-Applied Herbicides - I

0

7

14

21

28

35

Dual Lasso

Herbicide

Acr

es -

%

1993 1995 1997 1999 2001


Trends in Peanut Weed ControlSoil-Applied Herbicides - II

0

7

14

21

Pursuit Zorial

Herbicide

Acr

es -

%

1993 1995 1997 1999 2001


Trends in Peanut Weed ControlPostemergence Herbicides - I

0

15

30

45

60

Paraquat (P) Paraquat +Basagran (B)

P + B + 2,4-DB

Herbicide

Acr

es -

%

1993 1995 1997 1999 2001


Trends in Peanut Weed ControlPostemergence Herbicides - II

0

15

30

45

60

Storm Classic Cadre Poast Select

Herbicide

Acr

es -

%

1993 1995 1997 1999 2001




What about reduced rates? not labeled but not illegal companies will not support

failures not a guarantee to minimize

crop rotation issues part of a total program future R&D and new

products

Reduced RatesDo they work???

The Response of Weeds to Various Cadre Rates in Georgia

0

20

40

60

80

100

P. nutsedge Y. nutsedge sicklepod

0.36 oz/A

0.72 oz/A

1.1 oz/A

1.44 oz/A

Webster et al. 1997 Applied EPOST (C-2LF)

The Response of Weeds to Various Cadre Rates in Georgia

0

20

40

60

80

100

smallflowermorningglory

annualmorningglory

cocklebur bristly starbur

0.36 oz/A

0.72 oz/A

1.1 oz/A

1.44 oz/A

Webster et al. 1997 Applied EPOST

Hophornbeam Copperleaf ControlRandolph County, GA - 2001

6 WAT

UntreatedStrongarm

(0.45 ozs/A)Valor

(3 ozs/A)

Strongarm 0.113 ozs+ Valor 0.75 ozs/A

Weed control in peanuts with reduced rates of Strongarm and Valor, 2002.

Untreated Strongarm0.45 oz/A

Valor3 oz/A

Strongarm0.113 oz/A

+Valor

0.75 oz/A

Attapulgus, GA7 WAP

Reduced rates can work if……..

The weed is susceptible good growing/application conditions exist the application is timely (small weeds)

Full rates help to overcome variability of application due toweed size, improper sprayer calibration, environmental conditions, etc.

What kind of grower might consider using reduced rates?

regularly calibrates his sprayer has irrigation or can predict when it will rain gets consistent weed control at full rates understands the difference between 2” and 4” can cover his acreage in a short time period is willing to scout his field regularly is willing to accept less than 100% weed control is not a lawyer or close friends with one

A grower who ……...



Trends in Peanut Weed ControlTank-Mixes

herbicides fungicides insecticides foliar fertilizers reductions in time and

money may not be well

researched or clearly labeled

Herbicide/Fungicide Tank-Mixes



Trends in Peanut Weed ControlWeed Shifts

Top 5 Most Common Weeds in GA Peanuts

Tropical spiderwortCommelina benghalensis

annual or perennial seeds and rhizomes above and below ground

flowers 1600 seeds/plant high soil moisture and

fertility problem weed in other

countries (Holm’s)

Tropical spiderwortHow bad is it?????

Grady County, GA 2001



Herbicide ResistanceAround the World

261 Resistant Biotypes

157 Species (95 dicots and 62 monocots)

over 210,000 fields

Source: Heap, I. The International Survey of Herbicide Resistant Weeds. Online. Internet. December 2, 2002 .

Herbicide ResistanceSoutheast

Glyphosate ResistanceThey said it was unlikely!

Horseweed

* DE (2000)

* TN (2001)

Goosegrass * Malaysia (1997)

Italian Ryegrass * Chile (2001)

Rigid Ryegrass

* Australia (1996)

* California (1998)

* South Africa (2001)

Weed Technology, 1997 11:189-198

Biotechnology Varieties Planted in the US in 2002

22

13 09

36

75

2

22

0

33

7175

0

20

40

60

80

100

Corn Cotton Soybeans

%

Insect Herbicide Stacked Total

Source:USDA/NASSJune 2002

Herbicide Resistant WeedsStrategies for Control/Prevention prevention is the key!!! utilize other weed control tactics (cultivation,

row patterns, etc). rotate herbicides with different MOA rotate crops scout fields prevent seed production clean tillage and harvesting equipment



Trends in Peanut Weed ControlR & D

have had a few good years (Cadre, Select, Strongarm, Valor)

peanut is a minor crop only 2 products currently

in pipeline (Spartan, Cobra) Will they make it? Do we need them?

The Peanut Weed Control Toolbox

The Future?My Predictions

limited new herbicides $25 or less on herbicides increase in reduced rates and

combinations new uses for older products increases in resistance weed shifts

– perennials– unknowns

University ofGeorgia

Extension Weed Science

(gaweed.com)

Documents

Trends In Peanut Weed Control Dr. Eric P. Prostko Extension Weed Specialist University of Georgia Tifton December 2002