Cost-Effective Weed Management in Peanuts Eric P. Prostko Extension Weed Specialist University of Georgia Tifton

How much do you spend on weed control? USDA surveys indicate that peanut farmers in GA and AL spend $116/A on agri-chemicals 34% of total operating costs Source: USDA/ERS

Weed Control in Peanuts A Typical program PPI: Sonalan (2 pts/A) = $5.66/A CRACK: Gramoxone Max (5.5 ozs) + Storm (1.5 pts) + NIS (0.25%) = $15.01/A POST: Cadre (1.44 ozs) + COC (1%) = $14.62/A Total Cost = $35.29/A

Has the recent price reduction of Cadre made weed control in peanuts a no-brainer??? cost no longer an obstacle What about cotton rotations? Should we still be applying reduced rates?

What can we do better? read label calibration and measuring incorporation timeliness expert systems reduced rates???

Why must you read the label? good source of info weeds rates timings potential problems

Why must you read the label? Avoid potential problems!

Before anything else, calibrate your sprayer!!! The only way to make sure the correct rate is applied. to low = poor control too high = waste money accurate measuring also important

Sprayer Calibration Some Surveys said……… only 33% of operators were within 5% of target output (NE) 60% of the applicators were over or under applying pesticides by more than 10% (ND)

The foundation of weed management in peanuts is the yellow/DNA herbicides! Sonalan, Prowl, Pendimax, Repose inexpensive Texas panicum Florida pusley must be incorporated by tillage or irrigation

Herbicide Incorporation Equally as effective Center-pivot irrigation is $2-7/A cheaper! Less variable?

What about other soil-applied herbicides?? use as needed can be expensive need moisture broad spectrum may reduce/limit need for POST’S

Postemergence Herbicides Timing,Timing, Timing!!!! Smaller weeds easier to control If removed early, weeds cause less or no effect on yield lower rates can be used don’t need 100% control

Optimum Timing of POST Applications definitely No way!!! probably

Palmer Amaranth Control with Blazer Applied at Different Timings 99 57 48 25 50 75 100 3-5" 7-9" 11-13" Timing Control (%) Mayo et al. 1995 (KS)

“Expert” Systems postemergence HERB (DOS) HADSS (Windows) weed density weed size yield goals economics

HADSS Herbicide Application Decision Support System Web-based version is free Can be purchased for $95 Database needs to be updated for SE time input for scouting and data entry http://www.hadss.com

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

What kind of grower might consider using reduced rates? A grower who ……... 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

Reduced Rates Do they work???

The Response of Weeds to Various Cadre Rates in Georgia 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 Applied EPOST (C-2LF) Webster et al. 1997

The Response of Weeds to Various Cadre Rates in Georgia 20 40 60 80 100 smallflower morningglory annual cocklebur bristly starbur 0.36 oz/A 0.72 oz/A 1.1 oz/A 1.44 oz/A Applied EPOST Webster et al. 1997

The Response of Weeds to Various Cadre Rates in Georgia 20 40 60 80 100 coffee senna Florida beggarweed 0.36 oz/A 0.72 oz/A 1.1 oz/A 1.44 oz/A Webster et al. 1997 Applied EPOST

Hophornbeam Copperleaf Control Randolph County, GA - 2001 Strongarm (0.45 ozs/A) Valor (3 ozs/A) Strongarm 0.113 ozs + Valor 0.75 ozs/A Untreated 6 WAT

Weed control in peanuts with reduced rates of Strongarm and Valor, 2002. Untreated Strongarm 0.45 oz/A Valor 3 oz/A Strongarm 0.113 oz/A + Valor 0.75 oz/A Attapulgus, GA 7 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 to weed size, improper sprayer calibration, environmental conditions, etc.

Cost-Effective Weed Management Summary read label calibrate sprayer use yellow herbicides use other soil applied herbicides as weeds and rotations dictate make earlier applications with POSTS utilize “expert” systems? Reduced rates? Not for everyone or every situation but can work

University of Georgia Extension Weed Science (gaweed.com)