Conducting Harvest-Aid Conducting Harvest-Aid Research in CornResearch in Corn

E.P. Prostko and A.S. CulpepperE.P. Prostko and A.S. Culpepper

Dept. Crop & Soil ScienceDept. Crop & Soil Science

University of GeorgiaUniversity of GeorgiaWSSA 2004

Field Corn Production in Georgia Field Corn Production in Georgia

340,000 A planted (03’)340,000 A planted (03’) 55% irrigated55% irrigated 45% dryland45% dryland 1999-2003 Avg yields1999-2003 Avg yields

* 118 Bu/A - grain * 118 Bu/A - grain

* 16 tons/A - silage* 16 tons/A - silage

Source: GASS

Top 10 Most Troublesome Weeds in Top 10 Most Troublesome Weeds in Georgia CornGeorgia Corn

TX panicumTX panicum sicklepodsicklepod morninggloriesmorningglories pigweedspigweeds nutsedgesnutsedges

cockleburcocklebur FL beggarweedFL beggarweed crabgrasscrabgrass johnsongrass johnsongrass PA smartweedPA smartweed

Webster and MacDonald, 1999

Why are late-season weeds a Why are late-season weeds a problem in the SE?problem in the SE?

early harvest (Jul-Aug)early harvest (Jul-Aug) warm temperatureswarm temperatures ample rainfallample rainfall high humidityhigh humidity wider rows (36”)wider rows (36”) limited herbicide inputslimited herbicide inputs reduced atrazine reduced atrazine

residual residual delayed applications delayed applications

earlier in seasonearlier in season

ObjectiveObjective

to develop a to develop a method for method for conducting small conducting small plot harvest-aid plot harvest-aid researchresearch

Research Problems and Concerns?Research Problems and Concerns?

no previous experienceno previous experience

plot size/layoutplot size/layout design/treatment #design/treatment # How do we spray?How do we spray? water volumewater volume weed speciesweed species harvest-ability ratingsharvest-ability ratings

Plot Size/Layout/DesignPlot Size/Layout/Design

RCB 4 repsRCB 4 reps 6 treatments6 treatments 4 rows X 25’4 rows X 25’ 10’ alleys10’ alleys drivewaysdriveways Sweet Corn HybridSweet Corn Hybrid

* ACX-9454* ACX-9454

*Why? It was short!*Why? It was short! Planted April 14Planted April 14

Weed SpeciesWeed Species

planted annual morninggloryplanted annual morningglory Dual II Magnum @ 1 pt/A - PREDual II Magnum @ 1 pt/A - PRE Prowl @ 2.4 pts/A - 9 DAPProwl @ 2.4 pts/A - 9 DAP cocklebur, sicklepod, starbur problemscocklebur, sicklepod, starbur problems should have sprayed with Basagran or should have sprayed with Basagran or

done some hand-weedingdone some hand-weeding

Application TechniquesApplication Techniques

July 14 (3 months after planting) July 14 (3 months after planting) JD 6500 High-Boy SprayerJD 6500 High-Boy Sprayer 4 row boom (18”)4 row boom (18”) XR110015 nozzlesXR110015 nozzles 5 GPA5 GPA 4.5 MPH4.5 MPH flushed boom with clean water and COflushed boom with clean water and CO2 2

after each treatmentafter each treatment

4 row boom attached to High-Boy 4 row boom attached to High-Boy sprayersprayer

COCO2 2 tank, spray cans, on-off valve tank, spray cans, on-off valve

Weed Size At Application - 90 DAPWeed Size At Application - 90 DAP

Harvest-Ability RatingsHarvest-Ability Ratings

subjective rating subjective rating ease of mechanical ease of mechanical

harvestharvest 1-5 scale1-5 scale 1 = no problem1 = no problem 5 = severe problem5 = severe problem

ResultsResults

Corn Harvest-Ability Ratings - 14 DATCorn Harvest-Ability Ratings - 14 DAT1-5 Scale1-5 Scale

4.9

3.43.8

2.92.4

4.8

0

1

2

3

4

5

6

Untreated Aim (1 oz) Aim (1.6ozs)

2,4-D (1.5pts)

RoundupWM (22

ozs)

Harvade (8ozs)

aa

bcb

bcc

Untreated Untreated

Aim 2EC @ 1.0 ozs/A + COC @ 1% v/vAim 2EC @ 1.0 ozs/A + COC @ 1% v/v

Aim 2EC @ 1.6 ozs/A + COC @ 1% v/vAim 2EC @ 1.6 ozs/A + COC @ 1% v/v

2,4-D @ 1.5 pts/A2,4-D @ 1.5 pts/A

Roundup WeatherMax @ 22 ozs/ARoundup WeatherMax @ 22 ozs/A

Harvade 5F @ 8 ozs/A + COC @ Harvade 5F @ 8 ozs/A + COC @ 0.83% v/v0.83% v/v

Tips for Future ResearchTips for Future Research

limit number of treatments (< 10)limit number of treatments (< 10) need to add sodium chlorateneed to add sodium chlorate control undesirable weedscontrol undesirable weeds identify a short field corn hybrid (mechanical identify a short field corn hybrid (mechanical

harvest)harvest) longer alleyways (15’)longer alleyways (15’) get better at rating for defoliation/desiccationget better at rating for defoliation/desiccation conscious of drift conscious of drift possible funding??? possible funding???

University ofGeorgia

Extension Weed Science

(gaweed.com)