Date of Graduation

12-2018

Document Type

Thesis

Degree Name

Master of Science in Crop, Soil & Environmental Sciences (MS)

Degree Level

Graduate

Department

Crop, Soil & Environmental Sciences

Advisor/Mentor

Burgos, Nilda R.

Committee Member

Ross, William J.

Second Committee Member

Roberts, Trenton L.

Third Committee Member

Popp, Michael P.

Keywords

Edamame; Herbicides; Weed Control

Abstract

Vegetable soybean [Glycine max (L.) Merr.], known as edamame, needs weed management tools. Releasing locally adapted edamame soybean varieties and registering herbicides are necessary for successful production and expanding the edamame industry. This research aimed to 1) identify herbicides labeled for grain soybean for potential use on edamame; 2) evaluate differential tolerance of edamame soybean varieties to selected grain soybean herbicides; and 3) identify a feasible edamame-based crop rotation system. For objective 1, 26 herbicide treatments were tested on AVS-4002 edamame including preplant (PPL), preemergence (PRE) and postemergence (POST) herbicides labeled for grain soybean. Preplant herbicides caused 9 to 28% crop stand loss and <12% injury on remaining plants 21 d after planting (DAP). Plots treated with pyroxasulfone PRE had 8 to 30% crop stand loss with no effect on yield. Postemergence herbicide treatments (acifluorfen, acifluorfen+bentazon, fomesafen, imazethapyr, imazamox+bentazon, and S-metolachlor+fomesafen) caused some injury, but did not reduce yield. For objective 2, 11 edamame and grain soybean varieties were treated with flumioxazin, metribuzin, sulfentrazone, and pyroxasulfone PRE and fomesafen POST. Metribuzin caused the highest crop stand reduction and injury. Flumioxazin and sulfentrazone caused 54% and 60% stand reduction, respectively. Postemergence application of fomesafen caused 11% leaf necrosis at 7 days after treatment. Grain soybean UA 5612 had the highest tolerance to sulfentrazone but was sensitive to metribuzin. Edamame varieties AVS 4002 and R07-7645 had good tolerance to pyroxasulfone. In summary, fomesafen and pyroxasulfone are good herbicides for edamame. Sulfentrazone can only be used on tolerant edamame varieties. For objective 3, four crop rotation systems were evaluated at Kibler and Rohwer, Arkansas. Rotations were composed of greenbeans/edamame (Rotation A), short-season soybean/edamame (Rotation B), sweet corn/edamame (rotation C), and edamame monoculture (Rotation D). Yield of fall-harvested edamame relative to the monoculture in rotation C was 128% and 77% in 2014 and 2015, respectively. Inclement weather in both years compromised crop performance at Rohwer. The monoculture rotation is not sustainable; thus, possible crop diversification schemes need to be investigated. Edamame-based crop rotation systems will have more chance for success in the southern US where the crop growing period is longer.

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