Abstract
S-metolachlor is used to control/suppress yellow nutsedge, annual grasses and several broadleaf weeds in sweetpotato. However, a decline in storage root quality is suspected when excessive rainfall occurs within 24-h after application. A greenhouse study was conducted to determine the effect of S-metolachlor application timing on sweetpotato growth and development. S-metolachlor treatments (0 and 1 kg·ha-1) were applied over-the-top at 0, 5 and ten days after transplanting (DAT) and a simulated rainfall treatment delivered 25 mm of rain, 51 mm·h-1 intensity, immediately after herbicide application. Plants were harvested at 5, 10, 15, 20 and 80 DAT. During the first four harvests, roots were scanned and analyzed with WinRHIZO-Pro image analysis system to estimate root number, length, volume, and surface area along with aboveground growth parameters. At the final harvest, plant growth and biomass components, and quality of storage roots were recorded. Plants treated with S-metolachlor on day 0 and 5 DAT were significantly less than those of 10 DAT and untreated control for all measured parameters for the initial 20 days of plant growth. Even though vine length, leaf number, stem biomass, and total storage roots were not different among the treatments at 80 DAT, all other plant components and total biomass production and leaf area development for plants treated at 0 and 5 DAT were significantly (P % and 16% for plants treated at 0 and 5 DAT, respectively, relative to the untreated check. These results indicate that delaying S-metolachlor application to 10 DAT will be less damaging to sweetpotato growth and development, particularly marketable storage roots and yield.
Highlights
Effective weed management, within the first six weeks after transplanting, is essential to optimize sweetpotato yield [1] [2] [3]
A greenhouse study was conducted to determine the effect of S-metolachlor application timing on sweetpotato growth and development
Marketable storage root conversion efficiency declined by 18% and 16% for plants treated at 0 and 5 days after transplanting (DAT), respectively, relative to the untreated check
Summary
Within the first six weeks after transplanting, is essential to optimize sweetpotato yield [1] [2] [3]. Growers use a combination of hand-weeding, mechanical, and chemical practices to manage weeds. S-metolachlor is physically and chemically equivalent to metolachlor (a 1:1 mixture of R- and S-isomers) but requires use rates 35% lower than metolachlor due to increased activity at the site of action in susceptible plants [6]. It is applied pre-emergence (PRE) to weeds and post-transplanting to sweetpotato [7]. Metolachlor causes loss of root cell integrity through its interference of phospholipid synthesis, an important component of plant cell membranes [10] [11] and has been reported to induce leakage of 32P-labeled orthophosphate from roots of susceptible species [11]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
