Early Applications of XtendiMax® Herbicide with VaporGrip® Technology, a Restricted Use Pesticide, in the Roundup Ready® Xtend Crop System in Conventional Tillage Systems

Trial Objective

 

  • Determine if XtendiMax® herbicide with VaporGrip® Technology, a restricted use pesticide, provides a broadacre benefit of residual weed control when used in conjunction with pre-emergence (PRE) residual herbicides in a conventionally tilled soybean system.

Research Site Details

 

  • There were 15 research sites in 2021 chosen by University researchers in 12 states (AR, IA, IL, LA, MI, MN, MO, NC, ND, NE, SD, WI) with 11 sites providing useable data, representing various soil types and environmental conditions.

  • The protocol included conventional tillage prior to planting to remove existing weeds.

  • Pre-emergence (PRE) products were applied at either planting or prior to soybean emergence. 

  • There were no post-emergence (POST) applications to determine the effective length time of PRE residual products.

  • Weed control was evaluated 14, 21, and 35 days after treatment (DAT).

Understanding the Results

 

  • At 21 days after treatment (DAT), the percent control ranged from 83 to 92% for the pre-emerge products only and 95 to 97% control for pre-emerge with the addition of XtendiMax® herbicide with VaporGrip® Technology (Figure 1). However, the control across all locations with the addition of XtendiMax® herbicide with VaporGrip® Technology was more consistent. At 35 DAT, control was more consistent across locations and improved over base PRE applications (Figure 4). 

  • At 21 days after application, treatments of MON 301886, Warrant Ultra Herbicide, Valor EZ herbicide, and Authority MTZ herbicide were all improved with the addition of XtendiMax® herbicide with VaporGrip® Technology (Figure 1).  All products with the addition of XtendiMax® herbicide with VaporGrip® Technology provided a higher level of control at 35 days post application than base PREs alone (Figure 2)  

  • Focusing on Amaranthus species only 35 days after application, Fierce® EZ herbicide, Valor® EZ herbicide, and Authority® MTZ herbicide were improved with the addition of XtendiMax® herbicide with VaporGrip® Technology (Figure 3).  

  • Focusing on large-seeded broadleaf species, the addition of XtendiMax® herbicide with VaporGrip® Technology significantly improved control in 5 out of 6 PRE products at 21 days after application and all products at 35 days post application (Figures 4 and 5). 

Figure 1. Average percent control of pre-emergence products alone and with XtendiMax® herbicide with VaporGrip® Technology, a restricted use pesticide, at 8 locations 21 days after application. (Averages followed by same letter are not significantly different using Fishers Protected LSD at < 0.05).  Figure 1. Average percent control of pre-emergence products alone and with XtendiMax® herbicide with VaporGrip® Technology, a restricted use pesticide, at 8 locations 21 days after application. (Averages followed by same letter are not significantly different using Fishers Protected LSD at < 0.05).
Figure 2. Average percent control of pre-emerge products alone and with XtendiMax® herbicide with VaporGrip® Technology at 9 locations 35 days after application. (Averages followed by same letter are not significantly different using Fishers Protected LSD at < 0.05).  Figure 2. Average percent control of pre-emerge products alone and with XtendiMax® herbicide with VaporGrip® Technology at 9 locations 35 days after application. (Averages followed by same letter are not significantly different using Fishers Protected LSD at < 0.05).
Figure 3. Average percent control of Amaranthus species with pre-emerge products alone and with XtendiMax® herbicide with VaporGrip® Technology at 7 locations 35 days after application. (Averages followed by same letter are not significantly different using Fishers Protected LSD at < 0.05).  Figure 3. Average percent control of Amaranthus species with pre-emerge products alone and with XtendiMax® herbicide with VaporGrip® Technology at 7 locations 35 days after application. (Averages followed by same letter are not significantly different using Fishers Protected LSD at < 0.05).
Figure 4. Average percent control of large-seeded broadleaf species with pre-emerge products alone and with XtendiMax® herbicide with VaporGrip® Technology at 7 locations 21 days after application. (Averages followed by same letter are not significantly different using Fishers Protected LSD at < 0.05).  Figure 4. Average percent control of large-seeded broadleaf species with pre-emerge products alone and with XtendiMax® herbicide with VaporGrip® Technology at 7 locations 21 days after application. (Averages followed by same letter are not significantly different using Fishers Protected LSD at < 0.05).
Figure 5. Average percent control of large-seeded broadleaf species with pre-emerge products alone and with XtendiMax® herbicide with VaporGrip® Technology at 8 locations 35 days after application. (Averages followed by same letter are not significantly different using Fishers Protected LSD at < 0.05).  Figure 5. Average percent control of large-seeded broadleaf species with pre-emerge products alone and with XtendiMax® herbicide with VaporGrip® Technology at 8 locations 35 days after application. (Averages followed by same letter are not significantly different using Fishers Protected LSD at < 0.05).

Key Learnings

 

  • The addition of XtendiMax® herbicide with VaporGrip® Technology increased control of broadleaf weeds in almost all cases, but particularly in large-seeded species such as giant ragweed, morningglory species, and velvetleaf at both 21 days and 35 days post application.

  • Control of problematic Amaranthus species (Palmer amaranth, pigweeds) was improved with the addition of XtendiMax® herbicide with VaporGrip® in three of the six pre-emerge products at 35 days post application. 

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