Research: Under Heavy Insect Pressure, CruiserMaxx Protected Yield - UNL CropWatch

Research: Under Heavy Insect Pressure, CruiserMaxx Protected Yield - UNL CropWatch

January 27, 2012

Most Sites Showed No Yield Difference between Treated and Untreated Soybean

CruiserMaxFig1

Figure 1. Yields for early planted soybean (May 2-5) in untreated and CruiserMaxx treated trials. At one site, Clay Center, the Cruiser Maxx treated trial showed a significant yield increase of 15 bu/ac.  At the other sites there was no significant difference. The Clay Center site, unlike the other three, had heavy bean leaf beetle feeding.

 CruiserMaxFig2

Figure 2.  Yields for late planted soybean (early June) at two sites with untreated and Cruiser Maxx treated seed.

CruiserMaxx® seed treatment trials were conducted at four locations in Nebraska to determine the effects on yield in early planted (early May) and later planted (late May-early June) soybean. The sites, part of the 2011 Soybean Management Field Days, were Bancroft (northeast Nebraska), Clay Center (south central), Cortland (southeast), and Elba (central).

Research Model

The design used in this study was a randomized complete block for both planting dates, with two treatments for each planting date. Treatments were CruiserMaxx (thiamethoxam + mefenoxam) treated seed and untreated seed. Plots were four rows wide and approximately 20 feet long. Standard soybean production practices were conducted. Yield was the primary measure, but plant stand, seedling defoliation, and bean leaf beetle numbers also were measured to help explain any effects. All yields were adjusted to 13% moisture. No disease measurements were made.

Results

Due to planter malfunction, the Clay Center and Cortland late planting dates were compromised. Cool and wet weather resulted in uneven emergence, particularly at Clay Center. Bean leaf beetle counts were generally very low, but defoliation indicated beetle presence, particularly at Clay Center during VC-V1.

There were no significant differences (α = 0.05) in yield between CruiserMaxx treated and untreated soybean at Bancroft, Cortland, and Elba for the early planting, and at Bancroft and Elba for the late planting (Figures 1 and 2).

There was a significant difference in yield between CruiserMaxx treated and untreated soybean at Clay Center for the early planting date. CruiserMaxx treated soybean was approximately 15 bu/ac higher than the untreated soybean. This likely was in part the result of bean leaf beetle feeding, as all untreated plants had feeding (up to 100%) injury at VC-V1, and feeding likely continued through V2-V3. Although feeding was present at other sites, it did not reach yield-damaging levels.

Thomas Hunt
Extension Entomologist