No. 23 Article 6/October 7, 2005

Preliminary Root Ratings for the Corn Rootworm Control Trial in Monmouth

As indicated in the article "Preliminary Root-Evaluation Ratings Available for DeKalb and Urbana Corn Rootworm Product Trials" published in issue no. 22 (September 2, 2005) of the Bulletin, "[d]ata from a third trial (Monmouth) are still being evaluated. We look forward to sharing the results from the Monmouth study in our next issue of the Bulletin." A few weeks ago, we learned we made an uncorrectable error in collecting and evaluating the roots from one of the Monmouth replications. So we have analyzed the data based on three of the four replications (i.e., the data collected from one replication were excluded from the analysis). Based on this analysis, the node-injury ratings from the trial in Monmouth are presented in Table 3.

The mean node-injury rating in the untreated check at Monmouth was 2.25 (Table 3), indicating that 2-1/4 nodes of roots were destroyed. Under this heavy rootworm larval feeding pressure, most products provided very good to adequate protection of the root systems (i.e., node-injury rating less than 0.5). Exceptions were Capture 2EC (mean rating of 0.99), Cruiser Extreme (mean rating of 1.70 (refer to the subsequent article), Poncho 1250 (mean rating of 0.55, the lowest mean rating for Poncho 1250 among all three of our standard corn rootworm control trials), and Regent 4SC (mean rating of 1.53). The mean node-injury ratings for all products except Capture 2EC, Cruiser Extreme, and Regent 4SC were not statistically different. With only minor exceptions, these results were very similar to those obtained from our standard corn rootworm control products efficacy trials in DeKalb and Urbana.

Other data from this and other rootworm-control trials will be shared in future issues of the Bulletin and in forthcoming educational meetings and materials.--Kevin Steffey, Mike Gray, Ron Estes, Jared Schroeder, and Darren Bakken

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