Poncho® 1250 Seed-Applied Insecticide Controls CRW and Other Insects

Murt McLeod, Steve Butzen and Paula Davis

Summary | Introduction | Agronomy Sciences Replicated Trials | Agronomy Sciences On-farm Strip Trials

• Pioneer is introducing a new-generation seed-applied insecticide for corn hybrids in 2004, Poncho® 1250. This just-approved product will be applied at a rate of 1.25 mg active ingredient (clothianidin) per kernel.
• The primary pest target for Poncho 1250 is corn rootworm (CRW). But in addition, it offers the broadest insect protection available in a seed-applied insecticide for a number of other problematic insects.
• Secondary soil insects on the Poncho 1250 label include wireworm, white grub, grape colaspis, and seedcorn maggot. Above-ground insects are billbug, chinch bug, flea beetle and black cutworm. It is expected that imported fire ants will be added to the label soon.
• Poncho 1250 users will find advantages in convenience, handling, safety, grain marketing and hybrid availability over other corn rootworm management options.
• Poncho 1250 allows growers to “stack” corn rootworm protection with the newest hybrid genetics, including the latest Pioneer brand hybrids with Herculex³ I or YieldGard Corn Borer⁴ insect protection, or the Roundup Ready⁴ trait.
• Pioneer Agronomy Sciences researchers have conducted tests of Poncho 1250 under various levels of corn rootworm pressure. Results demonstrate the effectiveness of this new corn rootworm management solution.
• This Crop Insights will discuss corn rootworm control using Poncho 1250, the newest on-the-seed and in-the-bag insect management technology.

Corn rootworm larvae are one of the most destructive insect pests of corn in North America. To prevent devastating losses from this pest, producers have historically used crop rotation or a soil-applied insecticide. But in many areas, changes in corn rootworm biology have reduced or eliminated the effectiveness of rotation to prevent damage from this pest. In parts of northern Iowa, southwestern Minnesota, and southeastern South Dakota, an estimated 40 to 60% of northern corn rootworm eggs exhibit extended diapause. These northern corn rootworm eggs hatch after two winters and place corn in a two-year rotation at risk to damage. In an expanding area centered in eastern Illinois and western Indiana, western corn rootworms developed the ability to deposit eggs in soybeans or other crops rather than only laying eggs in corn fields. In this region, corn is at risk regardless of the rotation, so another management system must be implemented. In Nebraska, western corn rootworm adults have developed resistance to some commonly used foliar insecticides, requiring a new mode of action or management system to achieve control.

Corn rootworm larval feeding on non-treated hybrid.

As these problems have spread and intensified, growers have begun to experience significant losses where previous management methods were once highly effective. In areas where rotation was the predominant management solution, many growers have never treated for corn rootworm and do not have the equipment to apply granular or liquid insecticides.

To help manage these challenges, Pioneer is introducing an alternative CRW control option. Poncho 1250 comes on-the-seed and in-the-bag, eliminating the cost and time required to install soil-applied insecticide equipment, calibrate equipment and load products during planting, and handle and return insecticide containers.

The manufacturer notes that there are no extra requirements for disposal of seed bags and no special protective clothing required (other than safety equipment normally recommended for handling seed corn.) Poncho 1250 is a non-restricted-use product, offering excellent human and environmental safety. This is in stark contrast to many other highly toxic corn rootworm insecticides.

Pioneer Agronomy Sciences researchers conducted experiments with Poncho 1250 in 2001 to 2003. Their objective was to evaluate this new product for efficacy against corn rootworm larval feeding and determine its impact on yield compared to a standard granular insecticide application.

Experimental Procedures

Small plot replicated trials were conducted at 10 to 12 locations per year from 2001 to 2003. Table 1 shows products and rates evaluated:

Table 1. Insecticide treatments evaluated in Pioneer Agronomy Sciences studies, 2001-03.

Two Pioneer brand hybrids with different root lodging scores were evaluated in each year of the study. All treatments were replicated four times per location in a split plot design with insecticide treatment as the whole plot and hybrid as sub-plot. Plots were 17.5 feet long by 10 feet (4 rows) wide. Plots were maintained consistent with local agronomic practices.

The previous crop in these studies was corn, except for two locations each year where plots were planted on soybean stubble to evaluate the treatments against first-year western corn rootworm variants. All infestations represent natural population densities of corn rootworm; plots were not manually infested with rootworm eggs.

At approximately V2, the total number of plants in the center two rows of each plot was recorded as early stand count, to determine if any of the treatments either enhanced or reduced stand establishment. Five consecutive plants per plot were dug from row one in mid to late July and rated for corn rootworm larval feeding damage using a 0.00 to 3.00 node injury scale developed at Iowa State U. (Table 2).

Table 2. Corn rootworm damage rating system* used by Pioneer researchers for scoring corn rootworm feeding damage in this study.

Damage in-between complete nodes eaten is noted as the percentage of the node missing, e.g., 1.50 = 1 1/2 nodes eaten, 0.25 = 1/4 of one node eaten, etc.

*Rating system developed at Iowa State University.

At harvest the number of root lodged plants per plot was recorded. The middle two rows of each four-row plot were machine-harvested for grain yield.

Northern (left) and western (right) corn rootworm adults, (images courtesy of Donald Specker, Pioneer Hi-Bred.)

Results and Discussion

Corn rootworm feeding damage was at high levels at most but not all of the testing locations over the three-year study. Only those locations with significant rootworm larval feeding pressure (node injury scale ratings for the untreated check equal to or greater than 1.0) were combined for analysis each year.

Early stand count was not affected by treatment at any of the testing locations over the three-year study. This indicates that the seed treatment does not reduce germination or plant stand establishment.

Node injury scale ratings for Poncho 1250 and Force 3G from 2001 to 2003 are presented in Figure 1. In both 2001 and 2002, ratings in Poncho 1250-treated plots were not significantly different compared to ratings in Force 3G-treated plots.

Figure 1. Control of corn rootworm with a seed treatment and a granular insecticide, 2001-03. Pioneer Agronomy Sciences Research.

Conversely, in 2003, Force 3G-treated plots had a significantly lower rating compared to Poncho 1250-treated plots. The difference in results is due to the fact that Force 3G treatments resulted in better performance in 2003. The average rating for Poncho 1250 was identical in all three years of the study.

Yield data for 2001 to 2003 small plot trials are presented in Figure 2. In all years, yield for plots treated with either insecticide was significantly higher compared to untreated check plots, but yield was not significantly different among insecticide treatments.

Figure 2. Yield (Bu/acre) for a seed treatment and a granular insecticide, 2001-03. Pioneer Agronomy Sciences Research.

Significant root lodging occurred at testing locations only in 2002. The average percent root lodged plants by treatment in 2002 is presented in Figure 3. Root lodging was considerably less in Poncho 1250- and Force 3G-treated plots compared to untreated check plots.

Figure 3. Percent root lodged plants with a seed treatment and a granular insecticide, 8 locations, 2002. Pioneer Agronomy Sciences Research.

Experimental Procedures

Pioneer conducted on-farm strip trials in 2003 to study corn rootworm control. In these Technology Advancement Trials (TAT), Poncho 1250 was compared to a soil insecticide and an untreated check in 50 locations in the Midwest U.S. All major corn-producing states including Iowa, Illinois, Nebraska, Indiana and Minnesota were represented in the study. The soil insecticide compared in the strip plot was chosen by the cooperating grower for field. Aztec¹ comprised about 50% of these comparisons, Force² G about 25%, and Capture⁵, Regent⁶, Counter⁶ and Lorsban⁷ the remaining 25%.

In July, roots were rated by digging 10 plants per strip and scoring the CRW feeding damage using the Iowa State 0.00 to 3.00 node injury scale (Table 2). Just prior to harvest, root lodging counts were taken in replicated sub-plot areas, and percent root lodging calculated for each strip. Grain yield and moisture were measured at harvest.

Results and Discussion

A high level of corn rootworm feeding damage (root ratings greater than 1.0 for the check) occurred in 25 of the 50 locations tested in 2003. Medium CRW feeding pressure (root ratings of 0.5 to 1.0) was found in 6 locations, and low pressure (root ratings less than 0.5) occurred in 19 locations in 2003. Root damage ratings, root lodging and yield for 2003 are broken out by CRW pressure in the graphs below.

Figure 4. Control of corn rootworm, Poncho 1250 vs.soil-applied insecticides, on-farm strip trials, 2003. Pioneer Technology Advancement Trials (TAT).

Root damage ratings for Poncho 1250 and soil insecticides were statistically the same at low and medium CRW pressure. At high CRW pressure, Poncho 1250 plots were significantly better than the untreated plots, but not as good as the soil insecticide-treated plots. Under high pressure, Poncho 1250 maintained its consistent rating of about one root node destroyed (1.1 in this case), just as it did in the small-plot trials.

Yield data for 2003 TAT strip trials are presented in Figure 5. At each CRW infestation level, Poncho 1250 and soil insecticide-treated plots were statistically the same for yield. Poncho 1250 was statistically higher yielding than the untreated plots at all CRW infestation levels. Soil insecticides were higher yielding that the untreated plots at medium and high CRW pressure.

Figure 5. Yield (Bu/acre) for Poncho 1250 vs. soil-applied insecticides, on-farm strip trials, 2003. Pioneer Technology Advancement Trials (TAT).

Corn rootworm larvae (left) and pupa (right), (images courtesy of Jim Kalisch, Univ. of Nebraska.)

Root lodging data are summarized in Figure 6. Root lodging in Poncho 1250 plots was statistically no different than that of soil insecticide-treated plots at low and medium CRW infestation levels. At high CRW pressure, root lodging was more severe in Poncho 1250 plots than in soil insecticide-treated plots. However, The root lodging in Poncho 1250 plots did not reduce combine harvest speed below that of the soil insecticide plots, except in one location out of 50.

Figure 6. Root lodging* due to corn rootworm feeding, Poncho 1250 vs. soil-applied insecticides, on-farm strip trials, 2003. Pioneer Technology Advancement Trials. (TAT). *Plants were counted as root lodged if stalk angle was 30 degrees or more from vertical.