Test Drive the New Corn Seed Treatment

The last of the corn seed treatment containing lindane (e.g. Agrox D-L Plus and D.L.+C.) will be used up this spring. This may be a good time to conduct an on-farm seed-treatment trial to look at the merits of using Poncho 250, which is a newly registered seed treatment. Poncho 250 (clothianidin 0.25 mg ai/seed) is available as a commercially pre-applied seed treatment to control a number of seed and seedling insect pests such as wireworm, seedcorn maggot and European chafer.

While on-farm trials can provide good information, the information generated can also be dangerously misleading if the trial is not properly set-up and carried out. If you conduct a seed treatment trial, you need to know that the outcome measured is the result of the treatments tested rather than the result of chance, management or field variability. Below is a sample protocol, which can be used as a guideline to ensure the results obtained are as accurate as possible.

Seed Treatment Trial Protocol

Site Selection and Management

The plot should be located in a first year cornfield to avoid the risk of corn rootworm damage. The trial should be planted perpendicular (90^o angle) to known sources of potential variables such as tile lines, primary tillage or dead furrows. Also, where possible, apply herbicide, fertilizer, manure or other inputs perpendicular to the direction of the trial treatments. This reduces the potential for added variability that may be associated with overlap or misses of crop inputs applied in the same direction as the treatments. The goal is to reduce inherent or applied variation in the whole plot to ensure observed treatment differences are real and not due to unrelated underlying variations.

Treatments

Compare a Poncho 250 treated hybrid to the same untreated control (check) hybrid using side-by-side comparisons. This is best accomplished using the split-planter method. Fill one half of the planter seed hoppers with treated seed, the other half with the untreated check. This method gives multiple replications across the field as the planter travels back and forth. Trials with multiple replications (3 or more) provide far better results than a single replicate. If space and time allows, half way through the plot, switch the seed treatment from one side of the planter to the other to nullify planter variations.

Treated and untreated seed for the trial should be of the same hybrid and size. Prior to planting, check seed drop to ensure a uniform drop from each of the planting units (with and without seed treatment). Planter recalibration may be required if the drop is not uniform between the treated and untreated seed. Treatments should be clearly marked in the field and a plot map showing the type and placement of treatments should be drawn and stored in a safe place.

Data Collection

Production information such as soil type, previous crop, tillage, planting date, hybrid, fertility and herbicide program, plant population at harvest, weed control, growing conditions and harvest date need to be recorded during the growing season. A sample form is available in OMAF Publication 811, Agronomy Guide for Field Crops, page 11.

It would be of value to take a plant count between the 3 – 8 corn leaf stage at several locations in each treatment (i.e. 5 times down the field in each treatment in each or at least two replicates). At the same time, the plot should be scouted to determine the insect population pressure (e.g. wireworm, seedcorn maggot and cutworm). This will impacts how the data is analyzed to determine the effect and cost/benefit of the insecticide seed treatment.

Harvest

The appropriate equipment needed to collect yield data (eg. weigh wagon, weigh scales) should be identified prior to harvest. At harvest, record the data from each individual plot. Don’t lump all treatment types together or you’ll lose the value of replication.

Contact us for additional information on trial set-up, in-season insect evaluation, or to obtain project data recording forms. Given the small yield differences to be measured, we need at least 25 trial locations to get really valid data. If you conduct a corn seed treatment trial, help us learn by sending us your data at the end of the season.