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Bruce Burdick
1109 S. Birch St.
Albany, MO 64402
660-726-5610
Email: BurdickB@missouri.edu

Hundley-Whaley Center phone
660-726-3698

SOYBEAN SEED TREATMENTS

Objective: To determine the value of fungicide seed treatments for soybean producers, as influenced by planting rate and row width.

Summary: Two years of yield data from Mid-May planted soybeans at the Hundley-Whaley farm at Albany indicate that there was no improved soybean yields from fungicidal seed treatment. Neither was there a significant difference in yields between 15 & 30 inch-wide rows. There was no difference in soybean yields due to seeding rates of 100, 150 and 200 thousand seeds per acre. This lack of differences, if consistent across time and soil types, could substantially reduce soybean production costs.

Situation: Soybean seeds planted into soils within 12-36 hours of a major rainfall event are most subject to seed and seedling diseases caused by fungi. Cool wet soils favor seedling diseases. The cool temperatures slow seed germination and seedling growth and favor the growth of many fungi that cause seedling diseases.

Seed treatment of soybeans with a fungicide before planting will usually help to improve germination and seedling vigor by reducing seed decay, damping off and seedling blights.

This study was designed to answer the question of whether the additional costs yield profitable results.

Methods: The seed used in this experiment was Merschman Houston V RR, treated and untreated. The treated seed was what Merschman calls ABonus Coated@ seed. The treated seed was treated with a formulation of four fungicides (Captan, PCNB, Thiabendazole and Metalaxy). The fungicides are supposed to provide maximum seedling protection against Rhizoctonia and Pythium plus seed borne pathogens like White Mold, Pod & Stem Blight and Alternaria.

We had hoped to plant this study at a time immediately proceeding a rain event. Due to the very dry spring, that was not possible. We planted on May 12 into near ideal soil conditions and the soybean stand was well established before we received significant rainfall.

The study was planted into a soil type characterized as a Grundy silt loam with 3.1% organic matter. The soil surface was dry at planting time but there was adequate moisture in the soil profile to get rapid germination of the seed. The study was planted into a conventionally prepared seedbed with historically light weed pressure. The previous crop was soybeans.

Seeding rates were 100, 150 & 200 thousand seeds per acre in this study. The seed was counted to represent these seeding rates and then planted with a cone planter set to plant the seed 1" deep. The study was designed as a Split-plot with six replications. Gylling's Agriculture Research Manager 6.1 was used to design and analyze the study.

Weed control was accomplished with multiple applications of Roundup applied as needed. Roundup applications were made at the rate of 1 quart/acre of roundup Ultra on June 12 and June 30.

Rainfall through the summer was considerably below average.

Results: Seedlings were counted on June 14. Seedlings were counted from 3 foot of row length at three places within each plot that were subjectively selected as representative stands within the plots. Table 1 & 2 shows the results. The 1999 data is in Table 3. The stand count data indicates that fungicide seed treatments did not aid in securing stands in 1999 or 2000. The final stands ranged from a low of 87% to high of 99% of the seed planted in 2000. Row width and seeds/foot of row had no effect upon soybean seedling count.

Harvest was done on October 4 this year and the data is shown in Table 4. Harvest data for 1999 is shown in Table 5. There was no significant difference in soybean yields regardless of seed treatment, planting rate or row width for either year.

Discussion and Conclusions: The data provided by this study for both 1999 and 2000 can be concluded as follows.

1. For planting dates of May 27, 1999 and May 12, 2000 at the Hundley-Whaley Farm at Albany, MO, fungicidal seed treatments were of no value in securing soybean stands, regardless of row width or planting rate.
2. There was no significant difference in soybean yield performance in 1999 or 2000 for soybeans planted at seeding rates of 100,000, 150,000 or 200,000 for mid-May planted soybeans at the Hundley-Whaley Farm at Albany. This regardless of row widths of 15 or 30 inches wide.
3. There was no significant difference in soybean yield performance in 1999 or 2000 for soybeans planted in either 15 or 30 inch wide rows for mid-May planted soybeans at the Hundley-Whaley Farm at Albany. This regardless of planting rates of 100, 150 or 200 thousand seeds per acre.

Do these conclusion indicate that fungicidal seed treatments are of no value? Certainly not! However, they were not of value to us in these two studies.

Do these studies support the idea that narrow rows are of little value when it comes to soybean yield performance? Possibly, but the producer needs to remember that these plots were kept weed-free by multiple, bulk applications of Roundup to all plots within the study. There would have been a difference in time required for soybean canopy closure between 15 and 30 inch wide rows and this could have an impact on how producers controlled weeds under commercial field situation.

Is there a reason to plant soybeans at planting rates in excess of 100,000. Two years of data for mid-May planted soybeans at the Hundley-Whaley farm would suggest that the lower seeding rates are sufficient. However, there are cases where this might not be the conclusion. These tests were conducted in years with dry summers. The results of higher seeding rates could very well be different in years with more favorable summer-time moisture. Another concern relates to the lack of a soil-compacting rainfall following planting in either 1999 or 2000. If the soil would have crusted due to a hard rain after planting, then higher seeding rates could have been beneficial in getting a soybean stand.

Producers could certainly reduce production expenses if they could reduce seeding rates from 200,000 down to 100,000 seeds per acre. It is not uncommon for producers to spend $28.00 per acre for 200,000 seeds per acre of Roundup Ready soybean seed. If a producer could reduce seeding rates by one-half without adversely effecting yield, as was the case in this study, then producers could save $14.00 per acre in production costs.

Outreach: The data for the 1999 experiment was shared with 165 soybean producers attending the NW Mo. District Soybean Meeting in Maryville in February, 2000. It was also included as a part of the 2000 Hundley-Whaley Research Farm field day report that was distributed to over 800 people who attended the field day and tour. This years data will be shared with producers at these two 2001 events.

Future Plans: This was the second year of a three-year study.