http://www.ag.ohio-state.edu/~corn/agcrops.html

Effect of Fungicide Seed Treatment
on Soybean Yield in Ohio in 2001

by Dr. Jim Beuerlein
Dept. of Hort. and Crop Science
The Ohio State University

Soybean diseases in Ohio have increased in number and severity over the past 10 years, so that today the loss of productivity is greater from disease than from any other factor except weather. The increase in disease pressure is due primarily to short crop rotations or no crop rotation. It is estimated that Ohio soybean producers lose an average of five to eight bushels per acre per year to disease. In most years, few disease symptoms are recognized due to low levels of infection by any particular disease. However, several diseases are active in each field most years. It is noteworthy that by the time symptoms of a particular disease appear, the yield loss has already reached seven to ten percent. In many fields there is significant yield loss to disease even though no symptoms are evident.

In the past, we have relied on disease resistance and tolerance to provide some measure of control. Many of the Phytophthora control genes are no longer effective because the pathogens have evolved and can overcome the plant's defense mechanism. During the past ten years, fungicide seed treatments have been used effectively to improve soybean stands and increase the general health of soybean root systems.

In 2001 a series of soybean fungicide seed treatments and soybean fungicide seed treatments plus inoculation materials were evaluated at six sites in Ohio. The following tables contain the results of those test:

Table 1: Effect of Fungicide Seed Treatments and Fungicide Seed Treatments plus Inoculation Materials on Soybean Yield at Six Test Sites in Ohio in 2001.

*Warden™ RTA is a registered trademark of Agriliance LLC,  registration pending.

Table 2:  Effect of Fungicide Seed Treatments and Fungicide Seed Treatments plus Inoculation Materials on Soybean Yield at Six Test Sites in Ohio in 2001.

*Warden™ RTA is a registered trademark of Agriliance LLC,  registration pending.

Table 3:  Profit ($/Ac) due to Fungicide Seed Treatments and Fungicide Seed Treatments plus Inoculation Materials on Soybean Yield at Six Test Sites in Ohio in 2001.

*Warden™ RTA is a registered trademark of Agriliance LLC,  registration pending.
** numbers in ( ) are negative.
+ Soybeans = $5.00 per Bushel.

This study was conducted using a Roundup Ready variety, Ebberts E1311RR, obtained from Ebberts Field Seed, Inc. The variety had a relative maturity of 3.4, the Rps 1k gene for Phytophthora resistance, and a field tolerance to Phytophthora of 5.9.

Five of the six test sites experienced an excellent growing season which allowed the untreated check treatment to produce yields of 58 to 67 bu/ac depending on the test site. Even at those high yield levels, fungicide seed treatments increased yield by an average of 2.9 bu/ac with increases of up to 8.4 bu/ac, depending on location and treatment. Plots at the N1 site received over 10 inches of rain in the two weeks following planting and stands were generally poor. Fungicide seed treatments improved plant stand and increased yield dramatically. Often, under such extreme adverse pressure, fungicides are not totally effective in controlling disease. The take home message is that fungicide seed treatments are very effective tools for improving plant stands and root system health. Seed treatment fungicides should always be used on soybeans, regardless of variety, crop rotation, soil type, planting data, or tillage. The next two tables show the cultural practices used for this study at each test site and the rainfall received at each test site.

2001 Cultural Practices by Test Site