Fargo, North Dakota
April 26, 2006Soybean
seeds and seedlings are susceptible to a number of pathogens
lurking in the soil, waiting for the right conditions. These
pathogens include Pythium, Phytophthora, Rhizoctonia and
Fusarium species. In North Dakota, soil conditions can turn wet
and cold overnight. Under these cool (less than 60 degrees) and
wet soils, the soybean seeds will germinate and emerge very
slowly, making them more susceptible to attack by seed and
seedling pathogens.
Fungicide seed treatments might be a valuable tool to use to
protect soybean seeds and seedlings against diseases. Research
conducted in multiple years and locations (14 total
environments) by Carl Bradley,
North Dakota State
University Extension Service plant pathologist, shows that
there may be an overall benefit using seed treatments on
soybeans.
"The biggest benefits were observed in years and locations where
soil conditions turned wet and cool after planting," Bradley
says. "In years and locations where 'big' benefits were not
observed, the seed treatments, generally, paid for themselves.
Averaged over all 14 environments in the study, the net return
with the use of seed treatments ranged from $10 to $20 per acre
compared with untreated soybeans, depending on the product
used."
Under certain soil types, management practices and field
histories, the probability of getting a benefit from a seed
treatment probably increases. These conditions include:
* Heavy clay or poorly
drained soils
* No-tillage or reduced-tillage
* Early planting
* Tight crop rotations
* Disease history of the field
"When choosing a fungicide seed
treatment, choose a product that contains either mefenoxam or
metalaxyl," Bradley says. "These chemicals protect against
Pythium and Phytophthora. The product also should contain at
least one other chemical, such as fluidoxonil, azoxystrobin or
others, that will protect against Fusarium and Rhizoctonia."
In general, most "newer" seed treatment products are safe on
nitrogen-fixing Bradyrhizobium found in inoculants, but some
products and formulations may be better than others.
For more information about specific seed treatment products,
check the 2006 North Dakota Field Crop Fungicide Guide available
through the NDSU Extension Service, as well as the NDSU
Extension Plant Pathology Web site at
www.ag.ndsu.nodak.edu/extplantpath/.
Always read and follow
manufacturers' label directions. |