Fungicide Seed Treatment

Research shows that fungicides can control cotton seedling diseases. Growers and consultants should consider several major factors to determine the use of fungicides.

Research shows that soil fungicides can control cotton seedling diseases. Growers and consultants should consider several major factors to determine the potential benefit from fungicide seed treatments or in-furrow fungicide applications.

The seedling disease complex can vary greatly from field to field, and from year to year, depending upon several cultural and environmental conditions.

The use of seed treatment or in-furrow fungicides should be determined by the presence and intensity of nine factors:

  • Soil Temperature: Low soil temperatures create conditions that will slow seed germination and seedling mergence, thus extending the vulnerable period for infection. Many soil-borne pathogens are active at lower temperatures.
  • Five-day Forecast: Environmental conditions during the first week of planting are important to consider. A critical factor to evaluate is the combination of low soil temperatures and high soil moisture. Any condition that slows germination and growth of the seedling favors the seedling disease complex.
  • Seed Quality: Poor quality seeds germinate and emerge slower than good quality seeds under similar conditions. Slow germination and emergence extends the period seeds are vulnerable to infection.
  • Field History: The history of each field should be evaluated to determine if it has had a stand-establishment problem, which may have been caused by factors including: soil type, drainage, soil pH, and levels of organic matter.
  • Tillage: A no-till, or stale seed bed has a tendency to be slightly cooler and wetter than a conventional seed bed. This combination may be conducive to carryover of disease inoculum on the past year’s crop debris.
  • Seeding Rate: Recommended seeding rates have gradually declined in most parts of the Cotton Belt. This increases the importance of getting a higher percentage of seeds to germinate, emerge, and become established.
  • Insecticide/Nematicide Use: Experience shows that the use of a soil fungicide can be a "safening" factor when certain soil-applied insecticides/nematicides are used.
  • Soil Moisture: When soils are saturated with moisture for prolonged periods, seeds and seedlings are adversely affected. These conditions are ideal for the growth of several soil pathogens.
  • Planting Date: A field planted prior to normal planting dates for its area will have conditions that favor greater seedling disease pressure.