There are two types of seed treatments available for wheat; fungicide seed treatments, and seed treatments that include a mix of fungicide and insecticide.
Fungicide seed treatments control seed borne diseases that are present on the seed surface or inside the seed such as smuts and bunts. They can also help manage soil borne seed pathogens such as pythium, rhizoctonia and fusarium, which can cause root and crown rot in wheat. Seed treatments that include a mix of fungicide and insecticide are usually beneficial for early planted wheat that is more susceptible to aphid infestations or in situations where grasshopper or wireworm problems are anticipated.
I often get questions regarding the benefits of using seed treatments at this time of year. Plant pathologists will tell you that in many cases the use of a seed treatment often does not translate to increased yields. However there are some circumstances that will increase risk and the chance of an economic return from a seed treatment.
Fields that have a history of diseases like root rot complex, smuts, and bunts will be more likely to benefit from the use of a seed treatment. Planting into crop residue that hosts these diseases such as wheat planted into wheat residue, any grass crop, or a field that had grassy weeds growing in it poses a higher risk than following clean fallow or a broadleaf crop.
When planting seed with any degree of seed borne fungal disease such as loose smut or bunt, seed treatment has an excellent chance of providing an economic return. A few diseases, such as scab (Fusarium head blight) and black point, are not directly expressed in the crop the seed produces. However fungicide seed treatment has been shown to improve germination and seedling vigor when planting seed containing either of these diseases. Although it is not recommended to plant wheat seed that contains ergot, seed treatment containing a triazole fungicide will reduce the viability of the ergot bodies and limit their ability to produce ergot spores.
Fungicide seed treatment will not compensate for poor quality seed, such as shriveled, mechanically damaged or impure seed, nor will it be effective against bacterial diseases. It is always recommended that producers start with clean, good quality seed whenever possible.
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