Seed Treatments Strongly Recommended for 2014 Wheat Crop - Here's Why
Figure 1. Bare patches in a wheat field resulting from the combined damage caused by seed-transmitted and soilborne fungal diseases.
August 15, 2013
(Updated with a revised table of seed treatments, 9/19/13)
Figure 2. Bunt balls containing spore masses of the common bunt (stinking smut) fungus. Common bunted grain is usually unmarketable.
Figure 3. Loose smut on a wheat head. Note that all kernels have been replaced with fungal spores.
Figure 4. Scabby wheat with kernels infected by the scab (Fusarium head blight) fungus. Severe seedling blight can result if this grain is used as seed.
Figure 5. Black point causes discoloration of the embryo region of wheat grain. It is caused by several fungi including Bipolaris and Alternaria when wet weather coincides with grain maturation.
As the wheat planting season approaches, it is recommended that growers treat seed with fungicide before planting. Seed treatments control seed-transmitted diseases that lower yield (Figure 1) and grain quality. These diseases include common bunt (also known as stinking smut) (Figure 2) and loose smut (Figure 3).
The fungi that cause these two diseases infect seed or seedlings and grow within the plant until heading, at which time they invade the developing kernels and replace them with fungal spores. Common bunt in particular can lead to 100% loss because grain elevators usually will not accept common bunted grain. This year several growers who had common bunt in their grain were not able to sell it.
Another group of seed-transmitted diseases causes root and crown rots and seedling blights. The fungi that cause these diseases infect grain during the heading and grain maturation stages. If grain affected by these fungi (Figures 4 and 5), including species in the genera Fusarium, Bipolaris, and Alternaria, is not treated with a fungicide and is used as seed, severe root and crown rots and seedling blights can occur. Together with soilborne fungi such as Pythium and Rhizoctonia that cause damping off, damage can result in uneven stands and bare patches in wheat fields (Figure 1).
Benefits of Treating Seed Before Planting
- A good stand establishment and healthy and vigorous seedlings optimize the opportunity for high yields.
- Diseases such as common bunt that lower grain quality and can lead to 100% loss are controlled.
- Root and crown rot diseases, seedling blights, and damping off which result in uneven stands and bare patches in fields are controlled.
- Treating seed with a fungicide-insecticide combo can reduce fall infections by insect-transmitted diseases such as the aphid-transmitted barley yellow dwarf virus.
- If systemic fungicides are used to treat seed, additional protection from fall foliar diseases is provided.
Treating Seed
It is best to buy certified treated seed or use a commercial seed conditioner to clean and treat seed. Seed treated on-farm should be cleaned before treatment. Thorough coverage maximizes effectiveness of the seed treatment. For a list of wheat seed treatment products, see Table 1.
Due to the increased prevalence of seed-transmitted diseases this year, it is highly recommended that certified, treated seed be planted for next season's crop. If farmer-saved or bin-run seed must be used, it should be thoroughly cleaned and treated with fungicide before planting.
Stephen Wegulo
Extension Plant Pathologist
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