Wheat Seed Treatments

Currently, wheat is grown on more land than any other commercial crop. Wheat cultivation appears very early in human history. It is a major diet component because it is easy to store, easy to convert to flour and palatable. Greater yield per acre relies on management techniques, high-yield, disease resistance and seed treatments. Seed treatments depend on costs, crop history, seed quality, soil conditions and farming practices.

Types

• Two types of seed treatments exist. Protectant, or nonsystemic, seed treatments are effective only on the seed surface while systemic treatments have their effects within the seedling. Diseases controlled by seed treatments fall into three groups: smuts and bunts, seed and seedling and root rots. Seed treatments provide seedling protection for about three weeks.

Bactericides

• Bactericides are broad spectrum bacteria killers. The infective bacteria multiply extremely quickly in warm wet conditions, causing bacterial blight, bacterial spot, bacterial wilt and soft rot. Bactericides inhibit either bacterial growth or actions. Streptomycin is most commonly marketed under the trade names Ag-Streptomycin and Agri-Mycin. Also, novel antibacterial carbamate derivatives treat bacterial diseases, as do new copper-based fungicide/bactericides.

Fungicides

• Since many kinds of fungi affect wheat, correct disease analysis is needed for logical decisions on fungicide choice. Numerous fungicides exist for numerous fungal diseases. For example, fludioxonil is used against seed decays from asperigillus, fusarium and penicillium, while pentachloronitrobenzene is used for rhizoctonia in seedlings. Fungicides come in broad-spectrum and narrow-spectrum as well as in systemic and nonsystemic forms. All options must be explored for maximum wheat production.

Insecticides

• Insecticide usage depends on the insects present. The use of insecticides is only recommended for problems related to insect activity, not in the absence of insects. Aphids carry barley yellow dwarf virus and should be killed with insecticides, such as thiamethoxam and imidacloprid, within the first 30 days of emergence. Insecticide treatment for cereal leaf beetle is justified when the population reaches one beetle per stem. Several different insecticides are recommended for armyworms, grasshoppers and Hessian flies, depending on the extent of infestation.

Biologicals

• Living microorganisms applied to seeds are biologicals. Under favorable conditions, the microorganisms colonize the exterior of the seeds or plants to fight pests. Such organisms exist as viruses, bacteria, fungi and nematodes. Benefits include low toxicity to humans and nontarget insects. Drawbacks include short shelf life and no control over heavy infestations. Most biological insecticides use bacillus thuringiensis, a bacterium.