Country News

Seed bed preparation is vital

By Geoff Adams

Seed treatments are applied to seed to control diseases such as smuts, bunts or rust, and insects.

When applying seed treatments, always read the chemical label and calibrate the applicator.

Seed treatments are best used in conjunction with other disease-management options such as crop and paddock rotation, clean seed and resistant varieties, especially when managing diseases such as stripe rust.

There are risks associated with using seed treatments.

Research shows that some seed treatments can delay emergence by:
● slowing the rate of germination; and
● shortening the length of the coleoptile, the first leaf and the sub-crown internode.

If there is a delay in emergence due to decreased vigour, it increases exposure to pre-emergent attack by pests and pathogens, or to soil crusting; this may lead to a failure to emerge.

The risk of emergence failure increases when seed is sown too deeply or into a poor seedbed, especially in varieties with shorter coleoptiles.

As the amount of certain fungicides increases, the rate of germination slows.

Some seed treatments contain azole fungicides (triadimenol and triadimefon).

Research has found that these seed treatments can reduce coleoptile length, and that the reduction increases as the rate of application increases.

Product registrations change over time and may differ between states and between products containing the same active ingredient.

The registration status for the intended use pattern in your state must be checked on the current product label prior to use.

The principal reason for using a fungicide at sowing for wheat crops has been for the control of smuts, but with the increased incidence of stripe rust in recent years, fungicide is being applied both to the seed and in-furrow.

Jockey (fluquinconazole) seed dressing is being used for stripe rust mostly in lower rainfall areas or Impact (flutriafol) in-furrow is used for stripe rust in medium- and high-rainfall areas where the risk is greater.

If growers think they may have a problem with seed-borne infection, it is recommended they have the seed tested by the Cereal Pathology Subprogram, Plant Health and Biosecurity at the South Australian Research and Development Institute.

From Grains Research and Development Corporation