Understanding and using ratings to support disease management decisions is an important part of an integrated disease management plan.
Using ratings in practice
Using stripe rust and yellow leaf spot as an example for wheat, we know that the wheat cultivars Mace is rated SVS variety for stripe rust and MRMS for yellow leaf spot. In contrast Yitpi is rated MRMS for stripe rust and SVS for yellow leaf spot. In practical terms this means that to control yellow leaf spot, Mace can be sown into paddocks with wheat stubble present, whereas Yitpi needs to be sown in paddocks where there is no (or very little) wheat residue. Yitpi sown into a clean paddock will need monitoring for rusts and septoria but unless it is a bad rust year, it is unlikely to need much follow up management. The Mace crop on the other hand will need proactive stripe rust management that starts with a seed/fertiliser treatment and continues throughout the season due to the susceptibility of the variety.
When disease resistance ratings are used in this way they can become part of the overall farm management plan, helping with crop rotations and chemical management plans.
Understanding ratings
It is important to know what ratings mean in terms of management within each crop. Cereals and pulses differ slightly in terms of disease management in resistant cultivars and it is important to know how this affects disease management. For a pulse crop, if there is severe disease pressure on a resistant cultivar a fungicide application may still be required to control the disease.
A resistant cereal crop on the other hand should be monitored for breakdown of resistance but is unlikely to need fungicides for disease control.
It is also important to note the cultivars may be resistant to foliar ascochyta blight but will not be resistant to ascochyta pod infection. This means even resistant crops need to be monitored with a view to apply fungicide if there is infection during podding.
See the How they are developed section for variety rating definitions.
Please note: This book is also available on AppleBooks
