Foliar diseases inhibit grain filling by reducing photosynthesis, reducing translocation of photo-synthate and increasing respiration of the plant. This results in smaller grain which leads to increased screenings and lower grain yield. Less commonly, foliar diseases can reduce the number of kernels per spike if disease development occurs early in the season.

Most (approximately 75 per cent) grain filling occurs within the first 4-6 weeks after head emergence. It is during this period that it is most important to minimise the severity of disease on the top 3 leaves as they contribute the most photosynthate to grain filling.

Correct disease identification is critical in for the decision to apply foliar fungicides to an infected crop and to aid with selection of the most appropriate fungicide for the disease.

It is important to note that not all disorders on plant leaves are caused by a fungal pathogen. Disorders on leaves may be caused by viral diseases (e.g. BYDV), nutrient deficiency (e.g. Nitrogen) or toxicity (e.g. Boron), or physiological blotching. None of these disorders can be controlled with the application of foliar fungicides.

This Ute Guide is designed to assist in the identification of key foliar diseases in winter cereals including wheat, barley and oats.

It describes foliar diseases via symptoms on specific plant parts at crop growth stages.

A virulent pathogen (disease-causing organism), a susceptible host and a favourable environment must all be present for disease outbreak to occur. There are differences in the likelihood of damage among the foliar diseases of wheat and barley.

Some diseases are very prevalent, but only rarely cause significant damage, whereas other diseases are rare, yet can cause severe yield loss in certain seasons. It is therefore important to accurately identify the disease when making management decisions.

This Ute Guide will aid rapid identification of foliar diseases in order to aid effectively decision-making.

1. Ensure you have access to the current crop variety ratings. (See Further Reading)
2. Choose the relevant crop stage.
3. Choose the relevant plant part.
4. Trace down the decision tree via symptom to determine the likely disease.

Any recommendations, suggestions or opinions contained in this publication do not necessarily represent the policy or views of the Grains Research and Development Corporation. No person should act on the basis of the contents of this publication without first obtaining specific, independent professional advice. The Grains Research and Development Corporation will not be liable for any loss, damage, cost or expense incurred or arising by reason of any person using
or relying on the information in this publication. The Grains Research and Development Corporation owns the rights to the Ute Guide series.

© GRDC 2016

All work contained in this App is subject of copyright owned by or licensed to the Grains Research and Development Corporation. Apart from any use permitted under the Copyright Act 1968, no part of the work may be reproduced in any form or by any process without prior written permission from the Grains Research and Development Corporation. Requests and enquires concerning reproduction and rights should be addressed to:

Manager Publications
Grains Research and Development Corporation
PO Box 5367
Kingston ACT 2604
Australia

Telephone: (02) 6166 4500
Facsimile: (02) 6166 4599
Email: grdc@grdc.com.au

Any requests concerning material that does not originate from the Grains Research and Development Corporation will be forwarded to the appropriate copyright owner.

- See more at: http://www.grdc.com.au/About-Us/Policies/Legal/Copyright

Technical Editor: Penny Heuston

Photographs for the Foliar Diseases Ute Guide app supplied by:

Hugh Wallwork, SARDI; Bob Rees, QDPI; Andy Barr, University Adelaide; Simon Eyres, DAFWA; University of Adelaide; Trevor Bretag, Victorian Institute for Dryland Agriculture; Robert Loughman, Agriculture WA; Tim Williams; Terry Hahn; Nigel Wilhelm, SARDI; Paul De Barro, UA; Margaret Evans, Natural Resources and Environment Victoria; Vern Gibbs, PIRSA; NJ Grundon, QDPI; Ken Holden, PIRSA; D Ironside, QDPI; Tanveer Khan, Agriculture WA; Mark Newton, PIRSA; Robert Park, Plant Breeding Institute; DAFWA; GRDC; D Sawkins; S Davey; Mohammad Aftab, Victoria Government; Penny Heuston, Heuston Agronomy Services; Greg Platz, QDAF; John Minogue, Ag & General Consulting.


References

Wallwork, Hugh (2000) Cereal leaf and stem diseases. Grains Research and Development Corporation.

Department of Agriculture and Food (2015) Diagnosing spetoria nodurum blotch of wheat. Government of Western     Australia, https://www.agric.wa.gov.au/mycrop/diagnosing-septoria-nodorum-wheat

Department of Agriculture and Food (2016) Managing yellow spot and septoria nodurum blotch in wheat. Government of Western Australia, https://www.agric.wa.gov.au/grains-research-development/managing-yellow-spot-and-septoria-nodorum-blotch-wheat 

Department of Agriculture and Food (2016) Oats: leaf diseases. Government of Western Australia, https://www.agric.wa.gov.au/oats/oats-leaf-diseases?page=0%2C0

GRDC (2014) Septoria tritici blotch fact sheet. Grains Research and Development Corporation, Australia, https://grdc.com.au/Resources/Factsheets/2014/02/Septoria-tritici-blotch-fact-sheet

GRDC (2016) Barley yellow dwarf virus fact sheet. Grains Research and Development Corporation, Southern Region, https://grdc.com.au/~/media/E731AF4A67894975A02903961585889F.pdf

GRDC (2016) Sripe rust in wheat: Tips and Tactics. Grains Research and Development Corporation, Northern, Southern and Western Regions, https://grdc.com.au/~/media/Documents/Resources/Publications/Tips-and-Tactics/GRDC_Tips_and_Tactics_Stripe_Rust_WEB.pdf

Developed on behalf of GRDC by Seedbed Media and DHM Environmental Software Engineering. 

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