Week 10 Introduction to Cereal Disease Control 2024
No description yet. This curated deck is ready for daily study.
Card preview (17)
Fungal Diseases - Infections over the season 1- Seedling Diseases: 2- ‘Seed’ diseases 3- Stem diseases 4- Root diseases 5- Leaf diseases 6- Ear diseases
1* Seedling diseases – Michrodocium nivale (fusarium) 2* ‘Seed’ diseases – loose smut, Bunt (covered smut) 3* Stem diseases - eyespot, sharp eyespot 4* Root diseases - take-all 5* Leaf diseases - mildew, rusts, septoria sp., rhyncosporium, net blotch, etc 6* Ear diseases - fusarium sp., sooty moulds
Key Diseases for each cereal crop Wheat: 7
• Take-all • Septoria tritici • Mildew • Ear Fusarium • Eyespot • Yellow rust • Brown rust
Key Diseases for each cereal crop Barley 5
• Rhyncosporium • Net blotch • Mildew • Brown Rust • Ramularia (leaf blotch)
Key Diseases for each cereal crop Oats 2
• Mildew • Crown rust
Powdery Mildew 1- Whats it most common in? 2- Whats it look like? 3- At the end of season what does it show? 4- Wind dispersed conidia is ideally what?
1-Commonest of cereal diseases 2- Very distinctive symptoms Chlorotic flecks Distinctive white fluffy pustules Older pustules – grey/brown 3- End of season – shows as black cleistothecia 4- Wind dispersed conidia – ideally with 15-20 C / high
Slide 5 and 6 Life cycle of powdery mildew that im not learning :)
Yellow Rust Puccinia striiformis 1- How is it distinctive? 2- Is it a parasite? 3- What weather does it favor? 4- What does it survive on?
1- Distinctive pustules in stripes between leaf veins , foci infections (hot spots) 2- Obligate parasite , and has many specific races (sub-species) / pathotypes 3- Favoured by cool humid weather and very short latent period 4- Survives on volunteers , genetic resistance is key (breeding progs) diversification progs
Common diseases to each cereal crop , Fungal Diseases : eyespot take-all What are more prominent in wheat?
– eyespot (wheat > barley) – take-all (wheat > barley) fusarium species (more prominent in wheat)
Important diseases in specific cereal crops (2)
– Septoria sp. in wheat – Rhyncosporium and Net blotch in barley
Fungal diseases and weather Wet weather diseases (4)
– Septoria sp. in wheat – Rhyncosporium and Net blotch in barley – Fusarium species on the ear – Sooty moulds / Botyritis
Fungal diseases and weather Dry’ Weather Diseases (2)
– Mildew on all cereals – Rust diseases
Methods of Disease Control (3)
1-* Cultural – rotation (take-all, eyespot) – ploughing – stubble hygiene 2-* Varietial – use of resistant varieties e.g. for BYMV (barley yellow mosaic virus – for foliar diseases, e.g. yellow rust, mildew control – use of varietial diversification 3-* Chemical – seed dressing – foliar fungicides
Cultural Control - objective Whats the key objective?
Key objective is to reduce the incidence and severity of the disease To reduce the innoculum / initial infection level at the beginning of the season To delay the disease epidemic ( in relative terms ) – in late spring and early summer, GS 30 onwards – to delay the disease progress curve in a high disease season – to reduce the disease severity on the upper canopy late in the season
Cultural Methods of Disease Control: (3)
1* Rotation – excellent method for reducing take-all infection – it is claimed a two-year break needed for eyespot 2* Stubble hygiene / good ploughing – can be very useful for reducing net blotch infection – also very good for reducing Fusarium graminarium (after Maize in USA/Germany) 3* Delayed Sowing
Genetic Resistance: 1- What is a key to good ICM programme? 2- Whats the focus usually on? 3- What gene can be venerable? 4- What will fall overtime?
Varietial Resistance Ratings 1 – Key to good ICM programme for disease control – Ideally resistance rating of 7 plus 2- – Focus is usually on the more important foliar diseases 3– Major gene (single gene) resistance can be vulnerable so multi-gene R is more desirable 4– Resistance will often fall over time as diseases populations become more adapted to widely grown varieties
IPM Approaches to Disease Control: 1- What should plants develop? 2- What is a good principle to have? 3- What is the resistance determine?
1-* Disease Thresholds – Develop disease thresholds for specific diseases 2-* Decision Support Systems - DSS – DSS for various pathogens in many crops – Brings many challenges but is a good principle 3-* Varietal Resistance – Resistance ratings on individual diseases – Yield and Quality response to fungicide use – Survey of pathogen virulence Fungicide Efficacy / Spectrum / Performance
Cultural Methods and Disease Severity: (4)
1* Sowing Date – Early – many impacts on disease incidence / severity – Later sowing – yield / quality impact 2-* Low / High Crop Density – Increased epidemics – Open canopies and microclimate 3-* High N Inputs – Increased disease severity – Interaction with crop lodging etc 4-* Crop Rotation / Tillage – Minimum tillage effects