Side PanelExpand side panel Cereal Disease Control 2024 Part 2. Disease Control Strategies in Barley

Question 1

Rhyncosporium secalis
Leaf blotch of Barley – Leaf Scald

1- Whats it suited to?

2- What does it look like?

3- How does the primary infection occur?

4- How long is the disease cycle?

5- Whats a major gene in disease resistance?

6- Whats very important?

Answer 1

1- Suited by cool maritime conditions

2- Pale grey-green water soaked lesions
Mature lesion shows grey centre and dark
brown edging , lesions coalesce into
larger necrotic tissue areas

3- Primary infection from splash dispersal of
spores from crop debris

4- 14 day disease cycle in optimum weather
conditions – cool wet humid weather

5- Disease resistance is impt –
Polygenic and major gene
Resistance rating of 6/7 needed

6- Azole fungicides (Proline) very impt

Question 2

Just have a look at slide 3,4,5

Question 3

Disease Control and Fungicide
Programmes for Spring Barley

1- What are fungicides used for?

2- What do fungicides improve?

3- What are widely used products?

4- Whats the contact product?

Answer 3

1- * Fungicides are used to control disease, to increase
grain yield and to improve grain quality

2- * Fungicides improve grain quality by increasing the
grain size (1000 grain wt.) and by improving grain-
fill (hectolitre weight) and by reducing small grain
% (screenings)

3- * Widely Used Products Siltra , Ascra Pro, Proline,
Revystar, Priaxor, Elatus Era etc

4- * Contact product - Arizona (Folpet)

Question 4

Disease Control and Fungicide
Programmes for Spring Barley

1- Whats the key target:

2- When is portection against diease needed?

3- whats the standard approach?

4- Whats the cost?

Whats the yield responce?

Answer 4

1-* Key target are foliar disease - Rhyncosporium,
mildew, net blotch, ramulaira and rust diseases

2-* Protection against disease is needed for a period
of 50-60 days from late-May to end July

3-* standard approach is a two-spray fungicide
programme

4- * Cost is Euro 40-80/ha, requires 5-10% yield
increase to cover costs

5- * Yield response to fungicide use varies greatly
depending on variety and season and is in the
range 10-40% (0.5 to 2 t/ha)

Question 5

Fungicide Programmes for Barley: (3)

Answer 5

• Two-spray treatment , sometimes three e.g. winter barley
• Early-season - GS 30-31
• Mid-season - GS 39 (45)

Question 6

What is the frequent approach in both winter and spring crops if high levels of disease?

Answer 6

• Frequently a three-spray approach in both winter and spring
  crops if high level of rhynco on early-sown crops

Question 7

What is the Target is for high levels of wet weather disease control

Answer 7

• Rhynco, Net blotch, Ramularia, Ear Fusarium
• Less focus on mildew and brown rust

Question 8

Fungicide Programmes for Spring Barley

1- How many times are they sprayed, How many sprays and what gs?

2- When does most grain yield response happen when spraying?

Answer 8

1* Standard - two-spray programme : with
applications at GS 24-30 (T1)and GS 37-39 (T2)

• T1 spray - reduced rate application (30-40% of
  total) to give 20-25 days protection
• T2 spray - main spray (60-70% of total) to give
  30-40 days protection

2- Most of the grain yield response to fungicide is
expected from the second spray (main spray)
which protects the crop during the grain filling
period

Question 9

Barley Diseases and Weather Unpredicability

1- Wet weather diseases:

2- Dry weather diseases

3- What can be a problem in ireland?

Answer 9

1- Wet weather diseases
– Rhyncosporium (RHYNCO) and Net Blotch
– The spread and infection of Rhyncosporium and Net
blotch are favoured by high rainfall and high
humidity (rain splash diseases)

2- Dry’ Weather Diseases
– Mildew and Rust diseases
favoured by relatively dry warm weather but do
require moisture and humidity (in small quantities)

3- In a changeable Irish spring and summer both
wet and dry weather diseases can be
problems

Question 10

Background – ‘novel’ Barley Disease - Leaf Blotch- just read over

Answer 10

Incidence around the world
- mid-1980’s reported in Austria, New Zealand (Ovulaira leaf spot)
- late-1990’s Germany, Scotland, Ireland, Denmark, Czech Rep.,
Austria and also field trial research in New Zealand
the New Zealand research has reported that even at low levels of infection the disease has a
marked effect on the grain yield of barley
2000 to today – a disease threat in winter and spring barley in western Europe
in every season
- Very effectively controlled by Chlorothalonil at T2 up to 2020
- Now best options are contact (Folpet) plus Azole fungicides (variable)
- Lack of useful genetic resistance ( low-moderate Variety ratings)