Barley Disease Control Update

 

Ibarley the number of ears per m2 has a strong impact on yield and while it is possible to achieve some compensation for low ear numbers as crops with lower tiller numbers produce more grains per ear, the scope is limited in barley with this ability 30-50% less than in wheat. In other words ‘thick’ crops of barley tend to be the highest yielding ones.
 
‘Thick’ barley crops deliver higher yields
Therefore to achieve a high yield in barley it is important to maximise tiller production during early canopy growth and to maintain as many of these tillers as possible until harvest. Early disease control is important in maximising tiller numbers and ultimately in protecting yield. For more details on the importance of early season disease control in barley see http://www.agritrading.ie/The-Importance-of-Early-Season-Disease-Control-in-Barley 
Key point: Wheat has a higher ability to compensate for ‘thin’ crops than barley. ‘Thick’ crops of barley are essential for high yields.
Main Foliar Diseases
The main foliar diseases in barley are:
 
All of these diseases have the potential to reduce both yield and quality (KPH, screenings etc.). Their importance depends on the season (weather) and local conditions (field history etc.). Rhyncho and Net Blotch pose the biggest threat in Irish conditions to tiller survival early in the season. This is because they favour wet weather, with Rhyncho more common in cool conditions and Net Blotch in milder conditions. Overall, Rhyncho is probably the most important foliar disease of barley in Ireland, with Net Blotch number two.
Brown Rust is relatively rarely seen to any significant level as it favours higher temperatures (>15oC) but small outbreaks are common in susceptible varieties e.g. Leibniz winter barley and the spring varieties Mickle, Propino, Quench & Sanette.  Mildew epidemics have been rare in recent years due to resistant varieties, strong chemistry against the disease and unsuitable weather conditions. Even where outbreaks do occur, yield losses tend not to be as severe as other diseases.  However it can still cause tiller loss early in the season and therefore it needs to be watched for, particularly in susceptible varieties like winter varieties Saffron and Cassia plus the spring variety Mickle.  
Ramularia is a late season disease that tends to be more severe where other diseases are not prevalent and after periods of wet weather.  It is often confused with ‘spots’ produced on leaves for a range of other factors (commonly called physiological/abiotic spotting).
Non-Chemical Disease Control Factors
The disadvantage of having a wide range of fungicides that deliver good control of diseases in barley is the potential to become reliant on them and forget about husbandry factors.  It is important to employ non-chemical control measures wherever possible from a sustainability and now regulatory (Integrated Pest Management) perspective.  These include:
Choice of resistant varieties
 
Control of volunteers in stubbles
 
Use of certified/disease free seed
 
Disease Control Timing
Winter Barley
Trials carried out by Teagasc at sites in Cork and Carlow in 2010 (see table 1), have shown early spring disease control resulted in higher responses than previously thought. Traditionally fungicide programmes in winter barley favoured a higher spend later in the season however this work suggests an increased spend earlier in the season may be more profitable.
Table 1: Winter barley fungicide trials at sites in Cork and Carlow (Teagasc 2010)
Timing Significant response to Fungicide
Cork Site Carlow Site
Autumn No No
Tillering Yes Yes
GS 31-32 Yes Yes
GS 39-45 No No
GS 59 No Yes
The above results suggest the first fungicide should be applied during late tillering rather than the traditional GS 31-32. However, the average results from trials in Teagasc Oakpark (see figure 1) over the last four years, suggest a poor response from a spray during tillering and that a 2-spray programme commencing at GS 31-32 delivers the best yield response.
 
It could be argued that there is higher disease pressure in the Dairygold catchment area and a 3-spray programme is justified. In reality every year is different and there will be different responses to fungicide timings; but an early fungicide during tillering is essential where significant disease is present.
Perhaps even more interestingly, figure 1 suggests that the timing of the final fungicide should be GS 39/45 (flag leaf to awns emerging) rather than the traditional GS 59 (ears fully emerged).
Key point: A two spray fungicide programme at GS 31-32 and GS 39/45 delivered the best yield response in a 4 year Winter Barley trial at Teagasc Oakpark. A fungicide at GS 25-30 should be applied where significant disease is evident. 
Recommendations
T1 GS 25-30 (Late tillering)-if required
T2 GS 32-37 (Stem extension)-largest spend as greatest yield response
T3 GS 39-45 (Flag leaf just visible to first awns visible)
Spring Barley
The latest trials (six trials over three years) from Teagasc suggest your Spring Barley disease control programme should consist of a 2-spray fungicide programme; an early application at mid-late tillering and a second/final application at GS39/49. The results can be seen in figure 2 below.
 
This approach gives the best chance of tiller survival and green leaf retention to deliver the best yield. Note delaying the final application timing until GS59 can lead to a reduction in the yield potential of the crop and there additional sprays providing no additional yield benefit.
Key point: A two spray fungicide programme at GS 25-30 and GS 39-49 is likely to deliver the greatest return on investment in spring barley
Recommendations
T1 GS 25-30 (Mid to Late tillering to early stem extension)
T2 GS 39-49 (Flag leaf fully emerged to first awns visible)-largest spend as greatest yield response
Product Choice
Choose products and rates for your disease sprays based on:
1. Disease (symptoms) present in the field-the type and severity of symptoms should dictate your response. 
2. The variety-Certain varieties have good resistance against particular diseases and are weak against others e.g. Quench has good resistance to Rhyncho but is susceptible to Brown Rust. It is important to know this when choosing a product to ensure your crop is adequately protected (particularly if symptoms are not visible in the field)
3. Timing-Earlier timings target Rhyncho and Net blotch and to a lesser extent Mildew and Brown Rust. The final fungicide also targets Ramularia (inclusion of Chlorothalonil is a must).
4. The number of active ingredients in a product-always include product(s) that contain active ingredients with different modes of action against the targeted diease(s). This is important to prevent.
5. The yield potential of the crop-Your spend on fungicides to be dictated by the potential return on investment.  There is a higher return on investment on crops with a higher yield potential.
6. The price of grain-This again influences the potential return on investment.  However, it is worth noting that even in the absence of disease, cereal fungicides, particularly the newer chemistry; deliver a strong return on investment.  To find out more see http://www.agritrading.ie/Prevent-lost-Profit-with-Cereal-Fungicides 
 
Select products to deliver more tonnes and the best return on investment
Key point: Select products and rates based on what has the potential to deliver you the highest return on investment. The key factors are disease symptoms, the variety, timing, the number of active ingredients, the yield potential of your crop and the price of grain.

In barley the number of ears per m2 has a strong impact on yield and while it is possible to achieve some compensation for low ear numbers as crops with lower tiller numbers produce more grains per ear, the scope is limited in barley with this ability 30-50% less than in wheat. In other words ‘thick’ crops of barley tend to be the highest yielding ones.

Therefore to achieve a high yield in barley it is important to maximise tiller production during early canopy growth and to maintain as many of these tillers as possible until harvest. Early disease control is important in maximising tiller numbers and ultimately in protecting yield. For more details on the importance of early season disease control in barley see http://www.agritrading.ie/The-Importance-of-Early-Season-Disease-Control-in-Barley 
Key point: Wheat has a higher ability to compensate for ‘thin’ crops than barley. ‘Thick’ crops of barley are essential for high yields.
Main Foliar Diseases
The main foliar diseases in barley are:


All of these diseases have the potential to reduce both yield and quality (KPH, screenings etc.). Their importance depends on the season (weather) and local conditions (field history etc.). Rhyncho and Net Blotch pose the biggest threat in Irish conditions to tiller survival early in the season. This is because they favour wet weather, with Rhyncho more common in cool conditions and Net Blotch in milder conditions. Overall, Rhyncho is probably the most important foliar disease of barley in Ireland, with Net Blotch number two.
Brown Rust is relatively rarely seen to any significant level as it favours higher temperatures (>15oC) but small outbreaks are common in susceptible varieties e.g. Leibniz winter barley and the spring varieties Mickle, Propino, Quench & Sanette.  Mildew epidemics have been rare in recent years due to resistant varieties, strong chemistry against the disease and unsuitable weather conditions. Even where outbreaks do occur, yield losses tend not to be as severe as other diseases.  However it can still cause tiller loss early in the season and therefore it needs to be watched for, particularly in susceptible varieties like winter varieties Saffron and Cassia plus the spring variety Mickle.  
Ramularia is a late season disease that tends to be more severe where other diseases are not prevalent and after periods of wet weather.  It is often confused with ‘spots’ produced on leaves for a range of other factors (commonly called physiological/abiotic spotting).
Non-Chemical Disease Control Factors
The disadvantage of having a wide range of fungicides that deliver good control of diseases in barley is the potential to become reliant on them and forget about husbandry factors.  It is important to employ non-chemical control measures wherever possible from a sustainability and now regulatory (Integrated Pest Management) perspective.  These include:
Choice of resistant varieties

Disease Control
TimingWinter
BarleyTrials carried out by Teagasc at sites in Cork and Carlow in 2010 (see table 1), have shown early spring disease control resulted in higher responses than previously thought. Traditionally fungicide programmes in winter barley favoured a higher spend later in the season however this work suggests an increased spend earlier in the season may be more profitable.

The above results suggest the first fungicide should be applied during late tillering rather than the traditional GS 31-32. However, the average results from trials in Teagasc Oakpark (see figure 1) over the last four years, suggest a poor response from a spray during tillering and that a 2-spray programme commencing at GS 31-32 delivers the best yield response.
 
It could be argued that there is higher disease pressure in the Dairygold catchment area and a 3-spray programme is justified. In reality every year is different and there will be different responses to fungicide timings; but an early fungicide during tillering is essential where significant disease is present.
Perhaps even more interestingly, figure 1 suggests that the timing of the final fungicide should be GS 39/45 (flag leaf to awns emerging) rather than the traditional GS 59 (ears fully emerged).
Key point: A two spray fungicide programme at GS 31-32 and GS 39/45 delivered the best yield response in a 4 year Winter Barley trial at Teagasc Oakpark. A fungicide at GS 25-30 should be applied where significant disease is evident. 
Recommendations
T1 GS 25-30 (Late tillering)-if required
T2 GS 32-37 (Stem extension)-largest spend as greatest yield response
T3 GS 39-45 (Flag leaf just visible to first awns visible)
Spring Barley
The latest trials (six trials over three years) from Teagasc suggest your Spring Barley disease control programme should consist of a 2-spray fungicide programme; an early application at mid-late tillering and a second/final application at GS39/49. The results can be seen in figure 2 below.
 
This approach gives the best chance of tiller survival and green leaf retention to deliver the best yield. Note delaying the final application timing until GS59 can lead to a reduction in the yield potential of the crop and there additional sprays providing no additional yield benefit.
Key point: A two spray fungicide programme at GS 25-30 and GS 39-49 is likely to deliver the greatest return on investment in spring barley
Recommendations
T1 GS 25-30 (Mid to Late tillering to early stem extension)
T2 GS 39-49 (Flag leaf fully emerged to first awns visible)-largest spend as greatest yield response
Product Choice
Choose products and rates for your disease sprays based on:
1. Disease (symptoms) present in the field-the type and severity of symptoms should dictate your response.
2. The variety-Certain varieties have good resistance against particular diseases and are weak against others e.g. Quench has good resistance to Rhyncho but is susceptible to Brown Rust. It is important to know this when choosing a product to ensure your crop is adequately protected (particularly if symptoms are not visible in the field)
3. Timing-Earlier timings target Rhyncho and Net blotch and to a lesser extent Mildew and Brown Rust. The final fungicide also targets Ramularia (inclusion of Chlorothalonil is a must).
4. The number of active ingredients in a product-always include product(s) that contain active ingredients with different modes of action against the targeted diease(s). This is important to prevent.
5. The yield potential of the crop-Your spend on fungicides to be dictated by the potential return on investment.  There is a higher return on investment on crops with a higher yield potential.
6. The price of grain-This again influences the potential return on investment.  However, it is worth noting that even in the absence of disease, cereal fungicides, particularly the newer chemistry; deliver a strong return on investment.  To find out more see http://www.agritrading.ie/Prevent-lost-Profit-with-Cereal-Fungicides 

Key point: Select products and rates based on what has the potential to deliver you the highest return on investment. The key factors are disease symptoms, the variety, timing, the number of active ingredients, the yield potential of your crop and the price of grain.

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