The Take-all Problem
Take-all Facts
Problem Recognition
Disease Development
High Risk Conditions
Control Options
The Problem
More than 140 years after it was first recognised,
take-all is still a cause of major concern for cereal growers because of its widespread
distribution and the absence of any varietal resistance or chemical control. It is
estimated that control of the disease could increase yields by 10-50% in affected crops1.
In the UK over the last 25 years, 60% of wheat crops grown are
estimated to have been at risk from take-all. Yield losses of up to 50% have been
recorded. Overall losses are estimated to cost growers £40-60 million annually1.
The disease is important, however, not merely because it reduces
yields but also because it can restrict both cropping and sowing date options. Effects of
the disease are likely to be aggravated if restrictions are placed on the use of nitrogen.
Additionally, root loss caused by take-all has the potential of increasing the risk of
nitrate leaching. For such a serious disease and its potentially damaging consequences it
is important to understand the factors which contribute most to its occurrence and impact
on cereal production.
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Did you know ?
- The name 'Take-All' was first applied to a devastating attack on
wheat in Australia in 18522.
- Take-all is regarded as the most damaging root disease of cereals
worldwide. Infection of seminal roots can occur immediately after seedling germination.
- It is estimated that one infected root in 10,000 is sufficient to
cause an epidemic1.
- Agricultural Development Advisory Service (ADAS) experiments have
shown that early drilled second wheats can have twice as many roots infected in April than
late drilled wheats.
- Symptoms in barley, while similar to those in wheat, are less
noticeable because of a more rapid and uneven ripening of the crop, often masking the
'whiteheads' effect of the disease.
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Recognition
Take-all:Gaeumannomyces graminis
(formerly Ophiobolus graminis).
Main Hosts: Wheat, Barley, Pasture,
Annual and perennial grass weeds.
Symptoms: First visual evidence of
take-all is usually the occurrence, from Growth Stage (GS) 31 onwards, of patches of
stunted plants in the crop with pronounced leaf yellowing and the possible reduction in
secondary tiller development. Examination of affected plants for blackening of some roots
will confirm take-all as the causal agent. Between flowering and the grain fill period,
premature ripening of affected plants due to stress may result in the appearance of
distinctive 'whiteheads' in the crop. If dry conditions persist during the grain fill
period significant losses can still occur even in the absence of obvious patches or
Whitehead symptoms.
Diagnosis
Pre-drilling: Examine stubble from previous crop for blackened roots.
In-crop: Examine plant root systems for
blackening. Check for classic yellowing of stunted plants. Monitor any premature ripening
of ears, at GS 71-75.
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Disease Development
Sources
Volunteer cereals and grass weeds act as major sources of inoculum for
carry-over of the disease to subsequent crops. Perennial grass weeds such as couch play an
important role in carrying infection through non-susceptible break crops, and by competing
for nitrogen and other nutrients can increase the crop's susceptibility to take-all. The
presence of volunteer cereals or grass weeds will reduce set aside effectiveness as a
break crop from take-all.
Infected Stubble, in successive cereal cropping situations,
is the main source of inoculum build-up.
Survival of the pathogen in soil, has been observed in the
absence of a host, for at least 3 years. The period of survival increases with decreasing
soil pH1.
Spread: Germinating seedlings from a newly planted
cereal crop come into contact with the take-all pathogen, through any one of the sources
above. Colonisation of roots continues to occur as the season progresses, with infection
active at temperatures in the 2-25ºC range. Root infections lead to restrictions in
nutrient uptake and eventual losses in crop yield and quality.
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High Risk Conditions
SOIL
Light aerated soils.
Compacted heavy soils.
Poor drainage/structure.
High organic matter content.
Alkaline soils.
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PREVIOUS CROP
Wheat
Barley
Pasture
Set-aside
Oilseed Rape
Sugar beet |
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CULTIVATION
Short ploughing to drilling time.
Early sowing date.
High seeding rates.
Loose seedbed conditions.
Poor weed control conditions. |
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FERTILISATION
Low nitrogen levels.
Nitrate forms of nitrogen.
Manganese deficiency.
Low levels of P and K.
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CLIMATE
| Autumn Wet |
Winter Mild |
Spring Cool/Moist |
Summer Hot/Dry |
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Control Options
Cultural Practice*
- Avoid continuous cereal cropping practices.
- Avoid early sowing of cereal crops.
- Avoid loose seedbed conditions.
- Reduce seeding rates, to avoid dense cropping.
- Correct any drainage or soil structure problems.
- Avoid high nitrogen applications.
- Ensure high grass weed control in previous crops.
- Eliminate couch prior to planting.
* Always obtain the advice of trained local crop
consultants in deciding upon a control plan or practice.
Varietal Resistance
No varieties of wheat or barley exist with specific resistance to take-all.
Chemical Control
For information on control of Take-all see http://www.monsanto-ag.co.uk/latitude
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Sources:
1. "Take-all disease of
cereals", Home Grown Cereals Authority Research Review No.20,1991
2. "Biology and control of take-all", Asher&Shipton,1981
