By: Amy Grant
Barley take-all disease is a serious problem afflicting cereal crops and bentgrasses. Take-all disease in barley targets the root system, resulting in root death and can result in significant financial loss. Treating barley take-all relies on recognizing the symptoms of the disease and requires a multi-management approach.
About Barley Take-All Disease
Take-all disease in barley is caused by the pathogen Gaeumannomyces graminis. As mentioned, it afflicts small cereal grains such as wheat, barley and oats as well as bentgrass.
The disease survives on crop debris, grassy host weeds and volunteer cereals. The mycelium infects the roots of living hosts and as the root dies it colonizes the dying tissue. The fungus is primarily soil borne but soil fragments can be transmitted by wind, water, animals and cultivating tools or machinery.
Barley Take-All Symptoms
Initial symptoms of the disease arise as the seed head emerges. Infected roots and stem tissue darken until it is almost black and lower leaves become chlorotic. The plants develop prematurely ripe tillers or “whiteheads.” Usually, plants die off at this stage of infection, but if not, difficulty in tilling becomes apparent and black lesions extend from the roots up into the crown tissue.
Take-all disease is fostered by moist soil in areas of high rainfall or irrigation. The disease often occurs in circular patches. Infected plants are easily pulled from the soil due to the severity of the root rot.
Treating Barley Take-All
Control of barley take-all disease requires a multi-pronged approach. The most effective control method is to rotate the field to a non-host species or as a weed-free fallow for a year. During this time, control grassy weeds that can act harbor the fungus.
Be sure to till in crop residue deeply or remove it entirely. Control weeds and volunteers that act as hosts for the fungus especially 2-3 weeks prior to planting.
Always select a well-draining site to plant the barley. Good drainage makes the area less conducive to take-all disease. Soils with a pH under 6.0 are less likely to foster the disease. That said, applications of lime to change the soil pH can actually encourage more severe take-all root rot. Combine the lime application with a crop rotation of fallow period to reduce the risk.
The seed bed for the barley crop should be firm. A loose bed encourages the spread of the pathogen to the roots. Delaying fall planting also helps reduce the risk of infection.
Lastly, use ammonium sulfite nitrogen fertilizer instead of nitrate formulas to reduce root surface pH thus the incidence of the disease.
This article was last updated on
Take-all root disease
Black necrotic lesions on the roots and patches of prematurely senescing, thin and stunted plants with small ears and little or no grain filling.
Do you have Take-all root disease?
Biology and impact
Take-all is a serious root disease of wheat crops which is found worldwide. It is caused by the soil dwelling ascomycete fungus Gaeumannomyces graminis var. tritici. The fungus is also able to infect the cereals barley, triticale and rye, as well as a number of common grass weed species such as couch grass and the bromes. Another variety of take-all fungus (Gg var. avenae) is able to infect oats and other cereals but this is currently very rare in the UK. The disease develops in short wheat rotations where wheat or other susceptible cereal species are grown consecutively for two or more years in the same field. Second wheat crops in the rotation will typically yield around 10-15% less than a first wheat crop, primarily due to take-all. In notable outbreak years, where weather conditions are particularly conducive to take-all development (e.g. 2008, 2009 and 2012), yield losses of up to 60% have been reported and grain quality will also be greatly reduced. In the 2015/2016 season, the weather conditions were conducive for the take-all fungus and readily observable disease symptoms appeared from mid-June onwards in some cropping situations.
In the first wheat crop in a rotation, take-all fungal inoculum builds-up in the soil root-zone or rhizosphere but there is generally very little root infection or minimal risk to the crop’s performance. However, if a second wheat crop is then sown on the same site there is a risk of severe take-all disease developing. The fungus invades the root tissue causing black necrotic lesions which restrict the uptake of water and nutrients from the soil. In severe disease outbreaks, characteristic patches of stunted, prematurely ripening plants will develop after flowering and during grain filling. In between cropping seasons, the fungus survives on root debris from the previous crop.
Take-all fungal inoculum build-up in 1 st wheat crops and disease development in subsequent crops are both favoured by wet conditions in the spring and early summer. Take-all patch development during grain filling and yield losses can then be exacerbated by high evapotranspiration caused by dry, hot and/or windy weather during grain filling. Patches, 1m to 5m in diameter, first appear from mid-June onwards and are randomly present across a wheat or barley field.
Take-all is a fungal pathogen that is widespread in all UK arable soils and attacks the roots of cereal crops including wheat, barley, rye and triticale.
It can significantly reduce yield by hindering water and nutrient uptake of infected plants and is often most acute in second and third wheats, where inoculum has been allowed to build within the soil.
As winter barley is grown almost exclusively as a second cereal behind wheat, the crop is also at considerable risk of infection.
However, Jonathan Blake, a plant pathologist and principle research scientist at Adas, highlights that the long-held view is that it is less affected by take-all symptoms.
This is because winter barley’s yield potential – mostly determined by shoots/sq m and grains/ear – forms much earlier than in wheat. So when soil temperatures hit 10C+ in late April or early May and take-all bites, there is less yield loss.
This view had been reinforced by AHDB analysis investigating the impact of take-all in wheat and barley between 1999 and 2004, which showed little or no yield response to the specific seed treatment Latitude (silthiofam) in barley, despite positive effects in wheat.
Take-all in wheat © Blackthorn Arable
However, more recent additions to the winter barley Recommended List are setting new benchmarks for yield – particularly hybrid varieties.
Combined with an evolution of winter barley agronomy, where more emphasis is placed on pushing crops earlier in the season for greater biomass, crops are taking more time to fulfil their potential.
“Where you have boosted shoots/sq m and grains/ear, you are relying on late-season green leaf area to capture light and fill out the crop,” Mr Blake explains.
“As the need for that late season energy has increased, so has the likelihood of take-all having an impact on winter barley yield.”
Plant diseases are a significant yield and quality constraint for growers of broadacre crops in Western Australia.
Plant pathogens can be fungal, bacterial, viral or nematodes and can damage plant parts above or below the ground. Identifying symptoms and knowing when and how to effectively control diseases is an ongoing challenge for WA growers of cereals (wheat, barley, oats and triticale), pulses (field pea, chickpea, faba bean), canola and lupin crops.
The Department of Primary Industries and Regional Development has a strong research, development and extension focus to assist industry to reduce the impact of crop diseases on all broadacre crops.
Results of extensive field/lab/glass house research and surveys across the WA grainbelt every year contribute to disease management packages and forecasting tools, and identify new incursions of crop pathogens or strains into WA.
The department also gathers and extends industry disease reports (PestFax), provides a disease diagnosis service and a broad range of management information for specific foliar and root diseases and viruses.