current status & control of take-all disease in cereals

Take-all was seemingly quite bad last year (2024). Current data on Latitude is quite outdated and there are no updated figures on the efficacy of Latitude. So, what is the current status of take-all and available control?

Highlights

• Warmer and wetter conditions as a result of climate change may increase take-all severity and frequency
• As varietal and chemical options to control take-all are limited, current strategies focus on an integrated approach where possible. These strategies relate to rotation, cultivation, varieties, drilling dates, seed rates/treatment, and nitrogen applications.
• Current scientific research focuses on small-scale field trials and laboratory experiments to understand take-all mechanisms, forming the basis for resistance breeding and other solutions.

Take-all background information

Take-all is a soilborne disease in UK cereals, particularly UK winter wheat and to a lesser extent winter barley. Take-all is caused by two strains: the common Gaeumannomyces tritici and the rarer Gaeumannomyces avenae. The disease begins as soil-borne but spreads root-to-root. Take-all cause roots to become blackened, rotten and have a ‘rat-tail’ appearance. The reduction in root activity restricts water and nutrient uptake. This slows canopy growth and causes yellowing and stunting in severe cases. Patches of stunted plants and whiteheads (bleached ears) form. As a result, the fungus reduces yield and grain quality, with average yield losses of 5–20%; though more than half of a crop can be lost when take-all is severe. Take-all is the major cause of ‘second wheat syndrome’ when yields of second wheat crops are frequently 10–15% less than those of first wheats.¹

Take-all is challenging to control, as fungicides and varietal resistance are very limited. The seed treatment, Latitude, is currently the only crop protection product approved for used on the impact of take-all. The disease is very soil dependent, for example the disease is more prone in crops grown on Wick Soil Series than Hanslope Series, for example. Wick Soil Series is typically a light, sandy or loamy soil with good drainage but low water and nutrient retention. The lighter soil facilitates the spread of the fungus easily, and the loss of active roots has a large effect on crop water and nutrient uptake where there is already low water/nutrient retention of the soil. Contrarily, the Hanslope Series is typically heavy clay soils with a greater water holding capacity, which retains nutrients.² Additionally, take-all thrives in alkaline soils, though acidic patches can also suffer damage.¹ The unclear boundaries of how and where take-all is most damaging contributes to the challenges of trying to reduce its effect and manage future outbreaks.

Warm soil temperatures in the autumn (above 10–12°C) promote take-all activity, and a wet spring can exacerbate its spread. Considering the recent weather changes as a result of climate change, this may indicate that take-all may become more prevalent as we experience these warmer and wetter conditions. Additionally, moist soil conditions can build up take-all inoculum, impacting subsequent crops to a greater extent.

Current control/recommendations

As varietal and chemical options to control take-all are limited, current strategies focus on an integrated approach where possible, the main strategies provided by AHDB include:

1. Rotation

• One-year break crops not susceptible to the disease can prevent take-all inoculum build up in the soil, reducing its impact on a subsequent cereal crop. The bigger the rotation, the less impact take-all will have on the future cereal crop. Broad-leave crops and oats are particularly useful in reducing take-all inoculum in the soil because they encourage antagonistic soil fungi to supress the take-all inoculum, a ‘fungi family feud’, as some are calling it.
• Volunteer cereals and/or grassweeds can harbour the disease in break crops, so they require early destruction to reduce the risk of take-all on the following crop.

2. Cultivations

• Firm seedbed discourages disease growth. Though compaction can hinder root growth in heavy clay soils.
• Ploughing can bury take-all to deeper depths, allowing the crop time to establish before the roots reach lower depths and any take-all infected soil.
• Delayed sowing in colder soils can help mitigate the risk, considering take-all thrives in warmer soils.

3. Drilling dates

• Crops drilled later tend to develop root systems in cooler soils where fungal spread is slower. This leaves time for roots become more established before disease pressure builds. This encompasses trade-offs though, relating to a decrease in yield potential due to a potentially shorter growing season or an increased risk of planting in wet conditions, which may hinder crop establishment.

4. Seed rate/treatments

• Take-all can become more severe with higher seed rates because of the increased root density of many seedlings, but a lower seed rate may not be practical.
• Latitude seed treatment is currently the only chemical option to treat take-all.

5. Varieties

• Some wheat varieties have shown greater yield improvements and response to the addition of Latitude. For example, the 2022 ADAS field trial evaluating the efficacy of Latitude on managing take-all across different wheat varieties (Extase, Zyatt, Dawsum and Palladium) showed that Extase had a higher yield increase (1.85 t/ha) compared to Palladium (0.9 t/ha), both compared to untreated controls.

6. Nitrogen applications

• An early application of nitrogen followed by the main application later in the growing season to crops more at risk of take-all can be beneficial, compared to one main application at the start. This is because a diseased crop may be less efficient at taking up nitrogen, so little and often is a better approach.

Looking forward, what are the potential options?

From this recent review of the literature and advice presently available, the best advice to control take-all is using an integrated approach of the strategies already discussed above. However, there are new glimmers of hope in terms of alternative approaches to controlling take-all, which we should keep an eye on for future, commercial developments.

• Biological Control Using Bacillus subtilis: A study in China in 2023 has demonstrated that certain strains of Bacillus subtilis can effectively combat take-all disease in wheat. These beneficial bacteria produce antimicrobial proteins that inhibit the growth of the pathogen Gaeumannomyces graminis tritici. Field experiments have shown that applying these strains can reduce disease incidence.
• A biological fungicide, TOLTEK by Certis Biologicals, has been approved for use in France on Wheat and other cereal crops in 2024. The product contains a bacterial strain that has demonstrated effective antagonistic affects against take-all, thus providing protection against the disease. UK product registration is ongoing (as of Jan 2025), until which time the trials data for the product is not yet available.
• As the ADAS trial in 2022 showed, certain wheat varieties may have a more effective response to the seed treatment, Latitude. Whilst this study took place in 2022, a more recent news article on take-all in late 2024 still references this key field trial, suggesting its relative importance still. Chloe Francis, Senior Consultant in Plant Pathology at ADAS, shared that there are other seed treatments being investigated, but they have not been registered yet. Chloe also said that applications of the foliar fungicide, Amistar, have been reported to influence take-all but the effect is often quite small and inconsistent. The Amistar label explains that it can reduce the severity of take-all. Note, on cereal crops, Amistar must always be used in mixture with another product.
• Rothamsted Research are investigating crop genetics, specifically resistant gene varieties to take-all. One wheat line has been evaluated under field conditions and was found to display good resistance to take-all, but it is a low yielding crop and is not a commercial cultivar. Whilst the exact genes that display resistance are still unknown, commercial breeders can start to take this information to cross the traits with commercial wheat cultivars in a breeding program. This may take 5-7 years. This is not seemingly a priority for breeders, because take-all can be depleted within one year.
• A 2023 study suggests that there is a non-harmful relative of the take-all fungus which cannot penetrate crop roots and therefore does not cause the same level of damage as take-all. Infecting roots with this fungal relative could reduce the effects of take-all due to species competition. A further study in 2024, understanding the mechanisms behind take-all resistance, suggests that the non-harmful relative of the take-all fungus promotes the crops defence mechanisms, helping to reduce the effects of take-all.

Concluding remarks

Latitude continues to be a relatively effective seed treatment in response to take-all, but with warmer and wetter winters because of climate change, we may see a decline in its efficacy. Utilising multiple integrated management strategies and reducing reliance on a single chemical control method for reducing take-all offers significant advantages in terms of risk management.

The current scientific literature focuses on a combination of small-scale field trials and laboratory experiments to study resistant take-all gene expression, with the primary aim of understanding the mechanisms behind take-all. These small-scale experimental phases are crucial for unravelling the mechanisms of take-all, forming the foundation for breeding strategies targeting resistance and other effective solutions.

There does not seem to be any other treatments available or upcoming, except for TOLTEK, with no widely available data to support claims at present (due to ongoing regulation/registration in the UK). However, the foundational concept of TOLTEK as a biological fungicide is supported by the wider scientific literature, suggesting that some soil bacterial strains can have an antagonistic effect on take-all, thus helping to reduce its negative impact on crop growth.

References

1. Take-all disease in cereals: prevent, detect, control | AHDB
2. LandIS – Land Information System – Cranfield Environment Centre