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Offsetting the effects of take-all

After an unseasonably dry spring and hot, dry summer, the damaging effects of take-all are being seen country-wide, as the lack of soil moisture has put crop root systems under pressure.

After an unseasonably dry spring and hot, dry summer, the damaging effects of take-all are being seen country-wide, as the lack of soil moisture has put crop root systems under pressure.

“Take-all affects the roots of emerging crops, causing necrotic lesions which block the uptake of water and nutrients, meaning plants are unable to properly sustain themselves,” explains Openfield’s Head of Seeds, Lee Bennett.

“In previous wetter seasons, these effects have been offset by an abundance of moisture, allowing crops to thrive even with take-all infection. However, this year we’ve not had the rain, and root systems have struggled to establish. Hence, we are seeing the effects of take-all now.

“As thoughts turn to autumn planting decisions, it’s vital growers start thinking about the cultural and chemical controls needed to manage the known risks of take-all, and limit the potential damage it can cause.”

Nitrogen 

Mr Bennett explains that higher nitrogen (N) applications can really help to offset the effects of take-all, by increasing the amount of nutrients available to the damaged roots.

“The increased nitrogen levels will allow the compromised roots to reduce their search for nutrients and allow them to focus on their uptake, resulting in healthier crops, reducing some of the effects of take-all.

“One of the main problems when it comes to nutrient uptake of second wheats is the fact that they naturally follow a first wheat crop. This means that the residual nitrogen present in the soil will be much lower to start with than if directly following a break crop.

“Therefore, growers need to think about increasing their total nitrogen dose in order to counteract this, and the timing of the dose is vital in making sure that it’s being fully utilised by the plant,” explains Mr Bennett.

“In this case I’d advise applying 20 to 40 kg/ha more total nitrogen at the front of the application regime, usually over three to four applications.

“What we’re aiming for is getting the plant to ‘grow away’ from the effects of the disease, and establish a robust rooting system. This is where the additional nitrogen comes in.

“Growers do need to be aware that certain forms of nitrogen, such as nitrates, can actually increase the effect of take-all, along with phosphate, potassium and manganese, so having an effective fertiliser strategy in place is important.

“Overall, it’s imperative to make full use of all available tools in order to manage the disease, and the inclusion of integrated cultural and chemical controls within a take-all strategy, is vital,” he adds.

Seed treatment

“Although an increase of total nitrogen can offset the effects of take-all, it’s important to note that when used alongside a specialist seed treatment, such as Latitude (silthiofam), the crop is further able to capture the optimum level of nitrogen,” explains Certis’ Technical Manager, Adrian Sisson.

“The mode of action of Latitude works by disrupting fungal energy production of take-all inoculum within the soil, slowing down the development of disease, and effectively creating a protective zone around the roots.

“This zone shields the plant during the high disease pressure period and enables the plant to develop a robust root system. Then once the roots have grown beyond this zone, they are better able to cope when faced with take-all inoculum,” says Mr Sisson.

Trials have shown that seed treatments can increase the yield of second wheats by 0.55 t/ha, which is greater than the yield response needed to cover the initial seed treatment cost. It’s a no-brainer for growers who want to bring their second wheat yields closer to that of first wheats.

For example, in a medium risk situation at a seed rate of 125 kg/ha the yield needed to cover the cost of Latitude is 0.18 t/ha, based on a feed wheat price of £136/t and, as the average yield response from Latitude is 0.55 t/ha, this means the initial cost can be recovered from the potential yield gain.

“Ultimately, growers can’t overlook that take-all is still endemic to the UK. But, if cultural and chemical controls are observed, effective management of the disease can be achieved and an increase in second wheat yields, is possible,” says Mr Sisson.