Seed treatments remain an effective way of getting an active ingredient into a plant, and as they are used in a very targeted way, they offer environmental and

operator safety benefits, as well as reduced chemical use.

Seed treatments also offer protection to crops in the early stages where they are at their most vulnerable, creating a residual shield against pests and soil-borne fungal pathogens around the seed and early rooting structures.

However, despite their often good environmental profile, certain seed treatments have been subject to regulatory scrutiny. The most notable losses to key seed treatment actives in recent years are in oilseed rape, where establishing the crop without neonicotinoids has become a real challenge for some growers.

In cereals, the loss two years ago of Redigo Deter for use in winter wheat and winter barley has also meant aphid-transmitted barley yellow dwarf virus (BYDV) in

particular is a much greater threat than it used to be.

With land left fallow in some areas and many growers having to resort to spring cropping, wheat bulb fly and wireworm could be troublesome in the coming season, warns Mark Hemmant, technical manager at Agrovista.

These pests are an issue for later sown crops, particularly in areas where there are lots of root crops such as potatoes, sugar beet and onions. Wheat bulb fly lays its eggs in the soil in summer, so bare soil is a risk.

In a year where some growers considered fallow after the difficult winter, we suggested they plant a cover crop to keep soil covered and put some soil structure in ahead of autumn planting.

Wheat bulb fly

Following the loss of Austral Plus, Signal could be an alternative seed dressing for wheat bulb fly and wireworm, although it can only be used in winter-sown crops, adds Mr Hemmant.

If crops are sown after the end of January, we cant use it. Late-sown winter crops or early-sown spring crops would potentially be at risk of wheat bulb fly in high risk areas or high risk crops now. Which growers may need to think about.

Take-all pressure is also expected to be high in the coming season, says Mr Hemmant.

There might be more takeall inoculum about so growers should also be thinking about whether they need Latitude. If youre wanting to follow spring barley and plant early that is going to significantly increase your take-all risk.

Latitude is a product people naturally reach for, for second and third wheats or barleys, but dont tend to consider it when following spring barley.

New generation

But now a new generation of seed treatments, which not only offer protection against seed- and soil-borne disease, but show some growth promoting effects, are proving to be ‘game changers because they represent a shift in the way seed treatments are used, says Jim Knight, seed business development manager at Frontier.

He cites seed treatments such as Vibrance Duo and Prosper ST as examples.

Vibrance Duo gives winter wheat, winter barley and spring barley improved shoot and root development which can help speed up emergence and build more resilient plants. Were no longer using seed treatments just as protectants from particular pests, but more in helping the plant to get established as quickly as possible and get off to the best start in the hope a bigger and healthier plant will be able to look after itself better.

Growth promoting seed treatments can help to compensate for a range of detrimental conditions at drilling, says Mr Knight.

That could be poor seedbeds that were struggling to work down, delayed drilling through choice or necessity, or a combination of both, as we saw last autumn where, when drilling crops into compromised situations, we saw a clear benefit from growth promoting seed treatments.

There are a range of biological products now coming to market which are being marketed as growth promotion and plant health improvers.

With the regulatory landscape changing and it becoming increasingly difficult to get chemical seed treatments approved, biostimulants are likely to have an increasing role as seed treatments, says Jim Knight.

Biostimulant seed treatments are the future of seed treatments the biotechnologies which have been developed are fast providing more tools to growers that can, to some extent, take the place of some of the things we used to do with chemistry.

One example of the new products on offer is Sylas- ST for use on OSR, a highly concentrated seed treatment that improves the crops nutrient and water uptake,

leading to rapid establishment, growth and increased plant biomass, according to UPL.

Trials have shown that as well as improving emergence speed, Sylas-ST also improves a plants drought tolerance, due to an increased root structure and increased water uptake, according to Rob Adamson, technical Support for UPL UK and Ireland.

However, care is needed when it comes to choosing a biostimulant seed treatment, says Mr Knight.

Biostimulant products are reasonably new for the UK market and we have taken some time to understand how to get the best out of them. When youre dealing with natural plant mechanisms, they are not going to respond in the same way in every scenario, so its really important we understand the best place to use them and how to get the best out of them in a farm situation.

Prosper ST would be one where weve learned quite a lot in recent years about what it is actually doing to the plant and where we can use it to the best effect.

Root structures

Prosper ST is a phosphite and nutrient blend which works by signalling the plant to search for more available phosphate in the soil, which results in bigger root structures and, therefore, larger plant biomass, says Mr Knight.

Any seed treatment we can put on which helps with plant rooting is going to be worthwhile because better root structures give better nutrition and moisture, but also help with some of the things that can go wrong in a season, such as waterlogging and drought.

Another example would be Integral Pro from BASF, a biostimulant seed treatment that also brings some fungicidal activity.

This is important because we have no other products with fungicidal activity in our OSR seed treatments now, which makes Integral Pro a key part of protecting the seedling from disease, as well as helping the plant to germinate and establish more quickly. Given the challenges, anything that helps OSR out of the ground more quickly is going to have some value, says Mr Knight.

In cereals, JumpStart WT, which is said to improve phosphate availability, and ProStablish WT, which stimulates mycorrhizae and root development, were introduced to the market by Bayer last year.

Compounds

The active ingredient in JumpStart WT is a naturally-occurring soil fungus, Penicillium bilaiae, which produces organic compounds that break the bonds between phosphates and cations, so phosphate can be taken up by the plant.

Single-purpose seed dressing, ProStablish WT is co-applied with JumpStart acting as a signal compound to stimulate mycorrhizae fungi to germinate and colonise roots.

By applying the treatments in combination, phosphate becomes more available to be taken up by the roots and making it easier for the crop to access it, which results in both better nutrient and water uptake and a more effective root system, according to Bayer.

JA limited volume of Kinto Plus, a value-added single purpose dressing, is also now available after BASF received full authorisation from CRD for all winter cereals for autumn 2020.

This is not only bringing excellent disease activity against seed- and soil-borne fungal diseases, but its also bringing some growth promoting effects as well, says Mr Knight.

In oilseed rape, UK growers have been able to use Lumiposa-treated seed for two years. The systemic seed treatment containing the insecticide cyantraniliprole, has been developed to protect OSR seedlings up to the two-leaf stage against cabbage stem flea beetle (CSFB), cabbage flea beetle, cabbage root fly and turnip sawfly.

Large strip trials work at Agrovista exploring factors which influence flea beetle showed Lumiposa can give around 60% control of flea beetle, says Mark Hemmant.

In some areas flea beetle is so bad, even if we had neonics back, we would still lose crops in a bad year.

We need to take a new approach to flea beetle like we do with black-grass in wheat. By putting lots of control methods together that give moderate control, we can hope for more control all together and Lumiposa is

going to help in this.

Trials

In our trials we had berseem clover companion plants which does nothing to flea beetle but has a positive benefit on the crop, which we think is through improving soil structure and health. We have always seen an establishment benefit particularly where establishment is challenged on heavy soils and from flea beetle.

This is in line with AHDBs flea beetle traffic light system which considers factors most likely to influence CSFB pressure in winter OSR. Seed treatments and companion crops are both recognised in the study as offering ‘amber levels of control.

Lumiposa is showing the biggest benefit compared to other seed treatments we have trialled. When you put it together with a companion crop it can make quite a lot of difference, says Mr Hemmant.

In a high pressure situation we still lost some, but at least it means there will be a harvest.