Treating seed as a standard ‘run-of-the-mill’ practice means that it can be easy to overlook the level of insurance that comes with opting for this protective solution. Given the multitude of products available, it can also be difficult to differentiate between seed treatment performance.
With the risk of poor crop establishment at stake, Agronomist and Arable Farmer examines just how important this ‘insurance policy’ is and how careful product selection can maximise crop safety.
The vast majority of seeds are bought treated to guard against diseases such as fusarium from a very early stage, to encourage germination and good crop establishment. There are also some ear diseases such as bunt, which express themselves much later in the season and need to be prevented by seed treatments.
Morley Benson, Account Manager for crop protection firm Certis believes that, given their relative cost, seed treatments are seen very much as an insurance. “I think it’s probably fair to say that 90-95% of all cereal seed that’s used will have a dressing of some description. Most growers will expect to see their seed come treated with a fungicide as an expectation, and in many cases, with an additional insecticide treatment too.” A single purpose seed treatment refers to a fungicide dressing, but this will often encompass a diverse control spectrum protecting against a variety of infections, such as fusaruim, bunt and damping off diseases.
With at least a three to four month gap between sowing and the first spring fungicide foliar spray, the choice of seed treatment can be vital. This is particularly significant when early sowing and mild conditions increase pest and disease pressures, or when the soil and weather limit spray opportunities. Unpredictable weather is something that has seriously interfered with the timing and effectiveness of many autumn and spring spray programmes in recent years; the fact that seed treatment application is independent of difficult weather conditions is a key selling point for these products.
The HGCA have published materials highlighting how common diseases, including seed borne diseases, such as Bunt and Seedling blights in wheat can be controlled using a seed treatment solution. Evidence from trials, designed to analyse the efficacy of various products on seedling blight in winter wheat, demonstrate clearly that plant emergence in treated seeds was over twice that of untreated.
“Where factors such as rotation, soil type and geography raise the risk of pest attack, such as wheat bulb fly, a single purpose treatment may be combined with an additional insecticidal seed treatment such as Signal (cypermethrin). Growers will also often request that, at the same time, key nutrients, such as manganese are also added to the mix too,” says Morley.
The underlying factor with seed treatments is the importance to get the seed off to a good start, he adds. “Yet there are certain active ingredients that have been known to delay emergence, although this is perhaps more of an issue in later drilled crops where conditions are far from ideal”.
Certis have recently taken on the marketing of seed treatments Anchor (carboxin and thiram), Rancona iMix (ipconazole and imazalil) and Rancona 15ME (ipconazole); all of which do not hinder emergence. In fact, trials have revealed the products to have a growth promotion effect, which aids emergence and establishment in a range of conditions – late drilled, early drilled, dry seed beds etc. and to no detriment to the seedling.
Morley warns that when purchasing something like a seed treatment, which is almost routine, it’s often the case that growers become loyal to one brand or formulation and fail to analyse the broader market. There are however innovations within the seed treatment sector, with products including Rancona i-Mix being derived from a next generation, micro-emulsion formulation. As well as offering robust, broad spectrum control in the ground, the solution itself mixes very well with other products and binds well with the seed.
“This binding factor is a key advantage” says Morley. “Users can clearly identify products that have strong adhesion to the seed because there is minimal dust residue in the bag. This is obviously preferable from a handling point of view – however it is also the case that there is less risk of the treatment leaching into the soil and thus potentially reducing efficacy.”
He adds that growers have made a very deliberate choice when choosing which varieties they want to grow and this can also dictate their seed treatment options. “Rancona i-Mix contains ipconazole and imazalil and in addition to XYZ it offers additional leaf-stripe protection which is particularly valuable for winter barley seed; this formulation also has enhanced fusarium control.”
He describes how some milling wheat varieties are very prone to fusarium and growers will often apply a foliar fungicide to the ear at the back end of the season. “In these instances, seed treated with Anchor or Rancona i-Mix could provide additional early insurance as part of a more programmed approach.”
The real challenge when trying to take full advantage of a seed treatment, is deciphering the sheer range of different treatments and variety combinations possible.
"As a result, it is essential that growers work closely with their agronomists to identify individual variety needs and the most suitable treatments for their specific circumstances," says Morley. "Doing this as early as possible is key in order to secure the most appropriate seed package ahead of their target drilling window."
Choice of active ingredient and consideration of the wider foliar fungicide programme are also important. “Using Rancon i-mix as a seed treatment which contains ipconazole makes sense as it is not used as a foliar treatment unlike many other active ingredients.”
When considering disease prevention and control, Morley encourages growers to think of an integrated approach and to consider the entire crop's protection rather than just the seed. "A seed treatment is an investment and not just an extra cost," he affirms. “It also provides risk management so growers don’t have to be too quick off the mark with the first foliar spray.”
He adds that it can be hard to quantify exact figures when analysing the level of seed treatment investment compared with potential yield penalties, because the final cost of the seed per tonne varies depending on the variety of crop treated and the combination of products within the treatment. “However favourable trials results and a overall acceptance of the product’s value amongst growers proves that seed treatments fulfill an important role and the merits of specific treatments are worthy of exploration,” concludes Morley.