Seed treatments are used to protect against field, rather than storage, diseases principally Rhizoctonia solani, which causes black scurf and stem and stolon canker and black dot.
Available seed treatments vary in efficacy, formulation and method of application, with liquid products used on seed at grading by seed suppliers or pre-planting on-farm. There are also powder products applied at planting.
Last October, Bayer announced it was pulling sales of market-leading powder treatment Monceren (pencycuron), citing “uncertainty over its regulatory future” as the key reason.
This will force a big change in application practice because it was the only powder treatment still allowed to be hand sprinkled on seed tubers, either in the planter hopper, potato boxes or chitting trays.
It is estimated that this manual application method still accounted for about 30% of powder seed treatment use in 2019 and these growers will need to reconsider how they treat seed for 2020.
Here, Potato Review gets some expert advice on alternative treatments, the kit required to apply them and reminds existing powder applicator users how to get ready for the new season.
Try liquid seed treatments
With liquid products applied over a roller table a more accurate way of application, it could be time to try this method according to Suffolk-based potato application expert Richard Lapage.
There are a number of ways of applying liquid products, with those growers receiving seed on a “just in time” basis unlikely to be able to apply on farm, so can request treatment at source, depending on seed supplier.
Those willing to invest in their own application equipment can buy a Team Sprayers Storemaster tank and pump kit with CTC 2 air treatment canopy, which uses rotary nozzles and air assist fans to force the spray solution at the target.
“Where growers have time but aren’t willing to purchase application equipment, they can use a mobile contractor to treat seed in the yard,” adds Mr Lapage.
Distribution and agronomy group Frontier recently increased its fleet of mobile applicator units to six to meet increased demand, all of which utilise the Team CTC 2.
This typically costs about £10/t on top of chemical costs and includes the hire of the machine and a PA12 qualified operator to ensure correct application.
Independent seed tuber treatment expert David Turner says the advantage of applying a liquid product over a roller table is significantly improved seed coverage and disease control.
He adds that the Team CTC system has further improved deposition on tubers by up to 40% when compared with older available equipment.
“Also, planting is a very complex operation and applying treatments before planting is one less job for the planter operator to do,” adds Mr Turner.
Liquid options include RhiNo and Maxim 100FS and growers should be aware that both products must be applied before chitting, where practiced.
Invest in a powder applicator
Growers wanting to continue applying an alternative powder on planter – either RhiNo DS or Emesto Prime DS – will need to invest in an on-planter powder applicator.
Team Sprayers were the first to develop one 20 years ago and remain market leaders with about 600 running nationwide.
Each planter row has a hopper which dispenses powder via an electronically driven auger to a point on the planter where tubers are moving. For cup planters, this is in the hopper at the bottom of the belts, where seed is bubbling away.
For belt planters it is a bit trickier, but powder can be dispensed at the bottom of the hopper where seed drops onto the belt or brush kits are available which coat the seed with powder before it drops behind the opener.
The hopper must be fitted correctly to ensure that dispensing of product and subsequent seed coverage is optimised.
Team Sprayers’ Danny Hubbard recommends that this is carried out by a specialist potato application service and calibration engineer, who will know the correct fitting procedures for the various brands and types of potato planter.
A comprehensive list of engineers can be found on the Certis Tubercare website.
“Potato planting is a big, complex operation, so getting it right at the start will prevent problems in the field later,” explains Mr Hubbard.
The Team Sprayers powder applicator is twinned with the Digimon rate controller, which calibrates hoppers to an accuracy of +/- 5% and allows rates to be adjusted between 0.6kg/tonne and 5kg/tonne.
As motors move at different speeds, hoppers are calibrated individually by weighing output when run for a set time, ensuring each row is getting the correct application rate.
This is then fine-tuned depending on tuber size, with less applied to smaller seed and more for bulkier lots. The Digimon also adjusts applicator output to planter forward speed and has auto shut-off as the planter is raised or lowered into work.
Also available is Techneat Engineering’s Powder Pro applicator, which offers a similar hopper and dispensing mechanism, but its control box is calibrated in a slightly different way.
Like a seed drill, applicator augers are run for a number of rotations and output weighed. The control unit then regulates the speed of the auger to match the target kg/tonne seed treatment rate with the tonnes/ha seed rate.
Its control box can be hooked up to a GPS speed sensor or the tractor’s ISO speed output for accurate rate control.
Importantly, both electronically controlled systems adhere to National Sprayer Testing Scheme (NSTS) standards and Mr Lapage recommends getting an applicator serviced, calibrated and certified ahead of each season to ensure it is working as it should.
“If you are applying 5-10% too much, you are wasting money. If you are under applying, you can compromise the quality of your crop,” he adds.
A Team Sprayers system for a two-row planter, complete with fitting kit for the planter, costs about £3,000 fitted by a company such as RWL Services. Techneat’s Powder Pro with a fitting kit comes in at £2,800. Adding a GPS speed sensor will increase cost to £3,200.
Both systems require one control box for two- and three-row planters, with four- and six-row planters requiring an extra control box, which comes at additional cost.
Calibrate applicators for Monceren alternatives
When switching to alternative powders, users simply have to recalibrate applicators to the appropriate rate for each product.
With a Team Sprayers Digimon, this is simple. Where moving on to RhiNo DS, users can select the Monceren setting and just change the application rate to 2kg/tonne, which delivers the dose recommended by manufacturer Certis for controlling black scurf and stem and stolon canker caused by Rhizoctonia solani.
Alternatively, select Emesto Prime from the menu and the applicator will deliver the recommended rate of 1kg/tonne.
For Techneat’s Powder Pro system, re-calibration is required for any change in product formulation to ensure the correct rate is applied.
Seed treatment options – how do they stack up?
With Monceren unavailable, seed treatments – whether liquid or powder – will be more expensive, but there is variation in diseases controlled and per tonne price. Table 1 to the right summarises the key differences. Source: AHDB Potatoes for disease efficacy. Costings based on industry research.
Don’t forget to service existing power applicators this winter
Growers already using powder applicators are reminded to ensure kit is in good working order well ahead of planting to avoid problems in season. Richard Lapage of RWL Services and Danny Hubbard of Team Sprayers offer a checklist for the valuable winter service.