P1901285: AHDB Research Call - Potato Desiccation

P1901285: AHDB Research Call - Potato desiccation


To co-ordinate and deliver field trials of alternatives to diquat for desiccation of potato crops.


This research will inform guidance to potato growers on the best methods to desiccate crops in the absence of diquat. The emphasis is on the ‘hard to stop’ situations, with late, indeterminate varieties and seed crops.

This research is closely aligned with the AHDB potatoes knowledge exchange programme, so most of the sites are on strategic potato (SPot) farms.

Tenders are requested for (A) scientific coordination and for (B) trial implementation at the sites listed below. One organisation may tender for any part or the whole of this research. Tenders for scientific coordination should be submitted separately from those for implementation.


SPot North DN20 0NU to include ware and seed

SPot East tbc

SPot SW TA19 9EG (demonstration only)

SPot West SY4 4HG  (demonstration only)

James Hutton Institute’s Balruddery Farm DD2 5LJ

At two of the above sites, SPot West and SPot South West, there will be no replication, but in other respects the protocol will be standard. These sites are included to enable knowledge transfer.

There is potential to combine a seed equivalent crop onto SPot sites to reduce the number of sites.

The tender may cover one or all sites, or any combination.


Ware: Maris Piper and Markies

Seed: as agreed with hosts, Markies if possible.

Water rate

  • T1 400l/ha

  • T2 300l/ha or 400l/ha if there is still a large leaf area.


T1 to take place before any natural senescence is observable. Seven days gap between T1 and T2, and between T2 and T3, to reflect product labels.

Where ware and seed crops are on the same site the trials will be adjacent but separate. The timings of application to the seed crops will be considerably earlier than for ware.


Treatment T1 T2
1 Positive control Reglone1.5 Reglone 2.5 + Ranman Top
2 Flail, followed by Spotlight 1.0 + Ranman Top Ranman Top
3 Flail, followed by Spotlight 1.0 + Gozai 0.8 + Ranman Top Ranman Top
4 Spotlight 1.0 + Ranman Top Spotlight 0.6 + Ranman Top
5 Gozai 0.8 + Toil  1.5l adjuvant + Ranman Top Gozai 0.8 + Toil 1.5l adjuvant + Ranman Top
6 Spotlight 1.0 + Gozai 0.8 + Ranman Top Spotlight 0.6 + Gozai 0.8 + Ranman Top
7 Pelargonic acid + Ranman Top Flail followed by Spotlight 1.0 + Ranman Top
8 Pelargonic acid + Ranman Top no flailSpotlight 1.0 + Ranman Top
9 Control No desiccant. Ranman Top No desiccant. Ranman Top
10 Seed crops only Haulm puller, simulated by hand.  
11 Seed crops only Spotlight 1.0 + Ranman Top Gozai 0.8 + Toil 1.5 + Ranman TopFollowed by T3 Spotlight 0.6 + Ranman Top

Variance for seed crops: Replace Ranman Top with Infinito at 1.6l/ha.

A: Scientific coordination 

  • Write a protocol based on the information in this call and send to implementing contractors.

  • Discuss the protocol with contractors to ensure they understand and can adhere to it, including a visit to each site before treatments are imposed. The demonstration sites do not require visiting.

  • Set N rates for the crops in line with RB 209, using information from farmer hosts regarding residual N.

  • Plan trial layout in conjunction with the implementing contractors, who will liase with the host farmer. There will be four replicates. The plot size will be two beds (4 rows) of each variety giving at least 100 plants per plot (10m in length). Specify appropriate differences for the seed and ware crops, e.g. in seed spacing and fungicides.

  • Provide method and scales for assessment of % senesced leaves and stems, skin set and the post harvest assessment of seed size, tuber blight and other rots, vascular browing, black dot and black scurf.

  • Maintain contact with the implementing contractors to ensure that treatments are applied at the correct growth stage and dates, and that measurements are made and reported correctly.

  • Collate results, conduct statistical analysis and write a report. The analysis will include treatment effect on passive bulking compared with the untreated and Reglone treated controls.

The scientific coordinator will be asked to provide a minimum of three presentations as part of AHDB’s knowledge exchange programme. These will be paid separately at the standard AHDB rate, currently £475 per day plus T& S.

B: Trial implementation

  • Exclude from tenders for implementation the cost of the chemicals and payment to host for loss of product from the trial area. Provision for both these aspects will be made by AHDB.

  • Fields have been selected or will be identified in the winter by AHDB in conjunction with host farms.

  • Liase with the host farmers and scientific advisor to decide a suitable position in the commercial field(s) for the trial. A plan for layout will be provided by the scientific coordinator. The host farm will prepare the site including fertiliser and nematicide if required, and will control weeds and late blight as for the commercial crop on the same field.

  • Discuss the protocol provided with the scientific coordinator, raising any concerns at an early stage so necessary changes can be made. Meet the scientific coordinator on-site.

  • Plant, by hand or machine, within a few days of commercial planting in the host field.

  • Impose spray treatments using a suitable trials sprayer with a boom of the correct length to apply accurate quantities to each 2 bed plot without overlap. The nozzle chosen must enable the correct water rate to be applied without using pressure above 3 bar.

  • Impose the flail treatment with a hand held strimmer or hedge cutter, to reproduce the effect of a good quality topper, leaving 15-20cm of stem exposed.  

  • Assess approximately each seven days from day of application until harvest takes place when skin set is suitable, (consultation with scientific coordinator will be required)

At each date assess % of dead or brown material for leaves and stems separately

On day 14 and day 21 from date of last treatment assess skin set. Use 100 tubers per plot on each date.The contractor will require access to equipment for assessment of skin set.

On day 28 assess regrowth by a standard scale provided by scientific coordinator

  • At harvest, collect enough plants at random from the remaining areas in the central two rows to provide 100 tubers. Size by 5mm increments. Assess for blight, black dot and black scurf and other rots. Cut 50 to assess vascular browning.

  • Retain the remaining 50 tubers for 3 months under storage conditions representative of commercial stores. At the end of this period, for ware crops, record tuber rots and skin blemish diseases on a scale to be provided by the scientific coordinator. For seed crops also assess effects on germination as specified in the EPPO guidelines. Omit the observations recommended by EPPO on the succeeding crop.

  • Provide records of assessments promptly to the scientific coordinator.


Minor changes to the protocol may be made after award of the contract, by agreement between AHDB and contractors.

Application Procedure

Applicants should complete an AHDB Research and KE Application Form – Full Proposal Small, referring to the guidance notes to aid completion. 

Applications are made on the basis of the AHDB Research Funding Agreement and any organisation receiving funding shall comply with the terms and conditions specified in the RFA. AHDB will not be held responsible for any expenses or losses incurred by applicants in the preparation of an application(s).

Completed application forms should be submitted to research@ahdb.org.uk no later than 12:00 (noon) on the 12 February 2019.

Proposed timings for application and project delivery

Stage of Process


Call published

11 January 2019

Full proposal submission deadline

12 February 2019 (noon)

Applicants informed of outcome

26 February 2019

Project commencement

1 April 2019

Project completion

31 March 2020


If you have a specific question related to this call please email research@ahdb.org.uk. As part of the open tender process AHDB cannot discuss specific project details prior to submission of a proposal. All Questions and Answers are published.

Assessment criteria

The standard assessment criteria will be used.