‘PCN problem in Scotland can be addressed by all members of the industry’
FOR the third consecutive year PCN Action Scotland has held an annual public open day hosted at Barnyards farm in Tannadice to discuss the project’s field trials results.
In a cross-industry effort, the open days are organised by SRUC / SAC Consulting, while the field trials are conducted by Scottish Agronomy. Talk sessions and demos during the day were given by members of SoilEssentials, The James Hutton Institute, SASA (Scottish Government), SAC Consulting, and Scottish Agronomy.
The aim of these open days is to convey new information about potato cyst nematodes and their control from the nine research work packages of the project: Economics, Decision support, Resistance marker development, Dihaploid breeding, Variety tolerance, Groundkeeper control, IPM tools, Knowledge exchange, and Policy.
There are two species of potato cyst nematodes which cause significant damage to crops in Scotland: Globodera rostochiensis and G. pallida. Historically G. rostochiensis is most prevalent, however growing varieties with resistance to this species is helping towards bringing populations under control, according to Dr Kerry Leslie, Potato Consultant with SAC Consulting.
“Unfortunately many popularly-grown varieties do not have resistance to G. pallida, which has led to a sharp increase in their populations. The land used for PCN Action Scotland at Barnyards farm only has G. pallida populations present,” she said.
The open day is targeted at anyone involved or in contact with the potato industry and this year there was a record number of attendees across the morning and afternoon sessions. It is believed around 120 attended.
Those leading the project say the PCN problem in Scotland can be addressed by all members of the industry: Growers, landlords, breeders, processing/packers, and retailers (supermarkets). An example of this is breeders producing resistant and tolerant varieties that have a swift uptake onto accepted variety lists by packers and retailers, whilst being grown in larger quantities by growers.
“Correct deployment of these varieties would cause a rapid reduction in PCN populations. Following the four years of continuous field trials, PCN Action Scotland believe that the best way to tackle the PCN problem across the UK is to increase the uptake of varieties which are both highly resistant and tolerant,” said Kerry.
The industry also needs to show greater collaboration regarding groundkeeper control, those at the open day were told. Groundkeepers act as a host for PCN, allowing population growth during the rotation.
“With such a high proportion of our potatoes being grown on rented land, it is important to formulate plans between tenants and landlords, detailing how to tackle any groundkeepers left by previous potato crops. Tackling groundkeepers may also help towards other challenges the industry face by removing the disease reservoir for viruses,” she said.
This year’s open day saw talks from Dr Kerry Leslie on the potato varieties included in the 2024 trial, and results and trends from the 2023 trial data, including the tolerance status of some varieties.
Consistently, the highly-resistant varieties (e.g. Buster, Elland, Amanda etc) have reduced the PCN (G. pallida) population after planting. This is evident when compared to the susceptible variety Maris Piper which increased the G. pallida population from 7 to 383.3 eggs per gram of soil after harvest (See figure 1).
Varietal tolerance can also be implied from the yield response to nematicides, those at the open day were told. A less tolerant variety will have a significant increase in yield when treated with a nematicide. A tolerant variety will produce roughly the same yield regardless of nematicide treatment. Through this research project it has become apparent that some varieties fluctuate in their tolerance score, indicating environmental factors also play a role in this (see Figure 2).
It’s also important to recognise the difference between resistance and tolerance, attendants were reminded. “Resistance is the ability of a variety to limit PCN multiplication, while tolerance is the ability of a potato variety to maintain yield in the presence of moderate PCN populations. Resistance and tolerance are separate measurements. Repeated cultivation of susceptible, tolerant varieties can increase PCN populations to levels at which even the most tolerant varieties will fail to yield.”
