Strategies for Quantifying and Controlling Free Living Nematode Populations and Consequent Damage by Tobacco Rattle Virus to Improve Potato Yield and Quality

This project  brought together a consortium of companies with a grower base of over 500 growers and a number of companies with potential methods for controlling FLN populations: Cygnet Potato Breeders Ltd, McCain Foods Ltd, PepsiCo International, DuPont, The Cooperative Farms, Eden Research, Mylnefield Research Services Ltd, James Hutton Institute, SAC, Plant Health Care UK Ltd and Tozer Seeds Ltd in conjunction with Harper Adams University.

Approach

The project was divided into 3 work packages.

The aim of work package 1 was to develop a suite of molecular-based diagnostics for the detection of economically important nematodes. Specifically to:

• develop and validate a diagnostic primer for the genus Longidorus to be used with a previously published species specific primer for Longidorus elongatus;
• develop and validate a quantitative PCR diagnostic primer suite for the common species of Paratrichodorus and Trichodorus relevant to the UK potato industry;
• assess the efficacy of a published diagnostic primer for UK populations of Pratylenchus penetrans.

The aims of work package 2 were to:

• assess the importance of (Para)Trichodorus direct feeding damage on yield and processing quality,
• study the response of potatoes to a nematicide treatment;
• evaluate alternative control strategies for managing free-living nematode populations in the soil.

The aims of work package 3 were to:

• identify molecular markers which can be used to facilitate the breeding of new potato varieties with resistance to TRV.

Results

WP 1

The focus of this part of the project was the four most prevalent virus-transmitting species (T. primitivus, T. similis, P. anemones and P. pachydermus) in the UK. The project resulted in one of the first quantitative molecular diagnostics for these trichodorids.   

WP 2

The performance of 12 potato varieties was studied in replicated plot trials at four sites (Perthshire, Yorkshire, Norfolk, Shropshire) in each of three years. Replicate plots were either treated with Vydate 10G (55kg/ha, incorporated) or received no nematicide. In each site/year the trial design required that all varieties were harvested at the same time.  The FLN counts reported from individual plots ranged from 1-870 trichodorids and 0-141 Pratylenchus species per 200 g soil. The impact of FLN on the potato crop is dependent on soil conditions and the rate at which the crop can get established, and if crops can emerge rapidly, they can ‘grow away’ from even relatively high FLN populations without any significant reduction in yield and quality.

Overall, it was not possible to identify a consistent effect of FLN numbers on marketable yield. The analyses of the response of varieties to the use of Vydate 10G with differing FLN counts show that there is no clear indication of a FLN threshold population for impact on total yield or marketable yield. A summary of the information from the trials is provided below in the document Free Living Nematodes- Risks for Potatoes (R440 WP2 Risk)

Activity on work package 3 continued beyond the end of the project and is still ongoing at the James Hutton Institute.