PHOTO: PETER ROEK


CROP SCIENCE ▶▶▶


Resistant potatoes can tackle cyst nematodes


BY ADAM CLARKE S variety Maris Piper


ome promising varieties with resist- ance to this key pest are moving to the end of breeders’ pipelines. They have the potential to crack a fresh


market dominated by a handful of susceptible favourites. While in future certain nematicides might be lost, there is an increasing call for more non-chemical tools to be used on farm. The most important is varietal resistance, which can help growers reduce PCN popula- tions and, if combined with tolerance, do so without compromising yield and subsequent profit (see table ‘Differences between varie- ties…). Currently, many of the most widely grown po- tato varieties have strong resistance to Globod- era rostochiensis (single H1 resistance gene), but not for one or more of the three major G. pallida pathotypes (see table ‘Resistance status of…). The situation is changing quickly in the processing sector, which has some good


Potato growers battling potato cyst nematode (PCN) problems are set to benefit from significant breeding efforts into producing fresh varieties resistant to the key nematode species Globodera pallida. The starting point is knowing which subtype of nematode is present in problem fields.


pallida-resistant options, particularly Innovator and partially resistant Royal and Taurus.


Breeding efforts The fresh sector however is still searching for a commercial breakthrough that has robust re- sistance to G. pallida. This is certainly not from lack of effort from breeders, according to E Park & Sons agronomist Peter Blaylock. The Doncaster-based potato packer and producer is a stakeholder in the GPS (Grampian Parks Skea) breeding programme, which includes Scottish commercial partners Grampian Grow- ers and Skea Organics. Using commercially successful varieties with known G. pallida re- sistance and crossing with genetic material


Resistance status of the 12 most widely grown potato varieties across Britain in 2017


planted area (GB, ha) 16,31


Markies 6,03 Maris Peer


5


Melody 4,3 Lady Rosetta


3,46


Estima 2,99 Taurus 2,77 Pentland Dell


2,75


Marfona 2,4 Innovator


2,47


Sagitt 2,44 Roya


2,39


resistance to G. Pallida* 2 2 2 2 2 2 3 2 2


8, 9


not resistant 3


resistance to


G. Rostochiensis* 9 9 2 9 9 2 8 2 2


not resistant resistant 9


* resistance scores to Globodera pallida pathotypes Pa2/3,1 and G. rostochiensis pathotype Ro1 on a scale of 1-9, with 9 being most resistant


18 ▶ FUTURE FARMING | 22 February 2019


Difficult task This is a sentiment echoed by breeder IPM Po- tato Group’s Graeme Prentice, who says G. pall- ida resistance has been a focus of the compa- ny’s breeding programme – carried out in conjunction with Ireland’s agricultural research institute, Teagasc – for the past 15 years. Some are now approaching the end of the crucial field based trialing period, which typically takes a minimum of 12 years. “We are now just starting to see some promising seedlings come through,” adds Mr Prentice.


Unforeseen issues Even if a variety does show promise, once out in the commercial world it can soon succumb


from the James Hutton Institute, the group is searching for fresh varieties with resistance to G. pallida or, ideally, dual resistance to both G. pallida and G rostochiensis. GPS has many clones in trials across Britain and, for the first time, the Netherlands. They also have larger plots of more advanced selec- tions and varieties, tested on different sites. In 2018, these included an encouraging salad va- riety with dual resistance and several other po- tential table varieties that could help fresh growers manage PCN. “I think breeders have really woken up and responded well to the pallida problem. But it has to be remembered that using traditional breeding methods, it takes about 12 years for a variety to come to fruition, so it’s no easy task. “I think there will soon be wholesale opportunities for fresh growers to use dual resistance, which will be a big step forward,” explains Mr Blaylock.


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