Potato Review

www.potatoreview.com POTATO REVIEW MARCH/APRIL 2023 61 CROP HEALTH Spring crop health Fera entomologist and virologist discuss seasonal issues and considerations going into 2023. H OT dry weather and input cost in ation have dominated the 2022 potato season. While crops which have had access to water have thrived, others have senesced early, resulting in lower yields. At the same time, the marketable yield from some elds has been reduced by quality issues such as secondary growth, cracking and greening. Elsewhere, crops which have remained green later into the season are likely to have high dry matter, making them prone to bruising – and some growers have chosen to burn crops o early at the expense of reduced yields. ese factors have helped to ensure a long harvest window. Struggling maincrops were harvested in many areas well before the end of August, while others were still green and continuing to grow. As harvest ramps up through September and October, grower’s thoughts turn to next season. Quality issues, high production and energy costs, and subdued prices are making many consider their production plans. High energy prices mean high storage costs, and while ware growers are becoming more adept at managing sprouting without the use of CIPC, the dry weather has raised questions about the e ectiveness of maleic hydrazide treatments which will only be answered later in the season. Because of these challenges, and the ongoing situation around seed imports from Europe, a number of growers may be actively considering holding on to some of their smaller non-MH treated crops for use as home-saved seed. While industry experts accept that this may be a useful approach for many, they stress that growers need to consider the risks carefully and be aware of the potential for virus and other issues in home-saved seed. “We have seen very high aphid numbers – more than seven-times the average in some parts of the country – and in those areas we are anticipating very high levels of virus infection, particularly PVA and PVY,” says Fera entomologist Larissa Collins. “Numbers of Myzus persicae (peach potato aphid) have been seen at four-times the usual levels, and there have also been very high numbers of Aphis fabae (black bean aphid). With such high aphid populations, there is a very high probability of virus transmission and crops from the a ected areas will be particularly risky to use as seed.” In July, Defra’s Animal & Plant Health Agency (APHA) also warned that the hot dry weather could not only reduce yields, but also lead to late virus infections in crops, and advised growers to ‘take steps to make sure they are con dent stocks will meet marketing standards.’ Despite the ongoing restrictions on seed potato imports from the European Union, seed potato companies believe that many English growers will nd it easier to obtain the seed they require under Defra’s revised rules, although with high costs and potentially lower yields, some growers may be looking to reduce production costs through the use of home- saved seed. Anything which may be destined for seed use should be risk assessed and tested. “It may be that early-season infection has been the biggest risk this year, but whenever peak transmission actually occurred, due to the high risk of PVA and PVY infection this season it is vital that growers test potential planting material,” stresses Fera virologist Adrian Fox. “ e relatively small cost of postharvest tuber virus testing massively outweighs the risk of having an infected crop next year, and those bene ts are magni ed when the risks of cross contamination between infect home-saved crops and clean certi ed crops are considered.” Numbers of Myzus persicae (peach potato aphid) have been seen at four-times the usual levels. “We have seen very high aphid numbers – more than seven-times the average in some parts of the country – and in those areas we are anticipating very high levels of virus infection, particularly PVA and PVY.” Larissa Collins