Potato Review

www.potatoreview.com POTATO REVIEW MAY/JUNE 2021 27 BIOSTIMULANTS higher calcium levels in the cell wall which improves tuber skin nish. “Calcium de cits have been linked to a higher incidence of tuber defects, such as internal rust spot and hollow heart, so boosting calcium assimilation can be bene cial,” said Nick. “It also improves skin nish, which is important for packing crops.” e bene t of ProAct in supporting calcium absorptionwas demonstrated in a trial undertaken by NIAB CUF in 2019. Tubers of ware crops were found to have a higher level of calcium when ProAct was applied in combinationwith Stopit fertiliser. e combination of the two was better than seenwhen either product was applied alone, and signi cantly higher (28%) than the untreated control. Other trials have shown that the e ect ProAct in supporting skin quality. A trial with Scotland’s Rural College (SRUC), found virtually no black leg in a highly susceptible variety when ProAct was applied on a weekly basis. “Because ProAct works on the whole plant it can provide a number of bene ts depending on how it is used during the growing season,” said Nick. “Trials by Staphyt in Poland in 2019 show that early applications can increase tuber numbers, while later applications boost tuber size and quality. Both approaches resulted in an improvement in marketable yield and, depending on variety and sale price, net margin bene ts of up to £350/ha.” Because the plant’s natural stress defences are boosted, treated crops showed better resistance to diseases such as blackleg. “Initial work undertaken by Agrii and SRUC looked at the e ect of treating seed crops of Rubesse with a number of products, and in the initial trial the ProAct treatment was the only one not to show any blackleg. A weekly spray programme of ProAct at 100 g/ha showed signi cantly less blackleg than other treatments in the trial,” said Nick. Such successes are no longer a rarity but understanding what such a product can do and how it works, is fundamental to realising the full economic bene ts, he said. “ ere is still an aura of ‘muck and magic’ about many biostimulant products,” said Nick, adding that it was important to chooses those that showed demonstrable bene ts in terms of how they interact with the crop, as well as providing greater marketable yield and better crop quality. “The scepticism directed to many bio-stimulants is understandable but, in many cases, is misplaced.” Trials in Poland showed an increase in marketable yield from using ProAct. Calcium has been linked to incidence of tuber defects such as Internal Rust Spot and Hollow Heart, so boosting calcium assimilation in the tuber is beneficial.