Potato Review

40 POTATO REVIEW JULY/AUGUST 2022 TUBER BULKING Potassium is also involved in the activation of a number of enzymes, including starch synthase, which is crucial in the formation of starch, the key component in the tubers. Potassium also helps manage the export of photosynthates and other compounds from the leaves where they are formed to the tubers, where they play a role in bulking. “Potassium deficiency can lead to problems with internal blackening in the tubers, making them unsaleable,” warns Chris. “As well as affecting tuber quality directly, due to a shortage of starch, potatoes that are low in potassium can be more susceptible to damage during harvest, so you might get more bruising or damage during lifting and handling. This could be a potential risk factor for the variety Sagitta, as it often shows a deficiency a potassium. “A number of foliar nutrition products can be applied to help support the supply of all of these crucial nutrients, but for the supply of potassium, growers should consider KuruS®, which contains a highly soluble form of potassium to support plant growth and is a clear liquid fertiliser which is already in solution, making it easy to use and mix into the spray tank.” He advises using KuruS® at the start of the bulking phase, based on soil or tissue analysis, with a follow-up application after 10-14 days if required. As well as potassium, the product contains sulphur which is necessary for nitrogen utilisation and protein formation. “At this stage of crop growth KuruS® should be used as a foliar spray, and many growers choose to combine it with their blight control programmes at a particularly busy time. “It is physically and chemically compatible with a wide range of agrochemical products, but as with any tank mixes, growers should consult the latest information from their adviser regarding its compatibility with particular crop protection products,” said Chris. Seaweed extract increases yield in salad potatoes T HE Crop Smith Ltd recently released findings of scientific trials on potatoes which revealed that seaweed extract increased the yield on salad potatoes. The trials were carried out on potatoes in Northamptonshire in 2021 with the aim of understanding the effects of a programme of CS1 and CS6 on plant performance and to evaluate the crop safety of these products at different rates. The Crop Smith Ltd produces seaweed extracts and blended products. CS1 is an organic seaweed extract which is high in bioactive compounds while CS6 is a balanced blend of seaweed extract with phosphite and humic acid. Seaweed extracts, phosphites and humic substances have all been demonstrated to have positive effects on growth and yield parameters in potato cropping, according to Technical Director Samantha Brown. ‘Charlotte’, a second early salad variety which produces uniform oval tubers with yellow, smooth skin, a creamy-yellow flesh and a waxy texture, was used for the trials. It ranks in the top 30 potato varieties grown in the UK with approximately 2,000 hectares planted commercially each year. No phytotoxic symptoms were observed throughout the trial, even at higher than recommended rates of application for both products. Samantha said the team will continue to evaluate the beneficial outcomes of seaweed extracts and blended products in potato crops. This year, trials are being conducted by external research providers examining the effects of CS1 and Rhizofix, a granular, microbial, in-furrow seed treatment, in maincrop potatoes.