Potato Review

34 POTATO REVIEW MAY/JUNE 2022 APPLICATIONS nozzle, and 66% at the rear on the closing soil, through an 02 nozzle. “The relatively large nozzle orifice would be unlikely to block. More interestingly it is a pre-orifice nozzle design, so offers some level of drift reduction and may be a combination to consider, especially with higher speed planters,” Harry said. Harry reported that in all the Norfolk trials, undertaken in a field specifically selected for the high risk of soil borne black dot, the use of Amistar reduced the incidence of severe infection on the harvested tubers. Results were also improved disease control for silver scurf and greater marketable yield from all the Amistar application techniques. Syngenta Potato Technical Manager, Michael Tait, had warned research had shown that black dot (Coletotrichium coccodes) was proving extremely persistent in soils, along with some indication that the pathogen is involved with the early die back complex that is being increasingly reported in potato crops. “Microsclerotia of black dot can typically persist in the soil for eight years or more, which means that once established it can usually survive from one potato crop to the next in the rotation,” he said. The pathogen is favoured by warm, wet conditions often associated with changing climate. “Microsclerotia of black dot can typically persist in the soil for eight years or more, which means that once established it can usually survive from one potato crop to the next in the rotation.” Michael Tait, Potato Technical Manager “We have seen very good results from Maxim seed tuber treatment, to prevent transfer of seed-borne pathogen onto the daughter tubers. But with this disease now so prevalent in soils, growers and agronomists need to be looking at the combination of both Maxim and Amistar to manage its damaging effects,” he advised. The combination of seed and soil borne controls was also especially effective in countering Rhizoctonia black scurf, Michael suggested. Dutch trials had shown that Amistar in furrow and Maxim seed treatment individually had each effectively halved the calculated Rhizoctonia index – a measure assessing both the severity and incidence of infection - from 16 in the untreated to 7.5 or 8 respectively. When the two products were used together, however, the index was further significantly reduced, to just 3. FT90 nozzle set up. TR80 nozzle set up. Michael Tait, Potato Technical Manager.