Post-harvest rots in stored pumpkin is an issue that continues to rid growers of potential income, with reported losses of five-to-35 per cent. AHDB Horticulture project FV 439 was commissioned in 2014 to investigate the causes and how the issue could be solved. Debbie Rees at NRI leads the work with support from Peter Waldock of Growing Earth.
Peter first visited the USA, to find out how growers there were managing the problem. He reported that they invested more in nutrition and fungicide programmes not only to control preand post-harvest disease but also to promote fruit set and increase fruit size. US pumpkin breeding programmes are interested in stalk attachment because poor stalks are deemed to offer diseases a route into the pumpkin flesh.
The researchers investigated the pathogens causing rots and fruit characteristics that influence pumpkin susceptibility to rots. Phoma cucurbitacearum was identified as the causal agent for post-harvest losses. Fruit characteristics' results were inconsistent between varieties, seasons and locations.
The impact of fungicides and nutritional sprays on post-harvest rots was also investigated in trials that included Signum, Nimrod, Cuprokylt and Potassium bicarbonate as well as foliar products containing calcium, boron and manganese. Trials were carried out at Oakley Farms in Cambridgeshire and at Dan Mackeldens in Kent.
Mildew control gave higher fruit numbers in sprayed trials and it appeared to reduce rots at harvest, but it did not affect the rate of rotting during storage. The project is now drawing to a close and the final project report will be posted on the AHDB Horticulture website.
For details on all AHDB Horticulture activity, see horticulture.ahdb.org.uk
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