Novel production on the agenda at Hadlow with pepinos

Second-year students studying for a National Diploma in Horticulture at Hadlow College have been undertaking some interesting trials relating to pepino, from the family Solanaceae.

Known by a number of other names including mellowfruit, treemelo and sweet cucumber, the pepino has a golden skin that becomes streaked with a violet-mauve colour in its ripe state. Tasting something like a combination between a cantaloupe melon and a cucumber, the yellow-gold flesh is fairly juicy and has an enticing perfume. Best peeled - although the peel is edible - pepinos can be eaten straight away as a snack, used in fruit salads, added to breakfast cereals, or used as a refreshing ingredient in summer starters. The centre seed portion is also edible and pepinos can be stored in the refrigerator for a few days before ripening at room temperature.

Domesticated since pre-Hispanic times, pepinos were then a widespread crop. Throughout known history, the pepino has enjoyed periods of popularity mingled with unwarranted fears that it could cause illness, even death. Even today some farmers in Peru believe that, if eaten after drinking alcohol, it can kill. Commercially produced crops using advanced technology are grown in various parts of the world, including its native Peru, California, Ecuador, Colombia, New Zealand and Chile. Marketing is mostly to the Japanese, North American and European markets.

The Hadlow experiments originally came about as a propagation assignment, which meant collect the seed of any plant, find out about it, and store it until sowing in the spring. A couple of years back, some Hadlow students saw the fruit at New Spitalfields and then their successors noticed it at the East Malling Research Association meeting on ‘novel crops’ held in October 2008.

Enthusiastic recreational gardeners with anorak mindsets have been experimenting, with varying results, in growing the odd pepino or two for some time. The Hadlow experiments, the first of which were undertaken by an earlier group of ND2 students two years ago, are on a somewhat larger scale. Current experiments began last November, when cuttings were taken from two seedling cultivars of the Hadlow pepinos (labelled familiarly as ‘beefsteak’ and ‘plum’). They rooted readily and were then transplanted to rockwool cubes and placed under extended day length in the warmest house, maintained at 12°C, but at one point, this dropped to 2°C as the result of a problem with a circulation pump.

Returning after the Christmas vacation, the students set up a simple but effective hydroponic system and planted the young pepinos in Fytocell slabs. Each student has two plants to tend and they have been allocated time to monitor, measure, train and generally look after their rapidly growing crop. All the plants are looking strong, and first and second trusses are flowering and producing fruit.

Horticulture lecturer Stefan Jordan believes these relatively small trials could provide useful material regarding the possibilities of growing pepinos in the UK as an additional niche cold glasshouse fruit. He would be interested to hear from anybody carrying out similar trials (stefan.jordan@hadlow.ac.uk), including home gardeners whose experiments may have extended over several seasons. Packet seeds are available from Suttons, Thompson & Morgan and others.

Reports indicate that attempts have been made to grow them in various parts of the UK outdoors, both under polythene and in pots, with varying results. Although total failure has apparently been scarce, the majority of fruit produced has had to be picked and ripened indoors. As with many unusual products, impassioned interest from amateur gardeners can spark consumer enthusiasm, if and when pepinos are grown commercially in this country.

One of the limiting factors relating to commercial growing could be the Pepino Mosaic (virus PepMV). First detected in Peru in 1974 on pepino plants, the disease was reported on greenhouse-grown tomatoes in the Netherlands and the UK in 1999. Indications are that it spreads more rapidly than other members of the genus Potexvirus that affect solanaceous plants such as tomatoes, potatoes and tobacco.

Research carried out over a number of years indicates very substantially reduced marketable yields in affected pepino plants. In experiments undertaken in Spain some years ago involving wild, cultivated and inter-specific hybrids, 42 clones were tested for ToMV resistance and all but seven were shown to be susceptible. Non-susceptible clones demonstrated variable degrees of resistance. The most promising variations to resistance related to the cultivated species. Although no immunity was identified, plants from these clones remained asymptomatic and other promising factors were identified, indicating sources of resistance favourable for developing commercial clones. Since PepMV is believed to be largely spread mechanically, specifically by contact, control measures are concentrated on biosecurity and sanitation.

At a conference at East Malling Research, Dr John Samuels said that pepino fruits sell in the UK for about £4.99 each. Next year the college may well continue experiments with a view to increasing production in order to supply its own Broadview produce shop.