July is the month for strawberries, cream, Wimbledon… and now robots.

And while the fruit has long posed a challenge to machinery makers as it is easy to bruise and difficult to extract, a new piece of kit could be the gamechanger.

See also: Exotic and unusual harvesters: cotton pickers

Traditionally, most strawberry harvester operators run two conveyors on either side of a packing unit, on to which gangs of labour place the fruit. And yield depends hugely on how much irrigation you apply and the quantity of sunlight, but is about 7.5t/ha.

Now, however, Juan Bravo – a Spanish-born entrepreneur living in California – has developed a mechanical harvester called the Agrobot. It consists of a moving platform with robotic arms.

Vision sensors on the arms judge the colour and shape of the strawberries, so only the fruit at the right stage of ripeness is picked. The machine has taken a decade to develop but there are now three prototypes working in Australia, California and Spain. Commercial production will start in the next couple of years.

Sixty arms

Though the first machine has 16 robotic arms, a 60-arm machine is now being developed. However, it only works with varieties of strawberry that have a single stem with one fruit on it, rather than one stem with many fruits.

Workrate will be about 3ha/day and one machine could, in theory, replace up to 60% of the labour. This is good news in places such as California, where a rebounding US economy and tighter border controls led to a shortage of labour last year.

The result was that millions of dollars-worth of strawberries were left in the field and large growing groups are now enthusiastically trialling the Agrobot.

Will it come to the UK?

While pick-your-own strawberries are popular in the UK, most large, commercial growers use polytunnels with raised benches, making it unlikely that the Agrobot would sell over here.

The technology, however, could well find uses in the UK – colour- and touch-sensing and robotic arms can work equally well with crops such as lettuce.

Garfords of Peterborough already sells a robotic weeder, and at the recent Cereals event, the AHDB was demonstrating a concept lettuce harvester that could run between the rows, picking out just the ripe lettuces.

Blackcurrant harvesters

Ribena still accounts for a big portion of UK blackcurrant demand. Yield is about 10t/ha and 10 varieties are grown in the UK.

Blackcurrant harvesters have been operating for several decades – one of the best-known manufacturers is SFM of Martock, Somerset. Twenty years ago, the company used to sell about three machines a year but this has declined as grower numbers have shrunk to just 40 large ones. Exports, however, remain strong.

The machine works in much the same way as a grape harvester. It straddles the row and uses a set of vibrating rods to shake the fruit on to conveyors, which then take it up to a sorting and packing platform.

Workers target snails as well as stalks. Output is about 2.5ha/day and the machine costs £100,000. Specifying a cab raises the price to £130,000 but the air conditioning it brings allows the harvester to work as a sprayer, too.

SFM has experimented with increasing the weight of the shaking rods but in almost all conditions the level of shaking exceeds what is required. More promising has been a move away from steel to plastic conveyors.

These require less lubrication and are quieter, though not as durable. Raspberries can be harvested in a similar fashion.

Berry harvesters

There are harvesters for almost all types of berries – even rosehips are harvested by machine – and German company Feucht-Obsttechnik produces one for gooseberries and redcurrants.

Its machine is trailed, can be specified with either one or two shakers, and can harvest at a steady 0.1-0.2ha/hour. As with many specialist machinery makers, Feucht produces a full range of processing equipment, including fruit sorters and walnut cracking and hulling machines.

A different technology is employed for tree-based fruit such as walnuts, olives and cherries. The machines have an arm that extends to grip and shake individual trees, while canvas or plastic skirts clamp around to pick up the falling fruit. And, yes, as with almost all equipment, self-propelled versions are available.

Citrus fruit

Oxbo Corp in the US, parent company to PMC and Ploeger pea viners, has developed a range of harvesters to cope with blueberries, jojoba and Saskatoon, a berry that is native to Canada. Its 3220 Citrus harvesters are self-propelled machines that work in pairs either side of orange trees and can together harvest up to 400t/day.

The machine is fitted with huge arms and a series of horizontal propellers stacked on top of each other, looking not unlike a bottle-cleaning brush. These move into the trees and spin round, knocking the oranges on to large skirts that are underneath.

A conveyor takes the fruit to a rear discharge conveyor and into a truck that is usually being driven in reverse. The size of the trees rule out a machine that straddles them, hence they work in pairs.