Wonky and inedible vegetables will be eradicated by farm robots which do not harvest crops until they are perfect, scientists have predicted.

Engineers are already working on machines which can autonomously plant seeds, weed, water and spray without a farmer needing to venture into the field.

They would also be programmed to only pick crops when they were ready for sale. Currently, farmers harvest fields all in one go, a practice known as slaughter harvesting, which can see up to 60 per cent of the crop wasted because it was not ready, or over-ripe.