"Food waste occurs in all farming sectors but is particularly acute for fruit and vegetable crops," she said, adding that the UK "is one of the countries leading the way in finding solutions at most levels of the food chain".
However, the amount of fruit and vegetable waste on UK farms is currently unknown, she pointed out. "A lack of monitoring and data collection at this stage of the food chain significantly hinders attempts to accurately estimate the extent of the problem." But the NFU believes "hundreds of thousands of tonnes of perfectly edible fruit and vegetables never reach the consumer".
The problem may actually be worsening because retailers' specifications "have become tighter and more unrealistic leading to crops being destroyed or left unharvested in fields because they do not make the aesthetic grade", she said, suggesting that "up to 30 per cent" of the UK vegetable crop is never harvested.
In all the countries she looked at "the fear of not being able to completely fulfil retailer contracts can lead growers to produce more than the contract requires as insurance against unforeseeable problems and to avoid penalties". According to one tomato grower: "Overproducing to avoid undersupplying supermarkets is standard practice."
Growers may also lack facilities to store periodic surpluses, or lack alternative markets, or face logistical obstacles to supplying these, she added. Labour shortages have already led to some crops being left unpicked in parts of the USA, she noted.
Surveying a number of waste food initiatives in the USA, Belgium, Denmark and her native Ireland, Whyte called on growers to "be active partners using their skills and experience to find solutions, opportunities and shape outcomes", and to aim to co-operate both with other growers and with the rest of the supply chain.
Growers should also "be open to helping to ensure accurate data collection on food waste on farm", adding that this "may not be popular but it is necessary". Meanwhile, farmers and their union representatives "should work towards repositioning themselves at the heart of food waste discussions", she recommended. "Where farmers have not been at the forefront of developments relating to food and its production they have often suffered the consequences of measures determined by those beyond the farm gate."
Food waste - call issued for greater transparency in the supply chain
Broadcaster, writer and chef Hugh Fearnley-Whittingstall and food waste campaigner Tristram Stuart both gave evidence in Parliament to the first Environment, Food & Rural Affairs committee session on food waste, during which the two also called for greater transparency on waste volumes in the supply chain.
Stuart, founder of the campaigning group Feedback, questioned the statistic that half of all food waste happens in the home, given there have been no studies into waste volumes at farm, wholesale or retail level.
Fearnley-Whittingstall, who recently highlighted the issue of food waste in his BBC TV series Hugh’s War on Waste, said: "It is, to me, a little mysterious where this figure comes from. Transparency is key. It’s very clear we don’t know how much food is wasted."
He added that the problem of food waste "is not simply a lack of education, the culture is to a large extent dictated by supermarkets".
On measures to address the problem, Stuart said: "It doesn’t work to just tell consumers to not waste food because they are aware supermarkets waste more food. So it makes sense to communicate the two changes together." He also called for a legally binding national food waste target in England as in Scotland, which would "drive innovation".