PlantwisePlus Blog

by Daniel O’Hara

Harvested tomatoes with boll worm symptoms

Post-harvest losses are only part of the food waste problem © CABI

Yesterday saw the release of a report from the Institution of Mechanical Engineers which highlighted the shocking level of waste within the global food system.

The report, ‘Global Food – Waste not, want not’, claims 30-50% (or 1.2-2bn tonnes) of all food produced is wasted. In the context of a rapidly growing global population this amount of waste simply isn’t acceptable. The report also notes the waste that lies behind the front-line statistics. For each item of food wasted the resources which have gone towards producing it are wasted too. In a world of water shortages and energy crises this inefficiency can be devastating.

Despite its strengths, the report is limited in one respect. It fails to examine the entire food production process and does not take into account one of the biggest causes of food waste – pre-harvest crop losses. Although the report notes that “frequently poor weather conditions or attacks by pests of all types reduce the quality or quantity of crop harvested” it fails to properly account for the huge global losses which occur.

Estimated at up to 40%, pre-harvest crop losses to pests and disease are one of the biggest challenges to food security. Recent examples, such as the spread of Maize Lethal Necrosis in Kenya, which affected over 150,000 farmers and reduced harvests by more than 20%, emphasise the current and real threats that pests and diseases can pose. And whilst major outbreaks draw attention sporadically, for farmers on the ground the challenge of pests and diseases is constant.

CABI’s CEO Trevor Nicholls drew attention to these pre-harvest losses in his paper, ‘Helping Farmers Innovate to Harvest More from Less’, published last month. In it he discussed how tackling pre-harvest loss can be a sustainable method for increasing agricultural production without extra use of resources such as land, water and energy. Through programmes like Plantwise, farmers are provided with the knowledge they need to fight pests and diseases. Armed with advice given at Plantwise plant clinics, and the information freely available via the Knowledge Bank, farmers can mitigate crop losses and improve local, and global, food security.

Responding to yesterday’s report Dr Nicholls said, “We fully support the IME in drawing attention to the shocking figures of food wastage within the supply chain but would encourage a truly holistic approach which also takes account of pre- and post-harvest losses due to pests and diseases.” He also pointed out that “from field to fork, total losses and wastage may be as much as 70% of potential output. By reducing these figures all the way along the chain, using knowledge and technology in our hands today, we can make significant improvements to global food security and availability without extra land, water, energy or fertilizers.”

So whilst IMechE should be commended for their report, which highlights the key issue of food waste, they should also be questioned. Their assertion that “In the less-developed countries, particularly those of sub-Saharan Africa and South East Asia, crop harvesting, handling, storage and transport infrastructure needs the most attention” ignores the potential wins to be had in reducing the 40% of crops lost to pests and disease. If we are to truly address the challenge of food security these must be acknowledged.


  1. Jean-François on 13th January 2013 at 10:09 PM

    This is certainly hitting the headlines these days, and hopefully all this attention will lead to meaningful action and real solutions. That 70% is a staggering number on a planet that has about a billion people suffering from food insecurity.

  2. Daniel O'Hara on 14th January 2013 at 1:38 PM

    Thanks for your comment Jean-Francois. Agreed that its good to have the issue in the headlines and IMechE deserve a lot of credit for that. We just want to encourage a more holistic look at the food supply chain.

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