"We're in a situation where chocolate manufacturers are anxious about meeting demand, as there's rapidly increasing chocolate consumption in developing economies, paired with instability in cacao growing areas," Professor Guest said.
Cacao is produced from fruit of the tropical tree Theobroma cacao which translates as 'food of the Gods' and is grown in West Africa, South America, Southeast Asia and the Pacific.
"Cacao is grown in areas vulnerable to climate change, political instability, pests and diseases," Professor Guest said.
Threats to cacao production also include ageing plantations, poorly trained farmers and poorly managed trees, dependence on a narrow genetic base and crop substitution where cacao is replaced by maize because of the demand for bioethanol.
The chocolate crisis is exacerbated by the fact that global chocolate consumption is rising by two to three per cent annually.
"Chocolate consumption trends are different around the globe. In Australia, Europe and North America total consumption - around 6kg of chocolate per capita per year - is stable, but the trend is to dark chocolates or to niche marketed gourmet chocolates. Consumption dropped slightly during the global financial crisis in 2008 and 2009," Professor Guest said.
"In China, India, Eastern Europe and Brazil, however, per capita consumption rates are increasing rapidly, albeit from a relatively low base.
"One estimate is that global production will need to increase by one million tonnes per year by 2020 - from 3.6 million tonnes in 2009/2010 - to meet global demand."
To counter a chocolate catastrophe, Professor Guest's research supports the chocolate industry by improving the sustainability and profitability of smallholder cacao production.
Professor Guest and his colleagues' work with farmers in Indonesia, Papua New Guinea and Bougainville shows that good farm management increases yields, resulting in improved living standards, reduced rainforest clearing, political and social stability, and securing future supplies of chocolate.
"We work with farmers to select better genotypes of cacao, to demonstrate improved crop and soil management, to understand the constraints they face and what can be done to improve technical support," Professor Guest said.
"The keys to reducing diseases and pests are sanitation, pruning and regular harvesting. We have a mantra for the farmers to remind them to regularly harvest their cacao crops: 'Every pod, every tree, every week'.
"We've found it's really effective to explain to farmers that disease is caused by microorganisms similar to those that cause human disease. Showing farmers how the pathogens survive and spread helps their understanding and leads them to realise that they can reduce disease with improved management.
"Otherwise cacao farmers tend to blame nebulous factors like climate change or more virulent pathogen strains, which they feel powerless to do anything about."
Addressing a chocolate shortage is a challenge we have to meet if we are going to secure the world's supply of chocolate, while at the same time improving the livelihoods of cocoa farmers, Professor Guest said.
"While controlling disease is relatively straightforward in theory, changing farming practice to become more sustainable and rewarding is a much more complex challenge involving social, economic, political and environmental factors," Professor Guest said.
