On-Farm Almond Storage and Other Critical Control Points for Managing Food Safety R&D Roundup Ben Brown - Industry Development Manager Chin Gouk Project Leader (AL11009), Department of Environment and Primary Industries
Critical Control Point #1 - Hull Rot and Mummies Hull rot, caused mainly by Rhizopus stolonifer has been a wide spread disease of almond orchards in Australia in recent years, particularly in the 2010/11 season following frequent and heavier rainfall events occurring from early hull split. Rhizopus is common throughout the environment and it acts opportunistically once the hull splits and the perfect micro-climate for growth occurs. Rhizopus releases a toxin that is translocated into the fruiting wood causing it to die with mummified fruit remaining attached to the tree and not easily shaken off during harvest. Interestingly, Monilinia spp. is also listed in the literature to be a causal pathogen of hull rot but this fungus has not been detected in any of the samples assayed. The critical control point is that the mummified whole fruit also provides an ideal source of Aspergillus inoculum, with mummies
Australian almond production has increased significantly over the last few seasons with one of the largest increases occurring this past year from 50,000 tonnes in 2012 to 78,600 tonnes in 2013. Further production increases over the next three seasons are also expected with an estimated production of 90,000 tonnes by 2017. In 2011/12 a multidisciplinary team comprising expertise in mycology, biochemistry, plant pathology, entomology and integrated pest and disease management from DEPI Victoria and CSIRO were put together to investigate the issues of Aspergillus and aflatoxin contamination - ensuring Australia’s reputation of supplying high quality almonds that are food safe. In particular, the aim of the R&D project was to identify key contributing factors and critical control points for Aspergillus and aflatoxin contamination, and develop an industry-wide strategy to minimise contamination. To serve as a reminder; aflatoxins are compounds that give rise to serious human and animal health effects and are produced by a group of Aspergillus fungi. The project is part way through its existing contract, but I’d like to highlight the key preliminary findings from 2011/12 and 2012/13 seasons.
(sampled post hull split) harbouring up to 17 times more Aspergillus than new whole fruit on the tree (Figure 1).
Figure 1: Size of Aspergillus inoculum load on orchard substrates relative to the numbers on new crop whole fruit on tree, during hull split, 2012/13