Scoping Study of a disorder that reduces shelf life and consumption of green beans
A dilemma facing green bean growers is a post-harvest disorder that affects both the aesthetic of the produce and the shelf life. The objectives of this project were to determine the extent of the problem (i.e. localized, regional or nationwide), capture anecdotal observations related to the onset of the problem and factors contributing to the manifestation of symptoms and, where possible, to collect samples for diagnosis of pathogens/pests that may be associated with the disorder and to make recommendations for further R&D or on how to manage this problem. Symptoms of this post-harvest disorder of green beans, often referred to as ârustâ are, for the most part, consistent with symptoms of âchilling injuryâ. This is based on interviews with growers and their staff, pathologist, agronomists and industry representatives from Victoria, Queensland and Tasmania, a farm visit and a review of literature. This disorder appears to be well known throughout the industry. Those growers and companies that have recognized the symptoms as chilling injury have taken steps to mitigate the problem, at least in the part of the supply chain under their control. Beans are a highly perishable commodity and are particularly sensitive to cold temperatures. The expected shelf life for beans is 8-12 days when stored at 5-7.5ÂșC. Beans can be stored for 2 days at 1ÂșC, 4 days at 2.5ÂșC or 8-10 days at 5ÂșC before chilling symptoms occur. Descriptions of these symptoms include a general opaque discolouration of the entire bean, pitting of the surface, discrete rusty brown spots and rust-coloured diagonal lines. Exposure of mature bean pods to chilling temperatures before harvest exacerbates the problem. A good knowledge of the factors that affect bean quality and how best to manage these issues on farm and in the supply chain is essential in ensuring optimum life and quality of beans at the point of sale. Careful handling, quick, thorough post-harvest cooling and storage at optimum temperature throughout the supply chain are considered to be the key to maintaining quality and lengthening shelf life of green beans. The cause of a bacterial disease in a crop in Victoria was identified as Pseudomonas syringae. Based on interviews with growers, bacterial diseases are relatively common in bean production in Australia. There is no doubt that a significant infection of bean pods will, in its own right, reduce the quality of bean pods, a problem experienced by a number of growers. In this instance, however, the bacterium was isolated only from leaves, not from pods. There is detailed quality information available on chilling injury and on bacterial diseases. Growers would benefit from a precise of this material into a form for easy access and consumption. The diagnosis of chilling injury was based mostly on anecdotal evidence. A follow-up during the peak of the season would ensure a more accurate diagnosis of this and bacterial problems and this exercise could serve to raise industry awareness of how to effectively manage post-harvest disorders.