NT Country Hour By Lisa Herbert
Updated about 4 hours ago
Mango researchers are exploring two possible causes of resin canal discolouration (RCD), where black lines appear in mango flesh as the fruit ripens.
The disorder affects some Northern Territory and Queensland mangoes, with researchers acknowledging there is still a lot of work to do before they understand RCD.
00:00 AUDIO: Dr Andrew McNish from the Qld Department of Agriculture and Sydney based wholesaler, Carlo Ceravolo, discuss the possible causes of resin canal disorder (ABC Rural)
Sydney based wholesaler Carlo Ceravolo said resin canal was appearing on more fruit and consumers were shying away from the product.
"The last five years, I've seen it progressively getting worse, up until last year when I noticed a significant improvement in the outbreak of resin canal."
Mr Ceravolo said he believed the time of fruit picking was correlated to the occurrence of resin canal.
"It's only a personal theory of mine, but I think fruit maturity at time of harvesting plays a massive role," Mr Ceravolo said.
"I get to see a hell of a lot of different growers' fruit on the market.
"In many instances where there's a presence of resin canal, it is often in immature fruit."
But senior horticulturalist with the Queensland Department of Agriculture, Dr Andrew MacNish, said bacteria and fruit stress could be the causes.
"When we sample fruit progressively along the supply chain, we find the disorder is getting worse; there's more resin canal present and more severe resin canal," he said.
"This could be general stress that's causing this disorder to be expressed."
Researchers have also isolated a bacteria species from infected fruit.
"We've also found it in some of the dump water found in mango sheds and we've been able to induce symptoms of resin canal by inoculating fruit with the bacteria in more than 50 percent of cases," Dr MacNish said.
"We've also been able to reduce the level of resin canal in those inoculated fruit by treating the fruit with hot water, which is a common practice for managing pathogens in mango fruit at the shed.
"So this is providing some circumstantial evidence that bacteria may be involved, but we still need to do more work on this to be really sure that this is causing resin canal or at least contributing to it."