Rot hurts spud dig
• Pink Rot is slowing the potato harvest.
By Tony Scott,
MAY 05, 2021
A worsening epidemic of pink rot in processing potatoes has some North-East growers considering getting out of the industry.
Compared to last year’s excessively wet harvest period, digging has progressed well in the dryer conditions.
But Field Officer for processor Simplot Malcolm Bowen said up to a third of some paddocks was being written off because of the infection.
“I’m working closely with our plant pathologist to try to get to the bottom of it, but it will be too late for this year.
“We’re trying to get a handle on it, so we can be prepared for next season,” he said.
Pink rot is widely thought to be caused by a soil-borne bacteria, but growers say some areas that have never grown potatoes before have been affected, making them think it could be a seed issue.
The problem affects how long they can be stored for.
Several thousand tonnes of potatoes in storage were ruined last year, as when one tuber is affected the disease quickly spreads to all the others around it.
Potatoes with pink rot are suitable for immediate processing, but there’s not the capacity to process all straight after they’re dug.
And there is concern that there won’t be enough suitable for storage for processing once the harvesting is completed.
Mr Bowen discounted that suggestion, saying the storages would be filled and some crops could be left in the ground so they could be harvested and sent directly to the factory.
One of the biggest growers and contract harvesters, Mark McDougall, said the rot seems to be worse the further east crops are grown.
“They don’t seem to have it at all down the North West.
“But around here a lot of growers have been really disappointed.”
Mr McDougall’s theory is that potatoes don’t like heavy dumps of rain like happened more towards the East Coast in February.
“We’re having to halve the speed of the harvesters so the sorters have time to properly look at the potatoes and throw out the ones with rot.
“That means labour costs are pretty much doubled and there’s not much in it for growers.
“We should be doing about 30 loads a day, but we’re back to 16.”
Mr McDougall said the affected potatoes could be fed to cattle, but they had to be quick because once exposed to air the rot quickly turned potatoes to a watery mush.
He expects losses to amount to about $1 million.
Even with the delays the harvest is well ahead of last year, when digging went well into September because of the extended wet conditions.