GM technology 'may provide way to defeat potato pests'

Published on Friday 29 January 2010 18:04

WITH recent drastic reductions in pesticides that are allowed to be used in the control of pests and diseases in the potato crop, a claim was made this week that the potato industry in this country now faces real and serious issues that can best be tackled using genetic technology.

Dr Finlay Dale, leading potato breeder at the Scottish Crop Research Institute at Invergowrie, told a specialist conference in Perth that he believed this branch of science would supply the best answers to the problems facing the industry.

He said that in his 30 years as a potato plant breeder, those involved had moved from a basic position of "breeding the best with the best and then hoping for the best" to one where they were using gene markers to take some of the guesswork out of the breeding equation. Now the possibilities arising from taking another step to GM technology were vast.

Notable faults in existing varieties could be taken out and resistance to disease could be inserted, saving growers from having to use chemicals to protect their crops.

Dale urged consumers to look beyond the headlines when forming an opinion of GM technology. He pointed out that the unravelling of DNA was universal and he believed there would be a gradual acceptance of the benefits it would bring.

Agreeing with this assessment, Dr Stuart Wale, potato guru with the Scottish Agricultural College, said the arrival of GM into this country was inevitable. It was not a matter of "if", only "when".

Everyone in this country was already eating food which had GM components in it, he claimed.

Earlier at the same meeting, Wale advised potato growers to change part of their husbandry following a rise in the incidence of two of the main bacterial diseases that attack the crop.

There were, he said, increasing levels of both blackleg and gangrene in tuber samples in stores and the problem could be traced back to the cutting off of the crop prior to harvest.

Up until last year, the most common method of desiccation of the crop was the application of a dilute form of sulphuric acid; a practice which had been successful for 60 years.

However, this chemical was officially withdrawn last year and only stocks already in the system can be used this year. This has left growers looking at mechanically flailing down the crop, followed by the application of an approved haulm desiccant.

Wale said he was finding markedly higher levels of gangrene and blackleg in crops where this alternative approach had been used last year.

He added: "In 15 per cent of the stocks we have inspected this winter where the flail and spray system has been used, we have seen increased levels of both these diseases."

The problem for potato growers is this disease will carry forward in the tubers and bring problems for the 2010 crop.

He urged growers not to flail down crops when it was raining, as there was definitely a greater spread of disease when crops were wet.

And he also advised seed producers to install treatment applicators on potato harvesters to protect the crop prior to it being put into store.

Currently, only about 5 per cent of seed growers carry out this pre-store treatment.

For those producers with disease and damage in their stored potatoes, the prospect of electronically sorting out these problems is coming closer.

Lawrence Defty, of specialist machinery manufacturers Herberts, of Wisbech, said he expected electronic eye technology to be available to seed growers within a year or so.

Currently, potato prepackers who wash samples can use digital camera technology to remove any potatoes with blemishes, but this advance is not available to growers who work with dirty or "as grown" samples.

Advances in improving the resolution in cameras is now offering the prospect of being able to dispense with the hand sorting of the crop, he said.

The equipment now being produced can identify and remove 85 per cent to 90 per cent of the defects in a sample. This compares with a much more variable performance of a human, whose picking efficiency can vary between 17 per cent and 70 per cent depending on a range of issues, such as time of day and the attitude of the worker.