Predators can make Scots soft fruit pesticide-free

Soft fruit growers were yesterday treated to stories of murder, cannibalism and widespread genocide in their raspberry and strawberry polytunnels with success being counted by the number of body parts they could identify after the action.

But far from being disgusted by all this mayhem, they seemed very appreciative of how sophisticated biological controls have become, with good bugs increasingly being used to eat the bad bugs.

David Foster, of Dutch based company Koppert, was speaking at the annual soft fruit meeting held at the James Hutton Institute, Dundee, when he said that growers should not worry about the reducing number of chemical pesticides that were now available to growers.

"Don't be sorry to see them disappear, we have new technologies coming along," he said.

The control of pests by using other pests has received a boost with today's consumers not inclined to purchase fruit where control has been achieved by the use of chemicals.

Foster said that nowadays most of the insect pests that attack soft fruit have natural predators and these predators can be supplied by companies such as Koppert.

The whole range of aphids has enemies in the natural world and the controlled introduction of aphid killers such as lacewings, ladybirds and hoverflies helps keep the growing crops of raspberries and strawberries healthy.

He said that part of the secret of success with biological control was down to a better understanding the life cycles of both predator and victim.

He gave as an example the case of spider mites in strawberry crops where at one stage in their life, they slip into a less active mood. Through the introduction of a specific midge that can bite through the shell of the spider mite, any problem is quickly cleared up.

The science is still not complete as he admitted pests such as capsid bugs and raspeberry beetles still require the use of a naturally occurring pesticide such as a pyrethroid.

While the pest side of soft fruit production is being helped with this specialist use of nature, another long-term problem in the raspberry industry may also be coming to an end.

Through the use of genetic markers, Julie Graham of the James Hutton Institute said they were now able to make real headway with raspberry root rot, a disease which has afflicted every commercial plantation in Scotland for the past 30 years.

By using an old North American variety, Latham, which has never succumbed to root rot and comparing its genetic make up with that of a susceptible variety, she said they have been able to identify where in the gene sequence, the resistance lay.