HC Deb 20 January 2004 vol 416 cc1196-7W
Mr. Swayne

To ask the Secretary of State for Environment, Food and Rural Affairs what assessment has been made of using helicopters for the purpose of identifying trees infected with sudden oak death; and if she will make a statement. [148557]

Mr Bradshaw

It would not be possible to spot signs of infection of Phytophthora ramorum from the air unless infection and dieback of trees and shrubs was extensive. The employment of helicopters would therefore only be of assistance to identify areas of dense planting and woodland for further investigation in areas where the infection is considerably more severe than any of the UK outbreaks identified to date. Plant health inspectors already have access to an on-line aerial photograph mapping facility to assist them in planning ground based inspections. They also have experience of using aerial surveys to detect plant disease on arable crops, although this has been with fixed wing aircraft rather than helicopters. The possibility of aerial surveys will be kept under review.

Mr. Swayne

To ask the Secretary of State for Environment, Food and Rural Affairs what assessment has been made of the effects of using methyl bromide as the fungicide of choice for combating sudden oak death; and if she will make a statement. [148558]

Mr Bradshaw

Methyl bromide is a fumigant approved for use as a pre-planting soil sterilant against some soil borne diseases including some Phytophthora species mainly in horticultural situations. Its effectiveness specifically against Phytopthora ramorum has not been evaluated because this is a new species. The pesticide may already be used by nursery staff growing plant stock for the purpose of eradicating other known pests and diseases in soil pre-planting. However it is not approved for use against fungal pathogens on growing plants due to phytotoxicity problems caused by the high doses that would be necessary. The methodology of applying soil fumigants would also make it impracticable to use this a means of dealing with infection in the wider environment. There are considerable health and safety implications attached to the use of this acutely toxic substance.

The only form of treatment currently available to eliminate infection by Phytophthora ramorum is removal and destruction of plant material. Currently approved fungicides have a suppressive effect which masks symptoms rather than eradicating the pathogen from infected plants. However, Horticulture Development Council funded research at the Central Science Laboratory is looking at a range of substances to see how well they can eradicate infection or protect healthy nursery stock from new infection.