FAIR-CT98-9573 Biological control as part of an environment friendly future for eradicating dry rot in buildings

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FAIR Area 1.2 - Green Chemicals and Polymers Chain

	Contract No:	FAIR-CT98-9573
	Date Prepared:	June 2000
	Source:	Progress Report

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Progress Report Abstract

Objectives

The overall objectives of the project are:

• To determine if a biological control system based on two previously identified antagonistic fungi (Trichoderma virens and T harzianum), can be used to supplement environmental technology in controlling dry rot caused by S. lacrymans (dry rot) in structural and ornamental timbers in commercial and domestic buildings as well as in buildings of historic importance.
• To develop, using the same technology, a practical system for preventing dry rot outbreaks in buildings after a breakdown in normal building maintenance, for example after flood or storm damage.

Activities

The work program has been divided into various work packages as follows:

Task 1. To compare the efficacy of potential bio-control agents applied using different types of inoculum (spore suspensions in water or nutrient media, mycelium infested wooden dowels and bran pellets) in both large-scale models and in real building situations. This is divided into two sub-tasks covering 1.1.efficacy testing on large scale models and . 1.2. Field tests in normal building environments

Task 2 To develop systems for producing the different forms of inoculum for the bio- control agents.

Task 3. To determine the shelf live of different bio-control agents in different forms of inoculum and the long term viability of the agents after application. This has two sub-tasks, 3.1.to determine the shelf live of various biocontrol agents in different formulations and 3.2 to determine the long term viability of different bio-control agents after application.

Task 4. To determine the safety of the bio-control agents in use.

Task 5. To determine the mechanisms of action of the bio-control agents, whether antibiosis, parasitism or competition for nutrients.

Task 6. To develop biochemical fingerprinting for strain identification.

Task 7. To search for more effective bio-control agents.

Task 9. To carry out market research, specifically to develop training packages technical specifications and risk assessments associated with COSHH and CDM regulations.

Progress

Work has commenced on all tasks with much of the research involved in tasks, 3, 4, 5, 6 and 7 being on schedule. Task 1.1 fell behind schedule because the dry rot infestations in the models have developed more slowly than expected and it is now predicted that the task will not be completed until summer 2001. A further problem arose in finding a suitable property in which to carry out the field tests. Task 1.2, is also well behind schedule. The permit from the Health and Safety Executive, which authorises the tests to be carried out stipulated that access to any building, in which tests are carried out, should be restricted to those involved in the tests. Although a suitable building was identified in the summer of 1999 it was not available with vacant possession until June 2000 and it is not envisaged that the tests will be completed before the summer of 2001. The delay in starting the field tests has also delayed the start of those research tasks involved in tasks 3.2 and 4 that are dependent on the trials. The start of task 2 was also delayed while legislative matters relating to the movement of fungal cultures between countries were resolved.

Achievements

Useful results have come from the shelf life studies. Survival of the bio-control fungi was found to vary according to the substrate on which they are stored, with survival in infested wooden dowels (a potential delivery system) not being as good as survival on nutrient media. However, even on wood, survival would be adequate for commercial purposes if the dowels are stored at low temperatures, particularly in a deep freeze. Even at room temperature survival for several months has been achieved.

The studies on the mechanisms of action have provided significant information. All isolates of species of Trichoderma tested so far have inhibited Serpula by a mechanism of antibiosis rather than direct parasitism. For quality control purposes reliable and rapid procedures are required for the identification of biological control agents both in inocula and in building structures after application. Specific primers of polymorphic DNA sequences have been identified in several species and found to be useful for distinguishing between them in mixed cultures.

Future activities

Since the main task of the project involves testing potential bio-control agents in a normal building environment the emphasis in the final period will be to ensure the successful completion of these tests. The preliminary surveys to determine the extent and activity of the dry-rot outbreaks within the building are well underway and the tests themselves and those tasks associated with the tests will be commenced shortly. The tests in large-scale models are also behind schedule. Predicting the behaviour of organisms in complex model systems is difficult and in some models the Serpula infestations have developed more slowly than anticipated. However these tests will be completed well within the additional time required for the building tests. The laboratory-based work is generally well on schedule but as time permits all tasks will be pursued during the remaining time and in any additional time that is granted. In this final period we will hope to obtain more information on the shelf lives of the organisms and on their mechanisms of activity particularly in relation to antibiotic production. The molecular fingerprinting of the organisms will continue in order to develop procedures which are able to identify species and isolates reliably and rapidly even when the organisms are present in mixed communities in naturally infested materials.