Final Report

Prepared by
Dr Catherine Noakes and Katherine Roberts

School of Civil Engineering University of Leeds Woodhouse Lane Leeds LS2 9JT

16 August 2005

Introduction
This report describes the results from the repeat tests carried out on the Fugenex Dry Rot sensors at the University of Leeds

The sensors were tested according to the methodology supplied by George McGill, using cultures of Serpula lacrimans grown on Malt Extract Agar. Three tests (plates 1,2 and 5) were carried out using cultures directly supplied by George McGill (arrived 25/7/05). Three further tests (plates 3,4 and 6) were carried out using sub-cultures, prepared from George McGill’s plates on 28/7/05 and grown in the lab at the University on Malt Extract Agar.

The tests were prepared by sterilising sections of sensor and plastic support in an autoclave. In each test 2-4 sections of sterile sensor were placed in on a sterile plastic support on top of the Serpula Lacrymans culture growing in each petri dish. The tests were then incubated at 20°C for between 10 and 15 days and the change in the colour of the sensors was recorded.

Results
All the plates tested showed good growth of Serpula Lacrymans around the sensor and support, with only minimal contamination on plates 3 and 4. The best Serpula growth was seen on plates 1,2 and 5, as it was allowed to grow on these plates for a longer period of time prior to the tests being carried out.

Photographs were taken of the six plates on day 15, shown in the figures below. Although it is difficult to clearly see the colour change in the sensors due to the limitations of the camera, it is clear that in all cases the sensors are yellow rather than blue. The photos also show the good growth of the Serpula Lacrymans and the minimal impact of contamination on plates 3 and 4.

 

Plate 1: Tested 1/8/05, very good Serpula growth, strong yellow colour on all 3 sensors	Plate 2: Tested 1/8/05, very good Serpula growth, strong yellow colour on both sensors
Plate 3: Tested 5/8/05, good Serpula growth, yellow colour on both sensors, minor contamination at plate edge	Plate 4: Tested 5/8/05, good Serpula growth, yellow colour on all 4 sensors, minor contamination on right hand side of plate
Plate 5: Tested 1/8/05, very good Serpula growth, strong yellow colour both sensors	Plate 6: Tested 5/8/05, good Serpula growth, yellow colour on both sensors Conclusions

In all cases the sensors showed a colour change that was within the “evidence of dry rot” range when compared to the colour chart supplied by Fugenex.

The sensors on plates 1,2 and 5, which had been exposed for 15 days, showed a very strong yellow colour that was considered to be at the extreme of the range shown by the colour chart.

The sensors on plates 3,4 and 6, which had only been exposed for 10 days, showed a weaker yellow colour, however this was still considered to be well within the “evidence of dry rot” range on the colour chart.

From these tests it can be concluded that the Fugenex dry rot sensors turn yellow in colour when in contact with actively growing Serpula Lacrymans for a period of approximately 10 days.