WO1999055505A1

WO1999055505A1 - Diffusable antisapstain method and compositions

Info

Publication number: WO1999055505A1
Application number: PCT/NZ1999/000050
Authority: WO
Inventors: Robin Nicholas Wakeling; Jonathan Leslie Wakeman
Original assignee: New Zealand Forest Research Institute Limited; Chemcolour Industries (Nz) Limited
Priority date: 1998-04-29
Filing date: 1999-04-29
Publication date: 1999-11-04
Also published as: AU764584B2; AU3961399A; AR019119A1

Abstract

A method of inhibiting sapstain in wet wood comprises applying to the surface of the wood a composition comprising a solution or microemulsion comprising at least one mobile fungicide which will diffuse into the surface of the wood. Preferably the fungicide is methylene bisthiocyanate, optionally in combination with an isothiazolione. The composition also comprises a surfactant and organic solvent or water.

Description

DIFFUSABLE ANTISAPSTAIN METHOD AND COMPOSITIONS

TECHNICAL FIELD

The present invention comprises a method of inhibiting fungal attack, generally referred to as sapstain, in wood, particularly in logs while wet after felling. The invention also comprises compositions for use in the method.

BACKGROUND ART

When a healthy tree is felled there is a rapid cessation of its immune response to microbial attack. As a consequence, felled or sawn timber is susceptible to invasion by sapstain, mould and decay fungi - a large and diverse group of fungi. This attack often results in downgrading of timber, causing serious financial loss in the timber industry.

The sapwood of all timber species is susceptible to fungal degradation, albeit to varying degrees. There are only two proven, in-service, methods of preventing fungal degradation of freshly felled timber indefinitely: - —

(a) dry the wood to a moisture content of below 18% of its dry weight and maintain that level;

(b) keep the wood in a saturated condition by ponding or sprinkling with water, thereby maintaining an inhibitory oxygen concentration.

When these methods are not feasible, wood is protected by applying a prophylactic treatment, commonly called an antisapstain treatment, to the surface. An antisapstain chemical is obtained in a concentrated form, usually a liquid, consisting of a fungicide plus appropriate solvents and surfactants to disperse or solubilise the fungicide upon dilution with water. The diluted treatment or working solution is then applied either by dipping or spraying. A major problem with currently available antisapstain treatments is their failure to give adequate long term performance. This is a particular problem for protecting against sapstain and decay in logs. Under severe storage conditions logs can become unacceptably sapstained within 2-4 weeks. Conventional approaches to overcome this problem include application of increasingly higher concentrations of fungicide to the log surfaces; application of adjuvants, sometimes referred to as "wetters" or "stickers" to the fungicidal solutions, that are aimed at increasing effectiveness of the fungicide by improving fungicide uptake by the wood surface; achieving a more even distribution of fungicide on the surface, reducing susceptibility of the fungicide(s) to wash-off; improving contact between fungus and fungicide; aiding fungicide uptake by the fungus, and/ or by physico-chemical interaction with the fungicide and fungus at the molecular and cellular level in such a way that the potency of the fungicide is increased; and the application of water-repellents designed to increase the rate of drying of timber exposed to rain, by preventing, or reducing the extent of, rewetting of timber that has started to dry.

These approaches can in some instances achieve improved long terπT performance of antisapstain treatments, but the extent to which this occurs is limited, particularly in the case of freshly felled and debarked logs. Currently available antisapstain formulations give approximately 10 weeks protection to radiata pine logs. Industry requires 20 weeks protection. The degree of protection sought by industry is in the order of 100-90% (ie zero - 10% internal sapstain by volume).

The currently available antisapstain formulations were largely developed for treating sawn timber, and lack the attributes required for successful treatment of logs. The underlying difficulty, for log treatment, resides with delivering a fungicide layer or "envelope" evenly to every part of the log surface, and then keeping it intact during handling. Logs are liberally covered with pits gashes and scuffs of all shapes and sizes and it is inherently difficult to treat these areas. Also, having received an antisapstain treatment, sawn timber is handled with "kid gloves" compared to the average log. The great majority of the wood surface of sawn timber, within a stack, is not submitted to any kind of damage, that could breach the fungicide layer. In sharp contrast, a log surface is heavily abraded by machinery, other logs and any storage surface onto which logs are dropped. Sawn timber is also less prone to other surface fungicide depletion mechanisms. Obvious examples include greater exposure to rainfall and contact with dirty storage surfaces. Another possibility for fungicide depletion on logs is related to the more severe drying stresses that occur at the surface. As an uneven wood surface dries, movement between abraded wood fibres will occur, possibly breaching the fungicide layer. This is particularly the case for adhering bark residue which tends to curl back away from the underlying untreated sapwood. The slimy cambium residue left behind in those areas of a log surface where the debarker has not made contact with the sapwood, is also a difficult surface to coat with fungicide because it is very smooth. The cambium surface is also very turgid with water and shrinks dramatically, exacerbating surface movement and possible breaching of the fungicide layer.

Early antisapstain treatment is especially critical for logs. Domestic saw logs can cope with a greater degree of pre-antisapstain treatment fungal infection compared to export logs, in terms of post-treatment sapstain problems. This is because in situations where domestic logs have become slightly infected with sapstain fungi, the greater part of the outer infected wood is discarded and therefore the amount of infected wood that is transferred to the sawn timber is minimal. However the situation is different for export logs since they are not sawn for many weeks and an early infection has ample time to proliferate throughout large sections of the log. A surface envelope for fungicide applied after the infection is in situ, which can occur within 24 hours, is ineffectual because it remains on the surface where it is unable to arrest internal sapstain fungi. The logistics of the majority of logging operations, prevent antisapstain treatment before pre-treatment sapstain infection occurs. Therefore treatment with conventional antisapstain formulations that sit on the surface, is ineffectual under these circumstances.

Methylene bisthiocyanate (MBT) is widely used as a bactericide, fungicide and algicide, slimicide and has application as a marine antifoulant. Many MBT formulations form a suspension in the aqueous working solution. British patent specification 2, 118, 160 discloses MBT compositions in which MBT is dissolved in N-methyl pyrrolidone. It is proposed that such solutions are useful biocides. There appears to be no recognition that modifications of the invention of that patent application would have particular advantage in antisapstain treatment of logs.

The present invention provides an improved or at least alternative method of protecting wet wood, especially logs, against sapstain. It is believed that the method of the invention provides protection for a longer term than obtained by currently available antisapstain treatments, without requiring water treatment or early drying.

DISCLOSURE OF INVENTION

In one aspect the invention comprises a method of inhibiting sapstain in wet wood, especially logs, by applying to the surface a solution or microemulsion comprising at least one mobile fungicide. Preferably at least one mobile fungicide is MBT. Other fungicidal materials with similar physico-chemical properties, such that appropriate mobility in wood is achieved, can also be used.

Preferably the application of the fungicide is by spraying.

Preferably the composition applied to the surface of the wood is a microemulsion or a surfactant assisted solution. Microemulsions are stable transparent liquids with droplet sizes in the range of 10 - 80 nanometres whereas emulsions are unstable opaque liquids with droplet sizes in the range of 0.5 to 5 microns (500 - 5000 nanometres).

Preferably the composition applied to the surface of wood is a microemulsion. A microemulsion has different properties compared to an emulsion. A microemulsion is more stable than an emulsion and this is partly related to the thermodynamics of micelle formation and deformation. The superior stability of a microemulsion compared to an emulsion, is demonstrated by the fact that the microemulsion does not settle out of solution. This is a major advantage because fungicides and other ingredients that are solubilised, through formation of a microemulsion, will remain in solution for greater periods of time, often indefinitely, compared to an emulsion, which often settles within minutes or hours. Settling of fungicides is a major disadvantage when using a working solution because the concentration of fungicide in solution is depleted and this can result in an inadequate concentration of fungicide arriving on the surface of wood during application. A microemulsion is a clear liquid, whereas an emulsion is an opaque liquid. A microemulsion has a further advantage for the intended use, in that it will not "break" (destabilise) as rapidly upon contact with the- surface of wood. This is an advantage because it can increase mobility, or impart the appropriate degree of mobility, in wood, to fungicide(s) applied to the surface.

Preferably the composition applied is a microemulsion which is an oil in water microemulsion.

Preferably the composition applied to the wood comprises a polar organic solvent such as N-methyl pyrrolidone, dimethyl sulphoxide or dimethyl formamide as a solvent or cosolvent.

Preferably the composition applied to the wood comprises a quaternary ammonium salt such as benzalkonium chloride or didecyldimethyl ammonium chloride (DDAC). One preferred option is to use a combination of DDAC and nonyl phenol ethoxylate as surfactant.

The use of mobile fungicides allows treatment not only of the surface of the wood but also treatment of the adjacent 10-20mm of wood. The fungicides are chosen and formulated to achieve treatment to this depth.

The log is vulnerable immediately after felling. Mechanisms or circumstances whereby a conventional antisapstain may fail to achieve protection i.e. achieve contact between fungicide and fungus, can include the following:

1. If fungi arrive soon after felling, or are already present in, or on, wood, cambium or bark layers, near the surface, and are already at or subsequently penetrate to, a region of log that does not subsequently come into contact with required concentrations of applied fungicide, they will not be affected by the fungicide. In this situation they have the potential to cause sapstain. The great majority of conventional fungicides remain close to the point of contact with the log surface":- Consequently, it is likely that in many situations, these fungicides (non- mobile or low mobility) will not make contact with fungi, usually spores, already in situ in hard to reach regions. This is because fungal spores often end up in regions, inaccessible to the liquid containing the fungicide, that is applied. These fungicides rely on movement of the water carrier to gain access to surface regions, many of which contain inaccessible voids (air-locked pits and cavities produced during rough handling), where it is possible for fungi to reside. Alternatively, these fungicides will not reach fungi already in situ because sufficient time elapsed prior to treatment, to enable fungi already present, or which arrived after felling, to grow into the log, arriving at regions which do not subsequently come into contact with fungicide. 2. After antisapstain treatment, a conventional fungicide is particularly prone to removal as a result of surface abrasion, because it remains near the surface of the log (usually less than 1 - 2mm from the surface) .

A mobile fungicide is much less likely to suffer these problems because it:

1. Penetrates the outer 10 - 20mm of wood. This depth rarely gets removed, in it's entirety, by abrasion, and consequently an "envelope" of treated wood remains at or near the surface.

2. Some of mobile fungicides used, have rates of penetration into the wood, e.g. MBT, which are greater than rates of penetration by sapstain fungi. Consequently they come into contact with fungi that have already penetrated to regions that conventional fungicide do not reach, usually within the outer 10 -20 mm.

The treatment is preferably carried out within 10 days, preferably less than 5 days, most preferably within 1-2 days of felling. Early pretreatment allows minimisation of pre-infection by sapstain fungi. The use of the invention allows ΈΓ greater delay in application of fungicide which has commercial significance because of the extra costs in rapidly treating logs after felling.

The rate at which fungicide diffuses through wet wood, is partly determined by its affinity for wood which is determined by its chemistry and method of formulation. For example quaternary ammonium compounds such as benzalkonium chloride or didecyldimethyl ammonium chloride (DDAC) have a positive charge and are attracted to the predominantly negatively charged lignocellulosic components of wood. In general, mobile fungicides are not considered appropriate for protecting freshly sawn timber from wood degrading fungi. A fungicide applied to the surface of wood must remain at a concentration that is toxic to fungi (toxic threshold) for the duration of the length of protection sought. Whilst an antisapstain fungicide must be sufficiently mobile to move into the fungal cell

7 when it is in close proximity, if it diffuses too rapidly through wood it will not remain at the toxic threshold concentration, at any given location, for long enough. Consequently the great majority of antisapstain fungicides that have been selected for treating freshly felled sawn timber, have a high affinity for wood. This, in general, makes them more cost effective, for treatment of sawn timber, because the majority of fungicide remains where it is needed, at or close to the surface of the wood. Achieving the desired toxic threshold concentration to just the depth required (depth damage) is the difficulty associated with using mobile fungicides on logs as well as for sawn timber.

These disadvantages can be minimised by one or more of the following three methods:

1. Application of appropriate fungicides to a log which then move into the log at a rate which can be manipulated by affecting the rate of log drying by applying water barriers to the log's surface. Fungicide movement is basically a diffusion process. Dissolution of the fungicide in the water contained in woody elements is followed by diffusion through the wood at a rate determined by the concentration gradient across the log radiusr- The diffusion process is dependent on the wood moisture content. Once the wood elements begin drying, the diffusion process is slowed.

2. Use of a fungicide that moves into the log in a gaseous phase. Such fungicides have the advantage that they are less affected by log drying since gaseous fungicide can diffuse rapidly across wood of a wide range of moisture contents. MBT is an example of a fungicide which can diffuse in gaseous form.

3. Use of a further fungicide or further fungicides in addition to the mobile fungicide(s). The extra fungicide(s) may be a conventional antisapstain fungicide which remains on the surface. Thus a loss of the diffusable fungicide from the surface is countered by the retention of the further fungicide (s).

Use of a water barrier assists by preventing or reducing contact between fungicides and rain. Suitable water barriers include solid material such as a plastics film or alternatively a hydrophobic substance such as wool grease. Other suitable hydrophobic substances that may preferably be used as the water barrier include lanolin, petrolatum, paraffin oils, fish oils such as shark oil, animal oils, waxes, silicones, fatty acid esters, bitumen and vegetable fats and oils.

The antisapstain concentrate composition may comprise between about 10% and about 40% of a water barrier substance and between about 60% and about 90% of either an organic solvent, or water or a water based composition containing the mobile fungicide. Typically this is diluted up to 50 fold with water before application, but in some circumstances an organic solvent may be used.

When an organic solvent is used it may be a liquid hydrocarbon or mixture of liquid hydrocarbons. Preferably the organic solvent is kerosene, benzenep chloroform, toluene, ether, carbon disulphide, acetone, paraffin, diesel, white spirit, soya oil, linseed oil, or shark oil.

In a preferred embodiment of the invention the concentrate composition comprises:

10-40% (w/w) of a hydrophobic substance selected from lanolin, petrolatum, paraffin oils, fish oils such as shark oil, animal oils, waxes, silicones, fatty acid esters, bitumen, vegetable fats and oils, or more preferably wool grease.

0.5- 15% of a surfactant, preferably a quaternary ammonium salt such as benzalkonium chloride 1- 10% methyl pyrrolidone

0.2-5% MBT

30-88.3% water

A further preferred embodiment of the invention comprises an emusifiable concentrate containing 0.2- 10% MBT dissolved in a vehicle where the vehicle contains N-methyl pyrrolidone as a solvent and a surfactant preferably a quaternary ammonium salt such as benzalkonium chloride or didecyldimethyl ammonium chloride preferably in a ratio of between 1: 10 and 10: 1 by weight. Additional components which may be present include lactic acid as a solvent, a non-ionic surfactant, and a further fungicide which may be a conventional fungicide which does not diffuse as readily as MBT.

Fungicides which may be present in addition to MBT include substituted benzimidazoles such as carbendazim (methyl benzimidazol-2-ylcarbamate), chemical precursors of benzimidazoles such as benomyl (methyl l-(butycarbonyτ)^~ benzimidazol-2ylcarbamate or copper-8-hydroxyquinolinolate; triazoles such as hexaconazole ((RS)-2-(2,4-dichlorophenyl)- l-(lH- l,2,4-triazole- l-yl) hexan-2-ol); and quaternary ammonium compounds such as didecyldimethyl ammonium chloride, chlorothalonil (tetrachloroisophthalonitrile), fenpropimorph and isothiazolinones (eg 2-n-octyl isothiazolin-3-one).

These extra fungicides may usefully be present in other embodiments of the invention as well for their usefulness at the surface of the log. An advantage of embodiments of the invention where more than one fungicide is used is that this allows advantage to be taken of synergy between fungicides or to increase the spectrum of activity against wood degrading fungi.

10 The compounds benzalkonium chloride and didecyldimethyl ammonium chloride are particularly useful in that they have several possible functions. They can act as a surfactant, as a fungicide and also as a solvent.

In another preferred embodiment of the invention there is provided an antisapstain composition containing 1- 10% MBT dissolved in a vehicle containing 10-90% N-methyl pyrrolidone and 10-90% of a surfactant which is preferably a quaternary ammonium salt such as benzalkonium chloride.

One advantage of the use of a hydrophobic water barrier material together with a fungicide system is that it improves the homogeneity of the fungicide layer on the surface of the log. This results from reduction of the drying stresses at the log surface which result in movement of wood fibres which tends to breach the fungicide layer. Use of the water barrier material also provides a reservoir for fungicides which then diffuse into the log at a rate partly determined by the effectiveness of the water barrier. This effectiveness can be manipulated by the formulation technique.

It is preferred to use microemulsions or surfactant assisted solutions as working- solutions rather than dispersions of fungicides. This has several advantages. Logs are typically sprayed with antisapstain fungicides, unlike sawn timber which is often dipped. Spray systems are easily blocked by fungicide suspensions, whereas microemulsions behave like true solutions and do not cause blockages. Emulsified fungicides are more efficacious than suspensions. This is usually attributed to achieving better contact between fungal hyphae and fungicide. It is believed that the emulsification of key mobile fungicides enables a greater degree of mobility in the wood compared to suspensions of the same fungicides.

Preferably the composition applied to the wood is a microemulsion or surfactant assisted solution and comprises:

(a) 0.05- 1% MBT, more preferably 0. 1-0.5% most preferably 0.2-0.3%;

11 (b) 0. 1- 10% N-methyl pyrrolidone, more preferably 0.5-5%;

(c) 0.1 to 15% of a surfactant, preferably a quaternary ammonium salt such as benzalkonium chloride or DDAC, preferably 0.5-8%; and

(d) up to 99.75% water.

Optionally one or more further components such as a non-ionic surfactant (eg nonyl phenol ethoxylate), other fungicides and surfactants are included in the working composition.

In a preferred working composition a water barrier hydrophobic substance is present into an amount of 1-40%.

Spraying of logs is used in a preferred embodiment of the invention. Typically 200-500 ml of antisapstain treatment solution per m² is applied. The strength of the solution is generally adjusted to achieve a surface retention of MBT of 10-300 micrograms per cm² (preferably 20- 100, most preferably about 50 micrograms per^" cm²).

The concentrates, working compositions and methods of the invention are also useful with sawn timber.

After 12 weeks of exposure to the elements, wood dipped in 0.5% w/w MBT plus 0.22% w/w of 2-n-octyl isothiazolin-3-one, was completely free of fungal degrade. This level of protection of radiata pine in New Zealand has not previously been recorded by the applicant after eight years of extensive antisapstain testing.

12 EXAMPLES

The following examples further illustrate the invention. All ratios, percentages and proportions are by weight unless otherwise stated.

EXAMPLES 1A & IB

The constituents of these compositions are shown in Tables 1A & IB.

TABLE 1A

Constituent Constituent Active % w/w of Function active

N-methyl N-methyl pyrrolidone 25.9 Solvent/ surfactant pyrrolidone

Synthecol Quad HC benzalkonium chloride 64.75 Solvent/ surfactant

Methylene bis methylene bis 6.48 Fungicide thiocyanate thiocyanate

Acticide 45 4-n-octyl- 2.87 Fungicide isothiazolinon-3-one

TABLE IB - SENTRY-™

Constituent Constituent Active % w/w of Function active

N-methyl N-methyl pyrrolidone 25.9 Solvent/ surfactant pyrrolidone

Synthecol Quad HC Benzalkonium chloride 51.8 Solvent / surfactant methylene bis Methylene bis 6.48 Fungicide thiocyanate thiocyanate

Kathon 893 F 2-n-octyl-isothiazolin- 1.29 Fungicide 3-one

13 This composition is for SENTRY™ antisapstain composition as marketed by Chemcolour Industries (NZ) Limited, New Zealand.

The methylene bisthiocyanate is completely dissolved in the N-methyl pyrrolidone. The Synthecol Quad HC (benzalkonium chloride) is added followed by addition of the isothiazolinone compound.

EXAMPLES 2A, 2B, 2C & 2D

The constituents of these compositions are shown in Tables 2A-2D

TABLE 2A - SENTRY™ LX

Constituent Constituent Active % w/w of Function active

N-methyl N-methyl 25.9 Solvent/ surfactant pyrrolidone pyrrolidone

Synthecol Quad HC Benzalkonium 51.8 Solvent/ surfactant Chloride

Methylene bis Methylene bis 6.48 Fungicide thiocyanate thiocyanate

Kathon 886 5 chloro-2-methyl-4- 0.30/0.11 Fungicides isothiazolin-3-one / 2-methyl-4- isothiazolin- 3- one

This composition is for SENTRY™ LX antisapstain composition as marketed by Chemcolour Industries (NZ) Limited, New Zealand.

14 TABLE 2B - SENTRY™ DMSO

Constituent Constituent Active % w/w of Function active

Dimethyl Dimethyl sulphoxide 25.9 Solvent/ surfactant sulphoxide

Synthecol Quad HC Benzalkonium 51.8 Solvent/ surfactant chloride

Methylene bis Methylene bis 6.48 Fungicide thiocyanate thiocyanate

Kathon 893 F 2-n-octyl- 1.29 Fungicide isothiazolin-3-one

This composition is for SENTRY™ DMSO antisapstain composition as marketed by Chemcolour Industries (NZ) Limited, New Zealand.

TABLE 2C - SENTRY™ DMSO/LX

Constituent Constituent Active % w/w of Function active

Dimethyl Dimethyl sulphoxide 25.9 Solvent/ surfactant sulphoxide

Synthecol Quad HC Benzalkonium 51.8 Solvent/ surfactant chloride

Methylene bis Methylene bis 6.48 Fungicide thiocyanate thiocyanate

Kathon 886 5 chloro-2-methyl-4- 0.30/0.11 Fungicides isothiazolin-3-one / 2-methyl-4- isothiazolin- 3 - one

This composition is for SENTRY™ DMSO/LX antisapstain composition as marketed by Chemcolour Industries (NZ) Limited, New Zealand.

15 The methylene bisthiocyanate is completely dissolved in the dimethyl sulphoxide. The Synthecol Quad HC (benzalkonium chloride) is added followed by addition of the isothiazolinone compound.

TABLE 2D

Constituent Constituent Active % w/w of Function active

Lactic acid Lactic acid 15.95 Solvent

N-methyl N-methyl pyrrolidone 40.86 Solvent/ surfactant pyrrolidone

Bardac 2280 Didecyldimethyl 35.02 Solvent/ surfactant ammonium chloride

Hexaconazole Hexaconazole 0.58 Fungicide

Carbendazim Carbendazim 0.58 Fungicide

Methylene bis Methylene bis 5.84 Fungicide thiocyanate thiocyanate

Teric GN9 polyethylene glycol 1.16 Surfactant nonyl phenyl ether (nonyl phenol - 9 mole EO)

In a tank A Carbendazim is dissolved in lactic acid with stirring and heating to 40-45°C. In a separate tank B, methylene bisthiocyanate is added to N-methyl pyrrolidone while stirring and mixed till completely dissolved. Then the hexaconazole is added mixed in followed by the Bardac 2280 and then the Teric GN9 and stirred for 30 minutes. The carbendazim solution in lactic acid in tank A is then pumped into tank B and mixed for 30 minutes.

EXAMPLE 3 - ANTISAPSTAIN COMPOSITION CONTAINING WATER BARRIER SUBSTANCE

The constituents of this composition are shown in Table 3.

16 TABLE 3

Constituent Constituent Active % w/w Function of active

Woolgrease Woolgrease 35.9 Water barrier

N-methyl pyrrolidone N-methyl pyrrolidone 4.0 Solvent/ surfactant

Synthecol Quad HC Benzalkonium chloride 8.0 Solvent/ Surfactant

Methylene bis Methylene bis 1.0 Fungicide thiocyanate thiocyanate

Kathon 893F 4-n-octyl- 0.20 Fungicide isothiazolinone-3-one

Sorbitan Sorbitan monostearate 0.45 Surfactant monostearate

Tallow propane Tallow propane diamine 3.2 Surfactant diamine

POE 20 Sorbitan POE 20 Sorbitan 0.45 Surfactant monostearate monostearate

Acetic acid Acetic acid 3.2 pH Adjuster

Kathon LX 2.6% 2-methyl-4- 0.017 Fungicide isothizolin-3-one and 8.6% 5-chloro-2-methyl- 4-isothizolin-3-one

Water Water Balance Solvent

17 An aqueous emulsion of woolgrease is prepared as follows:

wool grease 42.5

Sorbitan monostearate 0.53 Phase A

Tallow propane diamine 3.83

POE 20 Sorbitan monostearate 0.53

Water (hot) 51.3 Phase B

Acetic 75% 3.8

Kathon LX 0.02

Total 100

Procedure: 1. Heat phase A to 65°C.

2. Heat phase B to 60-65°C.

3. Add phase A to phase B while mixing then homogenise for 30 minutes.

4. Add Kathon LX and continue slow mixing until batch is cooled to 40°C.

to 84.5 parts of the emulsion above is added 15.5 parts of Example 1 solution with thorough mixing.

EXAMPLE 4 - WORKING SOLUTIONS

The antisapstain compositions described in Examples 1A and 2D are mixed with water in the ratio of 1:5.5 and 1: 10.7 respectively and sprayed onto logs. The antisapstain composition of Example 3 was used without dilution.

18 EXAMPLE 5 - ANTISAPSTAIN LOG TRIAL OF C1098 AND C1099

The objective of this study was to determine the efficacy of the antisapstain formulations of Example 1A (C 1099) and Example 2D (C 1098) for protection of freshly felled radiata pine logs against fungal degrade.

Radiata pine logs were dip treated in several antisapstain formulations including C 1099, C1098 , NP- 1 (Kop-Coat), NP- 1 Ultra and Cutrol 375 (Fernz). In addition, a water barrier was applied to one set of logs treated with C 1099. After 12 and 16 weeks, logs were sawn into lumber and fungal degrade was then determined on the surface of each piece of lumber.

Materials and Methods

Log resource used

Logs were sourced from Otago Coast Forest compartment 128 (Akatore Block), New Zealand. Pruned log size diameter ranged from 35-50 cm and average log volume was 0.94 m³.

Logs were cut to length immediately after extraction to the skid, with standard mill lengths of 3.15 to 4.95m at 0.3m increments. Logs were colour coded with the actual felling date. The pruned logs were separated at the skid site and then were trucked to the debark/ spray/ dip facility 3 to 4 days after felling.

Logs were debarked under normal operating conditions. Debarking quality was variable with some logs having smooth surfaces while others had a scuffed fibre surface. Also, some of the logs showed butt fluting with some bark remaining which the debarker failed to completely remove. Logs were exposed to prevailing weather conditions from bush to processing.

19 Application of Antisapstain Chemical

Logs were dipped for 10 seconds in the treatment solution using a crane fitted with a grapple attachment.

Dip-treatments were performed four days after felling, except one NP- 1 treatment which was applied by spraying. Also, some logs were treated after five days because of difficulties encountered on the first day of treatment. The treatments most affected were the C 1098 formulation and five logs out of each of the NP- 1 treatments that were spray-applied and dipped. Twenty-two replicate logs were used per treatment.

TABLE 4: Treatments used for protection of radiata pine logs.

Product Concentration w/w Major active product ingredient

C 1099 + Water Barrier 15.5% MBT

C 1099 15.5% MBT

C 1098 8.5% MBT

NP- 1 4.5% IPBC*

NP- 1 (Spray Application) 4.5% IPBC

NP- 1 + Ultra additive 4.5% IPBC

Cutrol 375 6% Oxine copper

Control

IPBC = 3-iodo-2 propynylbutylcarbamate

20 Handling and Storage of Treated Logs

Treated logs were trucked to a sawmill and stacked in standing bolsters to form a single row which resembled a commercial stack, using NP- 1 sprayed pulp logs for bed logs and upright bolsters. The stack was aligned to the prevailing wind, so that the individual logs were at right angles to the wind.

Light rain fell when the bulk of the stack was set up. The water barrier sprayed logs were exceptionally slippery, and the hiab operator had trouble setting up that stack. Consequently those logs suffered more surface damage than was typical for the other treatments.

Assessment

Logs were assessed after 12 and 16 weeks. Seven logs from each treatment were selected from the stack, taking care to include a representation of top, middle and bottom logs. The selected logs were laid out on bearers, and 3 from each treatment had a 30 cm disc removed from one end, and were assessed for decay using a pH colour indicator (methyl orange) . This indicator changes from orange- to red in the presence of decay fungi due to a lowering of the wood pH caused by incipient decay. These three logs were also given an external rating using the following rating scale:

0 no degrade 1 < 5% surface cover of fungal degrade

2 6 - 25% surface cover of fungal degrade

3 26 - 50% surface cover of fungal degrade

4 51 - 75% surface cover of fungal degrade

5 76 - 100% surface cover of fungal degrade

Logs were sawn in batches according to treatment. All the timber pieces from each treatment were stacked in single packets, except thin boards. These

21 packets were sorted through piece by piece and assessed for fungal degrade. A total of 871 pieces were assessed and rated using the above scale.

Data Analysis

Fungal degrade rating which was applied to each piece of timber, was multiplied by its surface area. These "stain factors" were summed for each log and then divided by the sum of the surface area of the individual pieces. For each treatment, individual log stain rating were averaged to produce a rating for each treatment.

Results

After 16 weeks, C 1099, with and without Water Barrier, and C 1098, gave better protection against sapstain than any of the commercial standards tested (Table 5).

TABLE 5: Stain ratings for each treatment

Product Application Fungal Degrade Rating

Mean rating Derived Mean % Sapstain Rating

12 wks 16 wks 12 wks 16 wks

C 1099 Dipped 0.044 0.053 0.35 0.42

C 1099 + Water barrier Dipped 0.025 0.048 0.2 0.38

C 1098 Dipped 0.039 0.107 0.31 0.86

Cutrol 375 Dipped 0.259 0.704 2.1 6.0

NP- 1 Dipped 0.48 0.906 3.84 7.25

NP- 1 Sprayed 0.807 1.152 6.5 9.22

NP- 1 Ultra Dipped 0.864 0.853 7.0 6.82

Control 1. 151 1.686 9.2 13.5

22 EXAMPLE 6 - PERFORMANCE OF COMPOSITIONS OF EXAMPLES 1A AND 2D AGAINST FUNGAL DEGRADE ON RADIATA PINE LOGS

The objective of this study was to determine the efficacy of the antisapstain formulations of Examples 1A (C 1099) and 2D (C 1098) for protection of freshly felled radiata pine logs against fungal degrade.

Materials and Methods

Logs

Logs were sourced from Kaingaroa Forest, New Zealand. Pruned logs were 4.1 metres long and of a diameter range 35-50 cm.

Logs were specifically felled and cut to length immediately (within 24 hours) after extraction to the skid site.

Logs were maul debarked immediately prior to spray application of the antisapstain treatment.

Application of Antisapstain Chemical

The antisapstain spray facility was a modification of a commercial (Kermit) spray booth at Webbs road, adjacent to the Kaingaroa processing plant (KPP). Nine T- Jet 4 nozzles (70 PSI) were set up concentrically inside the booth. Each nozzle delivered 3.9 litres per minute at 5 bar (70PSI). A minimum of 10 replicate logs was used for each of the treatments (Table 6).

TABLE 6: Antisapstain formulations used and wood surface retention of active ingredients after treatment of radiata pine logs.

Treatment Concentration %w/w Analysed active on

23 wood*

Product Mean concentration (μg/ cm²)

1 C1098 15.5 26 (MBT)

2 C 1098 + WG 15.5 + WG 18 (MBT)

3 C 1099 15.5 65 (MBT)

4 C 1099 + WG 15.5 + WG 44 (MBT)

5 NeXgen (ISK 8.0 90 (MBT) Biosciences)

6 NeXgen + WG 8.0 + WG 1 18 (MBT)

7 Wolsin (BASF) 6.0 48 (boric acid)

8 Wolsin + WG 6.0 + WG 89 (boric acid)

9 NP- 1 4.5 + WG 530 (DDAC)

10 NP- 1 + WG 4.5 + WG 1455 (DDAC)

1 1 Untreated control

* = refers to key active or most easily analysed active (all formulations tested contained more than one active)

MBT = methylene bis thiocyanate, Hex = hexaconazole, OTZ = 3-n-octyl- isothiazolin-3-one, IPBC = 3-iodo-2-propynylbutylcarbamate, WG = wool grease

Handling and Storage of Treated Logs

Treated logs were stacked in the open at the KPP site for 16 weeks before trucking for peeling and assessment.

Assessment

Logs were assessed after 16 weeks. Percentage of sapstain cover was assessed on the surface of the veneer sheets immediately after peeling.

24 RESULTS

Mean percentage sapstain cover observed on veneers for each treatment was determined. Untreated control logs had a mean sapstain value of 43% indicating that the severity of hazard during the trial period was moderately high. C 1098 and C 1099, with sapstain values of 5 and 6%, clearly performed better than Wolsin and NP1, which had 16 and 27% sapstain. NeXgen had 4% sapstain.

Because NeXgen, C 1098 and C 1099, contain MBT it is therefore possible to make a direct comparison of efficacy on the basis of MBT concentration on the woods surface. Logs treated with NeXgen had a mean surface concentration of 90 μg/cm² compared to 26 and 65 μg/cm² for C 1098 and C 1099 respectively. Since NeXgen, C1098 and C 1099 gave very similar levels of control, but NeXgen treated logs had 3.5 and 1.4 times as much MBT on the surface, this demonstrates the superior performance of C 1098 and C 1099 per unit weight of MBT. This is evidence that emulsified MBT in C1098 and C1099, is more efficacious than suspensions, such as the MBT in NeXgen, often by a factor of several times.

It was clear from the efficacy data that application of a water barrier to the logs^' surface resulted in higher sapstain values for each of the antisapstain formulations tested.

The concentration of active found by chemical analysis in the working solutions were close to the expected values.

CONCLUSIONS

C 1099 and C1098 gave a level of protection against sapstain that was superior to the commercial standards NP1 and Wolsin.

C 1099 and C 1098 gave a level of protection against sapstain that was similar to NeXgen however the concentrations of MBT applied for NeXgen were considerably

25 higher than for C 1099 and C 1098, suggesting that C 1099 and C 1098 were more efficacious than NeXgen, on an MBT weight basis.

EXAMPLE 7 - ANTISAPSTAIN FIELD TRIAL TO DETERMINE THE EFFICACY OF C1098 AND C1099 AS ANTISAPSTAIN FORMULATIONS ON LUMBER

Two antisapstain formulations, C 1098 and C 1099, were tested for their effectiveness against fungal degrade of freshly sawn, block-stacked radiata pine. Commercial standards, Hylite Extra, NP- 1, NeXgen and Wolsin F35 were included at a range of concentrations including commercial usage rates. Treated packets were assessed for sapstain, mould and decay coverage after five, 12 and 15 weeks exposure to natural fungal infection.

Materials and Methods

Commercial antisapstain formulations Hylite Extra (Fernz), NP- 1, Wolsin F35 and NeXgen, were used as standards in this field trial. A water control set was also included. Each treatment concentration was made up in ten litres of cold tap water to give percentage concentration expressed as weight per volume- measurements (%w/v).

Experimental protocol

Thirty 40 x 100 x 1000 mm Pinus radiata D. Don sapwood boards, which had been sawn from logs the previous day, were individually given an agitated dip for ten seconds in ten litres of antisapstain formulation. Following dipping, boards were block- stacked (6 tiers high and 5 boards wide) on a pair of 100 x 40 mm bearers placed on an asphalt-sealed surface. Treated packets were covered with plastic sheets for two days to prevent rain wetting and allow chemical fixation to occur before being exposed to the weather and natural fungal infection.

The trial commenced in early summer and was completed by late summer.

26 Percentage surface cover of fungal degrade was assessed at 5, 12 and 15 weeks after dipping the following rating system described in Example 5:

Mean percent of surface coverage (% MSC) of fungal degrade was calculated for each treatment using a derived median percentage cover value for each rating. For example 15.5% is the median of the range 6 - 25% (rating of 2).

RESULTS

After fifteen weeks C1099 (8.5%) yielded 1.5% MSC of fungal degrade and gave significantly better protection than all commercial standards tested, except Wolsin F35 (4.0%)which had 4.55% MSC (Figure 3 and Table 3). Furthermore C 1098 (7.75%) showed equivalent protection to Wolsin F35 (1.0 and 4.0%) but gave significantly better protection against fungal degrade than all other commercial standards. C1099 and C 1098, at all concentrations tested, gave significantly better protection than the following standards: Hylite Extra (0.5 and 1.0%), NP- 1 (1.0, 2.0 and 4.0%) and NeXgen (1.0 and 2.0%).

CONCLUSIONS

After 15 weeks C1098 (1.9% w/v product) and C1099 (2. 125%w/v product), the lowest concentrations tested, both gave significantly better protection than the commercial standards: NP- 1 (4%w/v), Hylite Extra (l%w/v) and NeXgen (2%w/v).

C 1098 at 1.9% w/v, the lowest concentration tested, gave equivalent protection to NP- 1 at 8%w/v, Wolsin at 2%w/v and NeXgen at 4%w/v.

27 EXAMPLE 8 - LABORATORY DETERMINATION OF THE EFFICACY OF SENTRY™, SENTRY™ LX, SENTRY™ DMSO & SENTRY™ LX/DMSO FOR THE PROTECTION OF UNSEASONED WOOD AGAINST FUNGAL DEGRADE

The objective of this study was to determine the effect of changing the solvent system and isothiazolinone fungicide components of preferred compositions of the invention.

Materials and Methods

Wood

Discs were sawn from freshly cut radiata pine branches approximately 50 mm in diameter. Discs were frozen, gamma irradiated and then kept at -20°C until use.

Fungicides

The following compositions were

SENTRY™

SENTRY™ (LX) - new isothiazolinone

SENTRY™ (DSMO) - new solvent

SENTRY™ (LX + DSMO) - new isothiazolinone + new solvent.

Fungicide concentrations are shown in Table 10. A water control was included in the trial.

28 TABLE 10 - Fungicide formulations and treatment concentrations

Fungicide formulation Treatment concentration % w/w

SENTRY™ 0. 15, 0.31 , 0.62, 1.2, 2.5, 4.9 SENTRY™ LX 0. 15, 0.3 1, 0.62, 1.2, 2.5, 4.9 SENTRY™ DSMO 0. 15, 0.31 , 0.62, 1.2, 2.5, 4.9 SENTRY™ LX + DSMO

0. 15, 0.31, 0.62, 1.2, 2.5, 4.9

Fungi

Fungi were grown on 2% malt agar plates at 25°C in the dark for approximately two weeks (Table 1 1). An aqueous mould spore suspension was prepared by pouring 10 ml of sterile water onto an agar plate of each species, agitating the surface with a blunt sterile scalpel blade and adding the suspension from each to 500 ml of sterile water. Mycelial fragment / spore suspensions of sapstain and decay fungi were prepared separately by mixing the fungal colony plus agar with 500 ml of water in a Waring blender.

TABLE 1 1 - Fungi used in rapid laboratory disc trial on radiata pine

Moulds Sapstain Decay

Trichoderma viride O. piceae (27) Poria vaillantii Chaetomium globosum O. βoccosum (925) Phlebiopsis gigantea Cladosporium herbarum Diplodia pinea (4) Schizophyllum commune Penicillium sp. (x 2) Graphium (822) Leptographium ( 1790)

0. piliferum (4/97)

Experimental protocol

Discs were given a five second agitated dip in both the inoculum and then the antisapstain formulation, placed in a 'toast rack' and incubated at room temperature inside an aluminium foil covered plastic bin measuring 350 x 350 x 180 mm deep. The bins contained a one cm depth of water to maintain high humidity and prevent drying of the discs. Three replicate discs per antisapstain

29 formulation treatment were dipped separately in the mould, sapstain and decay spore suspensions (total of 9 discs).

Each bin contained three 'toast racks' each supporting three sets of three replicate treatment discs plus one control disc which had been dipped in one type of fungal inoculum.

Fungal growth on discs was assessed at one, two, and three weeks using the following rating scale corresponding to percent cover of fungal degrade shown:

Rating % cover of fungal degrade

0 zero

1 1 - 5 2 6 - 25

3 26 - 50

4 51 - 75

5 76 - 100

RESULTS

Table 12 shows the fungal growth ratings for each of three replicate disks dipped in the three spore suspensions for each fungicide treatment.

30 TABLE 12 - Fungal growth rating s by spore suspension and fungicide formulation

Fungal growth rating by spore suspension

Fungicide formulation Decay Sapstain Mould lwk 2wk 3wk lwk 2wk 3wk lwk 2wk 3wk

SENTRY™ (0.01%MBT) 5.0.0 0.4.0 5.5.5 4.3.4 5.5.5 5.5.5 5.5.4 5.5.5 5.5.5

SENTRY™ (0.02%MBT) 0.0.0 0.0.0 3.4.4 0. 1.0 2.3.4 4.4.5 5.5.5 5.5.5 5.5.5

SENTRY™ (0.04%MBT) 0.0.0 0.0. 1 1. 1.2 0.0.0 0. 1. 1 0.2.2 3.1.2 4.5.5 5.5.5

SENTRY™ (0.08%MBT) 0.0.0 3.0.0 5.3.0 0.0.0 0.0.0 0.0. 1 3.0.0 5.0. 1 5.3.5

SENTRY™ (0.16%MBT) 0.0.0 0.0.0 0.0.0 0.0.0 0.0.0 0.0.0 0. 1.0 0.2.0 2.4.1

SENTRY™ (0.32%MBT) 0.0.0 0.0.0 0.0.0 0.0.0 0.0.0 0.0.0 0.0.0 0.0. 1 0.0. 1

SENTRY™ LX (0.01%MBT) 0.0.0 0.0.0 5.5.5 3. 1.2 5.5.5 5.5.5 5.5.5 5.5.5 5.5.5

SENTRY™ LX (0.02%MBT) 0.0.0 0.0.0 2.4.4 0.0.0 3.3.2 5.5.5 5.5.4 5.5.5 5.5.5

SENTRY™ LX (0.04%MBT) 0.0.0 0.0.0 1.5.5 0.0.0 0.0.0 1. 1. 1 4.2.3 4.5.5 5.5.5

SENTRY™ LX (0.08%MBT) 0.0.0 0.0.0 0.0.0 0.0.0 0.0.0 0.0.0 2.2.2 5.4.4 5.5.5

SENTRY™ LX (0.16%MBT) 0.0.0 0.0.0 0.0.0 0.0.0 0.0.0 0.0.0 0.0.0 2.0.0 4.0.0

SENTRY™ LX (0.32%MBT) 0.0.0 0.0.0 0.0.0 0.0.0 0.0.0 0.0.0 0.0.0 0.0.0 0.0.0

SENTRY™ DSMO (0.01%MBT) 0.0.0 0.0.0 0.0.0 4.3.4 5.5.5 5.5.5 5.5.5 5.5.5 5.5.5

SENTRY™ DSMO (0.02%MBT) 0.0.0 0.0.0 0.0.0 0.0.0 4.5. 1 5.5. 1 5.5.5 5.5.5 5.5.5

SENTRY™ DSMO (0.04%MBT) 0.0.0 0.0.5 0.5.5 0.0.0 0.0.0 0.0.0 2.2.2 5:5 5.5.5

SENTRY™ DSMO (0.08%MBT) 0.0.0 0.0.0 0.0.0 0.0.0 0.0.0 0.0.0 0.0.0 2.0.2 5.0.5

SENTRY™ DSMO (0. 16%MBT) 0.0.0 0.0.0 0.0.0 0.0.0 0.0.0 0.0.0 0.0.0 0.0. 1 0.0.3

SENTRY™ DSMO (0.32%MBT) 0.0.0 0.0.0 0.0.0 0.0.0 0.0.0 0.0.0 0.0.0 0.0.0 0.0.0

SENTRY™ LX/DSMO (0.01%MBT) 0.0.0 0.0.0 1.0.0 2.2.2 4.4.4 5.5.5 5.5.5 5.5.5 5.5.5

SENTRY™ LX/DSMO (0.02%MBT) 0.0.0 0.0.0 0.0.0 0.0.0 2.2.0 4.3.2 5.5.5 5.5.5 5.5.5

SENTRY™ LX/DSMO (0.04%MBT) 0.0.0 0.0.0 0.0.0 0.0.0 0.0. 1 0.0.2 3.5.4 4.5.4 4.5.5

SENTRY™ LX/DSMO (0.08%MBT) 0.0.0 0.0.0 0.0.0 0.0.0 0.0.0 0.0.0 0.0.0 3.2.0 5.5.0

SENTRY™ LX/DSMO (0. 16%MBT) 0.0.0 0.0.0 0.0.0 0.0.0 0.0.0 0.0.0 0.0.0 0.0.0 0.0.0

SENTRY™ LX/DSMO (0.32%MBT) 0.0.0 0.0.0 0.0.0 0.0.0 0.0.0 0.0.0 0.0.0 0.0.0 0.0.0

Control 5.5.5 5.5.5 5.5.5 5.5.5 5.5.5 5.5.5 5.5.5 5.5.5 5.5.5

In summary, all of SENTRY™ LX, SENTRY™ DMSO, & SENTRY™ LX/DMSO gave further improved control of decay, sapstain and mould compared to SENTRY™.

31 SENTRY™ LX/DMSO gave better control of decay, sapstain and mould compared to SENTRY™, suggesting that use of DSMO as a replacement solvent for NMP and replacement of Kathon LX as a replacement fungicide for Kathon 893 F, improved performance.

The processes and compositions illustrated in the Examples are merely illustrative of the invention. For example other fungicides, surfactants and hydrophobic barrier substances may be used and the concentrations may be varied. Variations and modifications as will be obvious to those skilled in the art are intended to be incorporated within the scope hereof.

32

Claims

1. A method of inhibiting sapstain in wet wood comprising applying to the surface of the wood a composition comprising a solution or microemulsion (as herein defined) comprising at least one mobile fungicide which will diffuse into the surface of the wood.

2. A method according to claim 1 wherein said fungicide is methylene bisthiocyanate .

3. A method according to either one of claims 1 and 2 wherein the composition is an oil in water microemulsion.

4. A method according to either one of claims 1 and 2 wherein the composition comprises an organic solvent.

5. A method according to claim 4 wherein the solvent comprises dimethyl sulphoxide, N-methyl pyrrolidone, or dimethyl formamide.

6. A method according to claim either one of claims 1 and 2 wherein the_ solvent comprises kerosene, benzene, chloroform, toluene, ether, carbon disulphide, acetone, paraffin, diesel, white spirit, soya oil, linseed oil, or fish oil.

7. A method according to either one of claims 1 to 6 wherein the composition comprises a surfactant.

8. A method according to claim 7 wherein the composition comprises a quaternary ammonium salt as a surfactant.

9. A method according to claim 7 wherein the composition comprises benzalkonium chloride or didecyldimethyl ammonium chloride as a surfactant.

10. A method according to claim 7 wherein the composition comprises a combination of didecyldimethyl ammonium chloride and nonyl phenol ethoxylate as a surfactant.

33

1 1. A method according to any one of claims 1 to 10 wherein the composition also comprises a fungicide which will remain on the surface of the wood in addition to the mobile fungicide which will penetrate into the wood.

12. A method according to claim 11 wherein the further fungicide is selected from substituted benzimidazoles including carbendazim (methyl benzimidazol-2- ylcarbamate) and chemical precursors of benzimidazoles including benomyl (methyl l-(butycarbonyl) benzimidazol-2ylcarbamate or copper-8- hydroxyquinolinolate; triazoles including hexaconazole ((RS)-2-(2,4- dichlorophenyl)- l-(lH-l,2,4-triazole-l-yl) hexan-2-ol); and quaternary ammonium compounds including didecyldimethyl ammonium chloride, chlorothalonil (tetrachloroisophthalonitrile) , fenpropimorph and isothiazolinones.

13. A method according to any one of claims 1 to 12 wherein the composition also comprises a hydrophobic substance which will act as a water barrier on the surface of the wood.

14. A method according to claim 13 wherein said water barrier substance is selected from lanolin, petrolatum, paraffin oils, fish oils, animal oils, waxes, silicones, fatty acid eaters, bitumen, vegetable fats and oils and wool grease. - ΓÇö

15. A method according to any one of claims 1 to 14 wherein the mobile fungicide penetrates 10 - 20mm into the surface of the wood.

16. A method according to any one of claims 1 to 15 wherein the mobile fungicide penetrates into the wood at a rate greater than the rate of penetration by sapstain fungi.

17. A method according to any one of claims 1 to 16 wherein the composition is applied to logs within 10 days of felling.

18. A method according to any one of claims 1 to 16 wherein the composition is applied to logs within 5 days of felling.

34

19. A method according to any one of claims 1 to 16 wherein the composition is applied to logs within 2 days of felling.

20. A method according to any one of claims 4 to 19 wherein the composition is applied by dipping or spraying.

21. A method according to any one of claims 1 to 20 wherein the composition is applied to wood at a rate in the range 200-500 ml of antisapstain treatment solution per m² of wood surface area.

22. A method according to any one of claims 1 to 20 wherein the strength of the composition is adjusted to achieve a surface retention of the mobile fungicide of 10-300 micrograms per cm².

23. An antisapstain composition suitable for application to wood, which is a microemulsion or surfactant assisted solution and comprises:

(a) 0.05- 1% of methylene bisthiocyanate,

(b) 0. 1- 10% of a solvent,

(c) 0.1 to 15% of a surfactant, and

(d) up to 99.75% water.

24. An antisapstain composition according to claim 23 wherein said solvent comprises dimethyl sulphoxide, N-methyl pyrrolidone, or dimethyl formamide.

25. An antisapstain composition according to claim 23 or claim 24 wherein said surfactant is a quartenary ammonium salt.

26. An antisapstain composition according to any one of claims 23 to 25 also including 1-40% of a water barrier hydrophobic substance as a water barrier.

27. An antisapstain concentrate composition comprising:

(a) 10-40% (w/w) of a hydrophobic substance as a water barrier,

35 (b) 0.5- 15% of a surfactant,

(c) 1- 10% of an organic solvent,

(d) 0.2-5% methylene bisthiocyanate, and

(e) 30-88.3% water.

28. An antisapstain composition containing 1- 10% methylene bisthiocyanate dissolved in a vehicle containing 10-90% dimethyl sulphoxide, N-methyl pyrrolidone, or dimethyl formamide, and 10-90% of a quaternary ammonium salt as a surfactant.

29. An antisapstain concentrate composition comprising a mobile fungicide which will penetrate into the surface of the wood, about 10% to 40% of a water barrier substance, about 60% to 90% of either an organic solvent, or water or a water based formulation.

36