WO1989005574A1

WO1989005574A1 - Method for the cultivation of mushrooms

Info

Publication number: WO1989005574A1
Application number: PCT/AU1988/000477
Authority: WO
Inventors: Thuc Van Le; William Edward Jones
Original assignee: 3M Australia Pty. Ltd.
Priority date: 1987-12-15
Filing date: 1988-12-13
Publication date: 1989-06-29
Also published as: AU2822289A

Abstract

A method is provided for the cultivation of mushrooms and other edible fungi. The method involves seeding a compost layer with a mushroom inoculum and covering discrete areas or patches of the compost layer with a casing material. It is preferred that the areas of the compost layer not covered with the casing material are covered with a non-casing material. The method results in a substantial reduction in the amount of casing material used with no substantial decrease in the quantity of mushrooms produced. The method also enables the mushrooms to be cultivated in an orderly arrangement which assists in the production of a higher quality crop.

Description

METHOD FOR THE OTTIVZVITON OF MDSHROCMS Field of the Invention

The present invention relates to the cultivation of edible fungi and in particular to the cultivation of mushrooms. Background of the Invention

Artificial cultivation of mushrooms is carried out by seeding compost, which has generally been pasteurized, with a fungal inoculum. Once the compost has been colonized by the mushroom mycelium, the compost is covered with a casing material. This casing material typically consists of peat or a peat-like material. Embryo mushrooms appear after fifteen to eighteen days and are ready to be picked seven days later.

As used herein the term "casing material" is defined as a material which supports mushroom fruiting, and the term "non-casing material" is defined as a material which will not support mushroom fruiting.

The provision of a casing material is essential for mushroom fruiting to occur. As stated above, this material generally consists of peat. In practice, lime is added to the peat to raise the pH to 7 to 8, and the peat watered prior to the covering of the compost layer.

It is essential that the casing material be watered to maintain a sufficiently moist atmosphere for the fungus to grow through the casing layer. This is generally done by spraying the mushroom beds with sterilized water. However, water droplets which remain on the mushroom caps tend to cause "blotch" disease. This has the effect of lowering the market value of the crop. Two methods for overcoming this problem of the tendency to cause blotch disease by watering, have been put forward in the prior art. U.S. Patent Nos. 4,337,594 and 4,443,969 disclose the use of a casing material comprising peat and a foam forming, hydrophilic, synthetic, organic prepolymer resin. It is claimed that the use of this casing material significantly decreases the frequency at which watering must be carried out.

In GB 2,148,264 another solution to this problem is proposed. This involves the provision of a water absorbing sheet between the compost layer and the casing material. It is claimed that the provision of this sheet also leads to a decrease in the frequency of watering.

In addition to the problem of watering, a number of other problems are also presently encountered in the cultivation of mushrooms. The first of these is that peat only has a limited life as a casing material. This limited life is due to the build-up of salt in the peat during cultivation. Once the salt concentration reaches 2,000 to 10,000ppm the peat must be rejected as fruiting will not occur in peat containing high salt concentrations. At present, attempts to recycle peat economically have failed. Another difficulty is that peat is a natural material and may carry bacteria harmful to the mushroom fruit. Another difficulty encountered in the cultivation of mushrooms is that at present there is no feasible method for the mechanical harvesting of mushrooms suitable for the fresh market. At present, mushrooms harvested mechanically are only suitable for canning or soup production. One of the reasons that mechanical harvesting has not been developed is the fact that mushrooms grow randomly, i.e., mushroom beds typically consist of areas of high density mushroom population and other areas with no or very few mushrooms. It is believed that the production of a more ordered growing pattern should assist in the development of a mechanical mushroom harvester.

In addition when mushrooms grow in a crowded condition the quality of mushroom produced is lowered. The present invention seeks to provide an improved method of cultivating mushrooms in which the amount of peat used is reduced, and in which the mushrooms are grown in an ordered arrangement.

Summary of the Invention

In a first aspect the present invention consists in a method of cultivating mushrooms comprising seeding a compost layer with a mushroom inoculum and covering discrete areas of a surface of the compost layer with a casing material such as to provide alternating areas of casing material and uncovered compost. The area of the surface of the compost layer covered with the casing material is preferably less than about 50%, more preferably less than about 30%, most preferably less than about 20% and is preferred to be in the range of about 5% to about 18%. Preferably the mushroom inoculum is allowed to colonise the compost layer prior to covering discrete areas of the surface of the compost layer with the casing material.

In a preferred embodiment of the present invention the areas of the compost layer not covered with a casing material are covered with a non-casing material. Preferred non-casing materials are as follows:—

1. Non-woven fabric made of polyester, nylon, rayon, wool or other suitable fibres or a mixture of such fibres.

2. Woven fibres, such as waste carpets, hessian, cotton waste, rags, woolens etc.

3. Non-woven fibrous materials, such as coconut wool, felt, waste-paper and rope, rock or mineral wools, fibreglass, asbestos wool, bagass, geotextiles.

4. Absorbant solids such as cork, gypsum plasterboard, canite and stramit style boards, asbestos-cement sheet, compressed wood shavings, expanded vermiculite, light weight concrete, ceramics (bricks), charcoal, graphite, pumice, bark, leather. gels , sands .

5. Polymeric materials, such as foamed plastics, e.g. ethylene vinyl acetate, polyurethane, polystyrene, polyolefins, polycarbonates, phenylene oxide, acryionitrile butadiene styrene, nylon, with or without filler materials.

6. Corrugated or rib profiled rigid sheeting material of metal, plastics, glass reinforced plastics or the like which are slotted or holed in the peaks/valleys. At present it is preferred that the non-casing material is a self-supporting, coherent material which absorbs 50 to 800 grams E O/IOO grams of material. In this regard it is particularly preferred that the non-casing material consists of a non-woven fabric which may be coated with a hydrophilic resin to raise the water absorbance of the material to 50 to 800 grams H 0/100 grams of material. The hydrophilic resin may be an acrylic latex or acryionitrile-butadiene copolymer latex or other suitable resin. Where corrugated or rib-profiled sheeting material is used, this material may be laid over the compost layer and - the valleys filled with casing material.

In a further preferred embodiment of the present invention a slow release selective biocide is incorporated into the non-casing material. The selective biocide may be, for example, a nematocide such as the product sold under the name "Ne acur", a fungicide such as the products sold under the names "Benlate" and "Tecto 90", or a pesticide such as the product sold under the name "Birlane". However, any other known biocide which does not effect mushrooms could be used. These selective biocides would generally be rendered slow releasing by combination with an agent such as cyclodextrin using known techniques. In a further preferred embodiment of the present invention an indicator sensitive to moisture is incorporated into the non-casing material. Any of wide range of compounds which change colour in response to change in moisture, such as cobalt sulphate, may be used. The concentration of the indicator in the non-casing would preferably be adjusted such that a colour change was observed when the moisture level was outside a desired range.

In yet a further preferred embodiment the non-casing material is provided with a series of tubes to enable easy watering and air circulation through the casing layer.

In a second aspect the present invention consists in a mat for use as a casing layer in the cultivation of mushrooms, the mat comprising a self-supporting, coherent, non-casing material which absorbs about 50 to about 800 g. H₂O/100 g. of the material, and discrete areas of casing material extending through the mat, the discrete areas of casing material being surrounded by the non-casing material. In a third aspect the present invention consists in a kit for cultivating mushrooms comprising:-

1. Compost seeded with a mushroom inoculum;

2. A quantity of casing material; and

3. A mat comprising a self-supporting, coherent, non-casing material which absorbs about 50 to about 800 g. H₂O/l00 g. of the material, the mat being provided.with slots or holes extending through the mat.

In a preferred embodiment of the present invention the self-supporting, coherent, non-casing material consists of a non-woven fabric coated with a hydrophilic resin.

In a further preferred embodiment of the present invention the discrete areas of casing material are arranged as rows or pockets appearing at regular intervals in the non-casing material.

It is preferred that the casing material is peat, however, other casing materials well known in the art may be used. The present invention is particularly suitable for the cultivation of Agaricus bisporus. However, this method is suitable for the cultivation of all fungi which require the provision of casing layers for fruiting.

Where the areas of the compost layer not covered with casing material are to be covered with a self-supporting, coherent non-casing material, it is preferred that the non-casing material is in the form of a sheet which includes discrete areas of casing material extending through the sheet. The sheet is then laid over the compost layer as a casing layer. It is preferred that the discrete areas of casing material are arranged as rows or pockets at regular intervals in the non-casing material. Brief Description of the Drawings

Fig. 1 shows the cultivation system disclosed in GB 2,148,264.

Fig. 2 shows a plan view of the casing layer used in the present invention;

Fig. 3 shows a cross-sectional view AA of Fig. 2; Fig. 4 shows a cross-sectional view BB of Fig. 2; Fig» 5 shows the casing layer of the present invention including water/air reticulation system; Fig. 6 shows the casing layer of the present invention with an alternate arrangement of casing material in the non-casing material; and Figs.-7^~to 8 show graphically the results obtained in the larger scale trials described in Example 9. Detailed Description of Preferred Embodiments

Fig. 1 shows the prior art mushroom cultivation system disclosed in GB 2,148,264. This can be seen to consist of a compost layer 13, a casing layer 16 and a water absorbent layer 17 positioned between the compost layer 13 and casing layer 16.

Fig. 2 shows the casing layer 10 of the present invention comprising the self-supporting, coherent, non-casing material 11 including rows of casing material 12. Fig. 3 shows the compost layer 13 covered by the casing layer 10. As is shown the mushrooms 14 occur only in the discrete areas of the casing layer 10 which contain the casing material 12, and which are bordered by the non-casing material 11. This results in the mushrooms occurring only in predefined rows.

Fig. 5 shows an embodiment of the present invention where tubes 15, attached to the non-casing material 11, are included to provide a reticulation system for water and/or air.

Fig. 6 shows in plain view an alternate arrangement of the casing material 12 within the non-casing material 11. As shown in this arrangement the casing material is provided in discrete pockets. The present invention will now be described with reference to the following examples. Example 1

A compost was prepared from chicken manure and straw and was inoculated with mushroom spawn Aqaricus bisporus (Horst U3). The compost was kept at 100% humidity and 25°C for 10 days.

The colonised compost was placed into plastic tubs and cased with limed peat (pH 7-8) to a depth of 20-40mm. The tubs were sealed with plastic film and maintained at 25°C and high humidity for 10 days until the casing was fully colonised. The plastic film was removed and the tubs were cooled and maintained at 17-18 C with daily watering. The mushrooms were picked when they reached the button stage. Three crops were obtained, with the mushrooms fruiting at random positions in the bed. Water Absorption Yield Quality of Mushrooms of Casing Layer javerage for duplicate tubs) 1000g/l00g solids 17kg/m Low Example 2

A compost was prepared from chicken manure and straw and was inoculated with mushroom spawn Aqaricus bisporus (Horst U3). The compost was kept at 100% humidity and 25°C for 10 days. The colonised compost was placed into plastic tubs and cased to a depth of 20mm with a non-woven web of 50% 6 Dn polyester and 50% 13.5 Dn nylon, with rectangular slots 10mm wide and 30mm apart (centre to centre) . The slots were filled with limed peat (pH 7-8).. The non-woven web had been treated with a Rohm & Haas acrylic resin.

The remainder of the test was then carried out as in Example 1.

The mushrooms fruited only in the peat filled areas. Despite the reduced area available for fruiting, the mushroom yield was the same as for the control.

Water Absorption Yield Quality of Mushrooms of Casing Layer (average for duplicate tubs) 650g/l00g solids 17kg/m² High Example 3

A compost was prepared from chicken manure and straw and was inoculated with mushroom spawn Aqaricus bisporus (Horst U3). The compost was kept at 100% humidity and 25°C for 10 days. The colonised compost was placed in plastic tubs and cased to a depth of 20mm with a non-woven web of 50% 6 Dn polyester and 50% 13.5 Dn nylon, with rectangular slots 10mm wide and 30mm apart (centre to centre) . The non-woven web had been treated with an acrylonitrile- butadiene latex resin from Polysar. The slots were filled with limed peat (pH 7-8) . The remainder of the test was then carried out as in Example 1.

Water Absorption Yield Quality of Mushrooms of Casing Layer (average for duplicate tubs) 470g/l00g solids 17kg/m² High Example 4

A compost was prepared from chicken manure and straw and was inoculated with mushroom spawn Aqaricus bisporus (Horst TJ3). The compost was kept at 100% humidity and 25°C for 10 days. The colonised compost was placed into plastic tubs and cased to a depth of 20-40mm with a non-woven web of 15 Dn Polyester with circular holes 10mm in diameter and 30mm between centres. The web had been treated with an acrylonitrile-butadiene latex resin from Polysar. The pockets were filled with limed peat (pH 7-8).

The remainder of the test was then carried out as in Example 1.

Water Absorption Yield Quality of Mushrooms of Casing Layer (average for duplicate tubs) 300g/l00g solids 17kg/m² High Example 5

A compost was prepared from chicken manure and straw and was inoculated with mushroom spawn Aqaricus bisporus (Horst U3). The compost was kept at 100% humidity and 25°C for 10 days. The colonised compost was covered with a moisture laden web of 3 Dn Super Absorbent Viscose (20%), 15 Dn melting fibre (20%) and 200 Dn Polyester (60%). Half the pad was then covered with the limed peat (pH7-8) . The bed was maintained at 25 C and high humidity for 7 days, and then the temperature was lowered to 20 C. Over the next 21 days, there was no fruit development in the part of the bed not covered with peat, and only very light development of fruit in the part covered with peat. Water Absorption Yield Yield of Casing Layer (without peat) (with peat lOOOg/lOOg solids 0 2kg/m₂

This arrangement is similar to that shown in Fig. 1, however, as the yield of mushrooms was very low it would appear that material between the compost and casing layers interfered with the development of the mushrooms. Example 6

The raw compost of Example 1 was heated to 90 C at 30% solids in water for 1 hour. The solids were filtered off. The resulting solution was cooled to room temperature and limed to pH 7-8. Spawn inoculated onto grain was placed on a 75mm pad of 15 Dn polyester which had not been treated with a hydrophilic resin, and it was soaked with the extracted solution. The pad was kept at 25°C for 7 days, standing in a reservoir of the nutrient solution. The pad was not colonised and so the test was abandoned. Example 7

The test was carried out as in Example 6 except the pad was composed of an horticultural rockwool (CSR Bradford) . No colonisation was observed and so the test was abandoned.

Examples 6 and 7 both show that non-casing material is clearly unable to support mushroom fruiting. Example 8 Further small scale trials were conducted using the same protocol as in Examples 2 to 5 using a range of different non-casing materials. These tests were

2 conducted using beds 0.03m in area with the casing material arranged in either rows or holes. The results obtained in these trials are set out in Table 1.

For comparison, control trays of the same size were completely covered with peat and these trays yielded

17 kilograms mushrooms/m . However, the mushrooms obtained from the control trays were of low quality. Example 9

Following the preceding small scale trials large scale trials were conducted in wooden trays of the type used commercially by many mushroom producers. These trays had inside dimensions of 1125 mm. x 1730 mm. x 200 mm. deep.

A compost was prepared from chicken manure and straw and was inoculated with mushroom spawn Aqaricus bisporus (A-5.1), and placed in the trays. The compost was kept at close to 100% humidity and 25°C for ten days until the bed was fully colonised.

Two of the trays were then cased with a limed peat casing material which had colonised compost mixed with it to serve as controls. Ten other trays were covered with non-casing material which had either holes or rows cut into them. The holes were of 10 mm. diameter and were spaced at 40 mm. intervals centre to centre. The slits were 10 mm. wide and were spaced at 40 mm. apart centre to centre. The holes or slits were then filled with a limed peat casing material without colonised compost added. Watering of the beds was then carried out to maintain a high moisture content in the peat layers on the beds. TABLE 1

Non-Casing Water Absprbance Arrangement of Yield Mushroom Material (g/lOOg Material) Casing Material (Kg/in²) Quality

50% 6 Dn Polyester 220 Rows 17 High + 50% 13.5 Dn Nylon + Rohm & Hass Acrylic hydrophilic resin (E751) Holes High

13.5 Dn Nylon 230 Rows + E751 Holes

6 Dn Polyester 206 Rows + E751 Holes

15 Dn Polyester 404 Rows + E751 Holes

50% 6 Dn Polyester 272 Rows 16 High + 50% 13.5 Dn Nylon + Rohm & Hass Acrylic Resin (HA16) Holes High

13.5 Dn Nylon 179 Rows 21 High + HA 16 Holes 14 High

6 Dn Polyester 275 Rows 14 High + HA 16 Holes 3 High

TABLE 1 (continued)

Non-Casing Water Absorbance Mushroom Material (g/lOOg Material) Quality

15 Dn Polyester 269 High + HA 16 High

25% 4 Dn heat fusible polyester 126 High 25% 6 Dn polyester + 50% 13-5 Dn Nylon High

15 Dn Polyester/ 187 High polyurethane coating High to

Beaded 150 High Polystyrene foam

High I

- 13 -

When the peat casing materials were fully colonised, the air temperature was lowered to 17 to 18 C to cause "pins" to develop. Fresh air circulation was adjusted to maintain the carbon dioxide level at about 1000 ppm of air. When the mushrooms matured, they were picked and graded according to quality. The results are shown in Table 2 and Figures 7 to 9.

The yield from the control trays was slightly inflated due to the fact that the mushrooms in the control trays were at a more advanced stage prior to commencement of the trial. However, as can be seen from the results in Tables 1 and 2, even given the slightly inflated control values, use of a number of the non-casing materials provided a mushroom yield comparable to that of the controls. The mushrooms obtained using the non-casing material were of a much superior quality to that obtained from the control trays due to the mushroom not being overcrowded. Also, while the peat had to be thrown out after one cycle, the non-casing material could be recycled by washing and sterilising.

In addition, the use of the non-casing material resulted in a substantial reduction in the amount of peat used. While it is readily envisaged how the non-casing material results in decrease in the area of the compost layer covered with peat, it was found that the depth of the casing layer could also be substantially reduced. In the tests, the results of which are shown in Table 2, when a non-casing material with the casing material arranged in rows was used, an approximately 98% reduction in the amount of peat used was achieved, whilst the use of the casing material arranged in holes resulted in approximately a 99% decrease in the amount of peat used.

A further advantage gained by the use of the non-casing material with the casing material arranged in an ordered pattern is that there is no overcrowding of the TABLE 2

Non-Casing Water Absorbance

Material (g/lOOg Material)

Quality

50% 6 Dn Polyester 220 + 50% 13.5 Dn Nylon + E751

50% 6 Dn Polyester 272 + 50% 13.5 Dn Nylon

+ HA 16 I

6 Dn Polyester 206

+ E751

15 Dn Polyester 404 Rows 11 High + E751 Holes

Control 15 Low

- 15 -

mushroom crop. This enables the grower to pick mushrooms when they reach a particularly desired size and shape. This results in the greatest market value being obtained for the crop. This is not possible when the compost layer is completely covered with the casing material as the mushrooms are typically crowded. In such a situation it is not generally possible to pick one mushroom without damaging the neighboring mushrooms. Therefore, while it is generally possible with the prior art techniques to achieve a crop in which 25% of the mushrooms are of the preferred size, the method of the present invention enables a crop to be obtained in which approximately 90% of the crop are the desired shape and size.

It can be seen that yield of mushrooms grown following the novel cultivation system was comparable to that using peat in conventional systems although a much smaller amount of peat was used (up to 99% less). The mushrooms produced by the novel systems were superior in quality because their controlled distribution over the bed prevented crowding. They were also much easier to harvest for that reason.

The peat component of the casing layer, as well as the peat layer in the control test had to be discarded after the tests because of the salt build-up, whereas the synthetic fabric was available for reuse.

Claims

- 16 - CLAIMS : -

1. A method for the cultivation of mushrooms comprising seeding a compost layer with a mushroom inoculum and covering discrete areas of the surface of the compost layer with a casing material such as to provide alternating areas of casing material and of uncovered compost.

2. A method as claimed in claim 1 in which less than about 50% of the surface of the compost layer is covered with casing material.

3. A method as claimed in claim 2 in which less than about 30% of the surface of the compost layer is covered with casing material.

4. A method as claimed in claim 3 in which less than about 20% of the surface of the compost layer is covered with casing material.

5. A method as claimed in claim 4 in which about 5% to about 18% of the surface of the compost layer is covered with casing material.

6. A method is claimed in claim 1 in which the mushroom inoculum is allowed to colonise the compost layer prior to covering discrete areas of the surface of the compost layer with the casing material.

7. A method as claimed in claim 1 in which the areas of the surface of the compost layer not covered with casing material are covered with a non-casing material.

8. A method as claimed in claim 7 in which the non-casing material is a self-supporting, coherent material which absorbs 50 to 800 grams H₂θ/l00 grams of material.

9. A method as claimed in claim 8 in which the non-casing material is a non-woven fabric coated with a hydrophilic resin.

10. A method as claimed in claim 9 in which the non-woven fabric is made from polyester fibres, nylon fibres, rayon - 17 -

fibres, wool fibres or a combination thereof.

11. A method as claimed in claim 9 in which the hydrophilic resin is an acrylic latex or acrylonitrile-butadiene copolymer latex.

12. A method as claimed in claim 7 in which the non-casing material includes a slow release selective biocide.

13. A method as claimed in claim 7 in which the non-casing material includes a moisture level indicator.

14. A method as claimed in claim 1 in which the casing material is provided on the compost layer in an ordered array of discrete pockets or rows of casing material.

15. A mat for use as a casing layer in the cultivation of mushrooms, the mat comprising a self-supporting, coherent, non-casing material which absorbs about 50 to about 800 g. H₂O/l00 g. of the material, and discrete areas of casing material extending through the mat, the discrete areas of casing material being surrounded by the non-casing material.

16. A mat as claimed in claim 15 in which the self-supporting, coherent, non-casing material consists of a non-woven fabric coated with a hydrophilic resin.

17. A mat as claimed in claim 15 in which the discrete areas of casing material are arranged as rows or pockets appearing at regular intervals in the non-casing material.

18. A kit for cultivating mushrooms comprising:-

1. Compost seeded with a mushroom inoculum;

2. A quantity of casing material; and

3. A mat comprising of a self-supporting, coherent, non-casing material which absorbs 50 to 800 g. H₂O/100 g. of the material, the mat being provided with holes or slits which extend through the mat.

19. A kit as claimed in claim 18 in which the self-supporting, coherent, non-casing material consists of a non-woven fabric coated with a hydrophilic resin -