SHORT COMMUNICATION

Effect of spent mushroom compost tea on mycelial growthand yield of button mushroom (Agaricus bisporus)

Francisco J. Gea • Mila Santos • Fernando Dianez •

Julio C. Tello • Marıa J. Navarro

Received: 24 February 2012 / Accepted: 8 May 2012 / Published online: 23 May 2012

� Springer Science+Business Media B.V. 2012

Abstract Preliminary studies suggested that the use of

compost tea made from spent mushroom substrate (SMS)

may be regarded as a potential method for biologically

controlling dry bubble disease in button mushroom. The

aim of this study was to assess the effect of SMS compost

tea on the host, the button mushroom, to ascertain whether

the addition of these water extracts has a toxic effect on

Agaricus bisporus mycelium growth and on mushroom

yield. In vitro experiments showed that the addition of

SMS compost tea to the culture medium inoculated with a

mushroom spawn grain did not have an inhibitory effect on

A. bisporus mycelial growth. The effect of compost teas on

the quantitative production parameters of A. bisporus

(yield, unitary weight, biological efficiency and earliness)

was tested in a cropping trial, applying the compost teas to

the casing in three different drench applications. Quanti-

tative production parameters were not significantly affected

by the compost tea treatments although there was a slight

delay of 0.8–1.4 days in the harvest time of the first flush.

These results suggest that compost teas have no fungitoxic

effect on A. bisporus so that they can be considered a

suitable biocontrol substance for the control of dry bubble

disease.

Keywords Biological control � Mushroom cultivation �Spent mushroom substrate � Water extract

Introduction

Spent mushroom substrate (SMS) is the by-product of

Agaricus bisporus (Lange) Imbach cultivation after the

material has been removed from production (Yohalem et al.

1996). SMS consists of mushroom compost (wheat straw,

poultry manure and other ingredients composted and pas-

teurized in tunnels and then inoculated with commercial

mushroom spawn) and casing materials (peat moss and

ground limestone). The mushroom industry in the European

Union produces more than 3.5 9 106 tonnes of SMS annu-

ally, while Spain alone produces more than 5 9 105 tonnes.

Most of the SMSs collected in Castilla-La Mancha (Spain)

are based on casings consisting of mineral soils to which

peat is normally added in a low proportion (Pardo-Gimenez

and Pardo-Gonzalez 2008), although another type of SMS,

based on casings containing peat, is sometimes collected.

Several studies in recent years have indicated that plant

diseases can be suppressed by applying a variety of water-

based compost preparations. Among such preparations,

non-aerated compost teas (NCT) and aerated compost teas

(ACT) (Scheuerell and Mahaffee 2002), fermented aque-

ous extracts of composted materials, have been proposed as

potential alternatives to the use of chemical products for

the control of foliar pathogens (Weltzien 1991; McQuilken

et al. 1994; Yohalem et al. 1994; Zhang et al. 1998;

Siddiqui et al. 2009). One of the potential parameters that

affects the efficacy of compost teas is the target patho-

system (pathogen and host plant) (Scheuerell and Mahaffee

2006). In the specific case of mushroom diseases, it must

be borne in mind that both the host and the pathogen are

fungi, so that it is necessary to test the effects of these

biocontrol methods both on the host and on the pathogen.

Several preliminary studies have suggested that compost

teas made from SMS might be effective in the biological

F. J. Gea (&) � M. J. Navarro

Centro de Investigacion, Experimentacion y Servicios del

Champinon (CIES), Quintanar del Rey, 16220 Cuenca, Spain

e-mail: fjgea.cies@dipucuenca.es

M. Santos � F. Dianez � J. C. Tello

Departamento de Produccion Vegetal, Escuela Politecnica

Superior, Universidad de Almerıa, 04120 Almerıa, Spain

123

World J Microbiol Biotechnol (2012) 28:2765–2769

DOI 10.1007/s11274-012-1081-7

control of mushroom diseases. Favourable results for the

control of Lecanicillium fungicola (Preuss) Zare & W.

Gams, causal agent of dry bubble disease of the cultivated

mushroom (A. bisporus) (Fletcher and Gaze 2008), have

been obtained in vitro with grape marc aerated compost

teas (Dianez et al. 2006) and compost teas elaborated from

SMS mixed with amended light peat (Gea et al. 2009). In a

recent study, Gea et al. (2011) managed to control dry

bubble using compost teas from SMS in a mushroom

growth cycle artificially infected with L. fungicola. How-

ever, to date, there is no information available concerning

the effect of using SMS compost tea on the mycelium of

A. bisporus or on mushroom production.

The objective of this research was to assess the effect of

compost tea made from SMS on the host, in this case the

button mushroom, to ascertain whether the addition of

these water extracts has a toxic effect on A. bisporus

mycelium growth and on mushroom yield.

Materials and methods

In vitro effect of compost teas on A. bisporus mycelium

growth

The three SMS used in the in vitro experiments were

obtained from different mushroom growing crops: two

SMSs in which mineral soil ? Sphagnum peat 4:1 (v/v)

was used as casing layer, denominated ‘mineral soils I and

II’, and one SMS with a casing based on Topterra�, type

peat, denominated ‘peat’. These SMS were treated with

steam at 70 �C for 12 h to eliminate pathogenic organisms,

and were then re-composted for 57 days. The compost teas

were prepared by mixing SMS and water in a 1:4 (w/v)

ratio. The mixtures were incubated for 1 day at 25 �C with

(aerated compost tea, ACT) and without (non-aerated

compost tea, NCT) stirring (Scheuerell and Mahaffee

2002). Following the fermentation period, each mixture

was filtered through two layers of muslin. All compost teas

were used within 24 h of being prepared.

To determine the effect of compost teas on the mycelial

growth of A. bisporus, the NCT or ACT was incorporated

into agar-compost medium cooled to 45 �C. Agar-compost

was prepared as basic medium, containing 50 g of dried

mushroom compost and 20 g of agar per litre of water. The

compost teas were then mixed with the cooled agar-com-

post in two proportions, 10 and 20 % v/v, and immediately

poured into the Petri dishes. A mushroom spawn grain

covered with actively growing mycelium of two commer-

cial smooth white hybrid mushroom strains (Fungisem

H-25, Micelios Fungisem S.A., Autol, La Rioja, Spain; and

Gurelan 45, Gurelan S. Coop., Huarte, Pamplona, Spain)

were individually inoculated on the media and incubated

7 days in the dark at 25 �C. Two controls (A10 and A20)

were also prepared with agar-compost and sterile water (10

and 20 %, v/v) and two positive controls (P10 and P20)

with the same agar and the fungicide prochloraz 46 %

(Sporgon�, AgrEvo, Valencia, Spain), giving a final con-

centration of 10 and 20 ppm of active ingredient (a.i.).

There were six replicates per combination of A. bisporus

strain and treatment. Two perpendicular colony diameters

were measured on each dish after incubation period.

Effect of SMS compost teas on A. bisporus yield

To determine the effect of compost teas on A. bisporus yield

a cropping trial was set up in a mushroom growing room.

The compost teas (ACT and NCT) used were made from

SMS (mineral soil I) using the method described above.

Agaricus bisporus was cultivated in experimental trays

(16 l in volume, 870 cm2 in area) filled with 6 kg of

commercial mushroom compost spawned at 1 % (Gurelan

45 strain). On day 0 of the cropping cycle, trays of spawn-

run compost were cased with a 30 mm layer of a casing

soil (2.6 l tray-1) made with mineral soil ? Sphagnum

peat 4:1 (v/v). 7 Days after casing, the surface of the casing

soil was ruffled deeply. 2 Days later, the growing room was

ventilated to stimulate the production of mushrooms.

A temperature of 17.5 �C and RH of 85–90 % were

maintained throughout cropping. Irrigation of the culture

started when sporophores had reached the pea size stage.

The compost tea was applied to the casing mixture at

100 ml per tray. Three different treatments were made with

each compost tea (ACT and NCT): 1R (one drench appli-

cation on the same day as the casing material was applied

on day 0); 2R (two drench applications, applied on days 0

and 2) and 3R (three drench applications on days 0, 2 and

6). Two controls were used: one pure control (C), in which

drench applications were carried out with 100 ml tap water

per tray; and another consisting of the fungicide Sporgon�

(prochloraz 46 %) at 0.05 % (w/v) in the third irrigation

(P), at a rate of 100 ml per tray.

The mushrooms were harvested daily in three flushes.

The numbers and the total weight of the fruit bodies were

recorded for each treatment. The effect of the compost tea

and fungicide treatments was evaluated during the three

flushes by comparing the yield with that obtained in the

pure control. An estimation of the size of the mushrooms,

expressed as unitary weight in grams, was calculated from

the yield and the number of harvested mushrooms (Pardo-

Gimenez and Pardo-Gonzalez 2008). The effect of treat-

ments on mushroom productivity was also evaluated from

the biological efficiency of the crop, calculated as the ratio

of the fresh weight of total yield of harvested mushrooms

to the weight of dry substrate at spawning and expressing

the fraction as kg 100 kg-1 compost. In addition, the

2766 World J Microbiol Biotechnol (2012) 28:2765–2769

123

earliness or days to first harvest of each treatment was

expressed as the number of days between casing and har-

vesting of the first flush. The experiment on the effect of

SMS compost teas on A. bisporus yield was a randomized

complete block design with five replicates.

Statistical analysis

Data for radial mycelial growth, mushroom yield and

biological efficiency were examined using analysis of

variance (ANOVA). A Tukey test was used to establish

significant differences between means (P \ 0.05). Statis-

tical analyses were carried out using Statgraphics Plus 5.1

(Statistical Graphics Corp., Princeton, NJ).

Results and discussion

In vitro effect of compost teas on A. bisporus mycelium

growth

The radial mycelial growth obtained with all the compost

tea treatments was higher than that obtained with the water-

based controls (A10: 34.4 mm and A20: 31.0 mm) (Fig. 1).

There were significant differences between the three SMSs

used: the peat type SMS permitted greatest mycelial growth

(53.5 mm), while the growth registered with mineral soil I

and II was lower (47.1 and 41.1 mm, respectively), but

always higher than in the controls. Therefore, the SMS

compost teas used can be considered suitable as they did not

0

10

20

30

40

50

60

70

A-10 A-20 P-10 P-20 MS I MS II Peat ACT NCT 10 20

ConcentrationMethodSMSControls

Rad

ial m

ycel

ial g

row

th (

mm

) b ba

a

bc

a

b

a

cc

Fig. 1 Radial mycelial growth of two A. bisporus strains in pure

controls and positive controls. Effect of the SMSs (n = 92), the

method followed to prepare the compost tea (n = 140) and the

applied concentration (n = 140) on the in vitro radial mycelial

growth of two A. bisporus strains. Pure controls: A10 and A20, with

sterile water (10 and 20 %, v/v); Positive controls: P10 and P20, with

prochloraz 46 % (10 and 20 ppm of a.i.). SMS: MS I = mineral soil

I; MS II = mineral soil II; Peat = peat. Methods: ACT aerated

compost tea; NCT non-aerated compost tea. Concentrations: propor-

tions of compost-tea (10 and 20 % v/v). The representation’s bars are

standard deviations. The same letter above bars within the same

variable indicates no significant difference according to the Tukey’s

test at P \ 0.05

Table 1 Effect of the SMS compost tea treatments on A. bisporus quantitative production parametersa

Treatments Yield (kg m-2) Unitary weigth

(g mushroom-1)

Biological efficiency

(kg 100 kg-1 substrate)

Earliness (days

from casing)1st Flush 2nd Flush 3rd Flush Total

C 8.6 ± 1.3 7.9 ± 0.8 3.5 ± 1.3 20.0 ± 1.8 13.3 ± 1.7 113.8 ± 10.2 21.1 ± 0.3 a*

ACT-1R 9.0 ± 1.6 6.1 ± 1.6 3.2 ± 0.6 18.4 ± 2.7 14.1 ± 2.2 104.7 ± 15.4 21.9 ± 0.5 ab

ACT-2R 8.4 ± 1.5 6.6 ± 1.2 3.6 ± 0.6 18.6 ± 1.6 13.1 ± 1.2 105.8 ± 9.1 22.1 ± 0.6 b

ACT-3R 8.5 ± 1.3 6.2 ± 0.7 2.7 ± 0.6 17.4 ± 1.3 15.4 ± 3.6 99.0 ± 7.5 22.5 ± 0.3 b

NCT-1R 8.8 ± 1.3 7.3 ± 1.4 3.3 ± 0.4 19.4 ± 2.3 13.5 ± 1.1 110.5 ± 12.8 21.9 ± 0.6 ab

NCT-2R 8.3 ± 1.0 7.3 ± 1.2 2.7 ± 1.0 18.2 ± 1.9 13.9 ± 2.2 103.7 ± 10.6 22.4 ± 0.4 b

NCT-3R 9.4 ± 1.4 7.7 ± 1.1 3.2 ± 0.3 20.3 ± 2.3 14.9 ± 2.3 115.4 ± 13.2 22.5 ± 0.2 b

P 9.2 ± 1.5 7.1 ± 1.0 3.7 ± 0.8 19.9 ± 1.9 15.1 ± 0.5 113.3 ± 10.9 21.9 ± 0.6 ab

C Control, ACT aerated compost tea, NCT non-aerated compost tea, P positive control (with prochloraz 46 %); 1R, 2R and 3R one, two and three

drench applications

* Means within the same column followed by the same letter do not differ significantly at P \ 0.05 according to Tukey’s testa Data presented here are mean value ± standard deviation of five replicates

World J Microbiol Biotechnol (2012) 28:2765–2769 2767

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inhibit the mycelial growth of A. bisporus. In contrast, the

addition of the fungicide prochloraz produced a clear

inhibition of A. bisporus mycelial growth (P10: 25.4 mm

and P20: 16.2 mm) compared with water-based control

values. Increasing the concentration of the fungicide (from

10 a 20 ppm) significantly increased the inhibition of

A. bisporus mycelial growth. As regards the methods used

to prepare the compost teas, ACT led to significantly greater

mycelial growth (51.9 mm) than NCT (42.7 mm). Neither

method had a negative effect on A. bisporus mycelial

growth, although ACT was the more favourable to such

growth. Lastly, the 20 % concentration of compost tea

permitted significantly greater mycelial growth (49.8 mm)

than the 10 % concentration (44.8 mm).

Rapid mycelial growth is of special interest for the

control of pests and mushroom diseases since it implies

rapid colonization of the substrate, which should inhibit the

installation of harmful organisms because of the antago-

nistic characteristics of the A. bisporus mycelium (Vedder

1978; Binns 1980).

Effect of SMS compost teas on A. bisporus yield

The statistical analysis of the data pointed to no statistically

significant differences between the treatments in any of the

three flushes harvested or in total yield, although final

production fell by 13 % in one of the treatments (ACT-3R;

Table 1). Nor were there significant differences in the

unitary weight of mushrooms, or in biological efficiency.

Indeed, biological efficiency was high, since all the treat-

ments were close to or exceeded the threshold value of

100 kg of harvested mushrooms per 100 kg of compost.

As regards earliness, there was a slight delay in the

harvest of the first flush compared with the control in all

treatments involving compost teas. This delay was similar

with the ACT and NCT extracts (0.8–1.4 days), and

increased with the number of applications. The treatments

in which only one application of compost tea was made

showed the same delay as when the fungicide prochloraz

was used. The statistical analysis of the data pointed to

significant differences between the treatments after the

second and third drench with compost teas and the control

with water. This could be related with the high electrical

conductivity of the compost teas (5,190 lS cm-1 for ACT

and 5,245 lS cm-1 for NCT), which may increase the

conductivity of the casing layer.

Conclusions

The results obtained for the in vitro assays revealed that the

addition of SMS compost tea to the culture medium did not

inhibit the mycelial growth of A. bisporus, which contrasts

with the results obtained with prochloraz, the most widely

used fungicide in mushroom cultivation in Spain (Gea et al.

2010). In addition, the results obtained in the cropping trial

showed that the mushroom production parameters were not

significantly affected by the compost tea treatments

applied. There was only a slight delay in the first flush after

two or three applications of compost tea, perhaps because

of the increased conductivity of the casing layer. In con-

clusion, the fungitoxic effect of the SMS compost teas used

on A. bisporus was not very pronounced, so they can be

considered as potential biocontrol substances for use

against mushroom diseases.

Acknowledgments Funding for this research was provided by the

Ministerio de Ciencia e Innovacion (INIA) and FEDER (Project

RTA2010-00011-C02-01).

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