Spawn production is one of the important steps in the cultivation of mushrooms. Despite all efforts, the main hurdle for spawn production is frequent contamination of microflora (<xref ref-type="bibr" rid="bib001">Kumar & Sharma, 2006</xref>). In order to determine the role of weather conditions on extent of contamination, studies were made on the role of contaminants in Oyster (<italic>Pleurotus sajor-caju</italic>) mushroom spawn production on monthly basis.Spawn bags were labeled and shifted to the spawn incubation room at existing temperature and humidity. The spawn run in the bags took 2–3 weeks to complete. Ten spawn bags were raised in laboratory in the first week of each month and allowed for mycilium run. Daily inspection was made to trace any growth of unwanted microflora till complete mycelial run. Contaminated bags were recorded and placed separately after tagging with zinc plates. These contaminant microflora were identified and % infection rate was calculated.Three fungi <italic>viz. Trichoderma harzianum, Penicillium notatum, Aspergillus fumigatus</italic> and one bacteria <italic>Pseudomonas</italic> sp. were isolated and identified from contaminated spawn bags of <italic>Pleurotus sajor-caju</italic>. Among these, <italic>Pseudomonas</italic> sp. was observed to multiply rapidly and not allowing the growth of mushroom mycelium. In case of <italic>T. harzianum</italic> caused most severe suppression of growth of mushroom mycelium and covered highest area followed by <italic>A. fumigatus</italic> and <italic>P. notatum</italic>, respectively. The maximum contamination was observed in the month of July and August (62.4–83.3%) in the year of 2002–2003 and 2003–2004, when the maximum temperature was 32.0°C minimum temperature 25.2°C with R.H. 85.9% and heavy rainfall (72.4–398.6 mm). Incase of 2004–2005, maximum contamination was observed in the month of May and June (37.25–44.4%) when maximum temperature was 33.0°C minimum temperature 25.8°C R.H. 70.78%, rainfall of 235.2 mm. Contamination % of mushroom spawn was less during September to March in all the years (<xref ref-type="table" rid="tab001">Table 1</xref>). But contamination chances were least in the month of December and January due to low maximum and minimum temperatures because most of the contaminant microflora appeared during summer and monsoon season which could be avoided with application of tartaric acid, ascorbic acid and potassium metabisulphite at 12°±1°C (<xref ref-type="bibr" rid="bib002">Sharma & Babukhandi, 2003</xref>). Spawn contamination was assumed by the air borne microflora present inside the inoculation room. During the transfer of the mother spawn into the sterilized bags, some air borne microflora might enter into the bag quickly and led to contamination of spawn during incubation. <table-wrap id="tab001"><label>Table 1</label><caption>Multiple correlation coefficients between epidemiological parameters of mushroom spawn contamination</caption><table><thead><tr><th>Years</th><th align="center">Correlation coefficient</th><th align="center">Coefficient of multiple determination</th><th align="center">Regression equation Y=a+b1x1+b2x2+b3x3+b4</th></tr></thead><tbody><tr><td colspan="4"><hr /></td></tr><tr><td valign="top">2002–2003</td><td align="center" valign="top">0.7592</td><td align="center" valign="top">0.5765</td><td valign="top">Y1=251.67+(−9.456)x1+9.921 x2+(−.560)x3+0.0994x4</td></tr><tr><td valign="top">2003–2004</td><td align="center" valign="top">0.8061</td><td align="center" valign="top">0.6498</td><td valign="top">Y2=-37.708+6.543x1-4.553x2+0.2849x3+(−0.0132)x4</td></tr><tr><td rowspan="8" valign="top">2004–2005</td><td rowspan="8" valign="top" align="center">0.8357</td><td rowspan="8" valign="top" align="center">0.6984</td><td valign="top">Y3=153.963+ 1.353x1-2.039x2-1.483x3+0.0222x4</td></tr><tr><td valign="top">Y= Expected contamination %</td></tr><tr><td valign="top">a=Constant (Intercept value)</td></tr><tr><td valign="top">B=Values of coefficient</td></tr><tr><td valign="top">X1=Maximum temperature</td></tr><tr><td valign="top">x2=Minimum temperature</td></tr><tr><td valign="top">x3=Relative humidity</td></tr><tr><td valign="top">x4=Rainfall</td></tr></tbody></table></table-wrap>It was observed that R.H. and temperature (maximum/minimum) were positively correlated with development of contamination. The regression equation were also determined for obtaining expected contamination % on the basis of prevailing weather parameters.</sec></body><back><ref-list><title>References

APPS

Annals of Plant Protection Sciences

0971-3573

Society of Plant Protection Sciences

apps-15-1-080

SHORT COMMUNICATION

Effect of Weather Variables on Contamination of Oyster Mushroom Spawn

Mishra

R.S.

Shukla

P.K.

Mushroom Project, Directorate of Research, N.D. Univ. of Agri. & Tech., Kumarganj, Faizabad-224 229, India.

32007

151272273

Spawn production is one of the important steps in the cultivation of mushrooms. Despite all efforts, the main hurdle for spawn production is frequent contamination of microflora (<xref ref-type="bibr" rid="bib001">Kumar & Sharma, 2006</xref>). In order to determine the role of weather conditions on extent of contamination, studies were made on the role of contaminants in Oyster (<italic>Pleurotus sajor-caju</italic>) mushroom spawn production on monthly basis.Spawn bags were labeled and shifted to the spawn incubation room at existing temperature and humidity. The spawn run in the bags took 2–3 weeks to complete. Ten spawn bags were raised in laboratory in the first week of each month and allowed for mycilium run. Daily inspection was made to trace any growth of unwanted microflora till complete mycelial run. Contaminated bags were recorded and placed separately after tagging with zinc plates. These contaminant microflora were identified and % infection rate was calculated.Three fungi <italic>viz. Trichoderma harzianum, Penicillium notatum, Aspergillus fumigatus</italic> and one bacteria <italic>Pseudomonas</italic> sp. were isolated and identified from contaminated spawn bags of <italic>Pleurotus sajor-caju</italic>. Among these, <italic>Pseudomonas</italic> sp. was observed to multiply rapidly and not allowing the growth of mushroom mycelium. In case of <italic>T. harzianum</italic> caused most severe suppression of growth of mushroom mycelium and covered highest area followed by <italic>A. fumigatus</italic> and <italic>P. notatum</italic>, respectively. The maximum contamination was observed in the month of July and August (62.4–83.3%) in the year of 2002–2003 and 2003–2004, when the maximum temperature was 32.0°C minimum temperature 25.2°C with R.H. 85.9% and heavy rainfall (72.4–398.6 mm). Incase of 2004–2005, maximum contamination was observed in the month of May and June (37.25–44.4%) when maximum temperature was 33.0°C minimum temperature 25.8°C R.H. 70.78%, rainfall of 235.2 mm. Contamination % of mushroom spawn was less during September to March in all the years (<xref ref-type="table" rid="tab001">Table 1</xref>). But contamination chances were least in the month of December and January due to low maximum and minimum temperatures because most of the contaminant microflora appeared during summer and monsoon season which could be avoided with application of tartaric acid, ascorbic acid and potassium metabisulphite at 12°±1°C (<xref ref-type="bibr" rid="bib002">Sharma & Babukhandi, 2003</xref>). Spawn contamination was assumed by the air borne microflora present inside the inoculation room. During the transfer of the mother spawn into the sterilized bags, some air borne microflora might enter into the bag quickly and led to contamination of spawn during incubation. <table-wrap id="tab001"><label>Table 1</label><caption>Multiple correlation coefficients between epidemiological parameters of mushroom spawn contamination</caption><table><thead><tr><th>Years</th><th align="center">Correlation coefficient</th><th align="center">Coefficient of multiple determination</th><th align="center">Regression equation Y=a+b1x1+b2x2+b3x3+b4</th></tr></thead><tbody><tr><td colspan="4"><hr /></td></tr><tr><td valign="top">2002–2003</td><td align="center" valign="top">0.7592</td><td align="center" valign="top">0.5765</td><td valign="top">Y1=251.67+(−9.456)x1+9.921 x2+(−.560)x3+0.0994x4</td></tr><tr><td valign="top">2003–2004</td><td align="center" valign="top">0.8061</td><td align="center" valign="top">0.6498</td><td valign="top">Y2=-37.708+6.543x1-4.553x2+0.2849x3+(−0.0132)x4</td></tr><tr><td rowspan="8" valign="top">2004–2005</td><td rowspan="8" valign="top" align="center">0.8357</td><td rowspan="8" valign="top" align="center">0.6984</td><td valign="top">Y3=153.963+ 1.353x1-2.039x2-1.483x3+0.0222x4</td></tr><tr><td valign="top">Y= Expected contamination %</td></tr><tr><td valign="top">a=Constant (Intercept value)</td></tr><tr><td valign="top">B=Values of coefficient</td></tr><tr><td valign="top">X1=Maximum temperature</td></tr><tr><td valign="top">x2=Minimum temperature</td></tr><tr><td valign="top">x3=Relative humidity</td></tr><tr><td valign="top">x4=Rainfall</td></tr></tbody></table></table-wrap>It was observed that R.H. and temperature (maximum/minimum) were positively correlated with development of contamination. The regression equation were also determined for obtaining expected contamination % on the basis of prevailing weather parameters.</sec></body><back><ref-list><title>ReferencesKumar

Satish

Sharma

V.P.

(2006) Persistence of carbendazim and mancozeb on Agaricus bisporus. Ann. Pl. Protec. Sci., 14: 266–267.Sharma

R.K.

Bahukhandi

(2003) Studies on shelf life of white button mushroom. Ann. Pl. Protec. Sci., 11: 333–336.