Optimal Growth Conditions for Oyster Mushroom, especially ...



Optimal Growth Conditions for Oyster Mushroom, especially during Fruiting

Writer: Duk-hwan Kim / Date :2001-04-01 / hits: 148

|Recent days have seen diversification of oyster mushroom varieties with strong mycelial growth. Yet, some mushroom farmers might lose their|

|crop, facing some unwelcome cases: with temperature getting higher since mid-April, colonization of mycelia often occurs while mushroom |

|fully grows up, or fruitbody development turns out to be poorer or fruiting itself doesn't occur at all, as outside air gets too dry. |

|Growers need to take care to provide optimal growth conditions for mushroom, especially during fruiting. |

|Mushroom Growth Parameters |

|* Lighting |

|Light has a close relationship with mushroom's color and plays an important role in fruitbody development. |

|Poor or no light will lead to a crop failure or at least a reduced mushroom production. Oyster mushroom requires indirect lighting. |

|If lighting is insufficient, color of mushroom would be white and stalk enlongated. Therefore make sure of maintaining 120 lux light during|

|a day. |

|* Temperature |

|Oyster mushroom continues a vegetative growth stage at 20-25'C, but shifts itself to a reproductive growth stage below 15'C. |

|It is desirable for mushroom growers to lower temperature to a lowest limit of optimal temperature, since temperature for mushroom |

|development varies among mushroom varieties. In order to prevent the substrate block from losing moisture and being contaminated with |

|various germs, growers should let the light in and lower the room temperature with plastic covering on the block. |

|* Ventilation |

|Right after removing plastic cover, open ventilation windows for 30-40 minutes for air-exchanges. After that, leave just a few ventilation |

|windows open 4-5 cm wide. |

|Oyster mushroom shows a stunted growth by carbon dioxide if ventilation was poorly done during pinning and fruitbody development. The |

|mushroom also attracts various contaminants including green mold to a spot where mycelial colonization is not enough. |

|Excessive ventilation can cause heavy water loss and hardening of the substrate, with fruitbodies turning brown. |

|It is advisable to ventilate consecutively on a regular basis. |

|Growers are well recommended to use poly-ethylene duct when blowing fresh air into the growing room. |

|* Humidity and Moisture Content |

|After ventilation, raise the room humidity by spraying underground water onto corridors and into the air. |

|In order to prevent abrasion of the substrate surface and suffocation of young mushrooms, indoor humidity should be maintained above 90%. |

|The mushroom doesn't require frequent watering at an early stage of fruit-body development. |

| |

|Mushroom development and harvesting control |

|Lower indoor humidity when pinheads appear on the substrate and initiate reproductive growth. Increase watering frequency depending on the |

|fruiting rate. |

|After sprinkling, ventilate the growing room sufficiently until all water droplets on the surface of mushroom are gone. |

|If a mushroom absorbs too much free water, its texture gets too soggy. |

|Free water on the substrate makes mushrooms susceptible to bacterial blotch. |

|In winter or for young mushrooms, reducing watering time and ventilation frequency goes a long way toward heading off disease outbreaks. |

|The main causes for young mushroom's wilting and shriveling during harvesting period include excessive watering, high temperature and poor |

|ventilation. Growers can find out whether watering is sufficient or not by holding young mushrooms slightly. When you give young mushrooms |

|too much water, they will ooze water, when pinched. |

|At high temperatures, mushrooms which seem to wilt from the upper end of the substrate block don't ooze water. |

|If ventilation is poor provided, the stipe gets enlongated and cap remains small. Often young mushrooms begin to wilt from the middle or |

|upper part of the block. |

|In 3~4 days of fruiting, indoor humidity should be lowered to 85~95%. During harvesting period 80~85% of indoor humidity could guarantee |

|satisfactory mushroom quality. |

|90% of indoor humidity as in an early stage could cause malformed mushrooms or abnormal mycelial growth on the mushroom cap. |

|Excessive moisture could cause the lack of oxygen in the substrate, which, in turn, keeps mycelia from a vigorous growth and condemns |

|mushroom to a delayed and stunted growth along with distant gills and a thin cap. |

|When both substrate and room humidity are low, mushroom growth will be stunted due to lack of water. Even in a stage of young mushroom, cap|

|upturns earlier and releases more spores. |

|Ventilate the growing room every 3 hours for a complete air exchange between indoor and outdoor air. |

|At low temperatures, growers are highly likely to ventilate less frequently to maintain indoor temperature. Thus, they are recommended to |

|water during mid-day and ventilate enough but to avoid ventilation during mid night for indoor temperature to be kept in line. |

|When the room temperature goes up higher than the optimal temperature during fruitbody development, mushrooms should get enlongated stipes.|

| |

|Humidity and ventilation management in the growing room is one of the most important factors determining the length of stipe and resistance|

|to contaminants. |

|After harvesting, immediately get rid of mushroom remains scattered on the substrate blocks. |

|The second flush (a synchronized fruiting of mushrooms) is induced as with primordia induction by watering inside the growing room and on |

|the shelf racks block and maintaining temperature and providing lighting, after applying pesticides to mushroom blocks. |

| |

|Abnormal Symptoms and Remedies during Fruiting |

|* Mycelia dying from heavy water loss |

|Although waste cotton block holds enough water inside, its surface is likely to dry out. Yet, cultivation on rice straw shows less damages |

|from moisture loss, since rice straw in the bottom part of the block holds water through straw's capillary action. |

|If the surface of the block gets dry, the mushroom block attracts green molds easilier , with spawn run and colonization delayed. |

|-->Remedies includes preventing excessive drying after inoculation, and maintaining air humidity high up to 90~95% after cold shock. |

|-->In the case of cultivation on waste cotton, use humidifiers. |

|-->Make sure to maintain the optimum humidity level by sprinkling water on the floor. |

|* Fruiting failure due to a mycelium lump developing on the substrate surface |

|Mycelia seem to grow normal even on the surface of waste cotton substrate. During fruitbody development, however, fully grown-up mycelium |

|is prone to lumping and looks like a fried egg. From the center of the spot, where lumps of mycelia appear on the surface, mycelia start to|

|turn brown, with fruiting delayed and mushroom quality degraded. Sometimes mushroom decay to ooze brownish fluid. |

|Although causes for those symptoms vary among mushroom varieties, they occur when gas is over concentrated, waste cotton is over-moistened |

|or mycelia grow too fast due to high temperatures in the block. |

|When the surface of the block dries too fast and mycelia make a thick lump on the substrate surface or gets dry. |

|--> Remedy : frequent ventilation along with heating will do the trick. |

|--> Those symptoms can occur if indoor temperature is maintained low even when temperature inside the block is high. Make sure adequate |

|temperatures of the growing room and the substrate should be maintained. Growers might want to scratch off the mycelium lump or to remove |

|some of them from the block. |

|* Much smaller mushrooms and those wilting to death |

|Although young mushroom develop in large numbers, they can not be fully grown up, remaining young and small with earlier cap upturning. |

|Those mushrooms will be eventually dried out. |

|When you knock the dried mushroom block, you can hear sounds like drum to indicate there is an empty room inside the block. That is because|

|the inner part of the substrate block can easily degrade due to proper temperature and moisture inside the block, with its size slightly |

|reducing. But the surface of the block forms a thick skin as mycelia get entangled on the dry surface. |

|Mushrooms developed under these circumstances fail to connect with mycelia inside the block, which hinders water and nutrition supply |

|necessary for mushroom growth. |

|---> Remedy: irrigate the block with enough water after cutting the surface of the block at a certain distance. The substrate colonized |

|with oyster mushroom mycelia absorbs the irrigated water, which links the floating layers together, removing empty space inside the block. |

|This process helps mushrooms to grow. |

|---> Make sure to drain extra water by making tiny holes in plastic cover on the floor, lest it should remain on the covering. |

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