Friday, 11 May 2012

Button mushrooms cultivation [Agaricus Bisporus]

These are the most popular and widely grown edible mushrooms in the world. The world’s leader in button mushrooms cultivation is the USA. The button mushrooms cultivation requires relatively cool conditions for growth and fruiting body formation. These fungi lack the ability to form organic compounds for their growth. Their nutritional requirements for growth are therefore obtained from substrates or soil substitutes. Agaricus species requires composted substrates which have 70% moisture content. The commonly used materials are animal manure and cereal straws .The compost is pasteurized to kill insect and fungi pests. This is accomplished by placing the compost in the pasteurization chamber, injecting steam and allowing heating up to 60º C for 2-3 days, then cooling down to 45-50º for 4-5 days in order to condition. Air is then introduced into to the room to allow of growth of thermophillic organisms which are beneficial to the growth of the crop. When growing on very small scale, indoor pasteurization may be omitted and previously disinfected boxes filled with compost.

The compost is then transferred to a growing room and filled on the shelves. In practice the bed thickness varies from 10-20Cm.Increase in temperature occurs in thick beds limiting bed thickness. If button mushrooms cultivation is not under controlled conditions, the suitable thickness of the compost layer must be determined for the local climatic conditions. After spawning, the temperature is maintained at 22-25ºC to allow for good growth of mycelia within the compost. It takes about 3 weeks for mycelia to fully colonize the compost. The beds for button mushrooms cultivation should never be allowed to dry out. Casing layer is added to the surface of spawn run compost to stimulate formation of fruiting bodies and prevent drying up. A good casing medium should have an open texture, good water holding capacity and free from pests and diseases. Pasteurized garden loam soil or peat moss can be used as casing medium and PH adjusted to 6.5-8.5 by adding lime. The casing material is spread evenly on the surface and mixed evenly to a depth of 5cm. Water is sprinkled lightly on the casing medium, and incubation continued for 7-10 days at 18-24ºC.

To encourage fruiting, the temperature should be lowered to14-18ºC after casing and fresh air allowed into the room to lower the level of carbon dioxide, which may inhibit primordial formation and fruiting. It may also cause defects during button mushrooms cultivation. If cooling system is not available, button mushrooms cultivation should take off when the temperatures 12-18ºC. It takes about 20 days from spawning to harvest. The following hygiene measures are essential during button mushrooms cultivation:-
·        The growing building should be enclosed and easy to clean
·        Incoming air should be filtered
·        High standards of personal hygiene should be observed by the workers
·        At the end of button mushrooms cultivation cycle, spent compost should be ‘cooked out’ at 65ºC for 10 hours
Pest and diseases observed during button mushroom cultivation includes insects, mites, nematodes, bacteria, fungi and die back. Control measures include high standards of hygiene in the houses for button mushrooms cultivation, filtering of incoming air, and use of recommended pesticides, use un-infected compost, addition of sodium hypochlorite to irrigation water for bacterial control during growth, cleaning and disinfection of the houses used for button mushrooms cultivation after growing cycle.
Harvesting takes place before the fruiting bodies open. In high technology button mushrooms cultivation, the average yield is about 40kg /sq/M .3-4 flushes are harvested before the compost is removed. Agaricus species can stay fresh for one week at 10ºC.