5 lbssq ft of growing space in addition mushroom size

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Unformatted text preview: stimulate the fruiting mechanism and increase yield by having more mushrooms initiate and develop. Yields can be increased from 0.25 to 1.5 lbs/sq ft of growing space. In addition, mushroom size may also be improved in compost with higher spawning-moisture content. However, in substrate that is not selectively prepared, these nutrients become more available to com- petitor molds. Often, if a farm is having composting problems, not supplementing until the problems are corrected is more economical. Figure 13. Spawn growth in the casing and its thicker rhizomorph growth. Casing The only method of forcing mushroom mycelia to change from the vegetative phase to a reproductive state is to apply a cover of a suitable material—called the casing layer—on the surface of the spawned compost. The function of a casing layer is to trigger the mushrooms to switch from a vegetative growth to a reproductive or fruiting growth. The mechanism that initiates the spawn to change from vegetative to reproductive growth is unknown, though several theories have been presented. The casing also functions to supply and conserve moisture for the mushrooms and their rhizomorphs (thicker mushroom mycelia) and acts to transport dissolved nutrients to the mushrooms. Casing supports the mushrooms and compensates for water lost through evaporation and transpiration. Rhizomorphs look like thick strings. They are formed when the very fine mycelia fuse together and grow through the casing. Rhizomorphs are thought to carry water and nutrients from the compost to the developing mushrooms (Figure 13). Mushroom initials—primordia or pins—form on the rhizomorphs. Without rhizomorphs, there will be no mushrooms. The mushroom industry uses various materials to provide a suitable environment for fruit body formations. Presently, most mushroom growers use sphagnum peat moss or aged sphagnum peat moss buffered with limestone. Sphagnum peat is relatively inexpensive and readily available to North American growers. Pasteurized clay loam field soil; reclaimed, weathered, spent compost; and coir fibers are other materials used by growers. Most sphagnum peat has a pH of 3.5 to 4.5. A neutralizing agent—usually calcium limestone—is added to bring the pH level up to 7.5. Processed, spent sugar beet lime or hydrated lime can be used. Due to its higher neutralizing capability and its greater solubility, only small amounts are required. Soil, spent mushroom substrate, and coir fibers should be pasteurized to eliminate any insects and pathogens they may be carrying. However, peat moss–based casing does not need pasteurization because it is inherently free of mushroom disease spores and pests. Distributing the casing so the depth and moisture are uniform over the surface of the compost is important. Such uniformity allows spawns to move into and through the casing at the same rate and, ultimately, for mushrooms to develop at the same time. Casing should be able to hold moisture because moisture is essential for the development of a firm mushroom. CAC or CI Fully colonized spawn run substrate is used to introduce mycelia into the casing layer. This is often used to improve crop uniformity, crop cycling, mushroom quality, and yields (Figure 14). Spawn run compost at casing (CAC) is used to inoculate the casing during the mixing or application of the casing. CAC is now produced much like spawn—in aseptic conditions—by those who produce and supply spawn to growers. This process is called casing inoculum (CI). By adding the mycelia uniformly throughout the casing, the spawn growth into the casing is quicker and more even. The time from casing to harvest is reduced by 5–7 days so that the rooms can be cycled faster or more breaks can be harvested in the same 11 time. Mycelial growth is uniform on the surface, which encourages the mushrooms to form on the surface as well. Therefore, they are cleaner. Yields are improved since the mushroom growth is uniform and crop management is easier. In addition, more mushrooms are produced from areas that may have less nutrition. Managing the crop after casing requires that the compost temperat...
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This document was uploaded on 03/16/2014.

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