Figure 17 mature mushrooms ready for harvesting

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Unformatted text preview: ed to manage the pin set to achieve enough pins for good yield, yet, more important, to attain the right amount of pins to produce the large mature mushrooms for the Portabella market. Figure 17. Mature mushrooms ready for harvesting. Harvesting Mushrooms are harvested over a 2–4day period in a 7–10-day cycle called flushes or breaks. When mature mushrooms are picked, an inhibitor to mushroom development is removed and the next flush moves toward maturity. Timing of the breaks or flushes is managed by control of the watering, CO2, and temperatures. The first two flushes account for the majority of the total yield, with the subsequent flushes tapering off to relatively low levels of production. Mushrooms are harvested by hand and are picked at a time before the cap becomes soft, indicating the mushroom is past prime fresh-quality potential (Figure 18). Harvesting rates depend mainly on the amount of crop on the beds and size of the mushrooms. Rates vary from 30 to 80 lbs/ hour. Some consumers seem to prefer closed, tight mushrooms, while others prefer stronger-flavored, more mature, open-cap mushrooms. Mushroom maturity is evaluated by how open the veil is, not by its size. Mature mushrooms are both large and small, although both farmers and consumers favor medium to large mushrooms. Growers harvest just three to four breaks per crop—a shorter harvesting time allows more crops to be produced in a year and helps to prevent disease and insect problems. Diseased, malformed, and fly-damaged mushrooms are considered second-grade and are discarded. Diseased mushrooms should not be touched. Diseased tissue should be treated with registered chemicals, biopesticides, or common disinfectant materials such as salt or alcohol. 14 While mushroom yields vary, the average yield for the United States in 2001 was about 5.75 lbs/sq ft. With improving technology, such as airhandling systems, heavier compost dry weights, supplementation, and improved strains, growers have achieved yields higher than 8.0 lbs./sq. ft. However, these high yields are only achieved on farms that are properly equipped and have very experienced growers. Post-Crop Pasteurization and Spent Mushroom Substrate (SMS) When a house becomes unproductive, the crop is usually terminated. Before removing the spent substrate from the mushroom house, the grower “pasteurizes” it with steam to kill any diseases, pests or other biological activity that could interfere with a Figure 18. Mushrooms for the fresh market are only harvested by hand. The stem with some of the “root” attached is trimmed before the mushroom is placed in a market container. Figure 19. SMS being emptied from a mushroom farm. neighboring house or subsequent crop. The steaming-off procedure is accomplished by maintaining a compost temperature of 140–150ºF (60–70ºC) for anywhere from 8 to 24 hours. The spent compost should be removed from the farm to reduce the chances of contaminating the subsequent mushroom crops at the farm (Figure 19). Spent mushroom substrate (SMS) is the soil-like material remaining after a crop of mushrooms has been harvested. Spent substrate is high in organic matter, making it desirable for use as a soil amendment or soil conditioner. Sometimes this material is called spent mushroom compost. SMS still has some nutrients available for the mushroom. However, replacing the substrate and starting a new crop is more economical. Users should consider spent substrate clean of weed seeds and insects. The typical composition of SMS fresh from a mushroom house will vary slightly. Since raw materials and other cultural practices change, each load of fresh spent substrate has a slightly different element and mineral analysis. Sometimes fresh substrate is placed in fields for at least one winter season and then marketed as “weathered” mushroom soil. This aged material has slightly different characteristics because the microbial activity in the field will change the composition and texture. The salt content rapidly decreases during the weathering or composting. Spent mushroom substrate has many appropriate uses. SMS is excellent to spread on top of newly seeded lawns because it will provide cover against birds eating...
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This document was uploaded on 03/16/2014.

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