The right environment is essential to produce large pins that grow into heavy mushrooms.
temperature; by lowering the temperature to stimulate more pins and by raising it to delay pin development. On farms built along Dutch lines where the mushrooms grow without many problems, a significant influence on the number of pins can even be noticed if the temperature is increased or decreased by as little as 0.1 degree Celsius. With good quality compost, reducing the air temperature is done more slowly to prevent too many pins appearing on the beds. Cool down is generally started at an air temperature of 21 degrees and aims to reach 18 degrees in between eight to 11 days. However, this too greatly depends on the compost and the amount of pins formed during cool down. With poor quality compost, the air temperature needs to be decreased faster than with good quality compost. A customary procedure is to reduce the temperature slightly faster at the end of cool down, and if necessary take it briefly right down to 16 degrees (one to two days, depending on the compost temperature and number of pins present) before taking the temperature back to 18 degrees. The reason for applying this rather sharper air temperature drop at the end of cool down is to bring the compost to a temperature below 20 degrees to gain greater control over mushroom quality in the first flush, and in most cases to stimulate growth at the end of the first flush.
CO2 shot Some growers apply a CO2 shot at the right
moment during pinhead development to avoid over-pinning. The fan is switched off, or the fan RPM is slowed down quite radically. A good CO2
shot will also often result in good quality, heavy mushrooms on thick stems, that are
A good spread can be expected here.
easy to harvest, as this type of mushroom is normally larger than it would be without the CO2 CO2
concentrations, can slow
shot. However, there are risks involved. A
shot applied too early, or a longer period with excessive CO2
pin setting, which ultimately leads to under production in the first flush and too many pins developing in the second. If the casing soil surface is too wet when the CO2
shot starts,
there is a higher risk of encouraging bacterial blotch. Another important factor to consider is the duration of the CO2
shot. The margin of
error is very narrow and determining the right length of time very much depends on aspects such as the CO2
produced by the compost and
the thickness of the walls in the growing room. On a Dutch-style farm with panelled walls, a high CO2
concentration will be reached sooner after the fan has been slowed or switched off than on an older farm with plenty of gaps in the walls and ceilings.
Regulating the air temperature is the best and most accurate way of steering towards the right number of pinheads without taking too many risks. A difference of just 0.1 degree Celsius will already greatly influence the number of pins in good cropping cycles, depending on whether the temperature is increased or decreased. A huge advantage is that the altered air temperature can be set to another value again at any time, whereas with a CO2 excess CO2 with a CO2
shot the must be removed first. Moreover,
shot, the compost temperature can soon become too high, but this factor is easier to manage using the right air temperature. It is wise for growers to gain some experience before thinking that a CO2 time it is used.
shot will be successful each
MUSHROOM BUSINESS 11
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