The foundation for cultivating healthy mushrooms is well-pasteurised compost and pure casing soil. By providing good spore filters, well sealed growing rooms and correct monitoring, growers should be able to limit the use of chemical control agents to a minimum. This isn't only an efficient cost cutting exercise, but also important for the sector's image as a whole.
Scrupulous hygiene in and around the farm is of utmost importance. Growers shouldn't wait until they have to use crop protection agents to fight pests and diseases. Correct hygiene can be enough to ensure sufficient prevention and not force cure using various pesticides. Listed below are a number of general hygiene aspects to consider;
Disinfect rooms before each new cycle with formalin (100 millilitres formalin, diluted to 40 % in 5 litres of water).
Replace dust filters after each cycle.
Before filling disinfect all machinery, work floors and tools with formalin diluted to 2% per litre water. This should destroy all bacteria and moulds.
Ensure all workers wear clean clothing.
Close the doors promptly after filling.
Disinfect the room and the casing soil after casing with formalin and close the fresh air inlet for 6 to 10 hours.
Empty growing rooms with a high infection risk as quickly as possible.
Always clean with water. Never sweep - this creates too much dust.
Dispose of all remaining compost, casing soil and mushroom stalks etc after harvesting as quickly as possible. These are all possible sources of infection.
Cook out the compost at the end of each harvest. Keep the compost temperature at 70 degrees Celsius for 8 hours.
The most common fungal diseases in mushroom cultivation are;
Green mould (usually trichoderma).
Brown mould (botrytis).
White plaster mould (scopulariopsis fimicola).
Ink caps (coprinus spp.).
These fungal diseases indicate unfavourable conditions in the compost or casing soil. Once green mould is present in the growing rooms, its growth is stimulated by a number of factors such as: too high doses of formalin, RH higher than 85%, compost pH lower than 7 and a high substrate temperature.
If a trichoderma infection is discovered never cover the incubated compost with plastic. This will simply increase the risk of contamination and encourages development of the infection. Spraying these mould with pesticides etc. has no sense. The only effective method is good hygiene!
Wet bubble (verticillium fungicola).
Dry bubble (mycogone perniciosa).
Cobweb (cladobotryum dendroides).
These moulds are a constant threat to mushrooms. Good hygiene is essential here too.
As soon as the first signs of any infection have been noticed, quick action is imperative to prevent the disease spreading. Cover the infection with salt. It’s advisable not to move the bubble as this can also spread the infection.
If bubble is detected during the first flush, we recommend using Sporgon (prochloraz) for a cultivation cycle in a solution of 300 grams per 150 litres water per 100 square metres. Sporgon is the only effective fungicide for bubble. It is applied five days after casing or ruffling. Or: half after casing and half after ruffling. Extra strict hygiene must also be observed.
With a serious cobweb infection, carbendazim or benomyl in a solution of 0.5 gram in 1 litre water per 1 square metre can be applied. If infection is discovered, disinfect the corridor and adjacent areas with a solution of 2% formalin per litre water.
Flies lay their eggs on the developing mycelium in the compost and the casing soil. Casing quickly considerably reduces the risk of infection. The cycle from egg to fly lasts 22-24 days at a temperature of 25 degrees Celsius. Flies cause problems as they act as carriers for mould spores, mites and eelworms.
Midges lay their eggs in compost that hasn't yet been inoculated or in newly spread casing soil. The cycle from egg to fly is 21 days. The larvae feed on the mushroom mycelium and young pinheads and eat the mushroom stems. As well as spreading spores and mould they damage the harvestable crop.
With gal midges the transparent white or orange/yellow larvae are usually visible. They multiply incredibly quickly.
Mites don't cause any direct damage to the crop but can indicate the presence of mould spores or eelworms.
To prevent these pests, good hygiene must always be observed, and properly prepared compost and casing soil used.
To control flies and midges growers can mix diazinon 5 percent granulate (pellets) through the compost, 1 kilo per ton of compost. Apply diflubenzuron as 200 millilitre per 150 litre water per 100 square metre growing surface as quickly as possible after casing. Malathion can be misted: 100 millilitres in 2 litres water after inoculation and during mycelium growth and after casing up until a week before the harvest. Do not mist directly onto the mushrooms and switch off the air inlet for 1 hour. These are a few examples of treatment to control pests.
As brand names and quantities of active agents vary and not all pesticide classes are permitted in certain countries, please read all labels carefully before using any chemical agents. It's also better to alternate between using different products each cycle. Carry out treatment at the most effective moments - i.e. the infection period and the spreading period. Use special traps and lamps to keep fly numbers down.
When spraying or misting always wear personal protection equipment, both during spraying and when preparing the solutions. Protective clothing, gloves, rubber boots and mask are not unnecessary luxuries!
In mushroom cultivation, fine and coarse dust must be prevented. Fine dust includes mainly mould spores and mycelium traces.
Filtering the air is an efficient, relatively cheap and environmentally friendly way of controlling pests and diseases. It also means much less reliance on crop protection agents. It is vital to choose the correct filters (EU5-EU9) for an optimal effect.
Another important point is to try and eliminate any potential sources of infection in the surroundings.