A lot of farms are afraid that water directly on mushrooms will damage the quality but I disagree with that. Of course it depends on the amounts of water you use and the moment of watering, those details are very important but if managed well the water on the mushrooms will give them a smooth cap and some extra weight. What we need to keep in mind is that the moment of watering is very important. Wait for watering on the 1st flush until you see compost activity. If there is no rise in compost temperature wait with water until there is. Normally you see the activity starting on the first picking day when you pick about 0.5 to 1 kg/m2. I always like to water on that first picking day, where the compost just starts to get activity, and let the mushrooms dry naturally, with no force of the fan but with fresh air. What happens is that when you run higher fan speeds after the watering, the fresh air damper will close. You can put a drying program where you lower the CO2 a bit but still the higher fan speed will not increase the amount of fresh air that is needed to dry the mushrooms.

Instead dry the mushrooms naturally and without too much help from the fan speed. Speeding up the fan a lot is not sufficient and is actually working the other way around. When the room is watered the RH is high so the climate system will automatically start drying the room. Leave the fan speed the same so some extra fresh air will come in to do the drying process. Make sure to remove all the access water from the floor directly after watering, if not the process will dry the floor first and the mushrooms will stay wet longer. Make sure you watch your outside conditions to guide this process, with very high humilities you have to use a drying program or consider not too water.



If you look at this in a glance one might say: the filling has not that much to do with picking. But it is more relevant than many people think. Before the start of picking a first flush, the picking manager makes a plan. When is the room starting? Do I have to pick clusters or pre-runners? How many pickers do I need in this room during lets say 5 days of picking? And an important one, what is the activity of the room? This I need to interact on the growing from day 2 of picking. And this is where the filling of the room comes into the story.

Before the start of picking the picking manager and the grower have a talk about this room. This should start from the moment pins grow out, so about 4 days before the start of picking that room. The picking manager has knowledge about the expected sales that week, the desired size of the mushrooms and the number of pickers available. The grower has knowledge of the room regarding the activity of the compost, the strain and the number of pins developing. An even room is easy to evaluate but if the filling was uneven or two different types of compost were used, than the story gets a bit more difficult. The growing room will develop uneven and one side might start earlier. One side might give more mushrooms and this means that the picking is not the same on all shelves. And with the tendency to build bigger rooms, more trucks of compost are filled in a room. And every truckload of compost can be a bit different. Sometimes in structure, sometimes in moisture content and even in quantity. And every time the operator of the combine filling machine has the desire to change the settings on the machine. Often his order is to get the compost filled. All shelves full and no compost returning to the compost yard or no compost dumped. But by changing the settings the temperature development of the compost will change too. 2 cm deeper fill can result in a difference of a day for the flush to start. It will also have an effect on the number of mushrooms growing out. And during the flush one side will grow faster than the other.

So the general instruction at filling should be not to make any changes. Better a bit of compost left over or a part of the shelves not being filled. An even better way is to fill out of two trucks in one go with a cross conveyor. That way the compost out of two trucks is mixed and differences are ruled out. Another method is to do a mixed fill of the truck at the compost yard. So fill a layer, fill another layer in another truck and then let the trucks circulate. Of course the best possible way is to do the mixed filling of the truck, together with the combined unloading at filling. The growing will be a lot easier then. The grower has a better chance to produce the number of mushrooms required and the picking can be a lot more accurate.



Apr 21, 2021

A good start for a blog just around Spring time. But the meaning is different.
It just means: Keep It Super Simple.

On many farms I assist in the picking instruction and the complaint most often heard is that the pickers do not listen. This is not entirely true. They do listen but they do not store it. They are thinking of many things and the mushrooms is not one of them.
So it is up to the supervisor or trainer to make sure the information gets through. She (or he) first has to get to know the picker. Then decide what method can be used. The best supervisor changes her role according to the person she talks to. She can be a teacher, a mother or your worst nightmare if needed. Depending on the person and the situation. But she knows what is going on in the mind of the picker. For the picker money and nice work is important. But they have no notice of how mushrooms grow and how to pick more kilo’s per m². They want to pick fast because most of the time their bonus is related to pick rate. But often they do not realise that it is not about working fast but about working smart. And a good instruction can help with that.

How to do a thing like that in a practical situation?
Let’s say stems need to be longer.
First explain to a picker that a longer stem can give them up to 10% higher pick rate without working faster. Just look at the stem and do not cut it of completely. Then translate the 10% extra to a 10% higher salary. The farm by the way has a 10% higher production. If they understand that, the power is in repeating. Not just in spoken word but also in visual signs. Make a project of this. For one complete week only instruct on stem length in the rooms and do this on individual level. So no shouting through the room but address every picker personally. The next part is a good photo which is shown for a week on all possible places. In the canteen, on the tables, in the corridor and even in the toilets. Just for a week because after a week they do not see the photo anymore. The next week another subject is chosen.
And for the supervisor: the power is in repeating. Tell them once, twice and keep going on. If the pickers see you, they immediately think of stem length. This way it is imprinted in their way of thinking and it is much easier to have success.

So Keep It Super Simple and act like a parrot.


If a consultant is visiting a farm there are always many things to discuss in detail.

Shall we give more or less water and are we able to water over the mushrooms?

Do we need a slower or faster fructification?

Is the amount of pins sufficient or do we need more and how do we then get a decent stagger?

Even discussions about compost although many growers do not really know the details. But they know about structure, moisture and smell. Because this is what they discuss at filling.

The same about casing soil. Is it heavy this time or just fine? Wet or dry?

But talking about supplement one finds out that most of the growers have absolutely no idea how it works, what it really is and the choices they can make. Generally the price is the main buying point.

And this is strange to me. Because compost and casing are always changing during the year. This is mainly due to the seasonal effect on the raw materials. Straw is maturing in the storage, chicken manure will change in nitrogen level and peat is changing moisture depending on the season of the year. Manufacturing companies will react to that but smaller changes are inevitable.

To keep production at the same level or to enhance it, the supplement however can be changed to your liking. Most of the growers only know that there is a slow or normal release product. But it is possible to customise the supplement to the situation of that moment. Not just slow or fast but even pinpointed to a certain phase of the growing. To give an example: one of the farms I work on now wanted more activity in second flushes and a longer shelflife. In cooperation with the compost supplier and the supplement supplier they have now “composed” a supplement that can do that. Be aware though that it also needs adapting of the growing. You are putting more proteins into the compost so the activity changes too. This means that also the watering and the picking have to change.

But this way many combinations are possible.

There are different raw materials to mix and several processes to make the release time fitting your schedule.

A few remarks though have to be made.

It only works well in cooperation with the compost supplier. The ingredients of the supplement have to be an addition to the nutrients in the compost. So it has to fit the analyses of the compost.

The best way to use it if it can be mixed in at the compost yard. And this is only profitable with bigger quantities of compost. Mixing it in at filling is not as efficient as on the compost yard.

Do not just look at protein levels. Because some proteins are not available to the mushrooms and will still be in the compost at the moment of emptying the room.

So look at effective protein. This often is a matter of price. Good proteins come with a price.

And remember: good supplement makes good compost better. But good supplement makes bad compost worse.


One of the most seen disease in mushroom farms is the dry bubble, caused by the fungus Verticillium fungicola. Its easy to get an infection in the farm and because the disease is very infectious it can spread quickly through the whole farm. Especially in big farms, where many pickers are working, the dry bubble will spread very fast and can cause a lot of damage and be that bad that 3rd breaks may be lost. Pickers should be getting all the information about the dry bubbles so they can detect the infection in an early stage.

2021 Blog week 7 Article dry bubble

A dry bubble in a 2nd break.

Dry bubble is generally caused by spores around the farms in windy, dusty conditions. On filling days when its windy outside with dust in the air its very well possible to get the dry bubbles into the farm. When they are spotted before he 1st break, the infection came in at filling. Once inside it’s a matter of time before the spores are everywhere if not handled well. Hygiene on the farm should be checked and especially have a good look at all the materials that are used for your mushroom waste like stem bins. Spores of bubbles will be present there if not cleaned well and can be spread if materials are getting moved between rooms. Also pickers are a concern for spreading the infection. Spores are sticky so everything that gets touched after touching a bubble can get infected, be aware!!!, it can go rapidly.

Removing the bubbles is off course also very important. When the pickers don’t recognize a bubble and are picking mushrooms while touching dry bubbles it will be always be hard to control the infection rate. Educate them well and spread around as much information as you have to inform pickers about the diastase and the big risk it has on the results of the farm. Let them, or the picking lead, report the infection so a special crew can handle it the right way.

When the pickers recognize the bubbles, the next step is removing the infection as soon as possible. Makes sure when you remove the bubble you don’t spread the spores what will results in more bubbles within 4 to 5 days. Use a wet tissue to cover infected spots too avoid the spread and remove all the spot including the casing soil, using a plastic bag. Close the bag immediately after you have the bubble and surrounded casing soil inside and remove the bag from the farm as soon as possible. You can also leave it in the affected room and remove it after cook-out. After removing it use salt or ammonia to cover the infected area and inspect the area every day to see if the infection is spreading.

It all comes down to a good hygiene, organization and education. Infection can occur suddenly but if threated the right way can also be stopped rapidly. Organize it well so that infections get removed before rooms get picked or watered, those are moments when spores will spread. If everybody recognizes the disease and knows what to do and handles right, bigger problems can be avoided. Hygiene is key, not only for dry bubbles, and should never be underestimated.

Erik de Groot
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Chicken manure

Jan 26, 2021

Chicken manure is an important raw material in mushroom compost and for the composter as it is the biggest source of nitrogen. It is therefore vital to keep the quality as consistent and as high as possible. However, the quality of chicken manure is unimportant for the farmer, for him it is a waste product. So make sure you always pay attention to the following points yourself.

Achieve the best quality with: - a nitrogen content (N) of 3.5 to 4%. The higher, the better; - a moisture content between 20 and 50%. The majority of composters work with dry chicken manure. The most suitable type is manure from broilers. This contains a higher percentage of actual manure compared to the rest of the constituents such as sawdust.

Regular supplier
One of the main aims of composting is to create homogenous compost: ensuring that you always supply growers with the same quality of spawnable or incubated compost. This process starts with selecting your suppliers, including the ones who provide you with chicken manure. Always work with the same chicken farmer, who keeps his birds in the same way. If you do not have a regular supplier, then you will have to compensate for the differences in the chicken manure.

Analysis is essential
Even if you do use a regular supplier, analysing the nitrogen and moisture content in the manure remains essential, even though the results of the analysis are usually the same readings. If the birds are sent to slaughter earlier or later than usual, there will be a direct influence on the nitrogen content. You won't see it visibly in the manure, but it will appear in the analysis. Using the wrong recipe to blend the compost has immediate and far-reaching consequences for your mushroom production. You won't be the first person to have two weeks of bad production….

Distribute well
Distributing the chicken manure over straw can only be done well once. The blending done afterwards will not compensate for any bad initial mixing. Every single blade of straw must come into contact with the manure. You must avoid any large lumps of chicken manure ending up in the compost.

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