I am writing this blog on November 2. 2020.
It is the warmest November day ever. The outside temperature today will hit 20° C. Normally this time of the year in Europe growing is fairly easy. Older growers always say: just open the doors and let the outside climate do the job. This year and probably oncoming years the situation is different. It starts with arable crops being harvested later than normal. The potatoes are still being harvested and the corn is only gone this week. Meaning that there was a lot of dust and organic material flying around. Especially since many farms are situated in rural areas. All this organic matter being airborne has caused a big problem with Mycogone and verticillium. But another and maybe even bigger problem is that the insects are still there. It is known that phorids stop flying around 5° C and sciarids even fly till it starts freezing. And that situation seems to be far away. And that is why I see at many farms that the infection with sciarids was almost gone but is returning (rapidly) again. Because their hiding place in the corn is gone. Just at the moment when many farms are scaling down on fly control. The combination of these two factors, the insects and the dust causing bubble, is a dangerous one which may last for another month or so. What to do about it? Trying to kill the verticillium or Mycogone is the first thing growers do but if the vector (insects) to carry the spores is still there the problem stays. That is why I always try to aim at the insects first. In this case practically always a problem with mosquitos or sciaridae. Often chemicals are chosen and many times a combination of a short term chemical by fogging and a long term chemical as a drench on the casing soil. But lately I see very good results (as good as the chemical treatment) with the biological control with nematodes as a drench on the casing. In price there is not much difference but in application it does make a difference. It is not dangerous for the person who applies it and it is not dangerous for the environment. On the other hand it is noticed that many supermarkets want a clean, read: chemical free, product. And nematodes are not regarded to be dangerous. Even more, farms use it as advertising for their product. It is the same as with my own business “Akkie’s Tuin”. An apiary and orchard. We do not use chemicals, only biological control and we use that as a selling point. We notice that we can get higher prices for our products by working organic. The only thing is that the customer needs to know what you do. With the product goes the story about what you do. So if you have an insect problem at the moment take this into consideration. A few remarks on the use of nematodes. Make sure they are delivered fresh onto the farm and put them into the cold store right away. Overheated nematodes will die. When using them, you need sciarids on the farm. The nematodes feed on the larvae of the mosquito and if there is no food they will die. The manual about using the nematodes often says that they have to be applied directly after casing the compost. I however have better experience in the so called split application. So not the 2 million nematodes per m² directly after casing but 1 million on the casing day and the other 1 million 4 to 7 days later. I prefer 2 days before the start of the recovery period as the last day of application. So practically this means the second application on day 4 after casing. If you apply it a day before recovery you knock back the mycelium too much.

But whatever you do, do it now. If you think that frost will stay away for a while and you see some sciarids flying around, waiting is not an option. Especially is you also have a bubble problem. And the difference between sciarids and phorids is fairly big. As a reminder: Phorids have a nasty smell if you smash them under your finger, a sciarid has no smell. Phorids are fast moving. They walk fast. A sciarid has the tendency to just sit. Phorids are a lot smaller and the antennae are practically not visible while the sciarid has large visible antennae.

Climate control

Oct 12, 2020

A good climate control is of course vital for every mushroom grower even more if you want to stand out with the quality of the mushrooms. One of the most asked question I get as consultant is: How can we get better quality and how can we keep the quality of the mushrooms good until the end of the flush? Now, of course the quality at the end of the flushes will always be less than at the start, no illusions there. But improvements are always possible and most of that you can get from an ideal climate.

Before we had more advanced climate installations with more options, we always controlled the rooms on Air temperature, Relative humidity and CO2. However, with the new systems coming on the market there is a lot more to learn than we think and controlling rooms, especially in harvest stage, on moisture deficit, inlet moisture control and even measuring systems for evaporation are used.
To understand the difference between all the systems you need to know exactly what the Mollier Diagram stands for and if you manage to run the system well you will see advantages, especially in quality of the mushrooms. The Mollier Diagram is crucial in mushroom growing and climate computers make the changes in the room based on that Diagram with the Absolute humidity (AH) as the biggest factor. Let’s me explain a little bit more about of those controls, the moisture deficit.

As we are changing air temperatures in the flushes you will see in the Mollier Diagram that that will create differences in evaporation as we change the temperature but leave the RH the same, with other words, we change the AH. By controlling on moisture deficit we will maintain a constant evaporation, what will benefit the quality of the mushrooms, no matter what the temperature differences are. The computer will calculate the right RH for the current air temperature, to keep the same evaporation in the growing room.

Moisture deficit is the difference between the current absolute humidity in the room and the maximum possible absolute humidity at the same air temperature. Once this value is constant the evaporation capacity of the air is also constant.

To use this in a practical situation of course first of all you need a climate control computer that supports the moisture deficit system and change it from RH to moisture deficit control, in the computer that will be named as Absolut humidity control. Ideally this is linked with humidity control of the inlet air to get the best benefit. The mushrooms will have a constant evaporation and that will benefit the quality as changes in evaporation will disturb their growth. The mushrooms will get less water stems and go softer in a later stage what would give an extra picking days benefiting the yield as well as quality.

I recommend to change the computer 1 day before you start harvesting the flush from RH control to moisture deficit control. When you changed the control, set the AH in the computer so that the RH is at the same level as you normally run it in the flush. So if you normally run the flush on 17.5 degrees and 89% RH, keep the air temperature the same and set the AH so that he calculates the 89% RH as set point. Keep 0.2 difference between minimum and maximum AH. From that moment forward you let the computer calculate the right RH and change the air temperatures as you normally do, until the end of the flush. After the flush put the system back to RH control.

The only way to find out is try other controls to improve quality. Many option are out there and based on results on other farms worth trying. If you start and are seeing any improvement? Learn more and keep doing trials, good luck.

Erik de Groot
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The corona crisis makes traveling for a consultant difficult, if not impossible. That is why the question asked by Marco Deckers came just in time.
Henk, we are looking at picking on a different angle on our farm. GTL Europe is building my new farm with the tilting shelf system and we are creating a sparring team to start this up.
Now, that’s what I call a challenge.

akkies tuin picking from a different angleThe system is so completely different that picking has to be re-designed.
The pickers are not standing sideways to the shelf but they are facing it and they have to learn to pick with two hands at the same time.
At the same moment we have to get them on a level where they can work in a high tech environment where they have to keep an eye on moving belts, tilting shelves and moving trollies. And yes, they also have to learn how to pick mushrooms at a good speed.

The first thing we did was to create a good team of new pickers and new supervisors. Because also in supervising the job is different. It is very simple to control quality and size of mushrooms because every mushroom you see coming out of the room on the conveyor belt has just been picked. So corrections on size or quality can be made immediately. You do not have to wait for the first trays of mushrooms to come out of the room. So supervising is easier. The biggest change for the supervisor in this case is more in the logistic and technical areas.
For the pickers the change is bigger.
Picking with two hands sounds nice but everyone is either right- or left handed. Only few people are double handed in their natural movement. This means that every picker has a preference to pick most mushrooms with one hand and a few in the other hand.
But this was actually easier to learn than expected. One thing that helps is the picking position. The height can per perfect so the picker does not have to bend the lower back or overstretch arms. It was simply a trick the had to learn. A mind set to position the arms that way as if it is one movement. The one thing they had to learn was to pick within eyesight and keep the arms together.

All together it is surprising to see that most of the pickers like the system a lot. Picking is fast and at the end of the day nobody is complaining about neck or shoulder problems. The usual complaints of a picker after a long day of picking. It has to be said though that the picker has to be told to put the platform at the right position. Pickers all over the world are a bit stubborn and if it is nearly right, for them it is okay. But it may not be the perfect position.
Looking back now we can draw a few conclusions.
It is better to start with pickers who have no experience in picking.
The supervisor is the main person in the team. Even more than in a traditional system. There is more technique involved and the supervisor needs to see possible problems fast and solve them
People have no problems with the environment full of moving parts. Even the opposite, they like it because it makes the work easier.
Training is essential. That is why at the moment we are writing a manual for that system on that particular farm. And again, in the training the supervisor (picking manager) is the key person.

And as a consultant you have to keep an open mind about the system and the way of picking. From the start till now you can say we started with system 2.0. Now we are already operating on system 5.0. It is evolving and growing in an exciting way. That is the benefit of having a good sparring team with the farm managemant, building company, picking staff and consultant.


Mycogone or wet bubble is making its appearance again on many farms. Growers are looking for all different chemical solutions and are gearing up hygiene measures. Most of the times too late. Because chemicals also do a lot of damage to the crop and the schedule often is simply too short to give the right effect.
And as for gearing up hygienic measures, one real big grower once said to me:
If I have no disease I am really worried because nobody is paying attention anymore to hygiene. If on the other hand I dó have a disease everyone is doing what the can.
For Mycogone it is important to look at the origin and take that away. It is a fungus growing in soil, sand or rotting materials. That is why many growers point at the casing soil. Not really correct because it does not grow in deep dug peat because the ph is too low. But casing soil polluted with sand will be infected so it is better to look at transport, the act of casing the room and the circumstances around that.
The spores of Mycogone are not airborne by themselves. The need a vector of taxi. In most of the cases this is dust, animals, people or insects. Especially dust is a factor that is hard to control.
The moving of soil in the vicinity of the room that you are filling is a guarantee for infection. So is the harvesting of agricultural crops near the farm if the wind is blowing the dust to your farm.
So keeping the room that you are filling and the casing soil out of the wind to avoid dust is already a good thing. So is cleaning of the trucks before they enter the filling area. And flushing with plenty of water may be more effective than using a disinfectant.
At the same time keep the whole area wet so dust cannot fly around.
For growers who use casing soil in plastic bags, do not bring them into the room or wash them before use. Plastic is electro static and attracts dust.
It is a myth by the way that Mycogone comes in with the compost. It cannot grow in phase 3 compost.
The following point is people. If the filling team walks through grass or sand during filling, again that is a major failure. So is not wearing clean clothes at the moment of filing. Also do not let the filing team have their coffee break in the same canteen used by the pickers. When they return to the job they may be covered in spores.
A thing harder to control is insects. If you have an infection of sciarids or phorids on the farm an outbreak of bubble is likely to happen. But one of the next blogs will be about these creatures.
One general remark: keep the farm and the vicinity clean at all times. Free from rests of casing and compost but also free from paper, cardboard and other mess. This will help to fight all types of disease.


Europe is now at the time of the year summer will burst out. And every year the same growing problems occur at this time, getting worse and worse every year. Summers seem to get hotter and it is time to adapt before real growing problems are there. There are a number of things growers can do but of course a good cooling system is a must. Well calculated, fitting the circumstances of your own country. But even the best cooling system will not cover everything. If we take the summer temperature last year in Holland at 42° nobody has a cooling system which will handle these extreme temperatures in our country.
If at the same moment also the relative humidity is high it is not only cooling but also the heating that counts. And that brings me to the first mistake many growers make. In summer switch of the heating system. Its hot enough outside, I do not need heating. Wrong!!!

De-humidification only works if the cooling can work in combination with a bit of heating. So, by switching of the heating the system can make the air dryer anymore. And you need dry air to cool a hot room. The easiest way to cool a growing room is to give water to the casing soil. The best way is to give many small quantities up to 2 litres. That can be evaporated again. Spread the watering over 24 hours. The dry air coming into the room will take care of the evaporation and will help cooling the growing room. Keep the casing soil wet but the floor as dry as possible. That is why I do not close the room completely if the outside is hot but dry. It is possible to use air which is much higher than the compost temperature as long as the incoming air is dryer than the air in the room.

In the mollier diagram one can calculate how much fresh air is necessary to absorb the evaporated water in the room. And for that cooling by evaporation you only need a few litres of water extra. No extravagant quantities as some growers tend to do. An extra help will be some mobile coolers on the farm. They can be placed into the room just before the heat surge is starting. The price of such a mobile cooler is a lot lower than the costs of losing a room.But in the end, judging a room is important. If compost is active and the C/N ration is relatively high one can expect activity. It is of outmost importance that cooling starts before the surge starts. Once a compost is going up it is hard or impossible to stop it.


Floor humidity
If you want to maintain a natural climate in the growing room during the recovery period until about five days after ventilation you should water the floor and walls of the growing room. Do this at intervals of between one and six hours. You will notice the result as a shock effect in the graph displaying the RH and growing room temperature. I will explain what is actually happening and how to avoid a shock effect.

The effects of floor humidity
If you stand in the growing room while the watering system is wetting the floors and walls you will see several things happening. The watering system contains nozzles which moisten the floors and walls with water droplets and it also creates tiny, airborne droplets of water. If you shine a torch you will see the little water droplets floating in the air. Eventually the droplets fall onto the beds and the sensors of the climate computer. This has two disadvantages:

1. Climate disruption
The water droplets which fall on the sensors are cold. They disrupt the climate, which causes a response from the computer. The effect is minimal but your aim is to keep the climate as constant as possible. This uses the least energy.

2. Abnormalities
The water droplets fall on the beds where the mycelium is recovering. These water droplets disrupt pinning, resulting in cluster-shaped abnormalities which develop before the first flush.

How can you prevent this?
Make sure that there is sufficient water pressure (see photo) while the floors and walls are being wetted. In this way you prevent the droplets from floating in the air. In addition, make sure that the whole floor is wet. This approach means that the floors dry out less quickly, ensuring that the climate in the growing room is more uniform and favourable for growth.

Mark den Ouden

Next courses:
Live training Mushroom Signals Essentials: 12 – 16 October 2020
The e-learning course offers the theorical knowledge of the Mushroom Signals book that is necessary for the live training sessions. During live training, all participants have the same basic knowledge, so there is plenty of time to deal with individual questions. This is not only valuable for the participant but sharing knowledge between the trainer and the other participants makes the theory more relevant. The everyday practice at the composting facility and the mushroom farm of the participants will also be discussed.
Other courses in 2020: 30 November – 4 December 2020.

Always available:
E-course Mushroom Signals Essentials

More info about the course see www.mushroomoffice.com


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