Briefly about Strawberry Cultivation

Growing the fruit that is a favorite for many of us --given there is an adequate demand for it-- is a profitable agricultural business.

In the Netherlands I took a look at the workings of a family business specializing in growing strawberries. The current farmer is the third in the line but his sons already participate in the work every day, they operate machinery with ease. Also, any of them could take the management over from their dad. The farm is contemporary, organized through well organized processes in place, most of the tasks are also supported by machine power. Irrigation is in use to continuously supply the strawberry field with water. In the ground beneath all the fields run a net of hoses with sprinklers sticking out. The main building of the farm acts as a garage for the machinery, storage, packaging unit and the small local farm market. This is also where the refrigerators are. After picked, strawberries are chilled to 5-7 Celsius because they can be stored for up to a week at this temperature. The cargo bay of the trucks is also refrigerated.

Up to 3 tons of strawberries are prepared for wholesale every day. Quality expectations are very high, 'extra' is practically the only level there is. Every day hundreds of kilos of low-quality strawberries are thrown into metal bins.

The farm grows two types this year: Sonata on 16 fields, Elsanta on 4. Every field is 72,000 square meters.

After this conscise introduction, let me describe the cultivation of this popular summer fruit in detail.

The precursor of all current garden strawberries was the product of a spontaneous cross-polination between species. The north American Fragraria Virginiana crossed with the south American Fragaria Chiloensis. That's what resulted in the Fragaria x Ananassa, which is a self-polinating hybrid strawberry specie yielding big fruit. Every specie cultivated today is a descendant of this hybrid.

Almost everyone knows the wild strawberry (Fragaria vesca). Due to its fragrant and delicious small berries it was a common fruit grown in gardens all across Europe up until the discovery of America. Strawberries are classified as Angiosperm, Eudicot, Rosale and Rosoideae. The central part of the plant is the rootstock, from which the roots grow downwards while the leaves and flowers grow upwards. The offshoots responsible for vegetative reproduction grow from the buds in the armpits of the lower leaves. The generative reproduction of the strawberry is less significant. Species important in cultivation are reproduced using young plants growing on the end of the offshoots. The vast majority of the plants are sold as "fridge", because these yield a rich produce in the year following the spring at which they were transplanted. "Fridge" means a sterilized and batched young plant ripped of its leaves. These batches are slightly dehydrated then packed in plastic bags. They're put in a cold store between -1 and -2 C. Temperature in this case can vary only by half a degree celsius, because around 0 degrees life processes start to return in the plant while below -2 C frostbite damage occurs. Following their harvest in November and December, fridge plants can be used by the next summer. After transplantation rapid growth describes them.

Strawberry plants are introduced late in the summer (typically between the end of July and beginning of September). Late introduction is to be avoided, since plants wouldn't have enough time to prepare for the winter and also the buds would have a hard time developing during the next year. Growth of the buds is started by shortening of days. A good autumn determines the produce of the next year. Strawberries are very demanding despite their simple structure. If you think about it for a second then you'll realize why it requires so much water and fertile soil; we are those who demand very much from it to begin with. A strawberry plant must yield many sizeable fruits. Of course everything was supplied on the Dutch farm. The fact that a field of plants are kept alive only for 2-3 years is another matter entirely. Plants older than that grow more offshoots, which render them unable to give big berries. The simplest solution is to get rid of the field and make use of it with a secondary crop. The soil must rest for 4-5 years after strawberry in order to reduce the number of pests that threaten it. A practice that leads to erosion of the soil is to sterilize it and grow this particular plant again the next year.

 

In this picture you can see a handful of the soil from the strawberry field in my palm . That small white pellet is chemical fertilizer, which was spread evenly and abundantly in the top layer.

In South Netherland they grow strawberry on sand. The great benefit of sand is that it gets warm quickly in the spring. It is very easy to dig, but it also has serious drawbacks. It's low on topsoil therefore it hardly keeps any moisture; water literally "runs" through it. The main building of the farm stored different kinds of chemical and organic fertilizers of which the latter is added to the soil before deployment of the plants. The organic fertilizer substitutes for the lack of topsoil. Its nutrient content is utilized more slowly and it spurs life in the ground.

Strawberry requires nitrogen the most of all nutrients, but its overdose must be avoided as it encourages leaf and offshoot growth and makes berries soft and hollow therefore unfit for sale.

The second most important nutrient is potassium because it determines the quantity and quality of the product. The lack of iron, a micro element, can pest strawberry on calcareous soil. That said, strawberries require an array of different micro elements, the effect of which I need to study further. These include but are not restricted to magnesium, boron and manganese.

During the growing stage, fertilizers can be added to the irrigation. This nutritional watering causes the plants to yield a 15-20% higher fruit quality and quantity. Leaf fertilizer may be also used.

The picture above shows a container filled with calcium-nitrate. It stands next to the pump station that supplies the irrigation system.

In the Netherlands water is a central issue. Firstly, the land lies deep and for this reason the battle with sea is non-stop, secondly, clean-water supplies have almost disappeared due to decades of industrial activities. To conserve drinking water supplies, the country has enacted strict policies regarding preservation of the environment, water is also very expensive due to these regulations. The highest costing item on the whole bill of running a farm may very well be the cost of irrigation.

In this picture you can see beams of water leaving the sprinkler heads, drawing a rainbow as they do. This pinch of lyric sight dampens the fact that running an agricultural business is hard work. I took a good look at the farmer's hands, they were dirty with soil. I knew very well what he meant when he put a strong emphasis on how hard this job really is. My grandparents were farmers. My grandmother toiled the land when she was a young child, but kept the garden tidied behind the house until the day she died. So, when you eat the gift of the land with both hands, always remember that a piece of fruit is the result of lots and lots of effort. Effort by both humans and machines. There is a huge price tag on the way humans live today.

Now let's get back to strawberries.

Fields connected to the farm are cultivated using the double-row method. This solution leaves enough light for individual plants, maintenance is easy but protection of plants requires extra attention.

Rows are 50 centimetres away from one-another, while there is 25-30 centrimetres of distance between individual plants. Between double-rows runs a 70-80 cm wide pathway. The ground is layered with straw to ensure the soil retains enough water and to keep fruits clean. The picture shows a field that was planted last year and is in its flowering phase. Because the plants were still relatively small, you can still see the double-row layout and the neatly placed layer of straw.

The farm also had roughly 20 walk-in plastic tunnels. These contained young plants for early forcing. In these I could take a good look at a different cultivation method, one that's also prevalent in Hungary. Forcing brings forward the season of strawberry by about a month, which brought fruitation in the walk-in tunnels to early June. These fruits were getting smaller because they were products of flowers that had produced strawberries many times before. That said, strawberries under the plastic tasted better than those that grew on an open field. It was impossible to resist the scent, which made me fill my stomach until it put the 'Full!' sign on the door. Just a tip: don't go near where one type of product is made, or you'll have to deal with a shockingly undiluted experience. I'm still haunted by the scent of strawberries.

Next to each plastic tent were two boxes for transporting bumblebees. With these mobile accomodations the farmer helped the polination of flowers. Good polination is essential when producing strawberries, it motivates the growth of the stuff, which turns into the actual fruit. Under-polinated carpel causes the body of the fruit to end up deformed or undersized. For this reason the farmer used bumblebees to help the process. This solution is also in use in Hungary.

I saw home-made bee-hives next to the flowering strawberry fields. The plastic walk-in tents used the classic double-row method.

When following the black-foil Dupont method, porous pipes are run beneath the ridges. These pipes distribute water with a pressure just a couple tenths above the atmospheric. The water may, and often also does contain fertilizers. The areas between rows are covered with white plastic-foil to reflect sunlight back at the tent and to the plants. Conversely, if black foil was used -- which color absorbs light -- it'd cause the already hot tent to overheat.

In the picture you can see fruit bearing strawberry-rows. Unfortunately, I don't know which variety was grown there, but it was nothing short of great to eat up.

In this picture you can find the shortened 'lineage' of Sonata. The line could be continued further back, but I got stuck on the second pair. All six Sonata 'ancients' are propagated in the Netherlands. Elsanta and Gorella are both very common and popular in Hungary.

The main produce of the farm is Sonata, which is the mid-early ripening hybrid of Elsanta and Polka. It ripens 1-2 days after Elsanta. Produces stiff, big, shiny red-orange berries in abundance. Its seeds barely sink into the meat and are yellow. The berries aren't prone to size loss and are consistently regular shaped. There are very few deformed fruits. It's easy to store and transport. It can be grown on the open or under a walk-in plastic tent. It isn't prone to powdery mildew (Sphaerotheca macularis), but it is to withering (Verticillium) and rotting (Phytophthora cactorim, Rhizoctonia fragariae). It requires magnesium and iron-manganese supplies need to be taken into consideration. In the case of Sonata, Botrytis cinerea and Rhizoctonia fragariae are the two most important diseases to fight against. Because the fruit can withstand cold, the berries are vulnerable to heat; they may leak fluid and shrink. For this reason cooling of the tents is important on hot summer days. Given proper care, the amount of produce reaches that of Elsanta's. Since its berries are bigger, more appealing, its cultivation yields higher profit. It hasn't been a popular type in Hungary, although I'll have to gather more data about that.

This picture shows the boxes used for harvest stacked in the main building of the farm. Six of these are put on each of the harvest hand-carts. Each box contains ten smaller plastic holders capable of taking roughly 200 grams of strawberries. The hand-cart also had a small blue box for discarded fruits. Those also had to be collected so the potentially rotten pieces wouldn't contaminate the healthy ones.

In this picture you can see the strawberry field from behind the cart. Of course the worker doesn't look at the horizon during the work from 6am til noon, rather at the rows to the left and right. The cart carries six large boxes and one small. When one box is almost full, pushing the hand-cart forward becomes surprisingly difficult. Especially because the harvest requires the worker to kneel. You can imagine how physically taxing it becomes to kneel and crouch like that for a hundred meters, while turning your body to the left and right as you search for ripe fruit. Ruthless work, but not because of the job itself. Rather the crouching position is highly unnatural for the human body. That's why 900 out of 1000 workers drop out.

Although machinisation of the harvest is partially solved, machines can only pick strawberries for the canning industry. Strawberries are still picked by a human work-force for fresh consumption and deep-freezing. It requires the most human workers. The Dutch farmer knew the work-force requirement of his own farm very well. He employed around a hundred workers who were picked from the thousand that attempted the job so far. The job itself took care of the filtering, it's that difficult to keep up with.

The Dutch don't pick strawberries with a short stalk, they rather pinch the fruit between their fingers and rock it back and forth until the stalk lets go. Interestingly enough, it comes off with the small green cup still tightly

attached. The rest of the stalk for this reason takes some effort to remove. Harvestation is easier than removing the small green stalk from the berries.

Here is a parting picture about the field, taken from a distance. It captures some of the beautiful resemblance the Souther Netherlands have to the Great Plain of Hungary. Although I only spent a week in the Netherlands, I gained a lot of experience. Of course, my knees let me know they'd hate me for a life if I were to continue their torture. Unfortunately, I was rather slow in that kneeling position. I couldn't get faster and reach the norm, which was around a hundred kilos per person. This much can actually be collected from the big berries of Sonata. Seasoned, experienced workers could pick way more than this. I lagged a good 50 metres behind the professionals, dragging my screaming knees slowly. Regardless the foam inserts in the workers' waterproof trousers, regardless the fact that some wear knee-protectors, it's still down to the individual if their knees can actually take the unusual load or not. Mine couldn't.

Despite my failure this short trip was undoubtedly beneficial.

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Thank you for reading my blog. Knowledge is for everyone.
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Az eredeti változat itt olvasható el. A cikket Nagy Lajos fordította le. Sajnos nehezen boldogulok az angollal, pedig jelentősen javítana az életminőségemen a nyelvtudás.