Plants are just like people. The fitter they are, the more resistant they are to diseases. But how do you create such a fit crop? According to the experts it begins at the roots, the heart of the plant. In recent years more attention has been paid to strengthening the root environment. Good bacteria and fungi in the slab help the plant itself to fight disease. This makes chemical products completely or partly superfluous. Tomato grower Geert Koot of Gebr. Koot, of Poeldijk, the Netherlands, became open to ‘another way of thinking’ with positive results.

The horticultural sector and research institutes both agree that crop protection in horticulture needs to change. Resilience and resistance of the crop have become the magic words. Already in 2010 researchers explained, in the Dutch journal Onder Glas, that due to the narrower range of chemical substances available and higher demands regarding residues, a different mindset was necessary. Even then a robust root environment was mentioned as the area receiving the least attention. Fortunately during the last four years producers and suppliers have not stood still.
For example, grower Koot, of Poeldijk, has been implementing the Fytopro system by Biopol Natural. Last year the supplier, a specialist in natural pest and disease control, introduced this system to promote strong and healthy growth. It consists of three parts: microorganisms; organic materials; and training.

Beneficial bacteria and fungi

Advisor Mark Hoogendoorn explains exactly what the system comprises. “Traditionally, we believed that the environment in the slab should be sterile. Now we are moving away from that. Instead of being reactive we are acting proactively. The multi-species products Hansebac and Hansespor form the basis for our system. We build-up a preventative wall of good microorganisms that help the plant to fight against unwanted fungi and bacteria and improve the uptake of nutritional elements. The plant feels so much better.”
The first product contains a bacterium – a strain of Bacillus subtilis – and various Trichoderma-fungi. The beneficial bacteria and fungi compete in the slab for space and food with harmful types. The second product includes Glomus intraradices, an endomycorrhizal fungus that grows very quickly on the roots of the plant and promotes optimal growth. The products also contain amino acids and vitamins which provide nutrients for the fungi and bacteria.

More hair roots

Geert Koot is unable to say exactly how the products work. But they do have a positive effect he discovered last season and again this season. He grows cluster tomatoes in the mid sector and sells them via the distribution centre belonging to the growers group, Prominent, to German customers. Last season he applied the system to 1.8 ha of his 4.7 ha in total.
“In this 1.8 hectare greenhouse the weight of the tomatoes always lagged somewhat behind the rest. I applied Hansespor twice – once in the propagation phase and once at the beginning of the cultivation phase – and applied Hansebac five times, according to the recommendations. Last year for the first time the tomatoes in this greenhouse were similar in size.” In particular, the development of the hair roots in May and June was, according to the grower, especially good. That resulted in better uptake of nutritional elements.
In the end, the weight of the fruit was 5% higher than previously. “In addition, in that greenhouse I had less trouble from white fly because the leaves were thicker. Therefore, I could cut out three of the sprayings. All in all, it meant the cost of this approach was good. It amounts to between 16.5 and 20 euro cent per square meter.”

No chemical products

Due to last year’s good results the tomato grower decided to treat all tomatoes in this way this year. The results are similar: more root hairs, stronger plants and less pests and diseases. If the latter is a result of the system is not clear. “This year colleagues are likewise experiencing little incidence of mildew, aphids and white fly, despite the mild winter. I haven’t needed to use any chemical control but that’s the same for everyone.”
If Koot will also achieve a higher fruit weight this year is difficult to say. “I am now growing a new variety that produces heavier fruits. Actually this is not so handy for me because the middle segment goes up to 125 gram. I still don’t know what I’m going to do next year.”
The grower adds that opting for the Fytopro-system does require a slightly different way of growing. “Because the plant develops stronger roots, I’ve been giving more water. Also, I have to be careful with hydrogen peroxide which I use to clean the pipes. If I’ve applied the natural product than I can’t clean with that for two weeks. Otherwise the beneficial bacteria and fungi would suffer.”

Heavier cucumbers

Jaco den Bakker, Dutch cucumber grower, of Brielle, has had similar positive experiences with the system. His reason for choosing this resilient type of production is simple. “In principle, nature has a solution for every problem. That’s why this sort of natural substance appeals to me.” The grower produces two high wire crops per year and applies both products twice on the first crop.
“I applied the products to my entire nursery of 2.5 hectare. My impression is that more root hairs develop in the slab. Yield across the board is higher than last year, by about 10%. I can’t say if I can attribute this entire rise to these products. We did have an early and nice spring. But I do think that the extra root hairs lead to a stronger crop and that translates into heavier cucumbers. It just makes it easier for the plant and therefore it grows better.”

Bio stimulants

Other specialists in the natural control of pests and diseases also have products in their assortment that strengthen the root environment. For the last three years Koppert has been offering, under the umbrella Natugro, products such as bio stimulants, natural nutrients and plant improvers. Jan Rodenrijs, responsible for ‘special products’ says, “We start by strengthening the existing root environment. We stimulate the beneficial bacteria and fungi that are already present. In this way they can win the war over the harmful micro-organisms in the slab.”
Also Fortafol, a bio stimulant containing humic- and fulvic acids, which the company has been selling since 2014, belongs in this list. “Think of it as a vitamin shot for the plant. It builds up resistance which helps it to combat diseases.”

Natural balance in the slab

Both Rodenrijs and Hoogendoorn think there’s a lot to gain by developing resilient cultivation. Rodenrijs: “It is becoming increasingly important to grow residue free. A strong root environment helps in that respect. The roots were a forgotten zone but they actually form the heart of the plant. Strengthening the organisms around the root ensures that the mineralisation process is better, nutrients can be better absorbed and the plant builds up natural immunity substances.”
Hoogendoorn also sees opportunities. “It is another way of thinking, whereby we create a natural balance in the slab. We know there is constant communication between the plant, the roots and the microorganisms. We are now discovering exactly how this interplay works. There is still a lot to do.”


A strong and healthy crop begins with a strong root environment. Various suppliers are launching natural products that introduce beneficial fungi and bacteria into the slab or indeed strengthen their presence. These seem to produce a stronger plant that is more resilient to diseases.

Text: Karin van Hoogstraten. Photos: Studio G.J. Vlekke