For years Greenyard Horticulture has noticed that their substrate mats are more resistant to Crazy Roots. Little is known about Crazy Roots, however, and this is why the company is working with institutions to conduct intensive research. Last Thursday they caught up with the sector.
The fact that excess root growth is caused by Agrobacterium rhizogenes is now widely known in the sector. The bacteria changes part of the plant's DNA so that there is excessive root growth. The plant also becomes vegetative above the ground and the fruit setting and formation are negatively influenced. How this works exactly, however, is still unknown. How to control the Agrobacterium rhizogenes in particular is an important question. This is what Greenyard Horticulture is researching.
Their test show that the pH of the substrate is positively correlated to the presence of Agrobacterium, said Oliver Grunert of Greenyard Horticulture last week at the Proefcentrum Hoogstraten meeting. "This explains why there are barely any Crazy Roots in our growbags. Due to the peat the pH is more stable and you see there is less bacteria present, even compared to coconut." Through research we now know around which number the threshold for the ailment lies.
Rich soil life
Earlier tests suggested that the right physical chemical factors combined with a rich soil life provides protection against crazy roots. To Oliver it seems like the soil life present creates a kind of dike against bacteria. "This is the big difference with inert stone wool. There is just no space for it in natural substrate. You want your plant to be strong due to the microorganisms present." Due to the naturally present population of micro organisms, a disadvantage of this is that the use of biocides can disrupt the soil life and give the crazy roots more space.
Greenyard also researched the use of organic fertilisers and fertilisation with algae. "We get sweeter and more red tomatoes with algae," Olvier shows. "On the other hand the yields are lower and there is more nose rot when algae and organic fertilisers are used compared to the control group. "This means it isn't economically profitable yet. We are looking for the combination."
More research
Greenyard Horticulture isn't the only company researching Crazy Roots. In Belgium they have been working on research into organic prevention since November 2013. "We are looking at the cultivation technique, the irrigation system and the organic control," says Rob Moerkens of the Proefcentrum Hoogstraten. Here the Growbag is being compared to the other cultivation systems and cures. As the contagion is sometimes hard to spot, and mainly manifests differently on different substrates, they are also taking pictures of the material. This is how they monitor the development in stem thickness and leaf width. "The stem thickness is seen as the main parameter in judging Crazy Roots and we see no increase here on the Growbag."
As far as cultivation technique on mineral substrates goes it seems that if you do nothing you could lose 8% production just like that. Cutting open the mats is enough to prevent this in some cases, but this causes problems with the mats drying out and such. Breaking leaves turned out not to do anything.
The organic crop protection agents were also considered in the tests. It seems that those of Biopol Natural and Koppert Biological Systems both affect the attack. "Or it's visibility at least," says Rob. "This year it's too early to draw conclusions, but we will certainly continue."
For more information:
Greenyard Horticulture Belgium NV
Skaldenstraat 7a, 9042 Gent, Belgium
T +32 9 218 03 48
www.greenyardhorticulture.com
www.greenyard.group
For more information:
Greenyard Horticulture Belgium NV
Skaldenstraat 7a, 9042 Gent, Belgium
T +32 9 218 03 48
www.greenyardhorticulture.com
www.greenyard.group