"Plant-aphid combination is the solution"

Last week at the Horticontact in Gorinchem, Külling presented one of those solutions: the Artemisia. Artemisia is a plant with a very big fan, the aphid. The plant is usually infested from root to crown with these aphids, they feel so comfortable there that they are not going anywhere (they are, as it's called, monophagous). However, other critters like ladybug, wasp or other natural predators are fond of the parasite. They are attracted to the Artemisia, eat the aphids and lay their eggs there at the same time. So the aphid boosts the predators population, which subsequently move to neighboring plants, looking for more food.

One and one makes two, and yet someone must make the addition first before it is evident. We used to think: you've got a problem - aphids; a solution - pesticide; and a result – aphids gone. No flaw in that, right? However, the side effects have become annoying, so somebody reasoned: aphids + natural predator = aphids gone as well. This is still a solid conclusion and several companies in the horticultural sector now are doing very well with predatory mites, wasps and other natural enemies. The exciting aspect of the Artemisia Aphid is that these are not the problem, but the beginning of the solution. And moreover and indeed, you can economize on the predators.

But does it really work and is there no catch? Not if we are to believe Külling. "Combinations like these – which we call PREDAT, after PREDators ATtractor - are common in nature. It will not harm the plants and the aphids will do well, such combinations will ensure a constant production of food for predators. The release of natural enemies is good, but has the disadvantage that, when the predators have eaten the bacteria or the aphids, they will run out of food and even kick the bucket. Now you can breed them yourself and keep the predators alive. Several trials with different crops has shown convincingly that it really works this way, which in turn are hopeful signs that the market increasingly will pick it up."

The latter is done, but modestly. Already in 2012 a trial, in cooperation with a Dutch tulip grower, showed that the disease decreased significantly due to a little strip of Artemisia plants around the plot. The European Agricultural Fund saw its potential and subsidized the project. Gradually, more often, the plants find a spot between kale on the land, between trees at the tree nursery and in several greenhouse crops. One year ago the company placed a strip of plants among the hydrangeas at Plantenkwekerij P van Geest where, Claudia says, it has led to a large increase of the midge and has attracted many wasps.

Finally, a word about environmental awareness, according to Claudia lagging behind in the Netherlands. She sees its causes particularly in geographical circumstances. "In Switzerland there are many forests and proper functioning of these forests is important as protection against avalanches (snow and stones). Therefore no fertilizers are used. Also because of the many mountains and hilly areas more pristine nature has remained, intensification of agriculture is much more difficult than in the Netherlands, where you can easily drive around with large machinery. Moreover, there are more streams and lakes with fairly clean, drinkable water. The Swiss people like to go hiking in the forest and mountain areas and therefore feel more connected with nature than the Dutch, who have not been able to retain much real nature due to extensive agricultural intensification. Moreover, the former minister of agriculture and an important initiator of intensive agriculture, Sicco Mansholt, much regretted this in his twilight years. Because of these developments in the Netherlands, the world for humans and animals has changed significantly (the movie Georgica van Katelijke Schrama illustrates this wonderfully) and I find it alarming that now our children do not know how it was before."