May 2005. Minuscule scars in the tree's trunk betray the site of last year’s injection. Each elm is marked as a green dot on the land registry map of Pernis. Ten trees next to a car park on Deijffelbroekselaan, a lone elm near the football field a little further down the road, three more on the outskirts of the village, and six on a canalside near Willem Weysingel. A row of duck- lings follow a mother duck in the water. The trees are in full leaf. Their green makes a sharp contrast with the clear blue sky.

The two tree surgeons work their way methodically down the row of green dots. One of them looks at the map in their van and points out the elms requir- ing treatment, while the other wields the injection pistol. The ritual is repeated each time afresh. As he walks towards his next patient, the tree surgeon scru- tinizes its crown. When he reaches the tree, he thrusts the injection pistol into it with a short jabbing motion, at hip height. Rotating the pistol by 90 degrees, he pulls the trigger. He then withdraws it cleanly and chooses another injection site, about ten centimetres from the first. The process is repeated until the entire trunk has a circle of injections. Then the man cleans the hypodermic needle with a cloth drenched in disinfectant while walking towards the next tree and studying its crown. Meanwhile, his co-worker in the van ticks off the elms that have been treated.

The injection fluid is stored in giant test tubes in a refrigerator at the back of the van. The tubes contain a light blue translucent fluid with a suspension of a fungus, and have to be transported horizontally, explains one of the men. ‘Verticillium’, he specifies, half turning and talking to me over his shoul- der. ‘We inject a suspension of Verticillium. It was prepared by the University of Amsterdam.’

On the way to Hoogvliet, the men stop at a small side road leading to some allotments. At one corner stands a gigantic elm, swaying in the wind. Its crown has bare patches, like a worn carpet. The trunk is overgrown with ivy.