Frans had never seen this before, but an expert helped him

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A ball on a stem in a box hedge
Nico de Man sent me something special. In his photo you see a kind of ball on a stem in a box hedge. He would like to know what this is. I immediately thought of a gall, but I had never seen this gall before. That’s why I brought in Willem N. Ellis. He is an expert on leaf miners and plant galls of Europe. Do you want to know more about him? then take a look at this link. When he saw the photo, he came up with the name crown gall. This crown gall is caused by a bacterium with the scientific name agrobacterium tumefaciens. He further mentioned that this bacterium mainly produces galls at the root collar. In addition, he indicated that, unlike most bile pathogens, this species is not tied to a more or less related group of host plants. So you can actually encounter them everywhere, but mainly or often on shrubs in the garden.

Hole in the ground
Angelique van Breukelen had a question last week about a hole in the ground and soil around it. She informed me that the ground was very wet. The area around the hole was also very compacted. When I saw the situation I first thought of a dung beetle. But since the ground was wet and compacted, I have come to the conclusion that it might be the work of a young mole.

Ben Viedebantt emailed me that given the droppings and the size of the entrance to the hole, a dung beetle should be the culprit. I then looked at the photo again. Then I saw that the entrance is indeed only a centimeter wide and not two centimeters as I first thought I saw. In addition, there are a lot of droppings and dung beetles use them in the side tunnels of the tunnel that they dig, which is sixty centimeters deep, as food for the larvae of the dung beetle. And maybe the wetness isn’t too bad. In short, on closer inspection the perpetrator is the female of a dung beetle. Probably the common dung beetle, also called horse dung beetle.

Molehills only in the light strip of a meadow
Francine van den Broek saw during a walk that molehills were only visible on the light strip of a meadow. She is curious why not in the rest of the pasture? Does the mole have a preference for certain types of grass? Certainly not the latter, the mole is a real meat eater and not a vegetarian. Moles only eat animal food, animals that they catch in their extensive tunnel system. The main menu mainly features earthworms. In Francine’s photo you can clearly see that the molehills are on the light part. I suspect that this is mainly not too wet soil. The surface of the rest of that pasture is probably too wet and moles do not like to dig in that area. Firm, somewhat moist sandy soil is more suitable. If they can choose to do so, they will. Earthworms also like nutrient-rich, moist soils.

Strange looking twigs in the Ardennes
Dinie Kuijten came across something special during a weekend in the Ardennes. She described it as twigs, but she wondered what it really is. This is ice hair. This phenomenon occurs during light frost and is therefore often only visible for a short time. How does something like this come about? Fungi often live in tree stumps, but also in dead trees, and during their metabolism – extracting food from the tree – water is released, which is squeezed out through very small openings in the wood (wood rays). In light frost this will freeze and you will see a hair-like, woolly ice structure. This is called ice hair or an ice beard. What is needed is high humidity. Otherwise you won’t see that successful formation of ice hair. The water squeezed out cannot then evaporate, but remains available for freezing. If it freezes harder or there is not high humidity, you will not see the water pushed out, the ice hair. You only encounter this phenomenon on deciduous trees, especially oak and beech.

A large bump on a tree
Margriet Hermans went for a lovely walk in the Loonse and Drunense Duinen last week and saw a tree with a large bump. She wondered what was going on there. The large bump on the tree is a kind of growth. We call this a tangle knot, but there are also other names for it such as masercrop, maser tuber or root tuber. Whatever you call them, they are tumor-like growth disorders caused by fungi or bacterial species. These fungi or bacteria cause uncontrolled growth in infected wood cells. The knots take on extraordinary shapes that deviate greatly from the normal growth pattern of the tree. They can stick to the trunk like large balls and even enclose the entire trunk or root. Even though these tangles grow a little every year, they do not slow down the growth of the tree.