Dull with prolonged rain.
This Willow twig appears to be a little confused: new leaf buds are greening up. No sign of any damage or toxins.
A couple of shots of a very unusual sawfly larva on Alder - Platycampus luridiventris. This larva is unusual in a number of ways. First, it is flat: sawfly larvae are usually round in cross-section. Secondly, it is very slow growing, taking months to mature. It also eats sporadically, often resting exactly along the midrib of the leaf (as this one) for extended periods.
One might think that leaf-mining sawfly larvae would be flat, but leaf-mining sawfly larvae are more similar to the usual sawfly larvae than they are to this one, so it really is out on a limb. Quite fascinating.
Notice the rust on the undersurface of the leaf. I'd usually have this down as Melampsoria betulinum, which normally affects Birch, but is known to infect Alder. But it turns out there's a new rust infecting Alder - Melampsoria hiratsukanum, discovered in Japan in 1927, but now rumbling through Europe at quite a speed. The macro symptoms are a complete covering of the underside of the leaf, with associated leaf-curling and early leaf-drop. This tree has completely defoliated since the photograph was taken. I'll try to get some under the microscope.