Attack of the parasitic jelly fungus

 

This gloopy-looking stuff is Yellow brain fungus Tremella aurantia, growing on the dead branch of a tree along one of my favourite walks, in the Deerness valley, County Durham. It’s a jelly fungus with a rather sinister lifestyle, parasitising another common fungus, hairy curtain crust Stereum hirsutum, which you can just see, dying, on the underside of the branch.

The microscopically-fine hyphae of the parasite, invisible to the unaided human eye, creep through the decaying wood, find and clamp onto those of their host and eventually kill it. The damp, foggy weather we’ve had recently has been perfect for the growth of the gelatinous parasite.

There are two common species of Tremella in the British fungal flora - this one and Tremella mesenterica - which are virtually identical and can only be easily identified by the hosts they parasitise: T. mesenterica preys on another crust fungus called Peniophora, which often grows on gorse stems hereabouts.

And here, a little further down the dead branch bearing the yellow brain fungus, is some more hairy curtain crust, so there’s plenty more of its victim for it to feed on.

Tree sparrow courtship

 

Excited male tree sparrow, displaying to a potential mate, in the garden earlier this week. Flitting around her, cocking his tail, trembling his drooping wings and singing for all he was worth. He senses that spring is not too far away now. 

The Curse of the Black Spot

 

The curse of the black spot! Tar spot fungus Rhytisma acerinum, that disfigures sycamore leaves in summer, continues to develop on its dead, decaying foliage in the leaf litter. The black spots become increasingly wrinkly as winter progress, then hundreds of asci - microscopically small flasks filled with needle-shaped spores - develop along the ridges. When spring arrives the spores are released into the air, just in time for them to infect a new crop of sycamore leaves, where they germinate and invade through the breathing pores (stomata) in the leaf surface.

Tar spot fungus is less common on urban sycamores that on trees in rural areas and it used to be thought that this was because the fungus was susceptible to sulphur dioxide in polluted city air. A more likely explanation could be that the fungus is less common on city sycamores because their fallen autumn leaves tend to be removed by councils from public places, so the annual cycle of reinfection from dead infected leaves is broken.