treeblog update (Set C, Day 522): the downy birches (Part 1)

Downy birch No. 1 – the tallest of the birches.

It’s been three months since the last treeblog update on the Set C downy birches. They’ve made decent progress since then. See them as they are today (522 days after I planted them as seeds) in this update and see them as they were 96 days ago in the last update on Day 426. Since then downy birch No. 12 has died. That leaves us with sixteen seedlings - Nos. 1, 2, 4, 5, 10, 13, 14, 15, 16, 21, 22, 23, 25, 27, 28 and 30 – the tallest (No. 1) and shortest (No. 28) of which are about 12 cm and 2 cm tall respectively.

I repotted all the remaining downy birches this afternoon. They were long overdue; many of the seedlings had been paired together in their tiny plant pots since last year, and over the summer loads of self-seeded silver birches had sprung up in the pots. While I was at it I repotted Set A cider gum No. 3 (the Runt), which has been living in the same tiny pot since summer 2007!

Downy birch No. 2 – there was a caterpillar on the stem today, which I relocated onto a mature silver birch. The leading shoot has recently been eaten, probably by the caterpillar!

Downy birch No. 4.

Downy birch No. 5.

Some of the seedlings have tiny yellow spots on their leaves, like No. 10 below. I think these are birch rust (Melampsoridium betulinum), a fungus that causes premature defoliation. The fungi produces spores in the spring from last year’s infected leaves that over-wintered in the leaf litter; these spores infect larch needles, and later in the year the larch fungi produce different spores that infect birch leaves. According to Diagnosis of Ill-health in Trees by Strouts & Winter, “This alternation of the fungus between two unrelated host plants is the classic ‘text-book’, full life cycle of a rust fungus.”

Downy birch No. 10.

Downy birch No. 13.

Downy birch No. 14.

Downy birch No. 15.

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That was the first eight seedlings; for the other eight you’ll have to see Part 2!

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