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June 2007

treeblog seedlings annihilated (Day 69)

I come bearing bad tidings. After returning from a camping trip in the Lake District, I was shocked to discover that the treeblog seedlings have been reduced to a pitiful number. I think it must be the damn slugs. So some changes have been made. All surviving seedlings were carefully transplanted from the seed trays into individual pots yesterday. The seedlings should benefit from deeper soil, and a slightly different soil mix (half compost / half garden topsoil, as opposed to 100% compost). And drastic times call for drastic measures. Up until now I have not used slug pellets, but a liberal application is now laid down. The survivors must be protected at all costs!

Photos taken yesterday (Day 69).

In a horrific turn of events, the beta Scots pine seedling was devoured (by a hungry slug?) sometime during Monday night. After recovering from this hefty blow to treeblog morale, I transplanted the remaining root into the new pots but I am doubtful it can make a recovery. Therefore, out of the entire packet of Scots pine seeds that I planted 70 days ago, only two ever germinated and only one is still with us.

The cider gum seedlings have similarly suffered from bad fortune. Only three now remain. When I was transplanting these from the seed tray, I noticed little bits of half-devoured cider gum stems and leaves all over the shop. Bloody slugs.

The grey alder seedlings have also seen a decline in numbers. But four seedlings have survived (plus a recently germinated seed). The first proper pair of leaves are developing nicely in a couple of the seedlings. (The fourth seedling from the left in the photo is a weed that got in there by mistake).

The new set-up. Top row, left to right: Beta Scots pine; alder No. 1; alder No. 2. Middle row, l to r: alder No. 3; alder No. 4; alder No. 5 (seed). Bottom row, l to r: cider gum No. 1; cider gum No. 2; cider gum No. 3. The Alpha Scots pine is in a separate, larger round pot.

Posted in The treeblog trees

Grey alder No. 4: most advanced seedling

The grey alders are vying with the lonely Scots pine for seedling supremacy! After not a lot of growth-excitement, the alders seem to be finally going for it! The current champion is grey alder Number 4, with one lovely new leaf being quickly followed by another.

Grey alder No. 4 photographed yesterday (Day 74).

In light of this competition, the Scots pine is now building up for a second rosette of needlings! Photos coming soon!

Posted in The treeblog trees

Derwent Dam tree photographs

alder in front of Derwent Dam

Alders (Alnus glutinosa) in front of Derwent Dam.

Derwent Reservoir, in the center of the Peak District, has quite an unusual style of dam wall. Instead of the grassy embankments used to dam most reservoirs in the vicinity of the Peak District, the dam wall at Derwent (and neighbouring Howden Reservoir) is much steeper and faced with huge stone blocks. Large gothic towers loom at either end of the dam wall, and in wet weather, water overflows between the towers and cascades down the great stone wall in a magnificant spectacle.

elder inflorescence in front of Derwent Dam

Elder (Sambucus nigra) inflorescence in front of Derwent Dam.

During World War II, Derwent Reservoir was used for bombing practice by the RAFs 'Dambusters' (617 Squadron). The dam at Derwent was used as it was of a similar design to those in Germany's Ruhr Valley, which were to be the target of RAF bombing raids; with the dams destroyed and the reservoirs empty, it was hoped that German industry would be seriously impeded and thus their war effort hampered.

rowan (mountain ash) in front of Derwent Dam

Rowan a.k.a. mountain ash (Sorbus aucuparia) in front of Derwent Dam.

The barrel-shaped 'bouncing bombs' used by the Dambusters were designed by Barnes Wallis. The bombs were dropped spinning rapidly backwards at a low altitude in order for them to bounce over the reservoir surface to reach the dam wall. They would then spin downwards to the base of the wall before detonating.

Scots pine in front of Derwent Dam

Scots pine (Pinus sylvestris) in front of Derwent Dam.

I visited Derwent Dam this afternoon and took these photographs. Thanks to the recent very wet weather, the water rushing down the dam wall made for a very impressive sight.

hawthorn above Derwent Dam

Hawthorn (Crataegus monogyna) above Derwent Dam.

Posted in Gone for a walk

treeblog seedling update (Day 81)

Good news! All seedlings that made the transition into the new pots are still alive and well, with the possible exceptions of the beta Scots pine's root (unknown condition) and grey alder 5 (condition also unknown). The recent weather has been awful here. According to the newspaper, South Yorkshire had a whole month of rain in just two days! We've seen some local flooding and plenty of springs popping up all over the place. These generally find a road or lane to follow, and have caused quite a bit of damage to the road surface in places. All of this precipitation has left the treeblog seedlings in quite waterlogged soil, but the worst of the weather now seems to be behind us and the soil is returning to its non-saturated natural state.

Photos taken yesterday (Day 81).

The Alpha Scots pine seedling is looking strong and healthy. Its second rosette is coming on apace, and it has become an important support for a small spiderweb.

The grey alders are likewise doing well for themselves. The most advanced seedling, Number 4, has fleshed out a second proper leaf in the past week, and looks set to produce a few more!

The good news continues! The leading cider gums, Numbers 1 and 2, are both in the middle of squirting out their second pair of proper leaves. Cider gum 1 is taller than cider gum 2, although its stem does not look quite so sturdy, I'm afraid.

Posted in The treeblog trees

Chestnut blight (Cryphonectria parasitica)

The first recorded occurrence of chestnut blight disease was in 1904 within the New York Zoological Gardens. Its subsequent rapid spread throughout the forests of eastern North America was an ecological disaster, whereby the American chestnut (Castanea dentata) was reduced to an inconsequential component of the understorey, when once it had been the most important hardwood species in the eastern United States. The spread of the disease encompassed the entire natural range of C. dentata, with 3.6 million ha of the tree dead or dying in 1950. The disease was also discovered on the sweet chestnut (a.k.a. the Spanish chestnut) (Castanea sativa) in Italy in 1938, and spread throughout much of southern Europe. The disease is caused by Cryphonectria parasitica (formerly known as Endothia parasitica), which was unintentionally introduced on chestnut trees imported from East Asia. The economic, ecological, and social consequences of chestnut blight disease in North America were severe.

C. parasitica is a haploid ascomycete fungus producing both asexual and sexual types of spore. The fungus attacks through wounds, be they broken branches, breaks in the bark, or holes made by woodpeckers and beetles. The mycelium grows in the bark and outer sapwood, and spreads outwards from the source of infection until it has entirely girdled the trunk or branch. Necrosis and collapse of bark tissue forms a visible sunken canker, the expansion of which disrupts flow through the phloem and damages the cambium layer, limiting the ability of the host to produce new tissue. Girdling of the stem results in the wilting and death of the distal segment of the tree. The root systems of C. dentata often survive an attack of C. parasitica and continue to generate new shoots; however, these shoots rarely attain sexual maturity due to their remaining susceptibility to the blight fungus. Since two flowering trees are needed for seed formation (cross-pollination is required), sexual reproduction has been drastically diminished. As a result, there has been little chance for C. dentata to develop resistance.

The discovery of hypovirulent strains of the fungal pathogen has allowed highly successful therapeutic treatments of individual cankers. This process is well-suited to intensively managed, high-value orchards and plantations, although not to natural woodland. Natural hypovirulent strains of C. parasitica in Europe are known to be highly variable from one area to another in terms of hypovirulence. Deployment of hypovirulence in eastern North America has been an almost complete failure. Modern molecular approaches have been used to create transgenic hypovirulent strains of C. parasitica which themselves contain the genetic material of the natural hypoviruses. However, at present this new approach to biological control has not been entirely successful. Yet research continues, and in the near future a transgenic approach to biological control of the chestnut blight disease may well help restore the American chestnut to its former glory and ecological status.

[An abridged section of an essay for my third year uni course ‘Evolution and Ecology of Plants’.]

Posted in Pests and diseases

Cider gum resurgence: a second wave

This last week has seen more rain, rain, and even more rain. The treeblog seedlings have been continuously sitting in pretty wet soil for quite a while now. Yet so far they don't appear to be suffering from any adverse effects, thankfully. Even though I moved the seedlings out of their seed trays and into individual pots a while ago, I retained the seed trays in the hope of further germinations. This week, my optimism has been rewarded! A further seven cider gum seeds have germinated, although no more Scots pine or treeblog surprise have surfaced.

Yesterday I transfered six of the new cider gums into individual pots, and they joined the rest of the gang. The seventh new cider gum I left in the seed tray because of its sickly and runtish form. Harsh? Perhaps.

Anyway, take a look at the root development on these new additions to the treeblog stable. From left to right, we have cider gums Nos. 4 to 9:

new arrivals: the second wave of cider gum seedlings

the full treeblog complement

The treeblog trees (new cider gums on the right).

Posted in The treeblog trees

treeblog hit by floods!

There has been no internet access at treeblog HQ since Monday (hence the lack of updates), due to what is likely to be known henceforth as the Great Flood of 2007. In the treeblog post on Monday the 18th of June, I wrote that "the worst of the weather now seems to be behind us..." Oh, how wrong I was! It seems to have hardly stopped raining this month, but last Monday (the 25th) was stupendously rainy. Our road was turned into a virtual river, with huge gashes carved in the tarmac, over a foot deep in places. But across much of the North of England, especially around Sheffield, the damage has been much worse. I'm sure anyone in Britain will know all about this, but for you abroad who may not have heard anything, it was bad. I will post some extraordinary flood pictures in a couple of days.

The treeblog trees have come through more or less unscathed. I fashioned a makeshift cover to keep them dry after they were literally swimming in rainwater by Monday afternoon. One of the poor cider gum seedlings had keeled over and was stuck, submerged, to the soil. I righted it as best I could and it appears to have recovered somewhat. More details forthcoming in the near future!

Word on the street: A third wave of cider gum seedlings!?

Posted in The treeblog trees

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