The Blackthorn (Prunus spinosa) should perhaps have been the tree of the month for October, when the fruit is best picked, or for March when it is the first of the hedgerow to blossom and signal the coming Spring. But they are fruiting now and I am reminded of one September when I managed to persuade my then young children to taste the blueberry lookalike fruit. I must confess to a shameful tendency to schadenfreude and, as they bit into the berries and their expressions changed to  pictures of utter shock and horror, I dissolved into helpless hysterics. With a taste that is described as 'astringent', I would add that in September it is the most unbelievably sour and bitter thing I have ever experienced. Your mouth is immediately sucked dry of any moisture and your face instantly screws itself into an agonised scrumple. Most domestic plums are thought to be an ancient hybrid between the Blackthorn and Myrobalan Plum, but mercifully the astringency was lost. But for sheer schadenfreude value, Blackthorn is Tree of the Month for September.

The Blackthorn is often seen as more of a suckering shrub or small spiny tree, found wild in Britain and Europe as well as north Asia. It is common hereabouts in Dorset and its fierce thorns make a good cattle proof hedge - the thorns are even known to puncture tractor tyres. As well as in hedges, it is abundant in scrub and woodland and, being very tolerant of salt spray and wind, is a useful first line of defence in coastal areas. The pure white flowers, 1.5cm in diameter, are unmissable in March when they appear on naked wood, singly or in pairs from the previous year's buds. A cold spell of weather at this time, as frequently occurs, is known as a blackthorn winter.

My ever trusty Flora Britannica, by Richard Mabey, quotes at length a description of the tree by William Cobbett, written 150 years ago. Even better, Cobbett's book 'The Woodlands' is digitised by google and available for free here. It is a super account of the tree and I follow Mabey's example by quoting much of it here:

' Everyone knows that this is a Thorn of the Plum kind; that it bears very small black plums which are called Sloes, which have served love-song poets, in all ages, with a simile whereby to describe the eyes of their beauties, just as snow has constantly served them with the means of attempting to do something like justice to the colour of their skins or the purity of their minds and as a rose has served to assist them in describing the colour of their cheeks.
These beauty describing Sloes have a plum-like pulp which covers a little roundish stone, pretty nearly as hard as iron, with a small kernel inside of it. This pulp, which I have eaten many times when I was a boy until my tongue clove to the roof of my mouth and my lips were pretty near glued together, is astringent beyond the powers of alum. The juice expressed from this pulp is of a greenish black, and mixed with water, in which a due proportion of logwood has been steeped, receiving, in addition, a sufficient proportion of cheap French brandy, makes the finest Port wine in the world, makes the whiskered bucks, while they are picking their teeth after dinner, smack their lips, observing that the wine is beautifully rough.... It is not, however, as a fruit tree that I am here about to speak seriously to sensible people: it is of a bush excellent for making hedges , and is not less excellent for the making of walking sticks and swingles of flails. The Blackthorn blows very early in the spring. It is a Plum and it blows at the same time, or a very little earlier than the Plums. It is a remarkable fact that there is always, that is every year of our lives, a spell of cold and angry weather just at the time this hardy little tree is in bloom. The country people call it the Black Thorn winter and thus it has been called, I dare say, by all the inhabitants of this island, from generation to generation, for a thousand years.
This Thorn is as hardy as the White Thorn; its thorns are sharper and longer; it grows as fast; its wood is a great deal harder and more tough; it throws out a great deal more side shoots; and it is, in every respect, better than the Hawthorn for the making of a Hedge....This Thorn will thrive, and that vigorously too, on the very poorest of land....The knots produced by [the] side shoots are so thickly set that, when the shoot is cut, whether it be little or big, it makes the most beautiful of all walking or riding sticks. The bark, which is precisely the colour of Horse Chestnut fruit, and as smooth and as bright, needs no polish; and, ornamented by the numerous knots, the stick is the very prettiest that can be conceived. Little do the bucks, when they are drinking their Port wine, imagine that the beautiful stick with which they are tapping the sole of their boot, while admiring their legs...by possibility for the 'fine old port' which has caused them so much pleasure, they are indebted to the very stick with which they are caressing their admired Wellington boots.'

Cobbett goes on to describe propagation of the tree. He seems to have been a colourful character; he was author, MP, campaigner against poverty and its causes, and one time inmate of Newgate Prison for libel. At the time of his death he was described as being paranoid to the point of insanity and was planning to write a play called 'Bastards in High Places' - which I think is rather splendid.

The fruit is more likely to be used to make Sloe Gin these days, rather than Cobbett's imitation Port. They are best harvested after a frost, which reduces the tannin content of the fruit. The skins of the fruit are punctured and covered with sugar, and then placed in a bottle to one third of its capacity, before it is filled to the top with gin. The contents are gently agitated over a period of at least three months, after which the contents are strained. The remains of the fruit can be mixed with melted chocolate to make sloe gin chocolate, once the liquid has been strained. If you collect in October it will be drinkable for Christmas but will still improve for another month or two.

Blackthorn is the traditional wood for hay rake teeth and for Irish shillelaghs, once described by the Chairman of the pharmacology Department of the University College of Los Angeles as an 'ancient hibernian tranquiliser'. A shillelagh is a highly polished stick of blackthorn wood that was made and used in Ireland, and a blackthorn walking stick is still carried by commissioned officers of the Royal Irish Regiment. Blackthorn wood is especially hard and takes a high polish. The shillelagh was used in self defence and is now used in a form of traditional fighting or martial art. Stout sticks of blackthorn are highly prized since it is rare to find blackthorn grown to this size.

Fireblight is a potentially fatal disease of trees and shrubs of the sub-family Pomoideae (those of the  Rosaceae family with apple-like fruits). Common hosts in Britain are Hawthorn, Apple, Pear, Whitebeam, Cotoneaster and Pyracantha. The disease is caused by the bacterium Erwinia amylavora which originates from the USA and was first recorded in Britain in Kent in 1956. The disease can cause significant losses in orchards and nurseries where large numbers of trees can be killed in local outbreaks and cropping of more resistant species seriously reduced.

The bacteria quickly multiply and spread to kill the inner bark of shoots and spurs, spreading into branches and even the stem, causing cankers and death of bark. If branches or stems are girdled by the infection, the branch or tree will die. The blackening of flowers and leaves can have the appearance of being scorched by fire, giving the disease its name.

The disease cannot be cured but the spread of infection can be stopped by pruning out infected branches. These should be cut well below the last sign of staining and in dry conditions. Pruning tools should be swabbed with methylated spirits between every cut. Infected material should be promptly burned.