After the aphids

Through May and June black aphids were sucking the life out of the little wild cherry trees in the garden (funnily enough, they completely ignored the cultivated varieties).

The cherry aphids infest the underside of young leaves. They will keep on multiplying under the leaves and sucking them until they turn brown and crisp.
The cherry aphids infest the underside of young leaves. They will keep on multiplying under the leaves and sucking them until they turn brown and crisp.

These little suckers are almost certainly the black cherry aphid, Myzus cerasi. Their scientific name is apt as it more or less means a cherry sucker.

It is difficult to watch the destruction these aphids wreak. And it’s hard to believe that they won’t completely kill the trees they infest; especially if they are just young saplings. But, by and large, although these aphids make an unsightly and worrisome mess, cherry trees will recover.

By the end of June or early in July, the aphids will move on to their herbaceous wild plant hosts and leave the cherries with time to recover.

Now, in the third week of July, the aphids have left and the same cherry tree is putting on healthy new growth.
Now, in the third week of July, the aphids have left and the same cherry tree is putting on healthy new growth. The curled and crisped leaves damaged by the aphids are clear to see lower down the stem.

The bad news is that another generation of the aphids will come back in the autumn to lay their eggs on the cherry trees. Those eggs will sit there through the winter, ready to start the whole saga again the following spring.

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It’s raining birch seeds

It’s warm and dry today with no rain forecast, but in the garden there is a constant pitter-patter amongst the trees. It’s the sound of birch seeds falling – helped along by goldfinches and siskins who are tugging at the catkins to pull out the seeds.

Through the canopy, a constant stream of tiny birch seeds are falling down.
Through the canopy, a constant stream of tiny birch seeds are falling down.

Continue reading “It’s raining birch seeds”

Growing cork oaks from seed

In 2013 I was given three cork oak (Quercus suber) acorns to try growing.

The first cork oak seedling after one year's growth
The first cork oak seedling after one year’s growth

At the time, I was in the middle of bulb planting and I popped the three acorns into individual 9cm pots without much thought. That was at the start of December.

I was amazed when about a month later the compost in the pots started to heave, indicating that things were stirring underneath. I was more amazed when I went out one morning and found a hole where one of the acorns had disappeared completely from the pot. I don’t know who stole it – possibly a magpie. My lesson learnt, I covered the two remaining pots with pea netting to stop further thefts.

I then started reading about how to grow cork oaks from acorns: obviously, I should have done the reading first:) I learnt that I should have simply laid the acorn on the soil/compost and sprinkled a little more over the top – replicating what would have happened naturally. I hadn’t done that: I’d dibbed a hole and pushed the acorns quite deep (I blame it on the bulb planting frame of mind). And I should have used tall pots to allow long tap roots to grow.

So, I decided to tip out my two acorns and replant them with more soil beneath – for their long tap root – and less above – to let them reach the light quickly and easily. In so doing, I damaged the roots of one of the seedlings and it never recovered. Happily, despite all my maltreatment, the other one grew and grew. When it was about four inches tall, I planted it into the garden. Now, at just over a year old, it is just under a foot tall.

Last December, I decided to try again and to do things more correctly this time. I laid four acorns in tall pots (the kind usually used for raspberry canes and the like) containing a mixture of coir, multipurpose compost and garden soil, and I sprinkled a little more of the mixture over the top.

Cork oak shoots - this is about four months after planting
Cork oak shoots – this is about four months after planting

Initially I kept these pots out of doors, but with a propagator lid over them to prevent thieving birds and also to stop them getting too wet in our long damp winter.  Once the acorns started “moving” (germinating) I covered the pots with pea netting and got rid of the lid.

So far, two of the acorns have germinated properly and have sturdy young growth. Another one started to germinate, but I think it might have failed as it is a while since anything happened. The other seems to still be progressing, but very slowly: there are signs of root growth, but no shoot yet.

Clearly I can’t really draw any conclusions from such a little experiment, but it would seem that cork oaks are pretty easy to grow from acorns. The main things to watch out for are: thieving birds and rodents; to make sure that the pot you choose has sufficient space to let the acorn “move”; and to choose deep pots to let the tap roots grow. It’s also important that the acorns you use are fresh – plump and shiney, not crinkled and dull.

Cork oaks are relatively hardy, they can survive temperatures down to around -10C (depending on whose description you read – it may be a bit lower or higher than this) and they make beautiful trees as they mature.

Sycamore seedlings

It’s the time of year when sycamore seedlings start springing up seemingly everywhere.  Their long and narrow seed leaves look nothing like the broad, lobed leaves of the adult trees. And, unless the old “helicopter” that the seed fell to earth with is still attached, you might wonder what these vibrant narrow-leaved seedlings are.

Sycamore seedlings
Sycamore seedlings

Sycamores (Acer pseudoplatanus) are one of those trees which fall into, out of and back into favour with the passing of time.  They are classed as “non-native”, but they’ve been in the UK for hundreds of years. They’ve been classed as “invasive” but scholars and observers dispute whether they really are.  They’ve been planted for shelter and then pulled up because they’re “not natural”, only to be replanted a few years later with the aid of grants. One thing’s for sure: sycamores seed prolifically! If you want to propagate them, that makes it especially easy: just pop the seed or a seedling in a pot. But if you don’t want them sprouting up in every nook and cranny, it’s easiest to pull them out now, while they’re tiny. Last year, there were reports of ponies being poisoned after eating large quantities of sycamore seeds. So, if you keep horses you might want to be mindful of that.

Oak before ash or ash before oak: a dead heat

“Oak before ash, we’re in for a splash. Ash before oak, we’re in for a soak.” So the saying goes.  This year, here, it is a dead heat, with both species just breaking into leaf this week. I guess that means a year of “ordinary” weather, whatever that is!

Oak leaf buds bursting
Oak leaf buds bursting
Ash leaf buds bursting
Ash leaf buds bursting

Ash flower buds bursting - the ash trees, like most other tree species locally, have flowered prolifically this springAsh flower buds bursting – the ash trees, like most other tree species locally, have flowered prolifically this spring

Apple blossoms and hover fly

Hover fly (Melanostoma scalare probably) on the blossom of a Nant Gwrtheyrn apple
Hover fly (Melanostoma scalare probably) on the blossom of a Nant Gwrtheyrn apple

melanostoma scalare on apple blossom

It’s the 11th of May. It’s cold. We’ve had gale force winds. And we’ve just had a hail shower. There aren’t many pollinators of any sort about so far this year. This little hover fly is a welcome visitor to the blossoms on the Nant Gwrtheyrn apple tree. An incredibly tough little tree: it’s held its blossoms through the gales and the hail.

Grafting fruit trees

Spring is stirring and it’s time to get grafting.  More particularly, to get on with grafting apple trees.

Grafting has been going on for thousands of years.  Possibly originating in China, it was certainly commonplace in ancient Greece and the Roman Empire. 

Simply put, grafting involves splicing a rootstock and a scion (or shoot) together.  Provided it is done correctly, the cambium (the actively growing part) of the rootstock and the scion will readily fuse together and produce new phloem and xylem (the tubes that transport food and water in a plant) that run smoothly between rootstock and scion.

The scion wood comes from the tree that you wish to grow – e.g. a particular variety of apple.
 
Rootstocks are chosen for the characteristics that they will confer on the scion wood.  The main focus is on the size of tree the rootstock will produce, but much work is also done to develop rootstocks that confer some degree of disease or pest resistance through to the scion wood.  The rootstock also has a strong effect on the longevity of the tree: in general, rootstocks that produce a dwarf tree (e.g. M27) will be shorter lived than full-sized standard trees.  Most rootstocks used commercially for apples in the UK are known by an M number – e.g. M27.  The M refers to the East Malling Research Station where the rootstocks were originally bred and developed.  

Why bother?  As mentioned, grafting to a rootstock gives you control over the size and some elements of disease and pest resistance.  Moreover, it ensures that your crop tree will come true.  If you plant an apple pip, you’ll never really know what tree will result – it’s likely to be a hybrid (due to pollination) and is also, quite probably, going to produce inferior fruit.  Finally, grafting speeds up the propagation process.  In a couple of minutes you’ll have a small tree.  If you planted a pip, you’d wait two or three years to get a sapling of the same size.

Why not just root cuttings?  Well, you can do this.  However, by doing so, you won’t be gaining the benefits that a specially bred rootstock could bring (control of vigour, disease resistance, etc.).  What’s more, many of the tastiest apples either do not have a very good natural root system themselves, or they have such a prolific root system that within a few years your tree will have grown so vigorously you won’t be able to reach the fruit anyway!

Although February and March are the main times for grafting with scions, you also get a second chance for propagation during the summer when “budding” or bud grafting can be used.  For this, rather than using a stem from the parent tree, only a bud is needed.  This method is particularly popular with commercial propagators because they can bulk up their material very rapidly; just think how many buds are on one branch.  It’s also a useful way to save the genetics of old trees that may have become too gnarled and unproductive to take a viable scion from.

There is a wealth of information on all types of grafting on the internet.  Here in Wales, Paul Davis of Dolau Hirion Nurseries is one of the leading experts on all things apple and has some great information on his website.  If you don’t feel confident to graft your own trees, Paul offers a grafting service.