Friday, 26 May 2017

Goings-on at the allotment

It may be recalled that Chris and I took on an allotment back in mid-March. The ground was a bit rough, not having had a proper autumn dig. (I may try to allow the plot to evolve with a no-dig policy, but that's for next autumn.) The only significant problems have been pigeons and slugs. One of the first crops I sowed was rocket but foolishly overlooked the fact that it is a brassica. To be precise it is now Eruca sativa. It was formerly known as Brassica eruca - but the pigeons haven't been told of its re-classification. They gobbled up the lot! They also attacked out peas but I have subsequently netted them and we should now get a decent crop. The slugs are more problematic. They have attacked the courgettes and - surprisingly - the rhubarb. I have reluctantly put down slug pellets.
Of course I keep an eye open for wildlife, good, 'bad' and neutral.
In the neutral category are damsel flies. This Common Blue Damselfly, Enallagma cyathigerum, was no doubt on the lookout for new territory, but in its wanderings came to rest on some rampant couch grass on a neglected plot.

Common Blue Damselfly at Drayton Allotments, Daventry. 25 May, 2017

I also regard Dock Bugs, Coreus marginatus, as neutral. It is true that their larvae may sometimes use rhubarb as a host plant but their damage is negligible. Here a mating pair uses a raspberry leaf as a trysting place. 
Mating Dock Bugs on a raspberry leaf. Drayton Allotments,
Daventry. 25 May, 2017

Our plot is partially shaded by a moderately large cherry tree and its leaves display what appear to be galls. In fact they are glands and are referred to as extra-floral nectaries. They are found on most (all?) species of Prunus and, although they produce water and sugars their function is not that of attracting pollinators.

A pair of extra-floral nectaries is to be found on the petiole of each cherry
leaf. Drayton Allotments, Daventry. 25 May, 2017
Over 2000 species of plant are known to bear extra-floral nectaries and although much needs to be explained it is thought that they encourage beneficial insects to visit the plant. Certainly ladybirds have been known to visit EFNs and perhaps clear aphids on their visits.
A neighbouring allotment has redcurrant bushes whose leaves carry highly disfiguring blister-like growths. This is damage caused by an aphid, Cryptomyzus ribis, unsurprisingly called the Redcurrant Blister Aphid. A tar-oil winter wash will generally deal with the problem.
The red blisters caused by Cryptomyzus ribis. Drayton Allotments,
Daventry. 25 May, 2017
I am inclined to regard the  Swollen-thighed Oil Beetle, Oedemera nobilis,  as a beneficial insect as it is a pollen feeder and may inadvertently carry pollen from plant to plant, but in truth it is of very little importance in that context. Despite its name, only the male has these grossly swollen thighs (femora). It was feeding on the pollen of Poached-egg Plant, Limnanthes douglasii, which had been planted on several of the plots.
Oedemera nobilis visiting Poached-egg Plant where it will feed on the
pollen. Drayton Allotments, Daventry. 25 May, 2017

I'll be keeping a lookout for pollinators, pests and parasites. You have been warned!

No comments:

Post a Comment