Saturday, 21 July 2018

More allotmenty things

This spring I put some young Hollyhock, Alcea rosea,  plants into the allotment, more in hope than expectation as Hollyhock Rust, Puccinea malvacearum, has seriously disfigured plants in recent years. In fact they have put in a very pleasing display and have been much appreciated by bees. Indeed, in the U.S.A. it is visited by humming birds seeking nectar.
Against a typical allotment background, our hollyhocks are looking good.
8 July, 2018
There have been an astonishing number of Groundsel plants springing up on the plot. Why not compost them? Fine in theory but the snag is that the flowers continue to develop on the compost heap to produce seeds for the following season! I have been pleased to see lots of the caterpillars of Cinnabar moths, Tyria jacobaeae, chomping away at the plants and where this is happening I've left them to it. A few days later I noticed that they had begun to attack our Cosmos plants. Not so good!
Cinnabar caterpillars attacking Cosmos on our allotment!
15 July, 2018
In some cases the leaves of groundsel have been mined by the tephritid fly, Trypeta zoe. These mines are usually, but not always, on the midrib. Again I have left these for the fly larvae to pupate and go on to great things. Tephritid flies are generally referred to as Picture-winged Flies. Their wings bear distinctive patterns, useful in identifying each species, but I like to also note the plant to which a specimen was associated plus details of the body such as colour, etc. before putting a name to a specimen.

Trypeta zoe makes a distinctive mine on groundsel leaves.
Drayton allotments, Daventry. 8 July, 2018
Chria and I are very fond of broad beans, but they almost invariably suffer from black aphid attacks. This particular species, Aphis fabae, alternates between spindle and broad beans and, although there is no obvious spindle near to our allotment, an infestation invariably occurs. Indeed, as Ken Thompson has pointed out, 'spindle...has a strongly southern distribution (but) from this southern base they go on the colonise the entire country every spring' (Thompson, 2014). Ladybirds move in to consume the aphids but they are usually too late to prevent the crop from being very disfigured. Having said that, the beans are not really affected and taste delicious.
The fruit of Spindle, Euonumus europaeus, have not yet ripened. Gibberd
Gardens, Harlow. 14 July, 2018

Ladybird larvae are soon present too and in 90% of the cases are those of Harlequin Ladybirds, Harmonia axyridis. When they emerge from their pupal cocoon the ladybirds are in a teneral state, pale and with the fore wings not fully hardened.

When in the teneral stage a ladybird has not assumed its pattern of spots.
Our allotment. 21, July, 2018
After a few hours the pattern of spots appears and the fully developed imago can go about its business.

One of the many forms of the Harlequin Ladybird. On broad beans at
Drayton allotments, Daventry. 21 July, 2017 (An empty pupal case
is just above it.)
Next year I intend to pinch out the young tips of our broad bean plants to discourage aphid attack.


Thompson, K. (2014) Where do Camels Belong? Profile Books

No comments:

Post a Comment