Gardens
See no weevil
Ursula Buchan
To be fair to my daughter, she had no intention of being anything of the kind, having been bred in a robust school where these matters are concerned. Fortunately, there were no insect rights activists in the carriage who might have thought other- wise, only the garden-minded, so my remarks met with approving nods and understanding smiles.
I fell to thinking how many thousands of vine weevils must have been bought by unsuspecting gardeners at Hampton Court that day. It is one of the very worst pests of nursery container stock and is currently enjoying a population explosion.
The reason for this is simple. Three or four years ago, an unacceptably persistent organochlorine pesticide called aldrin was removed from the list of chemicals approved by the Government for use in commercial nurseries. For years it had effectively controlled vine weevil popula- tions there. Its withdrawal, coinciding with a string of mild winters, has ensured the weevil's present rip-roaring success.
Primulas, cyclamen, begonias, fuchsias, strawberries, bulbs — all can be severely damaged or killed by these creatures. The grubs, unattractively bloated and white as bodies lying on the beach at Cala Millor, are the most iniquitous, for they eat the roots and stem bases of many plants grow- ing in pots, both inside and out, between autumn and spring. The mainly nocturnal adults take random pieces out of leaves, and can disfigure shrubs and perennials in the garden in summer. Londoners, perhaps because they do so much of their gardening in pots and windowboxes, are presently enduring a plague of Biblical proportions.
Vine weevils are the `wimmin' of the insect world, but a great deal more success-
ful. They have developed the capacity to reproduce without males (indeed nearly all are female), instead of just sitting around and talking about it.
Just for once, there may be a happy end- ing to this story, however. A soil pest insec- ticide called chlorpyrifos has been formulated so that the active ingredient is encased in a polymer, which degrades slow- ly over two seasons in potting composts, releasing it to kill the grubs; this became available to commercial growers of orna- mental plants in February this year. It is called SuSConGreen and, unlike aldrin, once released, breaks down quickly. Because of the pest's life cycle, its widespread use has not yet had time to have a marked effect (hence the existence of at least one vine weevil at Hampton Court Show this summer), but it is hoped that by the autumn, and certainly by next spring, the problem will have substantially diminished. It should then be possible to buy from garden centres with more confi- dence. Unfortunately, the chemical has yet to be cleared for use in Holland and France, so — at the risk of being accused of a lack of communautaire spirit — I must enjoin you to buy British where you can.
Until the vine weevil ceases to be such a major pest in nurseries, may I suggest the use of a 'biological control' at home? Bio- logical control is the term given to the use of 'beneficial' creatures and bacteria, rather than chemicals, to combat pests. It is becoming very popular because we instinc- tively prefer the idea, say, of a slug-killing worm, or sexual pheromone traps to catch male aphids, or parasitic wasps, which lay their eggs in the bodies of whitefly. As with myxomatosis, we may, in fact, be sowing the wind, but the specificity of biological control is bound to attract us.
The biological control for vine weevil is a microscopically small eelworm (nematode) which burrows into the vine weevil grub and releases a bacterium which kills it with- in 48 hours, or so the manufacturer claims. This is sold to the trade as `Nemasys' (it is heartwarming to think of marketing men with classical educations) and to the ama- teur gardener as pbi `Biosafe'. At present, it is only available at Sainsbury's Home- base, but it will be distributed more widely next year.
I have never subscribed to the 'life would be so boring without difficulties to sur- mount' school of horto-masochism. I could quite happily do without pests generally, and vine weevil in particular. It pains me that they are so small, yet manage to bulk so large in our psyches. It is, therefore, pleasing to think that professionals and amateurs working together can see off at least one of the little blighters. By this time next year, I hope that pot-gardening will have become a matter of 'see no weevil'.
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