URBAN FARMER:The hands-on methods of organic pest control are not for the faint-hearted, writes FIONNUALA FALLON.
ORGANIC methods of pest control are not for the lily-livered but a namby-pamby approach to defending your vegetable patch from slug, snail and caterpillar attack doesn’t generally reap a bountiful harvest, and so the urban farmer must grit his or her teeth and go discover their inner assassin.
Some are better at it than others, as can be seen in the OPW’s walled kitchen garden in the Phoenix Park. For the last few weeks, gardeners Meeda Downey and Brian Quinn have been busily squashing the eggs and caterpillars of both the cabbage white butterfly and the cabbage moth, which have been appearing on the brassicas. But when it comes to killing the little blighters, Brian’s proving more than a bit squeamish. “He often gives them to me to kill,” says Meeda, jokingly rolling her eyes heavenwards, as she squishes a caterpillar between two stones.
She even has the stomach to kill the occasional butterfly that manages to find its way underneath the yards of netting protecting the neat lines of cabbages, Brussel sprouts, calabrese and cauliflower. “We’ve discovered that when they can’t get under the netting, the moths and butterflies land on the spots they can reach, where any leaves are pushed tight against the netting, and are trying to lay their eggs there rather than on the underside as you’d expect. But we’ve been keeping an eye out, so they haven’t had much success.”
Given half a chance, both the cabbage white (large and small) and the cabbage moth can wreak serious damage, not only on brassicas but also on other crops such as turnips, swedes and even onions.
The trick to preventing wide-scale damage lies in early netting and regular inspection for any signs of infestation. Over the course of the summer, each cabbage white (and there are two generations) can lay up to several hundred eggs, often in batches of 10-20, which then hatch out into caterpillars that feed on the leaves of host plants. Both the cabbage moth caterpillar (hairless and yellowish-brown or green) and the small cabbage white caterpillar (pale green) are particularly damaging, as their larvae will burrow deep into the heart of cabbages to feed, making them difficult to get at. The larvae of the large cabbage white (yellow and black) generally feed on the outer leaves, so are easier to remove. Along with netting the plants, squashing the eggs and hand-picking the caterpillars, organic gardeners have also had great success using biological methods of control, something that Meeda and Brian plan to experiment with next year.
The pathogenic nematode, Steinernema carpocapsae, which is applied as a water-based spray, kills cabbage caterpillars by infecting them with a bacterial disease. It’s safe to use on food crops and does no harm to pets, children, wildlife or bees – the only downside, as always, is the ‘yuck’ factor as you have to remove all the dead caterpillar bodies before harvesting. “But I’m okay with that,” says Brian cheerfully. “It’s just the squashing part that I’m not a fan of.”
TOMATO AND PUMPKIN UPDATE
Competitive urban farmers may be interested in hearing how both the pumpkins and tomatoes are faring in the walled garden. The latter, which are growing against a very sunny, south-facing wall in the slip garden (a smaller hidden section within the walled garden) are doing surprisingly well, given the sodden summer.
Already, the cherry varieties (Supersweet and Rosada) have begun to ripen, and by the look of the plants, there’s plenty more to come. “We’ve been nipping out all the side-shoots and taking off the lower leaves below the first truss, which encourages the plant to put all its energy into the fruit and speeds up ripening,” says Meeda. “We’ve also been feeding them weekly and using a copper-based spray to protect against blight. But what the plants would really love is a couple of weeks of sun.”
Meanwhile, the pumpkin plants are also taking off, despite the lack of good weather. “Compared to last year, they’re doing a lot better,” says Brian. “There is already lots of young fruit on the plants and every week we’ve been giving them a liquid, potash-rich feed, which also helps.”
Meeda and Brian are pouring the liquid feed directly into the raised mounds around the base of the plants, rather than as a foliar feed (they’re using the organic granular feed, OSMO, dissolved in water). The biggest pumpkin (at the time of writing) is already about 60cm in circumference, and is growing quickly. At some stage in the next few weeks, the OPW gardeners will ‘stop’ the plants by nipping out any flowers or unwanted fruit, which will encourage the remaining pumpkins to swell and ripen.
But if any readers are worried that their pumpkin plants have been producing lots of flowers yet no sign of any pumpkins, there’s a simple explanation and a solution. Brian explains that each plant produces both male and female flowers, it is the female flowers that produce pumpkins. “In early summer, the plants produce a higher percentage of male flowers, which won’t produce fruit but will pollinate the female flowers when they eventually appear. If you look closely at the flowers, you should be able to tell the difference – the male flower is narrower and longer, while the female has a swollen base, just like a tiny pumpkin. So if you want to hurry things along, you can pollinate the female flower by transferring pollen into it from the male (use a fine paintbrush or something similar).”
Some urban farmers, however, might just prefer to let nature take its course.
- Vegetable expert and author, Joy Larkcom, and gardener, Klaus Laitenberger of Milkwood Farm, will give a day-long course entitled Creative Vegetable Gardening at Hunting Brook Gardens near Blessington in Co Wicklow, on September 5th (180). See www.huntingbrook.com or tel: 01-458 3972.
Fionnuala Fallon is a garden designer and writer. This column returns at the end of August.
