Ladybirds come to the rescue after an aphid attack

Disease in the garden can be a cruel setback – but there are still plenty of successes, by FIONNUALA FALLON

TORRENTIAL spring downpours, blazing heat followed by summer deluges, Japanese knotweed, voracious pigeons, gluttonous slugs, sap-sucking aphids and gooseberry sawfly – at this stage, you’d think that OPW gardeners Meeda Downey and Brian Quinn would have had more than their fair share of horticultural tribulations. But no, it appears not.

Two staple crops in the organic walled garden have been hit hard by disease, one of them with particularly long-lasting consequences. The Red Samurai carrots, sown in April, were the first to succumb, with the foliage beginning to yellow or redden some weeks ago.

When the OPW gardeners uprooted a few plants to have a closer look, it was clear that the crop wasn’t developing as expected.

“It almost looked as if the plants had bolted before the roots had a chance to swell,” explains Meeda. “It was really strange, particularly when the two other varieties of carrots that we’re growing (Early Nantes and Flyfree) were, and still are, doing just fine.”

After careful examination, Meeda and Brian identified the likely cause as a combination of “carrot motley dwarf virus” and “carrot red leaf virus”, both of which are spread by aphids. Sadly, there’s no cure other than to dig up and dispose of the infected crop, while prevention of future attacks depends on controlling aphids. So out came the Red Samurai carrots last week, leaving bare soil and fresh opportunities for planting.

Next to succumb were the onions, but this time the disease was far more serious and the solution not as simple. “We noticed it first in the Sturon onions – the leaves started wilting and turning yellow,” says Brian. “And then, when we pulled up a few, we saw that the bulbs and roots were covered with a kind of fluffy, white mould – all classic signs of the fungal disease called onion white rot. We think it came in with the young onion setts when we planted them this spring.”

Again there’s no cure, and this time the infected crop, along with any nearby host crops, must not only be carefully dug up but also burnt.

For the awful thing about this particular disease (and all GYO enthusiasts will wince when they hear this) is the fact that it can persist in the soil for up to eight years, potentially affecting all other members of the onion family including chives, spring onions, ornamental alliums and leeks.

“Imagine if you couldn’t grow an onion in the garden,” says Brian forlornly.

“It’d be awful. Potatoes and onions are the staples of any vegetable garden,” agrees Meeda. Together, they’ve decided that a combination of very careful garden hygiene and crop selection is the best way to fight this persistent disease. “It’s contained within one bed so we’ll just have to be really careful not to spread it around the rest of the garden – that means cleaning all tools, boots etc every time that we work/dig in that area. And if we want to grow onions or any other related crop, we’ll grow them from seed, not setts, and it’ll be as far away from that patch as possible,” says Brian.

To suffer such setbacks seems cruel, particularly given the fact that the garden is so carefully tended, but Meeda and Brian can take some small consolation from the fact that growing-your-own has always been as much about the failures as the successes.

And when it comes to successes, there’s been plenty in the walled garden this summer. Beetroot, lettuce, endives, strawberries, cabbage, rhubarb, blackcurrants, early potatoes, Swiss chard, mange tout, sugarsnap and ordinary garden peas. Already, in midsummer, the garden is awash with tasty, organically produced fruit and vegetables. “We’ve been picking bucketloads of sugarsnap, which are deliciously juicy.

And the peas (a variety called Onward), are really tender and almost sweet eaten straight from the pod,” says Meeda. There’d be plenty of raspberries, red currants and white currants too, if the OPW gardeners had had the time to net them.

“We just didn’t get the chance to make a proper fruit cage this year, so the blackbirds have been able to gorge themselves,” says Meeda with a resigned smile. “Next year will be different.”

There have been other kinds of successes too, and ones which prove the longer-term gains of gardening organically. Some weeks ago, a mallard duck showed her approval of the walled fruit and vegetable garden by building her nest in the herbaceous border, cunningly concealing it under the overhanging leaves of a clump of hellebores. The OPW gardeners’ worries that the eggs would be discovered and eaten by predators were happily dismissed when the proud mother emerged from the border late last week, accompanied by her 10 newly hatched ducklings. “It was great,” says Meeda with a grin. “They just waddled off in a neat line, down the path and out of the gate.”

Another source of satisfaction has been the recent invasion of ladybirds (the beneficial, native variety), which are now greedily consuming all those nasty, disease-carrying aphids. Brian shows me the black and orange-spotted larvae, which, along with the fully formed adult ladybirds, are on the leaves of almost every fruit and vegetable crop in the garden. If they carry on devouring the aphids like they are now, then there’s far less chance of this garden pest producing its overwintering eggs , and surviving to attack next years crops (the aphid’s mating and subsequent egg-laying generally takes place in late summer).

Less aphids next year means less chance of damaging plant diseases. Meeda and Brian are both pleased and relieved.

“I suppose it makes you realise that if you just give it a bit of time, nature will take care of things in its own way,” Brian says philosophically, as he examines a ladybird munching happily on a plump greenfly. “I think you just have to be patient.”

Next week, Urban Farmer will cover growing sweet corn

Fionnuala Fallon is a garden designer and writer