Q: Can my gooseberry bushes recover from an attack of sawfly?
John Collins, Co Dublin
A: Most active between April and September, the larvae of the common gooseberry sawfly can rapidly defoliate not just gooseberry bushes but also red and white currant bushes by quickly devouring the foliage, leaving just the bare skeletons of stems behind. Two other species, the pale spotted gooseberry sawfly and the small gooseberry sawfly, cause similar damage.
Superficially similar in appearance to a caterpillar, these green or pale green and black-spotted pests are generally found in feeding clusters along the undersides of leaves, especially low down towards the centre of the plant, where the adult female likes to lay her eggs. Unfortunately, by the time they’re spotted, the damage is often already so severe that it can take affected fruit bushes a year or more to fully recover. But the good news is that even completely defoliated plants do eventually recover, although they typically won’t crop well in the year immediately following an attack. To help them, mulch around the roots with a layer of well-rotted manure or homemade compost plus a few handfuls of a slow-release, pelleted, organic fertiliser.
Can my gooseberry bushes recover from an attack of sawfly?
Gardening: A purifying herb, symbol of immortality, culinary linchpin - what’s not to love about rosemary?
‘What’s the best way to grow flowers for my son’s wedding?’
Yellow is a polarising colour with gardeners. Here are 10 subtler daffodils to try
To prevent any subsequent attacks, vigilance is key. Inspect your plants regularly throughout late spring and summer for any early signs of the larvae, which can then be handpicked and disposed of, although this is a time-consuming task. A more time-efficient method is to use a biological control such as Nemasys Natural Fruit & Veg. But bear in mind that this needs to be carefully timed and targeted and will only be effective if applied on a cool damp day when the caterpillars are already present (without them, nematodes have nothing to feed on).
[ My mother, busy raising nine children, always made time to make gooseberry jamOpens in new window ]
Other preventative measures include pruning the bushes to develop a more open, goblet-shaped shape (the adult female sawflies prefer dense growth for egg laying); digging around the base of the plant in late winter to expose any sawfly pupae overwintering in the soil to their natural predators; and covering the plants with a protective blanket of Enviromesh or horticultural fleece (luckily gooseberry and currant bushes are self-pollinating) to prevent the adult female sawflies from laying their eggs.
