Woolly bully

I HAVE been doing battle with some sticky creatures this week.

At home, at work and while visiting friends I have had an array of ‘samples’ thrust under my nose to identify. Fortunately, identification has been easy, because once you have seen and had to treat an infestation of woolly aphid, it is not easy to forget.

The first thing you will notice are white, or occasionally blue-grey, waxy residues which look like cotton wool which appear on the bark and branches of trees and shrubs, especially around old pruning wounds. There may also be droplets of sticky, sugary honeydew on the bark which may become infected with black sooty mould.

Cankers may also be present on infested areas. Scrape away this protective cover, though, and you will find the beast: a large sap-sucking aphid.

Adult aphids are up to 2mm long, oval in shape and are pinkish-brown (but their waxy coating gives them a white, woolly appearance).

Woolly aphids can give birth to as many as five live young a day, so rapidly produce large colonies. They do not over-winter as eggs but as young, under loose bark, or in cracks in bark or surface roots. These youngsters emerge in spring to re-establish the colony. After a few generations, winged adults develop and move to new trees. Susceptible specimens include apple, pear, prunus, crab apple, pyracantha, cotoneaster, elm, hawthorn and mountain ash trees.

The mild winters and warm wet summers seem to be encouraging a boom in the aphid numbers and new outbreaks are occurring all over the place.

While not being a hugely destructive pest, the aphid will weaken its hosts and may transmit disease and viruses from other sources. There are some chemical controls that can be used on the creatures if you are that way inclined to use them. Products containing bifenthrin, imidacloprid, pyrethroids and pyrethrin are all effective on apple woolly aphid.

If you are more organically minded, then there are still plenty of preventative and remedial measures that you can take. Firstly, make sure to check tree shoots and bark regularly for signs of the woolly aphid. Paint pruning wounds with a tree coating composition to help prevent infestations establishing in the first place. Something as simple as petroleum jelly will do the trick.

If the bugs do get a hold of your trees, there is no easy way to eradicate them apart from physically removing them. Scrub all the infected areas within easy reach with a brush and a bucket of soapy water. Try spraying infested areas with a firm jet of water to help reduce aphid numbers and then spray with natural fatty acids such as an insecticidal soap or diluted washing up liquid. Anything alcoholic will make short work of the creatures.

Methylated spirit is probably the cheapest fuel but vodka will also work well for smaller areas. Before you go up ending glasses of the stuff, I am not advocating that you drink the alcohol but rather rub the aphids off with a cotton bud or cotton ball dipped in the liquid.

Aphid predators such as ladybirds, aphidoletes, hoverflies, and lacewing larvae can be released or encouraged into affected areas. Colonies of ‘good’ bugs can become established in the garden by planting daisy-like flowers, yellow flowers and in particular, the poached egg plant limnanthes douglasii.

Try avoid using broad spectrum insecticides if you can, as these will kill beneficial insects as well as the aphids. You could also encourage insect- eating birds such as blue tits into the garden, by hanging feeders in winter and nest boxes in spring.

Finally, looking forward, if you are thinking of planting new apple trees, use rootstocks which are resistant to apple woolly aphid. Newer varieties tend to have more resistance to a wide variety of pests and diseases.

If all else fails, invite a troop of children round to the garden and set them off on a competition to see who can collect the most woolly aphid specimens in the space of an hour. I tried this with cabbage white caterpillars and it worked a treat.

■ Brigid co-presents the BBC Tees Gardening, green and great outdoors show every Sunday from 11am-2pm. Questions can be answered on the day by emailing brigid.press@bbc.co.uk anytime during the week, or texting 07786- 200995 and phoning 01642-225511 during the show. Written queries can be addressed to Brigid at East Durham & Houghall College, Houghall, Durham, DH1 3SG.

Jobs this month

■ Keep on top of those weeds in the borders by making sure that you spend five minutes every day pulling out anything obvious. Save the harder chores such as turning over the soil or digging out anything really nasty for the weekend.

■ Pull out any excess weed from ponds with a stick or rake, but make sure to leave the vegetal matter by the side of the pond for a few days, so that anything living has a chance to make it back to the water. After that, place it on the compost heap where it will quickly decompose.

■ If the pond is suffering from green algae, simply trim off a few bunches of lavender heads, tie them into a large bundle and place in the water. Within a few weeks there should be some improvement in the quality and clarity of the water in the pond.

■ Start taking cuttings of indoor geraniums. This can be done from now throughout until October and, done on a monthly basis, should result in a healthy selection of cuttings for next spring. Select a shoot without a flower and cut below where the leaves join the stem. Roughly three to five inches above that, cut the top off just above where the leaves meet the stem. Take this section and pop into a ready made hole (with a dipper or pencil) in some loose compost. Water and place somewhere warm and light for a few months.