A sure sign summer is on its way is that spring bulbs are fading and the herbaceous border is growing in leaps and bounds. Plants and lawns love the warmer weather of May, but unfortunately so do many garden pests.
One garden pest that many of you have been plagued with over the last couple of weeks is Green & Black flies also known as Aphids. Aphids are very common sap-sucking insects that thrive on soft, new sappy growth of most garden plants including roses, Philadelphus (mock orange) Lonicera (honeysuckle) to name just a few! Aphids can cause distorted growth, and often excrete a sticky substance (honeydew) on foliage allowing the growth of sooty moulds. Some species of aphid, known as woolly aphids, cover themselves with a fluffy white waxy substance and can be confused with scale insects. Aphids transmit viruses, which is a particular problem for strawberries, raspberries, tomatoes, cucumbers, dahlias and sweet peas. Virus infected plants should be destroyed to prevent the spread onto other plants.
Aphids have many natural enemies, including ladybirds, hoverfly larvae, lacewing larvae and parasitic wasps. Unfortunately, damaging aphid infestations often build up on garden plants before the natural enemies are active in sufficient numbers to achieve control. Where practical, infestations can be squashed by hand. The most commonly used non-chemical remedy is to spray them with soapy water. However, this method became illegal in September 2013 following new legislation from the EU. Which states: “Any chemical or other product used to control pests, diseases and weeds is strictly legislated, under EU and, therefore, UK law. All pesticides must be approved, and it is illegal to use unapproved materials even if these are household materials such as washing up liquid, coffee, vinegar or baking powder.”
During the growing season there are many insecticides that can be used to control Aphids.The three main types are:
- · Pesticides based on natural compounds and/or with a physical mode of action. These include Pyrethrum, fatty acids and winter tree wash.
- Contact Insecticides****. These usually have more persistence than those based on natural materials and so can give longer lasting control but will have limited effects on aphids within distorted leaves. Products include Deltametherin (e.g. Bayer Sprayday Greenfly Killer, Bayer Provado Ultimate Fruit & Vegetable Bug Killer).
- · Systemic Insecticides****. In addition to some contact action these are absorbed into plant tissues and may have an effect on aphids hidden within distorted leaves. (e.g. Bayer Provado Ultimate Bug Killer and Rose Clear Ultra).
Other garden pests to look out for this month include Lily beetles (bright red beetles). Use pesticides or hand picking to control this pest, but the long period over which the adults are active (late March to October), can make this difficult. Provado Ultimate Bug killer is an effective insecticide. Always follow the manufacturer’s instructions when using any chemical in your garden.
As well as looking out for garden pests, here’s a few other jobs to do in May:
- Earth up potatoes, and promptly plant any still remaining
- Collect rainwater and investigate ways to recycle water for irrigation
- Regularly hoe off weeds
- Open greenhouse vents and doors on warm days
- Mow lawns weekly
- Check for nesting birds before clipping hedges
- Lift and divide overcrowded clumps of daffodils and other spring-flowering bulbs
As a final note, beware of frosts. There is always a last frost in late May that catches us all unaware. Keep vulnerable plants and new shoots protected at night if frost is forecast.
Rachel Sobiechowski BSc (Hons) P&R Garden Supplies, Fengate Drove, Brandon 01842 814800 www.p-rgardensupplies.co.uk