Aphids are tiny insects about 3mm in length with the most popular types being black fly and green fly. Other types do exist but are rarer. They feed on juicy, tender young Japanese Maple shoots. As the colony gets larger in number they spread to the undersides of young Japanese Maple leaves.
They damage the Maples in two ways. Firstly, they lead to Japanese Maple leaf curl and sooner or later fall off. Aphids also excrete a gooey liquid frequently referred to as ‘honey dew’. This attracts a lot of diseases which becomes clearer when the ‘honey dew’ changes in color generally turning black.
Treatment of Ahids
Overfeeding, Japanese Maples particularly in spring, encourages aphids. The plant will rapidly produce a great deal of soft new shoots that are readily colonized by aphids. So, avoid overfeeding your Japanese Maple particularly in the spring.
Early action when greenfly are noticed will give you a more effective organic treatment of aphids. Roses are particularly impacted by by aphids so the minute you see aphids on roses inside your garden inspect your Japanese Maples for signs of an aphid attack.
If you are not especially squeamish. The aphids are often killed by running your forefinger and thumb over Japanese Maple leaf and shoot surfaces. This will basically squash them to death! Water over the leaves after doing this will wash lots of in the dead aphids away. A spray is even more successful.
A Preventative treatment for aphids the works well is by spraying with a mixture of two litres of water containing a teaspoon of dish liquid. It’s believed that the diluted dish liquid clogs up the aphids and causes them to die. It has no ill effects on the Japanese Maple plants themselves. Concentrate spraying on new Japanese Maple shoots as well as the undersides of leaves.
Encouraging other helpful insects which consume aphids can also be a different method which well. The primary ‘consumers’ of aphids contain ladybirds, hoverflies and lace wings. Encourage them into your garden by planting marigolds and calendula. Strangely, a patch of nettles can also be a superb way of attracting aphid consuming insects. They attracted towards the aphid species which colonize nettles but which impacts no other garden plants.
Use only as a final resort but sometimes it is the only answer when an aphid attack on your Japanese Maple has become out of hand. There are many systemic insect sprays out there which perform well.
Remember to inspect your Japanese Maples often in the Spring and treat them before the aphids get out of hand.