Q.Acer P. Atropurpureum Infested With Aphids. Is A Systemic Insecticide Safe?
Last January, I’ve planted my first Japanese maple (about 9 feet tall). I was pretty happy with its growth since March. But 2 weeks ago I noticed that leafs were curling and turning brown, and others had little shiny spots on top. I though it was drops of sap, and it could be excess of water, since it has been raining a lot. But yesterday I found hundreds of aphids underneath the leaves, mostly concentrated on new leaves and shoots… Did some research and sprayed all the tree with a solution of common dish detergent and water, waited 10 minutes and than washed it with a hose with some pressure, but not to much. Most of the aphids were removed or killed, but many still alive, and I can see hundreds of eggs. Also, several ants still there farming the aphids… I contacted my supplier yesterday and he sad that he sprays with insecticide all the maples every month. But the product he uses does not exist here… A local told me to spray a solution of Carnadine at night, wait 2 weeks, and spray again. Carnadine is a systemic insecticide (Composition: 200 g/L acetamipride; Chemical group: Neonicotinoid). My fear is that as I live on an island with no japanese maples around (I had to import mine from the mainland), there is no way to get proper local advice on what chemicals might damage this “unknown” tree. Also, its impossible to get ladybugs or other predators. Sadly, there is no such thing in here as ‘buying natural predators to control pests’… So, can someone help me? I know that I should never use chemicals on the tree, but I see no alternative but to use them to get rid of the pest. Will this type on insecticide harm my maple?
Certified GKH Gardening Expert
I don't know why it would harm the tree, but those are the chemicals that may kill bees and other pollinators. You can continue to use insecticidal soap; you can buy it too. Neem oil is safer for pollinators and is usually easy to find. Here is more:
http://ipm.ucanr.edu/PMG/PESTNOTES/pn7404.html
https://www.gardeningknowhow.com/plant-problems/pests/insects/homemade-aphid-control.htm
https://www.gardeningknowhow.com/ornamental/trees/japanese-maple/japanese-maple-problems.htm
