Scale insects - Knowledgebase Question

Ingleside, Il
Question by mgzaar
June 30, 2010
What can I do to kill or control scale insects on a 25' tall magnolia tree. There is honey dew all over my pavers and blacktop driveway.


Image
Answer from NGA
June 30, 2010

0

Besides making an unsightly mess, magnolia scale weakens the tree and can kill off badly infested branches. In the spring the mobile stage of this insect, called a crawler, moves over the tree looking for a place to settle down and feed. It then forms a protective shell over itself, under which the females lays her eggs. These hatch in late summer to early fall, when the crawlers emerge to overwinter on the tree. The scales secrete honeydew and it's in this sugary substance that the black sooty mold you see is growing. It's important to understand the life cycle of the scale because once it is under its shell, it is safe from insecticides. The time when it is vulnerable is when the crawlers are moving around. So spray your tree in late summer with horticultural oil to smother crawlers. Spray again in early spring before leaf or flower buds start to open, but when temperatures will stay above freezing for 24 hours after spraying. You may need to do this treatment for a couple of years to bring the problem under control. If there are a few branches that are really heavily infested, consider pruning these out and destroying them to reduce the scale population, if it won't destroy the form of the tree. You can also use the systemic insecticide Imidacloprid as a soil drench around the base of the tree. The tree will take up the pesticide through it roots. It needs to be applied several weeks before crawlers are active for best results. Check with your local Cooperative Extension Service office for info on the best timing in your area. This URL will take you to a web page with info on how to contact the Extension office in your county: http://web.extension.illinois....

You must be signed in before you can post questions or answers. Click here to join!

« Return to the Garden Knowledgebase Homepage

Member Login:

Username:

Password:

[ Join now ]

Today's site banner is by ge1836 and is called "Alteri Lily"