the effected branches have a brown flecking on them as well
26 April 2011 08:32 AM
The brown nodes that you have noticed on your citrus tree is black scale. The ants are there because they are interested in the honeydew that is produced by this sucking insect. From what you have explained, it does sound like the scale is quite thick and would have been on the branches of the tree for quite some time. The best time to control this pest is mid December/early January and then again in February. The product to use is called PestOil. You can certainly use this product now, but it may take repeated applications to get this pest population under control. If you wish, you can hand remove by rubbing the scale off the leaves and branches. It is important to check your tree each spring/summer for this pest and to act quickly by spraying the PestOil.
From your friends at Yates Gardening