What Are Spindle Galls?
Spindle galls are small round or oval shaped growths found on trees. They appear as small white dots on the trunk, branches and twigs. These spindly growths usually occur in areas where there is no sunlight and they grow slowly over time. When these spindly growths become large enough, they may cause damage to the tree’s health.
The spindle galls are caused by a type of fungus called Erwinia. There are several species of eriophyid fungi, but only one is responsible for causing spindle galls: Eriogon. Other types of fungi that can cause spindle galls include Aspergillus, Fusarium and Phytophthora.
How Do You Diagnose Spindle Galls?
There are many ways to diagnose spindle galls. One way is to look at the growth pattern of the spindly growths. If they are growing outwards from their original location, then it means that there is something wrong with the tree’s root system. Another method involves taking a microscope and looking under the microscope at different parts of the spindle galls. If you see little moving bugs, then that means that spindle galls are indeed the cause of your problem.
How To Get Rid Of Spindle Galls?
There are several ways to get rid of spindle galls. One way is to prune off the infected areas from the tree. Check the roots as well and if you see anything that appears to be a spindle gall come out of the roots, cut it off as well. Another way is to cut the spindle galls off the tree and examine them under a microscope. If the spindle gall has any visible bugs, then you can crush them with your fingers or a hard object such as a hammer. Check the undersides of leaves for small insects.
How To Prevent Spindle Galls?
Spindle galls are caused by eriophyid mites, which are very tiny bugs that can be difficult to see with the naked eye. These mites enter the plant through natural openings such as the roots and the stomata of the leaves. Once inside, these mites cause the tree to create a gall around them so that they are protected while they feed off of the nutrients in the tree. Fortunately, there are several things you can do to prevent spindle galls:
1. Use root barriers.
These consist of materials such as metal or very thick plastic that act as a barrier between the roots and soil. This prevents the roots from coming into contact with the eriophyid mites that cause spindle galls.
2. Eliminate or reduce watering.
Eriophyid mites love water, so make sure that your tree doesn’t get too much of it. This can be done by using a drip system rather than a sprinkler.
3. Avoid overfertilizing.
Eriophyid mites also love nutrition, so try not to over fertilize your tree.
4. Avoid pruning when possible.
Pruning trees helps the mites to move around easier and spread to other parts of the tree.
Whenever you see a gall on your tree, don’t panic. It just means that there are mites in the roots and soil that haven’t yet migrated up into the plant. You can treat the soil with a variety of different chemicals to get rid of the mites.
It’s also important to remember that not all spindle galls are caused by eriophyid mites. Some galls are caused by other insects such as aphids or adelgids. If you’re not sure what kind of gall you have, it might be best to consult a professional.
Sources & references used in this article:
Plant module size and attack by the goldenrod spindle-gall moth by SB Heard, GH Cox – The Canadian Entomologist, 2009 – cambridge.org
The effect of colchicine and X-rays on onion root tips by M Levine – Cancer Research, 1945 – AACR
Caterpillars of eastern North America: a guide to identification and natural history by DL Wagner – 2005 – books.google.com
Guide to insect borers in North American broadleaf trees and shrubs by JD Solomon – 1995 – books.google.com
Kingdoms and domains: an illustrated guide to the phyla of life on Earth by L Margulis, MJ Chapman – 2009 – books.google.com
Common insect and mite galls of the Pacific Northwest by K HYDE – The Botanical Gazette, 1922 – University of Chicago Press
Pesticide Selection Guide for Insects and Mites Affecting Woody Ornamentals and Herbaceous Perennials in Nebraska by H Larew, J Capizzi – 1983 – ir.library.oregonstate.edu
EC02-1566-S Pesticide Selection Guide for Insects and Mites Affecting Woody Ornamentals and Herbaceous Perennials in Nebraska by FP Baxendale, TM Heng-Moss, CK Osterloh – 2006 – core.ac.uk