- Author: Denise Godbout-Avant
Manzanita Pest
My first step was to go to the University of California Agricultural and Natural Resources Integrated Pest Management Program (IPM) website to possibly determine what the manzanita plants had. IPM is a wonderful resource with a wide range of links with information on science-based home, garden, turf, and landscape pest management. http://ipm.ucanr.edu/
After doing some exploring on IPM I learned the plants probably had Manzanita leafgall aphid (Tamalia coweni). I knew of galls caused by tiny wasps existing on some trees such as oaks but learning that some aphids can cause galls was new and fascinating knowledge to me!
This website also includes links to the Stanislaus Sprout which is a weekly blog packed with information, upcoming classes and workshops, and gardening publications. https://ucanr.edu/sites/stancountymg/
Managing the Manzanita Pest
One IPM solution given was to avoid frequent irrigation or with excessive amounts of water. Once manzanita plants are well-established, they thrive with less frequent watering, so I was already not watering them often. Pruning was not recommended since it would stimulate new growth, which could attract more aphids, though I did remove leaves with the galls on them.
Take Advantage of These Resources
You do not have to be a Master Gardener to take advantage of the science-based resources I have discussed, the Integrated Pest Management website and the Stanislaus County Master Gardeners' Help Desk. They are available to all, not just to Master Gardeners. Like me, you can continue to learn new information that you can apply to your garden!
Resources and Information
- Aphids: http://ipm.ucanr.edu/PMG/PESTNOTES/pn7404.html
- Beneficial insects, including lady beetle larvae and paper wasps: http://ipm.ucanr.edu/QT/beneficialpredatorscard.html
- Beneficial insects: http://ipm.ucanr.edu/QT/beneficialinsectscard.html
- Oak Galls: (http://ipm.ucanr.edu/PMG/GARDEN/PLANTS/INVERT/oakgallwps.html
Denise has been a Master Gardener since 2020. All photos taken by Denise Godbout-Avant unless otherwise noted.
- Author: Ed Perry
Aphids are a common garden pest in spring and are attracted to new, succulent plant growth. This year, heavy aphid infestations can already be found on roses and fruit trees.
Aphids often first show up along the edges of the garden. Many species infest the undersides of leaves first, so turn leaves over while looking for aphids. On some plant species, especially plum and apple trees, aphid feeding causes the leaves to curl. Once this happens, it's harder to obtain control because the curled leaves protect the pests from natural enemies or sprays.
When you find aphids, check for evidence of natural enemies like lady beetles, lacewings, syrphid fly larvae, and the mummified skins of parasitized aphids. Learn to recognize aphid “mummies,” as they indicate the presence of tiny parasitic wasps that lay eggs inside the aphids. The wasp larva hatches and feeds inside the aphid, killing it. The skin of dead aphids turns crusty and golden brown or black, a form called a mummy. Not long after, the adult wasp chews an exit hole and emerges from the aphid's body. During warm weather, parasitic wasps may have several generations and cause a rapid decline in aphid populations.
There are fungus diseases that infect aphids, especially when it's warm and humid. Entire populations of aphids may be killed when conditions are right. While aphids thrive under mild temperatures, populations of many species are reduced by hot summer weather conditions. If you have any of these natural controls at work, the aphid population may crash rapidly.
You may be able to control aphids in your trees by controlling ants. If large numbers of ants are seen climbing up and down tree trunks, it may mean an aphid infestation. Ants are attracted to the honeydew produced by the aphids. If you plan to use pesticides for ant control, first seek out and treat the ants' nests in the ground near the tree. Or, place sticky barriers around the tree trunk to keep the ants from reaching the aphids. Unprotected by the ants, the aphids may then be attacked by natural enemies.
You can help prevent aphid infestations, especially in vegetables, by removing weeds where aphids may be building up. Also, check transplants for aphids and remove them before planting. If you notice a few curled leaves on your fruit trees, the best control may be to simply prune out and dispose of the infested shoots and leaves.
