Advice for the Home Gardener from the Help Desk of the
UC Master Gardener Program of Contra Costa County
UC MG Help Desk Response: Thank you for contacting the UC Master Gardener Program Help Desk about the problem with your citrus and also thanks for sending that great picture as it allows for a clear diagnosis. Your citrus is infected with scale – but don't worry, scale can be managed.
Scale is an insect that sucks on plant juices. Left unchecked it could cause damage to or reduce the vigor of your plant. Regarding whether the quality of your fruit will be impacted - I don't believe so. The problem with the scale on the rinds is that it is primarily unsightly. If you were going to leave the rind on for your use of the fruit then you would want to scrub the surface to remove the scale bodies..
The scale on your citrus stems and fruit is an armored scale. From your picture I am unable to identify the particular species of armored scale but that does not matter because management would be the same.
What you see residing on your plant are females and immature who do not have wings and therefore simply reside there – feeding.
Understanding the basic life cycle will help to understand the pest management practices:
Adult females produce eggs that are usually hidden under their bodies. Eggs hatch into tiny crawlers (immatures) which settle down and begin feeding within a day or two after emergence. Settled immatures may spend their entire life in the same spot without moving as they mature into adults.
Chemical treatments are most effective when the crawlers are just emerging in spring. See the link at the end of the narrative (below) for additional information on monitoring when crawlers are crawling.
Management:
Provide plants with good growing conditions and proper cultural care, especially appropriate irrigation, so they are more resistant to scale damage. You can prune off heavily infested twigs and branches, if they are limited to a few parts of small plants.
Horticultural oil is effective in spring or summer on deciduous plants when sprayed soon after most crawlers have emerged and most scales are in the young immature stage. Late spring and summer are also the times to spray avocado, citrus, and many other broadleaf evergreens. Horticultural oil kills the scales through suffocation.
Where plants can be sprayed, complete spray coverage of infested plant parts with horticultural oil at the proper time provides good control of most scales. Horticultural oils (e.g., Bonide Horticultural Oil and Monterey Horticultural Oil) are specially refined petroleum products, often called narrow-range, superior, or supreme oils.
Other non-persistent, contact sprays for garden include insecticidal soap (e.g., Safer Brand Insect Killing Soap Concentrate II), neem oil (Bayer Advanced Natria Neem Oil Concentrate, Green Light Neem, Garden Safe Brand Neem), canola oil (Bayer Advanced Natria Multi-Insect Control), and other botanical (plant-derived) oils.
Thoroughly cover with spray the plant parts where scales occur, typically on twig terminals and the underside of leaves. Follow the product label with respect to target plant, timing etc. Do not apply oil or other insecticides when it is foggy, freezing (under 32°F), hot (over 90°F), when relative humidity is above 90%, or if rain is expected in the next 24 hours. Especially at locations with hot weather, be sure plants are well irrigated before spraying foliage.
Below is a link to the UC Integrated Pest Management website that provides additional information on Scale lifecycle and management.
Armored scale do not produce honey dew (a sugar based excrement) so disregard the information about monitoring honeydew and controlling ants.
http://ipm.ucanr.edu/PMG/PESTNOTES/pn7408.html
Help Desk of the UC Master Gardener Program of Contra Costa County (EDC)
Note: UC Master Gardeners Program of Contra Costa's Help Desk is available almost year-round to answer your gardening questions. Except for a few holidays (e.g., last 2 weeks December), we're open every week, Monday through Thursday for walk-ins from 9:00 am to Noon at 2380 Bisso Lane, Concord, CA 94520. We can also be reached via telephone: (925) 608-6683, email: ccmg@ucanr.edu, or on the web at http://ccmg.ucanr.edu/Ask_Us/. MGCC Blogs can be found at http://ccmg.ucanr.edu/HortCoCo/ You can also subscribe to the Blog (//ucanr.edu/blogs/CCMGBlog/)
Advice for the Home Gardener from the Help Desk of the
UC Master Gardener Program of Contra Costa County
Client's Request (visiting at the MG/Ag Office at 2380 Bisso Ln, Concord): I found these insects (see below) inside my house in my closet. A friend of mine thought they might be “kissing bugs”. Would you please identify them, what their presence and problems they might cause, and recommend what I should do about them?
The common name of the insects you brought in is the leafhopper assassin bug. Scientific name is Zelus renardi. The leafhopper assassin bug is considered a beneficial insect in that it feeds on other insects, including pests such as caterpillars of the cabageworm butterfly, leafhoppers, and aphids. Here is a link to some University of California information about the insect: http://ipm.ucanr.edu/PMG/NE/assassin_bugs.html
When you were in our offices, you said you hoped that the insects were not “kissing bugs”. You might be interested to learn that assassin bugs and kissing bugs are closely related in that they belong to the same insect family—the Reduviidae family. Apparently, assassin bugs are often confused with kissing bugs. The feeding habits of the two insect lines are quite different--kissing bugs feed on the blood of mammals (including humans). Here is a link to UC's information on the kissing bug side of the family: http://ipm.ucanr.edu/PMG/PESTNOTES/pn7455.html
You might be interested in reading this blog article which talks about the differences between assassin bugs like the ones you found and the kissing bugs: https://ucanr.edu/blogs/blogcore/postdetail.cfm?postnum=24611
It's hard to know how one of the assassin bugs found its way into your closet. I wonder if perhaps it flew in through a window or door and somehow made its way to your closet. In doing my research I found this story on the website for the Marin/Sonoma Mosquito/Vector Control District: https://www.msmosquito.com/the-bug-blog/2012/03/leafhopper-assassin-bug. It describes an encounter a citizen had with an assassin bug that had somehow found its way into the citizen's bed. As described in the link, the assassin bug can inflict a painful bite if they encounter a threat, but they don't seek to bite humans or other mammals.
Since I have determined that your insects are “beneficial” predators, I'll take them home and release them in my vegetable garden area. Since assassin bugs are not typically pests, you probably don't need to take any action. If you should find others in your house, you might want to be careful about leaving doors or windows open which could allow them a way into the house.
Hope this information is helpful. If you have other questions, you are welcome to contact our Help Desk. We're open Monday through Thursday from 9 a.m. to noon and are also here to support the Ag Dept on Thursday afternoons. You are welcome to stop by or you can phone us or email us to save yourself a drive.
Help Desk of the UC Master Gardener Program of Contra Costa County (TKL)
Note: UC Master Gardeners Program of Contra Costa's Help Desk is available almost year-round to answer your gardening questions. Except for a few holidays (e.g., last 2 weeks December), we're open every week, Monday through Thursday for walk-ins from 9:00 am to Noon at 2380 Bisso Lane, Concord, CA 94520. We can also be reached via telephone: (925) 608-6683, email: ccmg@ucanr.edu, or on the web at http://ccmg.ucanr.edu/Ask_Us/. MGCC Blogs can be found at http://ccmg.ucanr.edu/HortCoCo/ You can also subscribe to the Blog (//ucanr.edu/blogs/CCMGBlog/)
Advice for the Home Gardener from the Help Desk of the
UC Master Gardener Program of Contra Costa County
Client's Request (via phone): What is the nutritional composition of compost tea?
Our research did turn up some information about compost tea that you might find of interest. Here's a link to a slide presentation on the “Nutrient Value of Compost” which appears to have been given at a symposium sponsored by the University of California in 2009: https://vric.ucdavis.edu/events/2009_osfm_symposium/UC%20Organic%20Symposium%20010609%2005b%20Hartz.pdf Slide 4 in the presentation shows typical nutrient levels of compost. As you'll see, the NPK (nitrogen-phosphorous-potassium)l nutrient levels vary depending on the source of the materials used to make the compost—for example, does the compost contain manures or only crop residues. Slide 17 in the same presentation notes that when the compost is diluted to make compost tea, the nutrient effect of using the tea is likely “insignificant”.
Another University of California source indicates that a potential benefit of compost tea is that the leaves of the plants may be able to directly absorb nutrients that are present in the tea for a quick nutrient boost. See: https://ucanr.edu/blogs/blogcore/postdetail.cfm?postnum=13471. However, as you'll see if you further review the information at this link, that same UC source is skeptical about the disease prevention claims that are sometimes made for compost teas. The authors eventually conclude: “Plain old compost, not the tea, typically acts to release those same nutrients in a slower manner, plus it has the added benefits of cooling and cushioning the soil. So to really get the most out of your compost, perhaps it's best to apply it to the landscape, and let nature make the tea with rain or irrigation water, unless you have a specific need for a quick, but problematic, boost of nutrients.
We hope that this information is useful as you evaluate your use of compost tea. You are welcome to contact us again if you have other gardening or pest questions.
Help Desk of the UC Master Gardener Program ofCntra Costa County (TKL)
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Editor's Note: The editor has been following the use of compost tea for more than several years. While there is a lot of anecdotal enthusiasm for its use, conclusive scientific findings have yet to be made of its benefits. Prof Linda Chalker-Scott PhD of Washington State University has written extensively on compost tea. (click). If you are considering its use, the Editor recommends her various articles on its use. |
Note: UC Master Gardeners Program of Contra Costa's Help Desk is available almost year-round to answer your gardening questions. Except for a few holidays (e.g., last 2 weeks December), we're open every week, Monday through Thursday for walk-ins from 9:00 am to Noon at 2380 Bisso Lane, Concord, CA 94520. We can also be reached via telephone: (925) 608-6683, email: ccmg@ucanr.edu, or on the web at http://ccmg.ucanr.edu/Ask_Us/. MGCC Blogs can be found at http://ccmg.ucanr.edu/HortCoCo/ You can also subscribe to the Blog (//ucanr.edu/blogs/CCMGBlog/)
Advice for the Home Gardener from the Help Desk of the
UC Master Gardener Program of Contra Costa County
Client's Request: Below is a picture of a leaf from my oak tree in my yard. I believe I noticed these weird trumpet shaped “housings” on the fallen leaves last year, but this year it's very prolific. We have 3 large trees. I'm hoping they are not infested with something bad? Any advice would be very appreciated.
What you are seeing on the leaves are galls. Galls are abnormal growths that can occur on leaves, twigs, acorns, catkins, and petioles in response to irritation and/or stimulation of plant cells. In your situation, the galls are formed on leaves due to egg-laying by the gall wasps. Virtually all native California oak species are hosts to one or more gall wasp species. After female wasps lay eggs, the developing larvae produce substances that induce the plant to form a gall. The larvae remain small while they induce the gall to grow rapidly. As the gall nears its mature size, larvae feed on nutritive tissue produced in the center of the gall and begin to grow rapidly. Larvae pupate within the gall and adult wasps emerge from the galls to initiate the next generation.
The good news is that most wasp galls, especially galls on leaves, cause little or no lasting damage to oaks. A few galls may cause limited leaf or twig die back by blocking the vascular tissue. If the oaks are provided with proper environmental conditions and good cultural care, no other management is recommended because gall wasps can be very difficult to control and usually they do not seriously harm oaks.
If you are interested in reading about gall wasps, here are a few references:
http://ipm.ucanr.edu/PMG/GARDEN/PLANTS/INVERT/oakgallwps.html
http://cesanluisobispo.ucanr.edu/news_873/Livestock-_Range-_Watershed-_Oaks/Oak_Galls_/
USDA: A Field Guide to Insects and Pathogens of California Oaks – Pg 28 (https://www.fs.usda.gov/treesearch/pubs/25928)
I hope I have identified your problem to your satisfaction. Please do not hesitate to contact us if you have further questions. Happy Gardening!
| Editor's Notes: Versions of these oak galls were apparently quite common this summer in Contra Costa County, at least based upon interest from questions to Master Gardeners. As noted above, there are many manifestations of this “pest”, the most interesting is probably the pink galls. MGCC has provided some information on them in a previous blog at http://ccmg.ucanr.edu/HortCoCo/?blogpost=18522&blogasset=12496 |
Help Desk of the UC Master Gardener Program of Contra Costa County (BY)
Note: UC Master Gardeners Program of Contra Costa's Help Desk is available almost year-round to answer your gardening questions. Except for a few holidays (e.g., last 2 weeks December), we're open every week, Monday through Thursday for walk-ins from 9:00 am to Noon at 2380 Bisso Lane, Concord, CA 94520. We can also be reached via telephone: (925) 608-6683, email: ccmg@ucanr.edu, or on the web at http://ccmg.ucanr.edu/Ask_Us/.
MGCC Blogs can be found at http://ccmg.ucanr.edu/HortCoCo/ You can also subscribe to the Blog (//ucanr.edu/blogs/CCMGBlog/)
Advice for the Home Gardener from the Help Desk of the
UC Master Gardener Program of Contra Costa County
MGCC Help Desk Response: Thank you for contacting the UC Master Gardener Program with your question about bugs on your cabbage plants. Thanks also for the helpful photo. Since the tiny white bugs that you previously saw are now gone, it's hard to tell exactly what they were, but possibilities include whiteflies. This UC website has pictures of the various insects likely to affect cabbages - you might be able to identify them by scrolling through the 'invertebrates' section.http://ipm.ucanr.edu/PMG/GARDEN/VEGES/cabbage.html
Regarding the damage that you now see, I think the most likely culprit is the Imported Cabbageworm. This is a small green caterpillar, the larva of the white butterflies very commonly seen in vegetable gardens.
http://ipm.ucanr.edu/PMG/GARDEN/VEGES/PESTS/importcabwrm.html . If you look carefully on the young leaves of your plant you may see these caterpillars - when just hatched they are quite small.
Now for how to control this pest. Once they are present on the plant there are a couple of organically approved sprays that will kill the caterpillars on contact; Spinosad or Bacillus thuringiensis (BT). The Cabbage worm website (above) has links with more information on these pesticides. You can also pick them off by hand. One very useful strategy to prevent the butterflies from laying eggs is to cover the plants with lightweight row cover http://ipm.ucanr.edu/PMG/GARDEN/VEGES/ENVIRON/protectivecov.html . This material can be found at some nurseries or online - I use this myself, and have found that once the winter sets in the butterflies are no longer around and the cover can be removed. With some minimal
care you can use the row cover for many years.
I hope this is helpful, and that your cabbages will recover now. Once the head starts to form it's hard to get at caterpillars down inside the curved leaves, so you should try and kill as many as you can now! If you think that the problem is something else, and you can get a photo of any pests please do get back to us.
Help Desk of the UC Master Gardener Program of Contra Costa County (SMW)
Note: UC Master Gardeners Program of Contra Costa's Help Desk is available almost year-round to answer your gardening questions. Except for a few holidays (e.g., last 2 weeks December), we're open every week, Monday through Thursday for walk-ins from 9:00 am to Noon at 2380 Bisso Lane, Concord, CA 94520. We can also be reached via telephone: (925) 608-6683, email: ccmg@ucanr.edu, or on the web at http://ccmg.ucanr.edu/Ask_Us/.
MGCC Blogs can be found at http://ccmg.ucanr.edu/HortCoCo/ You can also subscribe to the Blog (//ucanr.edu/blogs/CCMGBlog/)
