- Author: Ben Faber
This odd pattern that has shown up on polyethylene irrigation tubing was sent in by an observant Santa Paula grower. The fruit trees were covered with aphids and there was sooty mold growing on the honey dew dripping onto the tubing. Such a beautiful pattern, but what causes it?
Turns out Mark Hoddle, Biocontrol Specialist at UC Riverside had an answer - snails. Brown garden snails are active with this warm, wet weather and they are enjoying feeding on the sweet taste of honey dew.
The bottom side of the snail has a mouth composed of raduli which are sharp teeth which scrape along the surface of the tubing, leaving marks.
All images from Los Angeles Natural History Museum - https://nhm.org/stories/microscopic-look-snail-jaws
Citrus trees need care throughout the year, including cultural practices to keep trees healthy and pest management. During the fall season, several pests can attack citrus trees in many California regions.
Monitor for this disease by checking for damaged fruit on your tree, as well as fruit in storage. Sometimes affected fruit develops a pungent odor and can ruin fruit held in storage. See the UC IPM web page on Brown Rot to learn more.
If you see what look like small “tunnels” on your citrus tree leaves, your tree might have citrus leafminer. The adult stage of this pest is a small, light colored moth; the larval stage feeds and develops inside the leaves of young citrus and other closely related plants.
Citrus leafminer rarely causes problems for mature trees, however, it can seriously damage very young trees. Read the UC IPM Pest Notes: Citrus Leafminer for recommendations for prevention or management.
Snails and Slugs
Asian Citrus Psyllid and Huanglongbing
You may have heard of the Asian citrus psyllid (ACP) and the deadly disease huanglongbing (also called citrus greening) that has been featured in the news. This disease doesn't pose a threat to humans or animals, but is deadly to citrus trees. Once a tree develops huanglongbing, there is no cure, so for this disease prevention is key.
UC IPM Web Site
For information on managing other citrus pests in the garden, see the UC IPM webpage on Pests in Gardens and Landscapes: Citrus.
By Cindy Watter, UC Master Gardener of Napa County
Snails and slugs never gave me trouble when I lived in the country because my hippie neighbors had a dozen ravenous geese that used to waddle over and gobble up the slimy little morsels. However, after I left that house and moved into town, I spent my tenth wedding anniversary date night plucking hundreds of the creatures off twelve dozen King Alfred daffodils and dropping them into a bucket of beer. Everyone told me that was the non-toxic way to do it. No one told me not to dump them in the compost pile, however. Lesson learned.)
Early spring is the time of year when snails and slugs appear. They love to chew on tender young foliage. If your garden suddenly displays leaves with holes and ragged edges, chances are you have slugs and/or snails. They hide in the cool damp areas of your yard and come out at night to do their work.
A patch of ivy or weeds or a collection of overturned flowerpots is a perfect habitat for them. You should leave a few leaf piles in your yard to promote biodiversity, but some tidying up can fix your problem. You can also capture them by propping a board on cleats to create a nesting place for them to hide in. Then you drop them in a jar of soapy water.
Or you could sprinkle finely ground diatomaceous earth around the roots of your plant or encircle plants or raised beds with copper strips. The diatomaceous-earth granules are uncomfortable to snails and they just don't like crossing copper at all.
You may also put out jar lids at night filled with beer to drown them. Don't use salt; it will hurt your plants. Make sure you have a space between the trunk of the plant and mulch, to make it harder for the snails to hide. If you must use commercial bait, find one made with iron phosphate. Baits containing metaldehyde are dangerous to pets and children.
Slugs and snails are gastropods, invertebrates that are part of the mollusk family. They have a round mouth, called a radula, with hundreds of tiny teeth that rasp and tear soft young leaves.
These creatures also act as nature's scavengers, removing all sorts of debris from forest and field. They have a purpose, but you don't want them destroying your plants.
The only real difference between a slug and a snail is the shell. Management is the same for both.
The brown garden snail (Cornu aspersa) is not native to North America. It comes from Europe and was brought here by well-meaning people who thought that escargots would become a popular food item. Alas, the snails escaped and became garden nuisances. Gourmets consider them a delicacy, and snails do appear on menus in the Napa Valley. However, most people think of these creatures as pests.
They look festive when they come out after a rain, and I should harden my heart and squash them then and there, but I don't. I keep hoping the birds will eat them.
Years ago, when there was a chemical solution for every problem, I stormed down to my garden store with murder in my heart. Snails had eaten my strawberries. I saw a box with an arresting brand name, promising “SLUG AND SNAIL DEATH.”
The package had a terrifying illustration that looked like a stone lithograph, printed on yellow cardboard. It featured three creatures—two slugs in the background and a snail in the foreground—with horns rampant, and the snail had an aggressive-looking frill on its front. These horrific invaders were so large they held their own against the background, a post-apocalyptic vermilion sun. I grabbed the box. Salvation was at hand.
And then I read the label in the lower left corner. (You should always do this, by the way.) It said: "Keep out of reach of children. CAUTION: This pesticide may be fatal to dogs or other pets if eaten. Keep pets out of treated area." So I went back to hand picking, because I had small children then.
The poison was metaldehyde. I have used iron phosphate bait but, unfortunately, my dog finds it attractive. (It smells like dried blood.) It doesn't hurt her, but it unnerves me. I will try diatomaceous earth.
I also have plenty of plants snails won't eat. Geranium, rosemary, lavender, California poppy and fuchsia don't attract them. Basil does, however.
I was discussing my pest-control quandary with an old friend, who told me I would no longer want to kill snails after I read The Sound of a Wild Snail Eating by Elizabeth Tova Bailey. I am sure that is true. Reading this book will make me feel better about the holes in my brugmansia leaves.
Find UC IPM Pest Note for Snails and Slugs here:
Find UC IPM Quick Tips for Snails and Slugs here:
Food Growing Forum: Second Sunday of the month through November. Sunday, March 14, 3 pm to 4 pm: “Fertilizers and Soil Health.” Register to get Zoom link: https://bit.ly/3r5bgwi
Workshop: UC Master Gardeners will lead a workshop on “Growing Tasty Tomatoes” on Saturday, March 27, from 10 a.m. to noon.” Register to get Zoom link:
Napa Library Talks: First Thursday of each month. Thursday, April 1: “Gardening on a Shoestring.” Register to get Zoom link: https://bit.ly/3rn3MF3
Got Garden Questions? Contact our Help Desk. The team is working remotely so please submit your questions through our diagnosis form, sending any photos to firstname.lastname@example.org or leave a detailed message at 707- 253-4143. A Master Gardener will get back to you by phone or email.
For more information visit http://napamg.ucanr.edu or find us on Facebook or Instagram, UC Master Gardeners of Napa County.
Advice for the Home Gardener from the Help Desk of the
UC Master Gardener Program of Contra Costa County
Client's Request: Hello. I'm looking for some help on what is eating leaves on my vegetable plants, and what may I do to help remediate. Below are some pictures.
MGCC Help Desk Response: Thank you for contacting the UC Master Gardener Program Help desk.
It is very hard to determine exactly what is causing holes in the leaves of your plants without direct observation. However, I think it may be slugs and/or snails, a common problem in spring. In order to determine if it is slugs or snails to implement an effective removal effort, you could look for slime on the leaves and slime on the ground around the plants. You could also go out at night with a flash light when they are active and check the leaves for snails and slugs.
The link following will take you to a UC Pest Management page on slugs and snails. It has some really nice videos (which are not long) on identifying whether or not slugs and snails are eating your plants. It also has a video on pest management of the slugs/snails (what to do about them). The pest note also has written information on management of snails and slugs. http://ipm.ucanr.edu/PMG/PESTNOTES/pn7427.html.
Managing snails and slugs can be done with trapping or hand picking and then snail and slug bait.
As you should always do when using pesticides, read the label on the snail bait box for use and cautions. The active ingredients that are in the snail/slug bait are in small print on the package. Metaldehyde and sodium ferric EDTA can be toxic to animals and harmful to the environment. Iron phosphate is safe for animals. The bait should be shaken around the plants.
It may also be cutworm. Management of this pest involves hand picking at night and protecting plants with cardboard collars, screens or protective cloth. The link following will take you to the UC Pest Management page on cutworms. http://ipm.ucanr.edu/PMG/GARDEN/VEGES/PESTS/cutworm.html
Finally, from my personal experience to reduce the snail/cutworm population, look for and destroy their daytime hiding places (e.g., wood debris, weeds, etc.). It's a lot easier than crawling around at night with a flashlight looking for them.
Please let us know if you have further questions.
Help Desk of the UC Master Gardener Program of Contra Costa County (DLD)
Note: The UC Master Gardeners Program of Contra Costa's Help Desk is available year-round to answer our gardening questions. Except for a few holidays, we're open every week, Monday through Thursday for walk-ins from 9:00 am to Noon at 75 Santa Barbara Road, 2d Floor, Pleasant Hill, CA 94523, although we will be moving this spring. We will notify you if/when that occurs. We can also be reached via telephone: (925)646-6586, email: email@example.com, 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 (http://ucanr.edu/blogs/CCMGBlog/)
Last Saturday, UC IPM staff greeted a swarm of visitors at their Picnic Day booth. Picnic Day, UC Davis' annual Open House event, invites people to visit the campus and interact with fun and educational exhibits. UC IPM has participated in Picnic Day for more than a decade and this year attracted visitors to their booth with live insects like hissing cockroaches, a termite colony, and crane flies. UC IPM staff answered many questions about pests, pesticides, and cleared up misconceptions about some common insects.
What did we talk with people about?
Ant control, indoors and out
Beneficial insects and spiders (natural enemies)
Invasive pests: why you shouldn't move firewood
How to tell the difference between green fruit beetles and the invasive Japanese beetle
Lady beetle (ladybug) life cycle- don't squish the “good bugs!”
Controlling termites around the home
How to tell ants and termites apart
Snail and slug damage
Mealybugs on cactus and succulents
Many people confuse jumping spiders with black widow spiders
Crane flies are NOT giant mosquitoes, nor do they eat mosquitoes
You don't have to attend Picnic Day to get this information! The UC IPM website is available anytime for help with home, garden, turf, and landscape pests. You can also contact your local UC Master Gardener Program or UC Cooperative Extension for assistance identifying pests and finding solutions.