If you have eucalyptus trees, you might have noticed white, crusty growth on the leaves. Or maybe you saw a sticky, blackened mess of fallen leaves under a eucalyptus tree. These are signs of the redgum lerp psyllid, one of the most common psyllid pests that damages eucalyptus trees in California.
The adult psyllid is very small and as nymphs, they are concealed under a waxy cap, or lerp. As they feed, they excrete honeydew which can lead to the growth of black sooty mold, the source of those sticky leaves under the tree.
Although under biological control in coastal areas, this pest is still a problem under some growing conditions and on specific Eucalyptus species. Cultural practices to manage lerp psyllids, such as avoiding fertilization of eucalyptus trees and pruning only when and where needed, can help reduce lerp psyllid problems.
The newly revised and expanded Pest Notes: Eucalyptus Redgum Lerp Psyllid, authored by entomologists Timothy D. Paine, UC Riverside; Kent M. Daane, UC Berkeley and UC ANR Kearney Agricultural Research and Education Center; Steve H. Dreistadt, UC IPM Program; and Raymond J. Gill, California Department of Food and Agriculture, contains detailed information about the identification, biology, and management of this pest.
This revision has more information about the lerp psyllid's biology and damage they cause on eucalyptus, a list of eucalyptus trees resistant to this pest, and an expanded section on biocontrol, with detailed information about the imported parasitic wasp that only attacks redgum lerp psyllid.
We're looking for your feedback! Please consider taking a quick, anonymous survey to help us serve you better: https://bit.ly/2ZJJVEI
- Author: Karey Windbiel-Rojas
Invasive pests threaten California's natural environments, agricultural production, structures, landscapes and gardens, causing billions of dollars of damage to our agricultural systems and natural areas each year.
Throughout history, humans have moved plants and animals around the globe, bringing them from their native lands to new settlements. In California, some introductions did unexpected damage while others, such as food crops, had positive outcomes. New species are often intentionally introduced, although numerous exotic species arrive in products brought into California accidentally by travelers or shipped in commercial trade. Many invasive plant problems began as ornamental plants for sale by nurseries and garden centers. Exotic and invasive plants are still available in commercial nurseries.
What can you do about invasive pests?
Here are tips and resources that you can use to help stop or slow the spread and introduction of invasive pests.
-
Don't plant or release invasive plants into the environment. Also, avoid dumping aquatic plants or aquarium water into local waters, since many aquarium plants are highly invasive.
-
Use plants native to your area for landscaping.
-
Don't bring foreign plant or animal material into California.
-
Be careful when moving firewood.
-
Learn to identify invasive species new to California.
-
Report invasive species in your area! Contact your local UC Cooperative Extension office or Agricultural Commissioner to report invasives and to get information on controlling invasive species on your property.
For more information and resources on invasive pests, visit the UC IPM Invasive and Exotic Pests page.
[Original article published in the Summer 2020 issue of the Retail Newsletter]
- Author: Belinda J. Messenger-Sikes
- Author: Karey Windbiel-Rojas
Weeds are usually thought of as native plants we don't want in areas such as landscapes, fields, or vegetable gardens either because they reduce economic output or they are considered aesthetically displeasing. Invasive plants are generally non-natives that infest natural ecosystems and can become problems.
There are four distinctions between a weed and an invasive plant. The first is how they are introduced to an area. Weedy plants in gardens, landscapes, or in agricultural fields are usually accidentally introduced. While that is sometimes true for invasive plants, they are more often intentionally introduced as ornamental plants, for aquarium use, or for food or fiber purposes.
Next, weeds require human disturbance, such as tilling, to establish and flourish in an area. Invasive plants do not require any human assistance to grow and spread.
Invasive plants tend to be more persistent in an area once established and don't require irrigation or fertilization so are capable of growing and flourishing in areas without human assistance.
Finally, most weedy plants grow on land as annuals or herbaceous perennials, but invasive plants can be aquatic, parasitic, vining, woody, or herbaceous. Their life cycles range from annual to perennial.
For more information about invasive plants, see the UC IPM Pest Notes on Invasive Plants and Woody Weed Invaders.
[Original article published in the Summer 2020 issue of the Green Bulletin]
We're looking for your feedback! Please consider taking a quick, anonymous survey to help us serve you better: https://bit.ly/2ZJJVEI
- Author: Donald R. Hodel
- Posted by: Elaine Lander
Damage and Signs
Identification and Biology
The shell of this snail is unusually variable in appearance, especially in the dark bands and other markings. The adult has a medium-sized shell about the size of a nickel or dime. The non-glossy shell is typically ivory white (rarely pink), but can be light beige with narrow, dark brown bands. A similar looking but much less damaging snail, the milk snail (Otala lactea), sometimes occurs with the white garden snail and can be confused with it. The milk snail tends to be larger, up to 1.2 inches in diameter, and the inside of the thick opening is dark.
Unlike most snails and slugs, the white garden snail climbs and rests in a dormant state (estivates) on the cooler and least wind-exposed sides of vertical surfaces like trees, shrubs, fences, posts, and walls during the hot, dry season (Figure 3). They can survive for long periods by forming a wall of dry mucus to seal the shell opening and reduce water loss. They typically congregate in great numbers in an exposed, conspicuous manner to “ride out” the hot, dry season until the return of more suitable conditions in the fall.
Management
Control of the white garden snail can be time-consuming, difficult, and costly because they have a high reproductive rate, they climb high on objects, and they estivate for long periods. Effective management of this snail must rely on a combination of methods, including exclusion, early detection, and a variety of treatments.
Like most land snails, they move slowly so in order to reach new areas, they must be aided by people. To exclude the white garden snail from your area carefully check crates, boxes, and plants shipped from infested areas. To detect this snail, search plants, fences, posts, walls, and other vertical surfaces.
Measures used to manage other snails, such as sprays, baits, traps, and barriers, are only effective when the white garden snail is active and foraging on or near the ground. However, unlike other snails, this snail estivates in the open where they are visible and conspicuous, perhaps offering the best opportunity for their control; thus, hand-picking, knocking down, and then sweeping or vacuuming might be the best option, especially with limited infestations or in small landscapes. Because it can estivate in vacant fields or untended areas adjacent to landscape sites, these untended areas should be carefully checked and mowed.
For extensive details on the various management methods for the white garden snail, including habitat modification, biological control, hand-picking, and chemical control, see the full article at https://ucanr.edu/sites/HodelPalmsTrees/files/294710.pdf.
Word of Caution
Use rubber or latex gloves when picking or handling snails and vegetation with their slime trails, and wash hands thoroughly afterwards. Snails and slugs are intermediate hosts of rat lungworm disease, which is likely present but not yet officially detected in California. Rat lungworm disease is caused by a parasitic nematode that can attack the human brain and spinal cord if ingested.
[Original article published in the Summer 2020 issue of the Retail Newsletter]
/h3>/h3>/h2>/h2>/div>/h2>
- Author: Cindy Kron
- Posted by: Elaine Lander
The spotted lanternfly (Lycorma delicatula) is a new exotic pest that was first detected in Pennsylvania in 2014 and has since moved to other nearby states (Figure 1). Everyone, including home gardeners and retail nursery and garden center employees, can play a significant role in keeping this exotic pest out of California by being the eyes and ears needed for early detection.
Each female produces one to two egg masses of 30 to 50 eggs each. Seedlike eggs are laid in multiple successive rows and covered with a yellowish-brown waxy deposit (Figure 4). The first three immature stages are black with white spots and lack wings. The fourth immature stage is red and black with white spots and have small wing pads (Figure 5).
Adults have a stout yellow abdomen with incomplete black bands and two sets of wings: the forewings and the hindwings. The forewings are a beige-cream color with black spots changing to small black rectangles toward the tips. The hindwings are primarily black and red, with black spots appearing in the red portions. The hindwings are not noticeable when at rest (Figure 6). Adults tend to hop when moving instead of flying.
The spotted lanternfly can negatively affect high value commodity crops in California if it were to become established. In a proactive response to this possibility, researchers at UC Berkeley and UC Riverside are testing biological control agents for this insect.
[Original article published in the Summer 2020 issue of the Retail Newsletter]