- 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]
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- Author: Belinda J. Messenger-Sikes
- Author: Karey Windbiel-Rojas
Like outdoor plants, houseplants can also experience pest problems. Did you know that too much or too little watering is the most common way that houseplants die? They can also suffer from too much or too little light, incorrect fertilization, and a variety of pests and diseases. Knowing the proper growing conditions for your houseplant and checking regularly for signs of pests or disease are the best ways to keep your houseplants healthy.
If your houseplant is looking unhealthy, our newest publication Pest Notes: Houseplant Problems can help you find out what may be wrong. Authored by UCCE Environmental Horticulturalists Dennis Pittenger and Donald Hodel, this new resource can help you narrow down the cause of a plant problem and decide what actions to take. If you find . You'll find sections on many common pests like aphids, mites, and mealybugs as well as leaf spots, wilting, or other disease symptoms. Once you've figured out the problem, you will also be able to find out how to manage to manage it use less toxic methods.
If you have feedback on this or other Pest Notes publications, let us know what you think by filling out this quick, anonymous survey.
Palm trees are commonly seen in California, making some think about the tree-lined streets of Hollywood, or sitting by the pool somewhere. These tropical or subtropical trees are beautiful and varied, with many different types of palms, each adapted for different growing conditions and each with specific disease-causing pathogens that can attack it.
Palm trees, like other plants, are susceptible to pathogens that can weaken or even kill the tree. Diseases such as diamond scale, pink rot, Fusarium wilt, and others can reduce the leaf canopy, discolor leaves and trunk, and cause distortion, stunting or death.
If you have palm trees or care for palms as part of your work, it's important to identify and know about these diseases and maintain healthy trees so they don't succumb to these potentially lethal issues.
Learn more about disease identification, selecting the right palms, and management for palms in UC IPM's recently updated Pests Notes: Palm Diseases in the Landscape by Donald Hodel, Environmental Horticulture Advisor with the University of California Cooperative Extension, Los Angeles County.
What's different in this version? Many new photos have been added along with a new section with information on petiole and rachis blights and tips to maintain healthy, vigorous palms.
[From the May 2017 issue of the UC IPM Green Bulletin]
History
Native to Australia, little was known about the bronze bug prior to 2002 when significant populations of the pest suddenly occurred on ornamental landscape plantings in Sydney. This pest spread rapidly to countries in Africa, Europe, South America, New Zealand, and now the United States.
Host Range
Over 30 species and hybrids of eucalypts in the genera Eucalyptus and Corymbia are recognized hosts of the bronze bug. Host eucalypts common in the southern California landscape include Corymbia citriodora (lemon-scented gum) (Fig. 2) C. maculata (spotted gum), Eucalyptus camaldulensis (red gum), E. globulus, E. grandis (flooded or rose gum), E. nicholii (narrow-leaved black peppermint), E. pulverulenta (silver-leaved mountain gum), E. rudis (flooded gum), E. saligna (Sydney blue gum), E. sideroxylon (red ironbark), E. tereticornis (forest red gum), and E. viminalis (manna or ribbon gum).
Insect Identification
Adult bronze bugs have a flattened, elongated body and are 2 to 3 mm long (Fig. 1). They are light brown, often shiny, and have darker or reddish brown areas. The head is broad with bulging, red eyes and elongate, conspicuous mouthparts. Antennae are light brown with black tips.
Eggs are lain in clusters on leaves and twigs (Fig. 3) and are dark, oval, 0.5 mm long, 0.2 mm wide and appear as tar-like marks (Fig. 4). Crawlers and young nymphs are orange with dark brown spots on their thoraxes and some abdominal segments. Eyes and the area around dorsal abdominal scent glands are red (Fig. 5).
Biology
Bronze bug adults and nymphs typically occur together on the same leaf. Developmental time is about 20 days at temperatures from 63-68°F with 5 instars. Adult females live about 15 days and a female can lay up to 60 eggs. Eggs hatch in 4 to 8 days and nymphal time is 17 to 25 days.
The bronze bug is thought to have dispersed to new regions primarily on infested plant material. Eggs can be borne on bark, flowers and inflorescences, and fruit; adults, eggs, and nymphs on leaves and seedlings; and eggs and nymphs on above-ground stems, shoots, trunks, and branches. Within a region, long-distance flight is thought to be the primary method of dispersal although wind and birds are also implicated. It is also possible that this pest can hitchhike on travelers' clothes, aircraft, land vehicles, and luggage.
Symptoms and Damage
Initially, leaves can be heavily infested yet show no discoloration or other symptoms. To date, we have been unable conclusively to confirm or associate the typical leaf discoloration described in the literature for the bronze bug in California. Previous studies reported that as bronze bug populations build and feeding intensifies, leaves typically have irregular reddish, reddish yellow, or yellow-brown areas that have a general bronzy tint. However, these leaf colors and other abnormal-appearing growth patterns are common on healthy and pest-free trees across the genera Corymbia and Eucalyptus, and can also be due to other factors, including cultivation, senescence, and unexplained, normal physiological responses (Fig. 7).
Advanced and or heavy infestations eventually lead to extensive areas of chlorotic and necrotic tissue that is tannish or silvery, as if chlorophyll has cleared in irregular patches. In these instances, abundant adults, nymphs, and black egg cases are typically visible. Severe infestations can lead to leaf loss, canopy thinning, branch die back, and even tree death. Severe symptoms are especially common on E. camaldulensis, E. grandis, and E. viminalis while in other species, symptoms are often less severe and include only silvering.
Management
Because the bronze bug is primarily spread over long distances among urban centers by humans, better monitoring and control at transportation hubs is critical to prevent spread of this pest.
Read the full article including cited references at http://ucanr.edu/sites/HodelPalmsTrees/ and direct link http://ucanr.edu/sites/HodelPalmsTrees/files/248430.pdf.
-Donald R. Hodel, Landscape Horticulture Advisor, UCCE Los Angeles County, drhodel@ucanr.edu; Gevork Arakelian, Entomologist, Los Angeles County Agricultural Commissioner/ Weights & Measures, GArakelian@acwm.lacounty.gov; Linda M. Ohara, Biology Sciences Lab Technician, El Camino College, lohara@elcamino.edu.
/span>[From the August 2016 issue of the UC IPM Green Bulletin]
A new psyllid pest that causes a distinctive, tight, typically complete rolling of leaves (Figure 1), has been found on Ficus microcarpa (Chinese banyan, Indian laurel fig) in Los Angeles, Orange, San Bernardino, Ventura, San Diego, and Riverside counties. This species of Ficus is one of our most common, useful, and widespread ornamental landscape trees. Incidentally, it has also long been a target for numerous exotic pests.
The psyllid, identified as Trioza brevigenae and tentatively named the Ficus Leaf-Rolling Psyllid (FLRP), was discovered in February 2016 south of Los Angeles in Carson, California and appears to have spread rapidly among the six counties listed above. It has only been observed on Ficus microcarpa (sometimes incorrectly called F. nitida or F. retusa).
Damage
Rolled leaves, though brittle, remain green throughout, although other pests, such as Josephiella microcarpae (the leaf gall wasp) and various mealybug species, might be present and may discolor or further deform them.
The rolled leaves could be mistaken initially for damage from Gynaikothrips ficorum (the Cuban laurel thrips), which creates a gall by folding the leaf blade adaxially (upper surface) along the rachis. However, careful observation will quickly show the distinct difference between the rolled leaf (caused by the FLRP) and folded leaf (caused by Cuban laurel thrips).
Description and Identification
Peeling back the rolled leaf blades typically reveals various developmental stages of FLRP nymphs (Figure 4). Early instars are 1–2.5 mm long, oblong, dark grayish-tan initially, changing to brownish and then brownish-green.
Advanced nymphal instars have skirts of long, white, waxy filaments at cranial and caudal parts of their bodies (Figure 5). Wing pads are typically visible in later developmental stages.
Cast skins of the final instar FLRP nymphs from which the adults have emerged are often seen attached to the leaves. Also, small, oval, mostly orange-colored nymphs embedded in leaf tissue on the outside of the roll and observable to the naked eye are likely very early instars of the FLRP, although we have not confirmed this possibility.
The FLRP exhibits two peculiar behaviors. In one (the more common of the two observed), an individual psyllid sits on a leaf blade or perches on the margin of a rolled leaf, raises its abdomen until it is at about a 45-degree angle (Figure 8), and then moves it from side to side like a dog wagging its tail. In another, it extends one wing until it is at a right angle to the body, then waves it back and forth while walking.
Management
One management strategy likely warranting evaluation includes vigilant scouting followed by judicious and immediate removal, bagging, and disposal of shoot tips with infested leaves.
Frequent, periodic pruning, as is done for hedges and topiary, might also be an effective management technique by constantly removing infested leaves. Such regularly pruned Ficus specimens have frequently been observed with less damage from foliar pests such as the leaf gall wasp, Indian laurel thrips, and the FLRP. Timing of such pruning, though, might be critical; if possible and practical, time pruning so that resulting new growth appears at a time when FLRP activity is low, typically during the cooler months.
The practices listed above could be combined with insecticidal treatment for noteworthy and valuable tree specimens, although no pesticides have yet been tested specifically for FLRP. In these special cases, soil applications of imidacloprid or similar materials applied to the soil might be beneficial.
—Gevork Arakelian, Entomologist, Los Angeles County Agricultural Commissioner/Weights & Measures, garakelian@acwm.lacounty.gov
—Linda M. Ohara, Biology Sciences Lab Technician, El Camino College, lohara@elcamino.edu
—Cheryl Wilen Wilen, Area IPM Advisor, UCCE San Diego, Orange, and Los Angeles counties, cawilen@ucanr.edu
—Surendra K. Dara, Affiliated IPM Advisor and Strawberry and Vegetable Crops Advisor for UCCE, Ventura, Santa Barbara, and San Luis Obispo counties, skdara@ucanr.edu
Read the full article, originally published in the eJournal PalmArbor at http://ucanr.edu/sites/HodelPalmsTrees/files/242336.pdf.
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