- (Focus Area) Pest Management
- Author: Kathy Keatley Garvey
For the beekeepers that's easy. They dislike the pests known as "wax moths" and their larvae.
The female wax moths hang around the hives at night and when the opportunity arises, slip in to lay their eggs. If the colony is weak, this pest can take over.
The honey bee bible, The Hive and the Honey Bee (Dadant Publication), says the wax moth female "produces less than 300 eggs during her life span of 3 to 30 days, but a few lay as many as 2000 eggs. Mated females fly to beehives one to three hours after dark, enter, and lay eggs until they leave shortly before daylight."
The Hive and the Honey Bee authors relate that "the presence of the wax moth larvae usually signals a major problem such as queenlessness, an infectious disease, poisoning and starvation."
In his book, Honey Bee Biology (2023 Princeton University), bee scientist Brian Johnson, associate professor, UC Davis Department of Entomology and Nematology, touches on colony pests in addition to his indepth coverage of everything from molecular genetics, development, and physiology to neurobiology, behavior, and pollination biology.
Johnson writes in part: "The greater wax moth (Galleria mellonella) and the lesser wax moth (Achroia grisella) are old and well-known pests of honey bees. The female moth lays her eggs on the comb and the larvae consume the wax, pollen and honey. In nature, these pests are mainly a threat to weak colonies, as strong colonies can kill their larvae." He goes on to mention that beekeepers who inadequately store large amounts of wax combs may be subject to wax moth infestations. He recommends air tight storage and the use of mothballs.
The larvae are not always unwanted. They've been introduced as an alternative model to study microbial infections.
So, in keeping with National Moth Week, the Bohart Museum of Entomology is hosting its annual Moth Night from 7 to 11 p.m. on Saturday, July 20 at its headquarters in Room 1124 of the Academic Surge Building, 455Crocker Lane, UC Davis. Inside, Jeff Smith, curator of the Bohart's Lepidoptera collection, and his colleagues will be displaying moth specimens and answering questions. Outside, Bohart research associate John "Moth Man" De Benedictus will set up a blacklighting display, complete with white sheet and a UV light to attract moths and other night-flying insects.
The open house is free and family friendly. Also free: hot chocolate and cookies, according to Tabatha Yang, education and outreach coordinator.
Founded in 1946, the Bohart Museum is the home of a global collection of eight million insect specimens. It also features a petting zoo (including Madagascar hissing cockroaches, walking sticks and tarantulas) and a gift shop stocked with insect-themed t-shirts, hoodies, books, posters, jewelry and more. The museum is directed by Professor Jason Bond, the Evert and Marion Schlinger Endowed Chair, UC Davis Department of Entomology and Nematology, and associate dean, Agricultural Sciences, UC Davis College of Agricultural and Environmental Sciences.
![Close-up of the larvae of the greater wax moth (Galleria mellonella), pests of honey bee colonies. Also shown is another bee colony pest, a hive beetle. (Photo by Kathy Keatley Garvey) Close-up of the larvae of the greater wax moth (Galleria mellonella), pests of honey bee colonies. Also shown is another bee colony pest, a hive beetle. (Photo by Kathy Keatley Garvey)](/blogs/blogcore/blogfiles/107877.jpg)
![This is the greater wax moth (Galleria mellonella) from the Bohart Museum of Entomology Lepidoptera collection. (Photo by Jeff Smith) This is the greater wax moth (Galleria mellonella) from the Bohart Museum of Entomology Lepidoptera collection. (Photo by Jeff Smith)](/blogs/blogcore/blogfiles/107883.jpg)
![This is the lesser wax moth, Achroia grisella, from the Bohart Museum of Entomology Lepidoptera collection. (Photo by Jeff Smith) This is the lesser wax moth, Achroia grisella, from the Bohart Museum of Entomology Lepidoptera collection. (Photo by Jeff Smith)](/blogs/blogcore/blogfiles/107884.jpg)
- Author: National Pesticide Information Center (NPIC)
Acetic acid, also known as vinegar, is used in products for weed control. Many people choose it because it is natural. However, acetic acid can damage skin and eyes, especially at concentrations commonly found in weed killers.
What is the difference between acetic acid, vinegar, and horticultural vinegar?
You may know acetic acid best as vinegar. Vinegar is a solution of acetic acid in water. Acetic acid is a naturally occurring substance that is found in all living things. It is formed during fermentation. Acetic acid can also be made industrially. It is used in many industrial processes, including the manufacture of dyes, plastics, some drugs, and other industrial chemicals. It is also used in textile printing.
Household vinegar such as distilled white vinegar used for cleaning or cooking generally contains 4-6% acetic acid, which is diluted in water. Higher strength acetic acid solutions are sold for other purposes. Horticultural vinegar typically refers to a concentrated solution of 20% or more acetic acid. It is sold to kill weeds. You may find even higher concentrations of acetic acid sold in stores or online.
Are there health risks of using vinegar/acetic acid?
Acetic acid is irritating to the eyes and skin. At concentrations above those usually found in household vinegar, it can be extremely irritating or corrosive. Acetic acid can permanently damage the corneas if it gets into your eyes. It can burn skin and the tissues of your mouth and throat if you accidentally swallow it. People have had irritation in their nose, throat, and in their lungs if they breathed in enough of the vapor.
Never leave any pesticide unattended around children or pets. Never leave any pesticide in an unlabeled container. "Natural" does not mean "safe!" Remember, the dose makes the poison. The higher the concentration of acetic acid, the greater the risk.
How does vinegar/acetic acid kill weeds?
Acetic acid is a non-selective contact herbicide. It must touch the foliage of the plant in order to work. It does not damage tissue it does not touch. It does not travel throughout the plant. Acetic acid breaks open cell walls and causes cell death. The plants die by drying out.
Acetic acid breaks down rapidly in the environment. It does not leave a residue.
Acetic acid readily turns into a vapor. Like other chemicals, warmer temperatures increase volatilization, or turning into a vapor. The vapor can irritate the nose, throat, and lungs if breathed in. Prolonged exposure to high concentrations of the vapor can cause fluid buildup in the lungs.
What sort of pesticide/herbicide products contain vinegar/acetic acid?
Products containing vinegar/acetic acid that have been registered by the United States Environmental Protection Agency (U.S. EPA) as pesticides/herbicides will have a signal word and an EPA registration number on their packaging. Label information includes where and how to use the product, what precautions to take, personal protective gear to wear while using the product, and first aid instructions in case something goes wrong.
Products registered to be used as herbicides have high concentrations of acetic acid, typically 20% or more. All registered herbicides containing acetic acid have a signal word of DANGER because of the high concentrations and high toxicity. Specifically, it is because of the risks of the acid to the eyes and skin. Low concentrations of acetic acid are used in insect lures.
Acetic acid is available commercially for many purposes. Consider purchasing a product registered as a pesticide if you plan to use acetic acid for weed control. Doing so means you will have directions for use as an herbicide and information on precautions you can take to keep risks low. Products that do not have an EPA registration number and signal word are not registered to be used as herbicides and may not have appropriate safety or precautionary information for that use. Look for an EPA Registration Number and a signal word to ensure you are purchasing a registered product.
How can I reduce the risks when using vinegar/acetic acid?
- Any time you use a pesticide, always read and follow all label instructions. The label is the law.
- If the label specifies personal protective equipment, you must use that equipment.
- Wear long sleeves, long pants, shoes, socks, and gloves at a minimum whenever using any pesticide.
- Consider wearing protective eye wear and chemical resistant gloves when mixing, diluting, or applying vinegar as an herbicide because of its acidic and corrosive nature. The label instructions may require their use.
- Keep everyone else away from the treatment area until dry.
- Keep all pesticides away from children and pets. Remember that horticultural vinegar can badly damage your eyes or blind you!
- Consider integrated pest management strategies that do not use chemicals to control weeds.
For more information about pesticides and pesticide safety, visit the National Pesticide Information Center (NPIC) website at npic.orst.edu.
[Originally featured in the Summer 2024 edition of the Home and Garden Pest Newsletter]
- Author: Michael Hsu
Detection of fungus causing red leaf blotch spurs call for grower vigilance
Symptoms of red leaf blotch (RLB), a plant disease caused by the fungus Polystigma amygdalinum, have been observed for the first time in California across the Northern San Joaquin Valley.
Molecular DNA testing by the laboratory of Florent Trouillas, University of California Cooperative Extension fruit and nut crop pathology specialist, has detected P. amygdalinum. Pest identification was confirmed by the California Department of Food and Agriculture and U.S. Department of Agriculture.
The disease, named for the characteristic orange-to-dark red blotches that appear on infected leaves, is typically nonlethal for trees but has been a long-standing problem for almond-growing regions across the Mediterranean. Causing trees to lose their leaves prematurely, the fungal pathogen can significantly diminish crop yields in the current year and the next.
“It is one of the most severe diseases of almonds for Spain and the Middle East,” said Trouillas, an associate professor in the UC Davis Department of Plant Pathology. He recently co-authored an explanatory article on the UCCE San Joaquin Valley Trees and Vines blog.
With symptomatic trees seen in multiple orchards across Madera, Merced, San Joaquin and Stanislaus counties, Trouillas said RLB is already “somewhat widespread.”
“From the first observations so far, it seems like it affects some of the most-planted cultivars, like Nonpareil and Monterey,” he added. “We've observed it in a diversity of cultivars already.”
UC Cooperative Extension specialist urges taking preventive measures
According to Trouillas, RLB caused by P. amygdalinum is “highly specific” to almond trees, and generally only affects their leaves. Infection typically happens at petal fall, when small leaflets are first emerging and most susceptible to disease. After the pathogen's latent period of about 35 to 40 days, the first symptoms appear – small, pale-yellow spots on both sides of the leaves.
Those blotches become yellow-orange and then reddish-brown in the advanced stages of the disease during June and July. Now, with RLB symptoms becoming more prominent, Trouillas and UC Cooperative Extension advisors across the Central Valley have seen an uptick in calls.
“PCAs [pest control advisers] have been confused because they've never seen anything like this,” said Trouillas, noting that the yellow-orange-red blotches are symptoms unique to RLB and cannot be confused with other known almond diseases.
Applying fungicides after RLB symptoms appear is ineffective, Trouillas said. The best thing growers can do at this point is to report symptomatic trees to researchers so they can track the prevalence and distribution of the disease.
Growers who see signs of this new disease in their orchard should contact their local UC Cooperative Extension farm advisor.
Preventive measures are the best way to manage RLB, Trouillas said. He urges concerned growers to think ahead to next winter/spring and plan for fungicide applications at petal fall and – if rains persist – also at two weeks and five weeks after petal fall. Fortunately, those are the same three key timings for managing other diseases, like shot hole and almond anthracnose.
“Because RLB is something that is introduced and potentially aggressive, it will be important for growers to keep that in mind next year and be on schedule for next year's spraying program,” Trouillas said.
Additional information on RLB can be found at https://www.sjvtandv.com/blog/first-detection-of-red-leaf-blotch-a-new-disease-of-almond-in-california.
/h3>/h3>- Author: Belinda Messenger-Sikes
Exotic and invasive pests threaten California's natural environments, agricultural production, structures, landscapes and gardens. Exotic pests are organisms introduced into an area beyond their natural range and become pests in the new environment. Most introductions have been unintentional and accidental, but some invasive plant problems began as ornamental plants for sale.
Invasive species prevention is the most economical and desirable approach to invasive species management. However, when prevention isn't successful, pesticides may be needed to eradicate or control invasive species.
What are some problematic invasive species?
Aedes mosquitoes can transmit some of the most debilitating and deadly mosquito-borne pathogens to humans, such as Zika virus, dengue virus, chikungunya virus, and yellow fever virus. One Aedes species is also capable of transmitting heartworm to dogs. These invasive mosquitoes are now present in many regions of California, from Shasta County to San Diego County.
![A long, speckled brown insect with a pointed head on a green leaf. A long, speckled brown insect with a pointed head on a green leaf.](http://ucanr.edu/blogs/UCIPMurbanpests/blogfiles/107885.jpg)
The glassy-winged sharpshooter is a large leafhopper that can transmit several important, often fatal, plant diseases in California. This includes Pierce's disease of grape, alfalfa dwarf, almond leaf scorch, and mulberry leaf scorch. Pierce's disease is of most concern in California since the state produces 94% of U.S. grapes.
Pampasgrass is a common ornamental landscape plant that readily naturalizes throughout California's coastal areas and some interior regions. Historically, pampasgrass was planted for erosion control, but it has since escaped cultivation and spread along sandy, moist ditch banks throughout coastal regions of southern California. Pampagrass can also grow in the hot, dry climate of inland areas of California.
Hydrilla is an invasive, aquatic weed that can be found in many slow-moving freshwater bodies in California. The plant forms large mats that can crowd out native plants, restrict water flow, and interfere with boating and fishing. These mats can reduce habitat for fish and other wildlife, degrade water quality, and increase the risk of flooding
What can you do?
- Learn to identify invasive species new to California. See the UC IPM Invasive and Exotic pests pages.
- Use plants native to your area for landscaping. Native plants can require less water, provide habitat for native butterflies and pollinators, and usually have fewer pest problems, too.
- Don't release exotic or invasive plants into the environment. Never dump your aquatic plants or aquarium water into streams or creeks, since many aquarium plants are highly invasive.
- Be careful what you bring back when you travel. Don't bring foreign plant or animal material into California.
- Don't move firewood. Buy it where you burn it.
- Report invasive species in your area! Contact your local UC Cooperative Extension office or Agricultural Commissioner.
- Cooperate with authorities during invasive species control activities.
[Originally featured in the Summer 2024 edition of the Home and Garden Pest Newsletter]
/h2>/h2>- Author: Belinda Messenger-Sikes
Pesticides and fertilizers applied around homes, residential or commercial landscapes, school sites, and other areas can enter our creeks, rivers, and oceans, degrading water quality. While pesticides and fertilizers can be useful in controlling pests and helping plants grow, their overuse and misuse can harm the environment and human health.
To find out more, see our updated pages on urban pesticides, fertilizers, and water quality. These pages feature plain language definitions of toxicity and water quality and explanations of how pesticides and fertilizers get into our waterways. There's also information about how you can protect our creeks, rivers, and oceans when managing your home and landscape.
Learn about urban water quality at https://ipm.ucanr.edu/home-and-landscape/urban-pesticides-fertilizers-and-water-quality/.
[Originally featured in the Summer 2024 edition of the Home and Garden Pest Newsletter]