- (Focus Area) Yard & Garden
- Author: Lauren Fordyce
While preparing your garden for planting this spring, you may have found white grubs in the soil. While uncovering these sometimes large, white grubs can be alarming, they usually won't cause significant plant damage.
Grubs are the soil-dwelling larvae of several beetles in the Scarabaeidae family. They are generally C-shaped with whitish bodies and 6 legs. The larvae of smaller species may be less than 0.5 inch long, while larger species may be over 1 inch. Some grubs feed on living plant material while others do not.
In most cases, the presence of grubs does not require pesticide treatment and populations of 6 or less per square foot won't cause significant damage. If you notice them in your garden beds, they can be hand-picked and killed. Some may choose to feed them to their backyard chickens or leave them out for wild birds. Beneficial nematodes can be applied to control grub infestations.
To learn more about common white grubs, visit https://ucanr.edu/blogs/blogcore/postdetail.cfm?postnum=56797
- Author: Trina Kleist
- Posted by: Gale Perez
Hanson: “Some weeds you can only eat once”
Our weed doctors will be available to identify weeds and give people advice during the UC Davis Picnic Day this year, from 10 a.m. to 2 p.m. Saturday, April 20, in the Plant & Environmental Sciences (PES) Building courtyard. Research staff have collected seasonal weeds for their “weed petting zoo” to help you identify what's in your lawn, flower bed or horse pasture.
People often ask for low-cost, easy and chemical-free solutions to eradicate weeds, said scientist Brad Hanson. “I usually tell them, ‘Weeds are weeds for a reason,' and they might be more successful if they pick two of those three specifications.” In the case of stubborn perennial pests, the weed doctors can recommend an effective herbicide.
Weeds are a huge problem in our natural lands, too. “Besides affecting landscapes and agricultural fields, weeds are driving ecosystem changes and altering fire regimes in California,” said weed and restoration specialist Justin Valliere. “In many cases, ecological restoration is primarily related to managing and preventing weed invasions.”
Careful what you eat!
Also at this year's "Ask the Weed Doctor" booth will be Jens Beets, the new research ecologist with the United States Department of Agriculture's Agricultural Research Service. Based at UC Davis, Beets is an expert in aquatic plant management.
Information also will be available about aquatic weeds.
Visitors can take home information sheets describing pests and guides from the University of California's Statewide Integrated Pest Management Program. Weed doctors also can point visitors to helpful books, local resources such as a UC Master Gardeners group, and online resources, Hanson added.
Faculty with the Weed Research and Information Center enjoy meeting people and hearing about their weeds. A memorable conversation, Hanson recalled, went like this: “Hey, this one shouldn't be called a weed! If you pick it when it's tender, you can eat it in a salad.” To that, the weed doctor responded, “You can eat any weed, but some of them you only eat once!”
Check out all the information available at the UC Weed Research and Information Center.
Original source: UCD Plant Sciences website • NEWS April 11, 2024
- Author: Kathy Keatley Garvey
Remember when San Francisco 49'ers wide receiver Brandon Aiyuk credited his spectacular 51-yard catch in the 2024 NFC championship game with the Detroit Lions to a ladybug (note that entomologists correctly call it a "lady beetle") landing on his shoe before the game?
Well, those attending the 110th annual UC Davis Picnic Day activities on Saturday, April 20 at Briggs Hall--home of the UC Davis Department of Entomology and Nematology--can also net some luck.
Children are encouraged to take home a couple of the beetles at the UC Statewide Integrated Pest Management Program (UC IPM) booth in the courtyard of Briggs. (Adults can do so, too. Maybe they'll name their beetles "Brandon" and "Aiyuk.")
The ladybug is actually a beetle (Coleoptera), not a bug (Hemiptera). It's associated with good luck because it eats the aphids that try to destroy our crops. It can eat as many as 5000 aphids in its lifetime, scientists estimate.
"These beetles have become a cultural icon of sorts because of their appearance and their beneficial habits," writes UC Davis distinguished professor Lynn Kimsey, former director of the Bohart Museum of Entomology, in her insect fact sheet on lady beetles. "Both adults and larvae feed on aphids and other small, soft-bodied insects...They are ferocious predators on small insects." (See what the UC Statewide Integrated Pest Management Program says about lady beetles.)
Ever seen a close-up shot of a lady beetle eating an aphid? The predator and the prey...
Ever seen a cellar spider snaring and eating a lady beetle? The predator and the predator...one becomes prey.
Ordinarily, the lady beetle's bright red coloration serves as a "warning" to predators. Plus, lady beetles are known to ooze a foul-tasting chemical that tastes so bad that predators leave them alone. This lady beetle engaged in "reflex bleeding," exuding an alkaloid toxin (which did not deter the predator).
Lady beetles will be just a few of the bugs at Briggs Hall during UC Davis Picnic Day. You'll also see cockroach races, maggot art, and displays featuring ants, bees, walking sticks, mosquitoes, nematodes, butterflies, spiders, whip scorpions, and more. Check out "bug" activities at Briggs Hall here. UC Davis Picnic Day is free and family friendly.
- Author: Judy Quan
In winter it's a normal process to see yellowing leaves and leaf drop. When we see this in other seasons, it indicates a problem. When we see the yellowing leaves on our citrus, we often jump to the conclusion there is an iron or a nitrogen deficiency, but there can be a variety of causes.
Before adding nutrients such as iron or nitrogen, consider things such as the time of year, watering practices, soil pH, general care practices, as well as the pattern of yellowing on the leaves.
Things to check first before adding nutrients:
√ Is it winter with cold soil temperatures?
√ Are rains or irrigation practices causing soil to be waterlogged?
√ Is soil pH alkaline, greater than 7.5?
√ What fertilizers have been applied?
√ What is the pattern of yellowing on the leaves, symptoms in older or younger leaves?
Certain conditions often make nutrients unavailable to plants, even though the nutrient may be present in the soil.
Alkaline soil pH. Soil pH is a measure of soil acidity/alkalinity, with 7.0 as the neutral point. Citrus, like other plants that are adapted to slightly acidic soil, are especially prone to iron deficiency when soil pH is above about 7.5 (alkaline). Alkaline soils hold onto iron, making it inaccessible to plants, even though typically iron is plentiful in most California soils. A pH of around 6.5 is ideal for citrus, but it can tolerate a range from 6.0 to 7.5. Adjusting soil pH needs to be done carefully and slowly to avoid unwanted effects in the garden.
Cold soil and soggy soil limit microbial activity important in getting nutrients to the plants. Microbes need porous soil and a certain temperature range to thrive, which is why chlorosis (yellowing leaves) is more common in winter. Porous soils have spaces in the soil that allow water and air to move easily in the soil. Compacted or clay soils are especially prone to a lack of porosity in cold, wet weather which may persist into spring.
Nutrient imbalances, especially an overabundance of zinc, copper, and manganese, can make iron less available. Causes vary, but imbalances can be due to over-application of certain fertilizers.
Identification: Iron deficiency symptoms: yellow leaves, green veins – primarily in young leaves. Nutritional deficiencies in citrus can be identified by the pattern of leaf yellowing and by noting whether it occurs on old or new foliage. The pattern of yellowing leaves between the small, darker green veins occurs primarily in young leaves. This happens as soils cool, reducing root activity. Other possible causes of that pattern of yellowing include zinc and manganese deficiencies. See the UC Integrated Pest Management website for pictures of various patterns of chlorosis.
What to do about iron deficiency?
Improve cultural practices and the soil environment.
- Make sure to irrigate with sufficient time between waterings to allow soil to dry but still provide enough water. Deep watering once a month is often sufficient, especially in summer.
- Make sure drainage allows roots to have air and water, avoiding waterlogged soil.
- Regularly add compost on top of roots, away from the crown of citrus. The addition of organic matter helps with iron deficiency as the organic matter decays and soil gradually becomes more acidic.
- If there has been a history of regular application of fertilizers, a soil test may be helpful to determine potential nutrient imbalances before applying more fertilizer.
- Iron, manganese and/or zinc deficiencies can be corrected with a foliar (leaf) application of a liquid micronutrient solution as the new growth emerges in the spring. You can also apply micronutrients, such as zinc sulfate or iron sulfate, to the soil. Microelements such as iron and zinc though, need an actively growing root system for uptake. Their soil application should be limited to the summertime.
Identification: Nitrogen (N) deficiency symptoms- leaves pale all over (light green or yellow), especially in older leaves. Nitrogen deficiency starts with older leaves near the bottom of the tree and foliage turns a uniform yellow. Slow growth and uniform yellowing of older leaves are usually the first symptoms of nitrogen deficiency. The causes include a true deficiency of nitrogen, adverse soil conditions, or unhealthy roots.
What to do about nitrogen deficiency in citrus?
Most citrus require regular fertilization with nitrogen. However, there are still conditions that would mimic nitrogen deficiency that would not be fixed by adding nitrogen.
- Wait until the soil is warmer, moist but not soggy, to apply nitrogen. Cold and soggy soil inhibits nitrogen uptake.
- Make sure to water with sufficient time between waterings to allow soil to drain well but still provide enough water to citrus. Deep watering once a month is often sufficient, especially in summer.
- Make sure drainage allows roots to have air and water, avoiding waterlogged soil, which often leads to rot and crown damage.
- Regularly add compost on top of roots, away from the crown of citrus. The addition of organic matter helps with iron deficiency as the organic matter decays and soil gradually becomes more acidic.
- Consider doing a soil test, either from a commercial laboratory or a home soil test kit. If there has been a history of regular application of fertilizers, a soil test may be helpful to determine potential nutrient imbalances and to know the current levels of nutrients such as N,P, K and pH.
- Remember it is possible to over-fertilize, potentially causing problems such as a delay in maturity and a reduction in fruit quality; so when in doubt, fertilize less.
When should citrus be fertilized?
Most mature citrus require regular fertilization with nitrogen.
- Begin nitrogen fertilization in February or March depending on the temperature, when soils are warmer and drier, just before pre-bloom.
- Fertilize only in the spring and summer months.
- Choose more frequent/small applications of nitrogen that allow more efficient nitrogen uptake, so less fertilizer is required.
- Or choose the more convenient schedule of three nitrogen fertilizations to be in February, early May and June – Valentine's Day, Mother's Day, Father's Day, with a last application perhaps in early fall.
- Stop applying nitrogen fertilizer if citrus leaf miner severely damages new foliage growth in late summer.
- Aim to go into winter with adequate nitrogen stored in the plant, so when spring comes, the nutrients are already there ready for the blooming period.
- Avoid late-season fertilization
- It may affect fruit quality, delay fruit coloring and make the rind rough.
- It stimulates new growth and makes trees more susceptible to frost injury. Subtropical plants, including citrus, develop some resistance to cold damage by going through quiescence, a resting time of no or slow growth when cooler temperatures arrive. Quiescence is induced several weeks after 40-50°F temperatures arrive. But that quiescence can be changed to active growing by pruning or nitrogen fertilization in early winter, increasing the possibility of cold damage.
- Avoid adding too much nitrogen, which can damage plants and cause other problems associated with nitrogen excess. Follow the directions on the package. If in doubt, fertilize less.
What fertilizer should be used?
- Nitrogen is the chief nutrient required by citrus and should be applied each year. Fertilizers commonly contain nitrogen (N), phosphorus (P), and potassium (K), listed as NPK on the fertilizer label. Look for a fertilizer where the first number (nitrogen) is the highest of the three, e.g., 7-3-3; fertilizers formulated for citrus typically have higher nitrogen with lower levels of phosphorus and potassium. Avoid balanced fertilizers such those labeled 10-10-10. The relatively high concentrations of phosphorus and potassium are not needed since they are held in the soil much longer than nitrogen.
- Choose the type that best fits your needs. Nitrogen can be provided as organic matter, inorganic compounds, or commercial slow-release (e.g., suffer-or polymer-coated urea). Some fertilizers add nutrients only; other fertilizers are also amendments that indirectly affect plant growth by improving the physical properties of the soil. You can find more information about fertilizers and amendments from The San Luis Obispo Master Gardeners in their pdf handout.
When we see yellowing leaves in our citrus, we want a quick easy answer. But by taking a more comprehensive look at our citrus, the soil and the moisture levels in the soil, as well as the seasonal temperatures, we are more likely to correctly diagnose the problem and then effectively adjust factors that will result in healthier citrus trees. And fertilizing with the right amount of nutrients, mainly nitrogen, at the right time will promote the health and productivity of citrus while minimizing problems associated with overfertilization.
This blog post is brought to you by the Help Desk of the Master Gardeners of Alameda County. Subscribe to our blog!
Have a gardening question? We'll help. You can reach us by:
- Emailing acmg@ucanr.edu. Please include a photo of the problem, if you can, plus your name, phone number, city and a description of the problem.
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Using our online form.
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- In person at our Hayward office, during our office hours, only by appointment.
Resources
- Adjusting Soil pH in California Gardens, a free downloadable PDF
- A Guide to Citrus Nutritional Deficiency and Toxicity Identification
- Citrus for the Home Gardener 2008 Vincent Lazaneo, Horticulture Advisor
- Diseases and Disorders of Leaves and Twigs
- Fertilizing Citrus in the Foothills by Cindy Fake
- Iron deficiency UC IPM
- Nitrogen deficiency UC IPM
- When to Fertilize Avocado and Citrus in California
- Author: Kathy Keatley Garvey
Well, it wouldn't be a picnic at all!
The UC Davis Department of Entomology and Nematology (ENT) is planning scores of displays and activities at Briggs Hall for the 110th annual campuswide UC Davis Picnic Day, to take place Saturday, April 20.
Think ants, bees, beetles, butterflies, flies, cockroaches, maggots, mosquitoes, nematodes, spiders and scorpions.
And more.
This year, all of the entomology exhibits, including those at the Bohart Museum of Entomology, will be at Briggs Hall. (The Bohart Museum headquarters in the Academic Surge Building will be closed on Picnic Day.)
Hours? From 9 a.m. to 5 p.m. The Bohart Museum's pop-up tent in front of Briggs, featuring insect specimens and an insect petting zoo, will be open from noon to 4 p.m.
The entomology displays traditionally draw some 3000 attendees, said the ENT co-chairs, doctoral student Grace Horne of the Emily Meineke lab, and faculty member and forensic entomologist Robert "Bob" Kimsey. It's all free and family friendly.
Among the crowd pleasers are the cockroach races, maggot art, stick insects, and the Bug Doctor booth. The doctor is always in!
New to the line-up is the “I IUV Bugs," an exhibit about plant-insect interactions under ultraviolet light. The "glowing bugs exhibit" is the brainchild of Horne and primarily designed by the Meineke lab, "especially (doctoral student) Marielle Hansel Friedman," Horne said. "We will have plants from the UC Davis Arboretum Teaching Nursery and local/pet-trade arthropods which glow under ultraviolet light. With this exhibit, we seek to highlight the interplay between light, color, and species interactions."
Doctoral student Veronica Casey of the Shahid Siddique lab designed the new nematode exhibit. Carla-Cristina "CC" Melo Edwards of the Geoffrey Attardo lab is coordinating the new medical entomology display. "The bumble bee observation hive is unfortunately not ready for the spotlight this year," Horne said.
Bug Doctor
Briggs Hall Entryway
Graduate students will answer questions about insects. What's that bug? Attendees are encouraged to bring an insect or photo for identification.
Cockroach Races
Front of Briggs Hall
American cockroaches, Periplaneta americana, from Bob Kimsey's forensic lab, race on a specially made track, while roach fans cheer for their favorites. (Sometimes the athletes are named for faculty, friends or bystanders.)
Medical Entomology
122 Briggs Hall
Carla-Cristina "CC" Melo Edwards of the Geoffrey Attardo lab is coordinating the medical entomology display. Her research focuses on investigating the physiological mechanisms underlying pyrethroid resistance in Aedes aegypti (the yellow fever mosquito).
Diversity of Arachnids
122 Briggs Hall
Doctoral student Emma Jochim of the Jason Bond lab is coordinating an exhibit she created last year to display the diversity of arachnids, such as vinegaroons, whip spiders, tarantulas, and scorpions. "We'll have live animals and fact sheets that will give a general overview of their diversity, behavior, and habitat," Jochim said. "I'll also bring some curated specimens to show what goes into creating a scientific collection and talk about why collections are important for understanding biodiversity. "
Maggot Art
Briggs Courtyard
Artists--children and adults alike--create maggot art by dipping a live maggot into water-based, non-toxic paint. It's suitable for framing (or at least a spot on the refrigerator door). This event will close at 3 p.m. this year (last year it was at 5 p.m.)
Dr. Death
122 Briggs Hall
Forensic entomologist Robert Kimsey will display and discuss his work in his "Dr. Death" booth. Last year Kimsey pin-mounted and identified flies from various cases and research efforts, and displayed studies on the sequence of development of individual maggots, calling attention to the development and sequence of communities of insect maggots. "By these means, approximations about how long a person has been dead can be made," he told the crowd.
Entomology at UC Davis
122 Briggs Hall
Displays of insects, including bees, ants and more. Graduate students, faculty and emeriti will staff the tables.
Bohart Museum of Entomology
Front of Briggs Hall
A pop-up tent, staffed by the Bohart Museum, will include stick insects (walking sticks) and Madagascar hissing cockroaches. "We are excited to be part of the bigger department's offerings," said Tabatha Yang, education and outreach coordinator. Give-aways are also planned.
Fly-Tying
Briggs Hall courtyard
Fly Fishers of Davis will show attendees how to tie a fly. The recipients take home the flies.
Insect-Themed T-Shirt Sales
Briggs Hall entryway
Members of the Entomology Graduate Student Association (EGSA), led by president Mia Lippey, will be selling their popular insect-themed t-shirts, including The Beetles. The T-shirt, EGSA's all-time best seller, is a take-off of the cover of The Beetles' Abbey Road alum. However, instead of the Beatles crossing the road in a single file, four beetles (family names Phengogidae, Curculionidae, Cerambycidae and Scarabaeidae) do so.
Mosquito Control Booth
Entrance to Briggs (below front steps)
Sacramento-Yolo Mosquito and Vector Control District will be providing information on mosquitoes, answering questions, and handing out give-a-ways, including mosquito repellent.
UC Statewide Integrated Pest Management (UC IPM)
Briggs Hall Courtyard
“We plan to have many of our usual materials on display and will be giving out the live lady beetles (aka ladybugs) again,” said urban and community IPM educator Lauren Fordyce. “We purchase them from a local garden center. In addition to that, we plan to have a prize wheel that adults and kids can spin, answer a question, and win a prize if they answer correctly. We may also have temporary insect tattoos to give away.”
Ranked Third in the Country. The UC Davis Department of Entomology and Nematology is ranked third among “The Best Entomology Colleges in the United States for 2024" by universities.com. The department includes 24 active and 19 retired faculty; 28 graduate students (five in the master's degree program and 23 in the doctoral degree program); 47 undergraduate entomology majors (based on the Office of Academic Support and Instructional Services (OASIS) Student Reports); and a staff comprised of 27 academics (non-faculty), 24 career, and 56 student assistants. Professor and chair of the department is molecular geneticist and physiologist Joanna Chiu.