Monthly Archives: August 2018

Protect your Pets from the Western Treehole Mosquito

From the Greater Los Angeles County Vector Control District
Buzzword Blog

You may have noticed all the media coverage recently about the Aedes sierrensis mosquito, which is more commonly known as the Western Treehole Mosquito.

This mosquito species can typically be found in California’s foothills and mountains, but a neighboring mosquito control district in San Gabriel Valley recently discovered heightened Western Treehole Mosquito numbers in their surveillance traps, triggering some concern among pet owners.

Although it is unclear what exactly caused the population upsurge, this year’s El Niño weather conditions of extra rainfall may have been a contributing factor. Particularly if you own a dog or a cat, be on the lookout for Western Treehole Mosquitoes this summer.

This nasty little pest is a frequent carrier of canine and feline heartworm which can be passed on to unsuspecting pets during blood feeding. This daytime biter is known by its colloquial moniker because it lays eggs and spends the immature stages of its life cycle in rotted wood and holes of trees. The female mosquito may also deposit her eggs in cavities or pockets between tree limbs and root systems that can hold rain or excess water. The eggs can stay dormant for years until water fills the tree holes and the eggs hatch.

It is important to keep in mind that Western Treehole Mosquitoes are day biters and to protect yourself and your pets accordingly. Also, these pests prefer to feed on their victims in shaded areas. Despite being persistent human and animal biters, they are currently not known to transmit disease to humans. Western Treehole Mosquitoes can be identified by their dark color, pointed abdomen, and white stripes on their backs and hind legs. They are generally half the size of other mosquitoes commonly found in the region. Adults typically occur from February through June. Summer broods are possible following abnormal rainfall.

As mentioned earlier, these mosquitoes pose a threat to dogs since canine heartworm can be spread through the bite of an infected female mosquito. It takes approximately seven months for the heartworm larvae to mature into adults once the dog is bitten. Adult heartworms adhere to dogs’ hearts, lungs and surrounding blood vessels, where they continue to reproduce. These adult heartworms can grow up to twelve inches long, and can live from five to seven years. Usually, your pet will not exhibit outward symptoms of the disease until the condition becomes more serious. Advanced symptoms include rapid tiring, shortness of breath, chronic dry cough, listlessness and weight loss.

Heartworm cannot be passed directly between mammals and can only be transmitted by an infected mosquito. A dog is, however, a reservoir host for the disease. If a mosquito bites an infected dog, that mosquito can acquire the parasite in its blood meal and possibly infect other dogs or animals. While dogs are most susceptible to heartworm, cats and wild animals, such as coyotes, can also be infected. Preventative medicines for animals are available. Blood tests can be conducted to identify the presence of heartworm in both the larval and adult stages. Consult a veterinarian for more information or treatment options. You can protect your pets from potentially harmful mosquitoes and the diseases and parasites they carry through proactive mosquito prevention. Eliminate standing water around your home and report problem sites. By working together as a community, we can help protect our pets, our family, and ourselves from mosquito-transmitted diseases.

It’s Not Just You. The Mosquitoes Really Are Worse This Year.

by Emily Guerin in on August 16, 2018 6:00 AM
LAist.com

Photo by azarius/Flickr CC

Can’t leave the house without getting bitten? Legs swollen from scratching? Welcome to the crowd. Because yes. The mosquitoes are worse this year.

Why? There’s a new type of mosquito in town. You might have heard of it — it’s the Aedes mosquito — and it first showed up in El Monte in 2010. Since then it’s been spreading all throughout Southern California. And it’s way more vicious than our native mosquito, the Culex.

Read more

The distribution of invasive Aedes mosquitoes in Southern California, as of Aug. 3, 2018. (Courtesy California Department of Public Health)

How to Help Plants Cope with Drought and High Heat

By Rebecca Latta

The worst plant-damaging high heat event I’ve seen in my career happened in early July of this year, affecting plants in the San Gabriel Valley and throughout the Southern California region. Many of you have asked for help on how to manage your trees and gardens in such a severe event. I’m responding with some tips gained from my 25 years of experience promoting healthy trees and landscaping. If you have questions, please do call on me to assist you, 626-272-8444.

In the record-busting heat wave in July, mature trees dropped green leaves, buds and fruit, plants wilted, sunburned and scorched. Shoots, seedlings and potted plants wilted and died. What caused it? Climate change is promoting heat events and drought conditions here and around the world. More extreme weather events of this nature are expected, and will continue. We need to learn strategies to protect our trees and landscaping, which I outline below.

This garden, protected by a top layer of mulch, features drought-tolerant native oaks and sycamores.

Choose the right species

Climate change presents significant challenges to the future of our urban landscape. As our once-mild Mediterranean climate heats up, we have to choose species that can adapt. Species such as redwood, birch, saucer magnolia, Victorian box and avocado tend to struggle in extreme heat events, and may need to be protected from heat and intense reflected light, or replaced with local natives, such as oaks and sycamores. Heat tolerant species from South America and the Sonoran desert, such as tipu, mesquite, desert willow, velvet ash, pinyon pine, California juniper, red willow, desert apricot and cypress may also be good choices.

Plant for both drought and heat resistance

Some plants from coastal climates can take dry soil but are not genetically adapted to high temperatures. Plants that thrive in hot conditions can feature waxy leaves, smaller leaf surface area, reflective surfaces or blue-gray color to reduce heat absorption, or can be drought deciduous, dropping leaves during dry parts of the year. Some plants store water below ground in roots or above ground in stems.

Heat damage can make plants more susceptible to opportunistic diseases and wilt, chlorosis and fruit drop. Excessive heat and sunlight can speed up disease issues. Reflected heat can do damage. Plants near hardscape, artificial turf and on sunny walls with a southern or eastern exposure can be scorched or burned. High soil temperature damages seedlings and may cause root and tissue damage that shows up later in trees and shrubs.


Burlap shade cloth protects this tomato plant.

Implement cooling strategies during the event

Provide shade. Plan ahead and plant tall annuals like sunflowers to shade smaller plants. During the heat event, use shade cloth, cardboard and patio umbrellas to protect plants from heat. Protect mature shade trees that are shading other plants in the landscape, and keep them well hydrated prior to high heat events. Wrap burlap on exposed trunks, or use a foliar spray, whitewash or latex paint on trunks for sunburn protection. Shade can also be sprayed on plants and trees in the form of a clay product called Kaolin that reflects sunlight, much as we use zinc oxide as a sun block. Apply with an inexpensive sprayer. Be sure to follow package directions and wear a mask and goggles.

Water strategically

Water to establish deeper roots – less frequent deep irrigation in the spring and fall. During the summer, watering may need to be based on the weather—weekly or monthly—even for established trees. Get ahead of any high heat events and water deeply several days in advance of the event.

Soak plants to 1-2 feet deep, and allow the top one or two inches to dry out before watering again. Make sure water is reaching the roots at and beyond the drip lines of plants. Check moisture with an inexpensive moisture meter, with a small shovel or long screwdriver.

Mulching, blowing and pruning

Mulching is the best way to protect soil and plant roots from heat. It’s also key to conserving water. Mulches hold moisture, encourage soil microbial activity, suppress weeds and improve soil structure.

As you phase out heat-and drought-sensitive plants and plant new trees and shrubs that can tolerate drier and hotter environments, be sure to chip and spread them on-site as valuable mulch. Your old plants can help protect your new plants and provide food for their growth.

Apply bark chip mulch or mulch/compost mix about 4 inches deep around plant roots. Don’t use rocks or inorganic mulch—it can retain heat in the soil at night when roots need to cool down. Artificial turf should not be used—it can overheat soil, damaging roots.

Keep your mulch in place, don’t blow it away. Plants need this organic cover to protect the roots from heat and drying. Remind gardeners that blowers are for paved surfaces only. Keep dropped leaves in planter beds—leaf litter is good plant food.

Remove understory competition such as ivy, creeping fig and vinca. These plants can take water and nutrients away from trees and shrubs. Mulch these areas or plant sparsely.

Resist the urge to prune. Keep dead leaves on plants and trees until cooler fall weather. Those dead leaves will offer some sun protection for the rest of the summer.


Patio umbrellas provide protection for squash and pumpkin vines

Wait until fall to plant and fertilize

Plant new shrubs and trees in the fall, after the weather starts to cool off. Encourage new root and shoot growth by using products with potassium, that strengthens cell walls.

Don’t fertilize during a heat event. When you do fertilize, use products that strengthen cell walls. If soil is so dry it repels water, buy a wetting agent to penetrate the soil.

Warm Regards,

Rebecca

Who will save LA’s trees?

The city’s urban canopy is disappearing—and new developer rules might make it worse


Preserving mature trees, especially ones that form a canopy, should be LA’s priority.
Getty Images/EyeEm

Curbed Los Angeles 
la.curbed.com

By Alissa Walker  

The Ficus microcarpa trees along Hollywood’s Cherokee Street create a majestic arch. Walking beneath them is an almost otherworldly experience. In the impenetrable shade, as birds chirp high in the deep green canopy above, the air is unmistakably cooler.

Trees are critical for cooling down warming cities like Los Angeles, where temperatures are expected to increase an average of 4 to 5 degrees Fahrenheit by 2050.

The shade that trees produce can cool surfaces like soil and pavement. But trees can also lower the surrounding daytime summer air temperature up to 10 degrees, thanks to water evaporating from their leaves.

That’s why preserving mature trees that form a canopy should be LA’s priority, says Glynn Hulley, a scientist in the carbon cycle and ecosystems group at NASA’s Jet Propulsion Laboratory.

“It’s a pretty precious resource in cities, and you don’t want to take them down—you want to be adding to them,” he says.

LA’s palm trees are iconic, but they require a lot of water, and don’t create a great deal of shade.
Getty Images/Collection Mix: Subjects RF

Instead, since 2000, many neighborhoods in the LA region have seen a tree canopy reduction of 14 to 55 percent, according to a University of Southern California study published in 2017.

In recent years, the city’s street trees have taken a hit. According to permits filed with the city of Los Angeles’s street services bureau, 263 street trees—including the 18 on the 1200 block of North Cherokee—are slated to be ripped out in the first five months of this year alone for sidewalk repairs and street widening.

Those numbers are for removals of three or more trees at a time and do not include instances where one or two trees are removed for repairs, which do not require a public hearing. They also do not include permits by developers to remove one or two street trees.

“People should be climbing into these trees to stop them from being cut down,” says Hulley.

Hulley is publishing a major study this summer looking at heatwave trends in the region, which he recently presented to a Los Angeles County sustainability task force.

The many devastating—and deadly—effects of heatwaves include increased wildfire risk.

“Heatwaves are not only increasing in frequency and intensity, but also their seasonality is changing, with more heatwaves earlier and later in the year,” says Hulley. “Trees are the most cost-effective way to cool down the urban environment.”

Since 2010, the region has experienced extreme drought conditions, which not only kills trees but also makes them more susceptible to disease. But the drought is only partly to blame for LA’s recent tree loss.

After an era that saw maintenance efforts plummet and budget cuts that restructured the city’s urban forestry efforts, in recent years, more healthy trees have been removed to make way for construction or sidewalk repairs.

Climate Ready Trees for Southern California

A UC Davis study evaluates tree species suited to a dryer,
hotter future environment

The purpose of this study, Climate Ready Trees,  is to evaluate the ability of promising but underused species to tolerate stressors of future climates. In so doing, the study authors hope to shift the palette of trees planted to species that will make urban forests healthier and more resilient. READ the study HERE

The study identifies trees that perform well under stressors associated with climate change in California’s Central Valley, Inland Empire and Southern California Coast climate zones. By replacing highly vulnerable species with species better adapted to future conditions, the palette of trees commonly planted can be shifted to species providing the most environmental, social and economic value in the future. The authors are conducting the study with the help of growers, designers, arborists and the public.

View the Trees by Climate Zone
Trees for Southern California’s Future Climate

Droughts, heatwaves and floods: How to tell when climate change is to blame

Weather forecasters will soon provide instant assessments of global warming’s influence on extreme events.

NEWS FEATURE
Nature.com
International Journal of Science

Plants growing from the dried out riverbed of Elbe. In the background can be seen churches and buildings of Dresden

Europe’s 2018 heatwave: the partly dried-out Elbe riverbed in Dresden, Germany, on 9 July. Credit: Jens Meyer/AP/Shutterstock

The Northern Hemisphere is sweating through another unusually hot summer. Japan has declared its record temperatures a natural disaster

The Northern Hemisphere is sweating through another unusually hot summer. Japan has declared its record temperatures a natural disaster. Europe is baking under prolonged heat, with destructive wildfires in Greece and, unusually, the Arctic. And drought-fuelled wildfires are spreading in the western United States.

For Friederike Otto, a climate modeller at the University of Oxford, UK, the past week has been a frenzy, as journalists clamoured for her views on climate change’s role in the summer heat. “It’s been mad,” she says. The usual scientific response is that severe heatwaves will become more frequent because of global warming. But Otto and her colleagues wanted to answer a more particular question: how had climate change influenced this specific heatwave? After three days’ work with computer models, they announced on 27 July that their preliminary analysis for northern Europe suggests that climate change made the heatwave more than twice as likely to occur in many places.

“With these studies … we are able to quantify the effect of climate change, in a specific location at a specific time of year.”

Soon, journalists might be able to get this kind of quick-fire analysis routinely from weather agencies, rather than on an ad hoc basis from academics. READ MORE