- (Focus Area) Yard & Garden
How is your garden holding up during our all-too-frequent summer heat waves? Chances are you're seeing scorched leaves, deformed flowers, severe die-back, blistered branches, constant wilting, and even plant loss. Plants are unable to tell us immediately that they're suffering heat stress and sunburn until the damage is evident. As their caretakers, we must observe our backyard environment, heed long-term weather forecasts, and plan for future extreme heat conditions, sometimes many months in advance. Let's look at the causes of heat-related problems and consider some emergency strategies to protect our gardens until the cool autumn weather arrives.
When it's hot and windy and the soil is dry, plants can experience wilt and leaf scorch. Wilt is the earliest and most noticeable signal of heat-related problems. Extreme solar radiation quickens it. Wilt is initially observed when leaves or tender new growth droops, curls, or twists unnaturally. Eventually an entire plant can look limp, a sign of extreme plant stress.
Leaf scorch appears as browned leaf margins that eventually become tissue-paper thin. When whole sections of plants display leaf scorch, it's easy to be misled into thinking that the plant is dying.
There are a few things that can be done immediately to address these heat-related issues when you notice them. A close examination of a specific plant's parts and its surrounding environment is essential. A "bottom-to-top-to-outside" strategy is recommended, meaning that you should address stressed root zones first, then the overheated plants, and finally the superheated environment around and above the plants.
Lack of water is the most likely critical factor in extreme heat-related garden problems. The higher the temperature, with increased sunshine intensity or drying winds, the faster water evaporates, leaves transpire, and the soil dries. Watering not only hydrates roots but cools them as well. Remember this point because the initial water in a hose that has been left in the sun might be scalding hot. While we do not advocate wasting water, in this case it is best to run water through the hose until the water is cool. You should have a few buckets near your faucets to collect the hot water to use later on when it has cooled.
Potted plants require even more attention. Watering them two or more times a day might be necessary. When a potted plant is very stressed, try submerging it in a larger tub filled with cool water to re-wet the soil. Leave it in it until all the bubbling stops, then remove it, let the excess water slowly drain out, and place the plant in the shade.
Remove all weeds around your plants because they are competing for water. In addition to sucking up valuable moisture, weeds steal critical nutrients that your plants require. For example, research shows that calcium helps protect plants from heat stress. Be diligent about removing weeds, grasses, and even seedlings if they're suspected of drawing up too much water from their mother plant.
While you're mulching, check for suckers around trunks or from root shoots. While seasonal pruning should be avoided during high heat spells, removing suckers will reserve water for the original plant. Also, refrain from removing unsightly scorched leaves; portions might still be photosynthesizing and shading stems or new growth at the leaf axils. Remember: don't immediately equate burned leaves to a dead or dying plant. Give it time to recover before removing it.
Now that you've addressed the root and plant issues, move on to the environment around and above the plant. One strategy here is to mist the plant, though this is not a replacement for direct watering. Misting helps reduce air temperature and physically cools leaves. When partnered with shading strategies, mist becomes very helpful in locally reducing extreme heat. It is recommended to mist mid-day to early afternoon, allowing moisture to dry before dusk. Excessive moisture on leaves in the evenings can promote unwanted pests and fungus. Many commercial misting systems have timers and attachments to help you create an overhead system that is best for you and your garden. If you don't want to invest in a misting system, periodic mid-day spraying from a cool garden hose can work wonders to perk up limp, stressed plants. One key consideration about misting is to hand water the stressed plant first to revive it before doing any misting. If you hand mist first, the weight and pressure of the water on a heat-weakened plant might snap off new growth.
It is also important to reduce exposure to the light and heat reflected off buildings, concrete hardscaping, and even gravel walkways. Again, applying shade above plants will reduce the problem, but hanging a dark cloth or tarp on a building's walls or temporarily putting mulch onto concrete or other hardscaping can further reduce issues brought on by reflective heat and light conditions.
Lawns can also suffer during extreme heat events. Watering schedules should be set for early morning, with increased frequency (number of days) and extended watering times. Longer watering periods help grass roots grow deeper into cooler soil, creating increased resilience to extreme heat. A good test to see if a lawn is receiving enough water is observing the grass blades after walking across the lawn: if they bounce back, the lawn is well watered. If they remain bent, the lawn is too dry. Let grass grow longer between mowings (set mower up an inch or more), and never fertilize in the summer months.
Finally, observe the changing areas of light and shade in your garden throughout the year. Note areas that are sunny, those that have morning sun and afternoon shade, those with all-day filtered sunlight, and those with deep shade. Take note of places where reflective light and heat might originate. Determine how wind generally moves through your garden. Take pictures every month from the same vantage points at different times of the day. Your mission is to track the movements of sun and shadow on your garden. Make sure to photograph plants damaged by extreme heat. These aren't beauty shots. You can use this information for future long-term extreme heat mitigation strategies.
Extreme heat conditions are tough on the garden. Incorporating these recommendations shouldn't add too much work to your current garden activities. You'll be happy knowing that you helped your plants survive another summer. And remember to use a good sunscreen and wear a hat when out in the garden yourself.
UC Master Gardeners of Butte County are part of the University of California Cooperative Extension (UCCE) system. To learn more about us and our upcoming events, and for help with gardening in our area visit our website. If you have a gardening question or problem, email the Hotline at mgbutte@ucanr.edu or leave a phone message on our Hotline at 530-552-5812. To speak to a Master Gardener about a gardening issue, or to drop by the MG office during Hotline hours, see the most current information on our Ask Us section of our website.
- Author: Kathy Keatley Garvey
He's a male Mantis religiosa, as slim as a string bean, and scanning his environment.
We're accustomed to seeing see the native Stagmomantis limbata in our garden, and not M. religiosa, the European mantis, which is found throughout Europe, Asia, Africa, and North America.
"Males are often found to be more active and agile, whereas females are physically more powerful," according to Wikipedia. "Adult females are generally too large and heavy for their wings to enable a take-off...The great variation in the coloration of M. religiosa from different shades of yellow, brown, green, and sometimes black has been the cause of numerous hypotheses and studies for over 100 years.However, no generally accepted answer about reason, benefit, or mechanism of the coloration or the change of coloration has been found."
The male is apparently quite good at avoiding sexual cannibalism during mating. Wikipedia says: "Instead of just observing them, sexually mature males approach sexually mature females when they see them, but due to the physical superiority of the females, males of M. religiosa face certain challenges in doing so. When a female spots a male, she is very likely to attack and kill him (see also: Sexual cannibalism). Therefore, males can be observed to be very slow and cautious in their approach; after spotting a female, the male usually freezes and turns his head to look directly at her. Since the foveae in his eyes face directly forwards, he has the most accurate and detailed view of her and can watch every one of her moves. He then proceeds to approach her from behind. Males can be observed to stop as soon as the female turns her head or even moves. Mantids are very good at detecting moving structures, but are almost unable to see immobile objects. Using this ‘stop-and-go' tactic, the male stalks closer to the female. This can often take several hours. Depending on the environment, males sometimes show a light ‘rocking'-behavior which is believed to imitate the leaves of surrounding plants to blend in with the background. Males doing this had no higher probability of being detected and attacked, which supports this hypothesis of concealment."
We asked praying mantis scientist Lohit Garikipati about this European species. He holds a bachelor's degree from UC Davis and a master's degree from Towson University, Md., and is now PhD-bound at the Richard Gilder Graduate School in the American Museum of Natural History in the Jessica Ware lab.
"In my time at Davis I observationally did--they hold a special place for me as they were the first species that ever kept and raised in captivity!" said Garikapti, who shared his mantises and expertise at the Bohart Museum of Entomology open houses. "But they also highlighted to me the potential impact of invasive species on both native mantis species but also prey populations--as low foliage and ground dwelling predators, they have a different niche from S. limbata, and may be contributing to the decline of native Litaneutria (even as they have for the California mantis, Stagmomantis wheelerii). Adult females have also been observed feeding on fence lizards, without much apparent effort as they can take lizards even larger than they are. All of these factors combined with their cryptic ooth (ootheca) deposition and large clutch size have made them one of the most if not the most successful mantis species on the planet - they tolerate both cold and hot climates being found in deserts to temperate forests and now have a Holarctic distribution."
Garikipati related that in the Ware lab, he will be "investigating the evolutionary relationships of praying mantises and what drove their diversity."
We look forward to hearing more from Lohit! As for our buddy, the male M. religiosa, he took flight. (See video on YouTube).
- Author: Michael Hsu
UC ANR Fire Network compiles expert advice on preparedness, evacuation tasks
The explosive growth of the Park Fire in Northern California was fueled by recent, intense heat waves and extremely dry vegetation – conditions seen at many locations across the state.
Given the potential for wildfire and smoke impacts during what is expected to be a protracted “fire season,” California residents should think ahead and complete emergency preparations: https://ucanr.edu/sites/fire/Preparedness/.
“If you are concerned that you or someone you know could be affected by fire or smoke, now is the time to take simple steps to prepare,” said Yana Valachovic, University of California Cooperative Extension forest advisor for Humboldt and Del Norte counties.
Valachovic and other members of the UC Agriculture and Natural Resources Fire Network are urging community members to tackle small but significant tasks to minimize potential fire damage. Many of these tasks can be finished in a weekend, such as:
- Clean debris from your roof and gutters.
- Inspect the area around your home and nearby structures and remove all combustibles (dead grass, plants, woody mulch, stored wood, etc.) in the first 5 feet, including under decks and stairs.
- Inspect the foundation, under-eave, and gable-end vents for holes and damage; add a layer of finer metal-mesh screens (1/8” mesh) to the vents to prevent ember penetration.
- Inspect the garage door bottom seal to make sure embers can't blow under the door.
- Replace the first 5 feet of wooden fences that attach to buildings with a noncombustible panel or gate.
A recently published report, “Retrofitting a Home for Wildfire Resistance,” also can help residents prioritize the measures that are most cost-effective and fit their budget.
Six things to do, six hours before evacuation
As evacuation warnings are issued for local communities, there are six important things to do in advance of an actual evacuation order, according to Valachovic:
- Close windows, pet doors and skylights.
- Move inside patio cushions, brooms and door mats; tie open wooden gates that attach to the house or deck to prevent a fire from traveling from the fence to the house.
- Relocate the barbecue propane tank away from home.
- Stage buckets of water and garden hoses in visible locations.
- Dress for evacuation: cotton clothes, sturdy shoes, hat and face protection and leather gloves.
- Put your “go bag” in your vehicle.
The UC ANR Fire Network website also includes downloadable checklists – in English and Spanish – for your go bag (https://ucanr.edu/sites/fire/Safety/Evacuation/Preparing_a_Go-Bag/) and for a host of important pre-evacuation tasks for your household, property, pets and livestock (https://ucanr.edu/sites/fire/Safety/Evacuation/).
“We want communities to be wildfire-prepared – not scared,” Valachovic emphasized.
Smoke exposure a significant public health concern
Hazardous smoke can blanket wide swaths of California – and much of the Western U.S. – during ongoing wildfire events. A primer on harmful health effects, a list of tips for reducing smoke exposure, and other resources and links can be found on the UC ANR Fire Network site: https://ucanr.edu/sites/fire/Safety/Air_Quality_and_Smoke/.
“If there's smoke in the forecast for the next few days, I would keep an eye on my local air quality at fire.airnow.gov,” said Katie Low, statewide coordinator for UC ANR's Fire Network. “And if the AQI – Air Quality Index – is high, I would limit my outdoor activity, wear an N95 mask if I do go outside, and run my air purifier.”
For instructions on making a DIY air cleaner, creating a “clean air space” in your home and fitting an N95 mask properly, visit the California Air Resources Board's “Smoke Ready California” page: https://ww2.arb.ca.gov/smokereadyca.
Another useful tool is the crowd-sourced #FireMappers fire activity map – powered by the National Alliance for Public Safety GIS Foundation, GISCorps, and CEDR Digital Corps – accessible through the UC ANR Fire Network site: https://ucanr.edu/sites/fire/Safety/Current/.
/h3>/h3>/h3>- Author: Lauren Fordyce
Are you noticing an abundance of cobwebs outside, on plants, fences, homes, or outdoor furniture?
While many people fear spiders or dislike their cobwebs, most spiders are beneficial to have around– even in the home! Spiders are predators of many insect pests and rarely cause harm to people. The only medically significant spiders in California are brown and black widows. While these spiders have the potential to cause harm, it is rare that they will bite, even in areas where they are very common. Like most spiders, they prefer to stay hidden and avoid people.
Some common web-spinning spiders you might encounter outdoors include:
- Funnel weavers: feed during the day and night near the ground in most types of vegetation, including low-growing plants and trees. Spin funnel-shaped webs, often with several-inch-wide, flat extension covering plants or soil.
- Sac spiders: spin silken tubes or sacs under bark, among leaves, and in low plants or on the ground, where they hide during the day or retreat after hunting. They are typically nocturnal, medium-sized, pale spiders with few markings.
- Garden spiders: feed on insects that fly, fall, or are blown into their web. Elaborate silken webs are spun in concentric circles.
- Dwarf spiders: prey on insects that fall, walk, or land in their web. They are diurnal (day active) spiders found in the plant canopy and among litter on the ground. Dwarf spiders produce sheetlike webs on the surface of plants or soil.
- Comb-footed spiders: feed on insects that walk or fly into their webs. They almost always are found hanging upside down by their claws in irregularly spun, sticky webs, waiting for prey. Generally they have a soft, round, bulbous abdomen and slender legs without spines.
Unwanted cobwebs can be swept, mopped, hosed, or vacuumed up. Insecticides should not usually be used against spiders outdoors and don't provide good control anyway.
For more information about spiders in and around the home, visit the Pest Notes: Spiders.
- Author: Kathy Keatley Garvey
So here's this female praying mantis, Stagmomantis limbata, camouflaged on a narrow-leaf milkweed, Asclepias fasciculari, in a Vacaville garden.
If she thinks she's going to ambush a monarch, she has another think coming. No monarchs in the garden.
If she thinks she's going to ambush a bee, no way. No bees in the garden early this morning.
If she thinks she's going to munch on oleander aphids (which she probably won't), there are plenty.
Fact is, she doesn't "think" like we do. She will wait, quite patiently, to ambush prey. Even in the pending triple temperatures of the day.
When the heat becomes unbearable, she will slip beneath the leaves, but still maintain a lookout.
Ms. Mantis will be patient. She is always patient.
Patience is her middle name (Stagmomantis "Patience" limbata) and prey is her game.