Posts Tagged: drought and trees
'Trees for Tomorrow Start Today' Workshop (via Zoom) March 9, 2021 (8:15 AM - 3:00 PM)
Landscape trees provide shade, cool urban heat islands, reduce interior energy use and related costs, provide habitat for pollinators and wildlife, and beautify our communities. They also help clean our environment by absorbing carbon dioxide emitted by vehicles and other producers of fossil fuels.
Taking care of our urban trees is an important way to maximize these benefits. Unfortunately, their average lifespan in our cities is less than 1/4 of their potential due to poor selection and care. You can help enact change and increase the health, longevity and canopy coverage of our urban forests by encouraging your city leaders, local non-profit organizations interested in ‘green cities' arborists, landscape architects, nursery growers, HOAs, and concerned citizens to register for our free ‘Trees for Tomorrow Start Today' workshop (via Zoom) on Tuesday, March 9, 2021 (8:15am – 3pm).
Please reach out to your city leaders and local ‘green industry' professionals to encourage their attendance and participation. While the workshop is free, registration is required through this secure link: http://ucanr.edu/u.cfm?id=264
A bevy of speakers including certified arborists, horticulturists, planners, water district personnel and other non-profit and green industry representatives will discuss the benefits of urban trees; recommended practices for their selection and care; how to avoid hazardous trees that damage property and structures; and share success stories resulting from partnerships through cities, non-profit organizations, the green industry, HOAs, and street tree committees.
A highlight of the workshop will be the opportunity for attendees to participate in breakout sessions that cut across professions and interest groups (city planners, community service directors, arborists, landscape architects, landscapers, water district managers, HOA managers, golf course superintendents, nursery growers, UC master gardeners, concerned citizens, etc.) to enact positive change regarding tree selection and care.
Thank you for sharing this opportunity to help ensure a healthy future for our children's children with your city leaders and decision-makers.
In the meantime, here are some tree care tips to ‘start the conversation' between now and the workshop:
• Select trees that perform well in your climate. The Sunset Western Climate Zone maps are more precise than USDA zones for our warmer climates. Trees should also be selected based on their adaptation to the ‘micro-climate' in each particular landscape, as well (shade, proximity to buildings, space needs below as well as above ground, soil type, water source, etc.)
• Plant trees the same depth they were in their container in holes at least 2-1/2 times wider. Do not add compost or organic matter to the hole. This practice can result in circled roots that never grow laterally out of the confines of the dug hole.
• Remove any tree ties that are cutting into the trunk or branches of your trees. If trees must be staked due to windy conditions, make sure that the ties are loose enough to allow trees to gently flex in the wind. This helps trees develop the necessary lower trunk strength and stability to support the tree as it matures. Over time, you may be able to completely remove the ties and stakes once the lower trunk becomes stronger and self-supporting.
• Keep all plants and mulch several inches away from tree trunks.
• Keep tree trunks dry. They should not come into contact with water from sprinklers or hoses.
• Regularly water newly planted trees but water mature trees infrequently and deeply. Watering too often reduces the level of oxygen in the rootzone and can lead to waterlogged soils prone to crown and root rots. During fall, trees require only about 15% of the water they require in the summer.
• Prune trees only as needed and avoid topping them. Invest in the services of a credentialed and knowledgeable professional to correctly care for your valued trees. Find a list of International Society of Arboriculture Certified Arborists in your area here: https://www.treesaregood.org/findanarborist.
Drought Update........How to Save Your Plants Under Drought and Water Restrictions......and Use Graywater!
California is in the midst of the worst drought in decades. But you can save your valued trees and landscape plants by following a few simple principles. Watering mature trees deeply just once during mid-summer will keep most species alive, especially if there is a three inch layer of mulch on the top of the soil to keep evaporation down. Be sure to water outward toward the dripline of the tree rather than near the trunk. Keep weeds out of your garden; they will win the water fight. Don't fertilize your landscape during the drought and avoid ripping out your current landscape in the middle of summer to replace it with a drought tolerant one; young plants require more water than established landscapes, and more frequent irrigations. For more information on how to reduce water use in your landscape and garden and to learn more about using graywater from your washing machine to irrigate your landscape click on this link. http://cesanbernardino.ucanr.edu/Drought_Resources/ Janet Hartin, Environmental Horticulture Advisor, University of California ANR Cooperative Extension, San Bernardino, Riverside, and Los Angeles Counties.
Save Trees during Drought with New Tree Ring Irrigation Contraption (TRIC)
Prioritizing Trees for Landscape Water Use
Many residents have been encouraged to reduce water use by turning off their outdoor watering systems, but this may be causing stress to established trees that are becoming increasingly thirsty for water.
In most traditional residential landscapes trees are surrounded by turfgrass. Turfgrass surrounded trees take advantage of the frequent and shallow watering schedule, typically set to help the lawn flourish. When residents eliminate or reduce water for lawns, trees cannot easily adapt to the new water shortage.
“Mature fruit trees and landscape trees are worth saving! Recognizing early signs of drought stress is important because irreversible damage can occur that no amount of watering will correct.” said Janet Hartin, UC Cooperative Extension advisor in a recent article, Save Water, But Also Save Trees During a Drought.
Replacing small plants, lawns and shrubs is easy compared to a large tree which takes years to become established. Saving mature trees during a drought should be a top priority in your landscape water use allocation.
“Two seasons without enough water can result in severe drought stress and even kill a tree,” warned Hartin. “Also, drought-stressed trees are more prone to damage from diseases and insects than non-stressed trees.”
Understanding how to water a tree effectively is important to avoid water waste and to ensure that the tree is receiving the correct amount of water for its survival.
One key factor to successfully watering a tree is understanding what soil type is present. Understanding soil types is an important factor in determining how much water is stored in the ground. For example, sandy soils dry out quickly while clay soils retain more water. Contact your local UC Master Gardener Program to learn how to determine your soil type.
Tree Ring Irrigation Contraption (TRIC)
Recently the Calif. Center for Urban Horticulture (CCUH) at UC Davis, UC Division of Agriculture and Natural Resources (ANR) and Ewing Irrigation devised a unique watering system called the Tree Ring Irrigation Contraption (TRIC). Using previous data from Netafim drip tube tables and from the Irrigation Association Landscape Irrigation Auditor manual, the partners envisioned a possible solution to mitigating drought conditions and the effect on landscape trees. The TRIC is an inexpensive kit that homeowners can put together for around $100 for one large tree.
The TRIC could enable homeowners to adequately water trees to a depth of three feet with confidence, by using the recommended parts and using the TRIC calculator with accurate information. Aside from a recommended parts list, there is a “plug-in” calculator created by Dr. Loren Oki, UC ANR Associate Specialist in Cooperative Extension Landscape Horticulture for UC Davis & UC ANR. The TRIC calculator helps determine the run-time needed for the device.
Learn more by visiting:
- CCUH – Tree Ring Irrigation Contraption website
- TRIC Parts List
- TRIC Calculator
- TRIC PowerPoint Presentation
Landscape trees also suffer drought consequences
Igor Lacan, UCCE advisor in Santa Clara, Contra Costa and Alameda counties, says it's difficult to make blanket statements about which species are in trouble, since a tree's water- and heat-related health depends on its location.
Some species on a south-facing slope might show drought stress, while the same species on a north-facing slope doesn't. Stress symptoms also show up on trees planted near paved surfaces, though not near other surfaces that don't reflect heat, Lacan said. Since many tree species are fairly resilient, damage comes on slowly and may take months or years to become apparent.
But Lacan was able to conclude with a positive comment.
"The good thing is that in all likelihood mature, established trees, if climatically appropriate (for their location), will make it through ... just fine," Lacan said.
/span>Subtropical Fruit Trees in a Drought
The talk of drought and water restrictions in the State has created a time for serious decisions. What can be done with avocado citrus trees that have been invested with time and money when there are allocations of water? Although this article is addressed to subtropicals specifically, the guidelines are generally applicable to all fruit trees.
Irrigation systems and scheduling
One of the surest, although not necessarily the cheapest, ways of managing with a decreased amount of water is to improve its application and scheduling. Insure that equipment is working properly, that nozzles are not plugged or worn, that pressures in the irrigation blocks are uniform, that leaks are repaired, and that no runoff or deep percolation are occurring. Many Resource Conservation Districts have Mobile Labs that can help make a system evaluation.
In the Ventura area, oranges use about 30 inches of water per year, however , the monthly amount varies with weather. Applying water in the amounts and at times for optimum production can be improved by using tensiometers. A gauge reading near 40 centibars has been recommended for the one foot tensiometer. The three foot tensiometer can be used to determine the amount of moisture stored in the lower horizon and to determine whether the irrigation was effective, whether the irrigation water infiltrated down to that depth.
Whatever reading is used there is no substitute for observation of the trees themselves and the soil.. Use a soil sampler or shovel to verify the depth of water applied. If time clocks are being used, turn them off or at least adjust them frequently enough to accommodate changing weather patterns. Use of CIMIS weather data can aid in correcting schedules to changing weather.
If water applications need to be curtailed, there will be a decline in yield and fruit size. Applying something less than about 75% of tree requirement will give reduced yields not only for this year, but will lead to dieback and low yields for 3 -4 years after. Abandoning the trees altogether will also yield little or no crop and dieback, but the trees will often return to normal yields in 3 - 5 years. If little water is available, it may be best for commercial operators to reduce the number of trees irrigated to those that can receive 85% of their water requirement and abandon the rest, hoping for more water in future years.
Cultural practices
Since it is the leaves that are the site of water loss , the best way to reduce water loss is to reduce the amount of leaves present. This is the ideal time to thin an orchard, get rid of those trees that are shading each other and reducing the per tree yield of fruit. This is a good time to topwork trees to better varieties, since the smaller trees will use less water. A good weed management program will reduce competition for water, and mulching the wetted area of the sprinkler will reduce evaporative loss from the soil surface. Once the leaf area is reduced, it is necessary to adjust the irrigations to reflect the decreased need for water.
This is an opportunity to identify the least productive trees in an orchard and cut of water to them. Trees with root rot or frost damage; trees growing on limy/iron chlorosis sites. Trees growing on ridges that receive the full force of the wind and have a lower yield per gallon of water should be considered first. Trees growing on the perimeter of an orchard also will transpire more water for a given amount of fruit. If all trees in the orchard look good, then these perimeter trees should be targets for saving water. If production records have been kept for different blocks of trees, it might be possible to identify low yielding areas that could be sacrificed.
This is an opportunity , as well. Many growers have kept poor producing parts of groves going because it is an emotional issue to cut up a tree. Seize the day and take advantage of the situation.
For more, check out the powerpoint
http://cesanluisobispo.ucanr.edu/files/183118.pdf
avocado leaf necrosis