- Author: Ben Faber
Avocado Irrigation Calculator using CIMIS
(California Irrigation Management Information System)
Updated March 13, 2024
Gary S. Bender
Farm Advisor Emeritus – Subtropical Horticulture
UC Cooperative Extension – San Diego County
The irrigation requirement can be calculated each week by using CIMIS (California Irrigation Management Information System). CIMIS is a network of weather stations throughout California that takes daily information on evapotranspiration (ETo) of eight-inch tall grass and sends this ETo to a computer in Sacramento. ETo is basically the amount of water lost each day from this grass; it is calculated in inches of water. You can download this information when you want to irrigate your avocados and put it into an “irrigation calculator”. This information will be multiplied by the crop coefficient developed for avocados by UC Cooperative Extension farm advisors and specialists . This will give you the amount of water lost each day by avocados through transpiration and evaporation from the soil surface. Then, assuming the weather doesn't change, you can replace that amount of water when you irrigate.
Follow the Attached Files "CMIS exercise" link below to see how it's done.
CMIS exercise
- Author: Ben Faber
For years, I thought I was seeing fountain grass, an invasive grass that is found in all kinds of wild and disturbed settings. I was told it got its name because it was the only thing that would grow around communal fountains where people tamped down the earth while waiting their turn to fill their water jugs. It's a pretty thing and it's been planted everywhere because it is a pretty little thing --- and invasive. There a whole USDA Guide on Fountain Grass Management. A pretty thing that has gotten out of the garden and into the wild- https://www.fs.usda.gov/Internet/FSE_DOCUMENTS/stelprdb5410113.pdf
The blue dots are distribution of Pennisetum villosum (Cenchrus longisetus): feathertop. from Calflora
But no, what I've been seeing has been a cousin called feathertop - Pennisetum villosum or at one time Cenchrus longisetus.
© 2023 Ron Vanderhoff - Calflora
Pennisetum villosum is an ornamental grass that is naturally distributed on hilly areas in warmer regions of Africa in the family Poaceae (http://foc.iplant.cn/). Several species of Pennisetum are popular in the garden for their bottlebrush spikes and cascading foliage. It has been widely planted and is found as escapes (got out of the garden) in California, Arizona, Kansas, Texas and other southern states. There have been more and more sightings in California, and Ventura county leads with the greatest number of observations according to the USDA Plant Data Base (https://plants.usda.gov/home/plantProfile?symbol=PEVI2). Most of the sightings in California have been coastal, so it's interesting that it's found in such diverse environments in other states. The findings here were made by Alison Colwell at the UC Davis Herbarium, https://herbarium.ucdavis.edu/index.html
It spreads by seed and rhizome, and in a few blinks of an eye, can spread rapidly into new territory.
I am interested to see how far feathertop has spread in the Ventura/Santa Barbara area, and for that matter from Santa Cruz to San Diego. Calflora has a website, where observations can be reported
https://www.calflora.org/ It's in the top left corner of the Home page "Add Observations".
- Author: Ben Faber
Please join us at one of our California Avocado
Growers Seminar Series.
Presented by
California Avocado Society, Inc., California Avocado Commission, and University of California Cooperative Extension
Check our previous recordings on YouTube
California Avocado Growers Seminars Series 2024
Scheduled Topics
April 11 (1 - 3 PM)
Fertilizers
Topics and Speakers
- Author: Ben Faber
Soil Biodiversity in California Agriculture: Framework
and Indicators for Soil Health Assessment
Prepared by: California Department of Food and Agriculture Below Ground Biodiversity Advisory Committee
Soil health depends on soil biodiversity.
However, external pressures from land-use change, climate change and certain agricultural practices threaten the biotic networks that underpin the delivery of soil's many ecosystem services. Yet measuring soil biodiversity is a complex task, with a wide variety of possible indicators, and methodologies that are evolving with recent technological advances. This report, prepared by the Belowground Biodiversity Advisory Committee (BBAC) convened by the California Department of Food and Agriculture (CDFA), focuses on how best to assess soil biodiversity in the context of working lands and considers current and future challenges faced by California agricultural producers, policy makers, governing agencies, and related stakeholders. The report presents information on the taxonomic and functional diversity of soil organisms, ecosystem services they provide, threats to soil biodiversity, assessment frameworks, and biodiversity indicators. Examples of how biodiversity indicators can be applied to specific use cases provide insights for soil health, sustainable and climate-smart agriculture, and biodiversity conservation in California.
Soil biodiversity is the interconnected ‘social' network of numerous species of living organisms that contribute to soil functioning. As these organisms grow, die, and interact with soil's abiotic components, they perform essential functions in carbon, water and nutrient cycling and plant growth, collectively described as multifunctionality, benefiting ecosystems and humans alike. Comprehensive assessment of soil biodiversity involves measurements of organism abundance, identity, and functional diversity or traits, ideally in tandem with measurements of soil processes, as well as interactions among organisms. Soil biodiversity and soil processes vary in space and time due to factors like location, climate, vegetation, and land management practices across California's diverse landscapes.
Soils are incredibly biodiverse habitats, containing a vast array of organisms ranging from macroscopic organisms like gophers to microscopic worms, fungi, and billions of bacterial cells. The physical and chemical properties of soils – soil texture, pH, water and oxygen content, salinity, organic matter inputs, and nutrients – determine the types of organisms found in a particular habitat. The array of organisms inhabiting soil spans over six orders of magnitude in size, and includes microorganisms (viruses, bacteria, archaea, and fungi); microfauna (protists, nematodes, and tardigrades); mesofauna (mites and springtails); and macrofauna (earthworms). Life in soil exists in ecological communities that are complex and interconnected. These interconnections provide stability to soil functions. Soil organisms are critical to regulation of greenhouse gases, both by consuming and producing gases such as nitrous oxide, carbon dioxide, and methane. Mycorrhizal fungi in symbiosis with most plant species promotes root growth and availability of water and nutrients. A broad range of soil organisms mediate the decomposition of organic inputs and enhance nutrient cycling. Other functions of biodiverse soils include soil structure formation, organic matter formation, carbon storage, water regulation, and pathogen suppression. But despite these critically important functions, the diversity and complexity of soil biodiversity makes it challenging to decipher these intricate relationships and understand the impact of human activities.
Soil biodiversity faces many of the major threats from human activities and global change that also impact soil health and sustainability of California's agroecosystems. Land use changes, intensive agriculture, climate change, pollution, invasive species, overexploitation, and loss of habitat connectivity all pose risks. These threats disrupt soil biological networks, reduce biodiversity, impair ecosystem functions, and degrade soil structure and fertility. Soil biodiversity loss reduces multifunctionality and the provision of ecosystem services, highlighting the need to recognize the value of belowground communities to overcome challenges such as climate change, land degradation, and overall biodiversity loss. Addressing these challenges through sustainable land management, agroecological approaches, and awareness campaigns is crucial for preserving belowground biodiversity to maintain provision of essential ecosystem services.
READ ALL ABOUT SOIL DIVERSITY in the Report:
https://www.cdfa.ca.gov/oefi/biodiversity/docs/Soil_Biodiversity_California_Ag_July_2023.pdf
- Author: Ben Faber
With all the rain last year, even extending into August and now with the rains since December there is a lot of natural ground cover growing, When it gets out of hand, we call it weedy. It might still serve the purpose of protecting the ground from erosion, but it can become an impenetrable mess and if allowed to go into summer, a major fire hazard. In the case of some young orchard, the malva and mustard is bigger than the trees themselves. Getting control of them before they get woody and go to seed is easier earlier than later. So it's time to do something about them if you haven't done so already.
A common practice on flat ground is to mow the middles and then weed whack/whip the tree row up to and around the tree trunk. In the case of trees that have their canopies down to the ground or near the ground or that have created a thick leaf mulch, there's not usually much weedy growth near the trunk. Then weed whacking around the canopy is not much of a problem. If on a slope like most avocados, it's a big, expensive, laborious, hot, sweaty, arduous process of weed whacking. Just waiting long enough for the leaf mulch to create a barrier to weed growth and for the canopies to grow out to rob the sun from the surface undergrowth.
In young trees without a large canopy, it can be a really difficult process of getting those weeds near the trunk. Care must be taken to avoid damage to the trunk. In a couple of recent examples, weed whacking got right up and on the trunks and significant damage was done to the trees. When a wound occurs in any tree, a process kicks in to generate tissue to cover the wound, much like what happens with humans and wound cuts. There's a scar left, but it heals over. If the wound is too large, many trees cant cover the woody tissue fast enough. The wood beneath the cambium ( the green tissue below the bark) is prone to fungal infection and eventually the fungus eats away at the interior of the tree. If the wound is large enough and girdles the tree, all the nutrients from the leaves feeding the roots is cut off. The photosynthate sugars that keep the roots functioning, and the roots stop doing what roots do. This is absolutely true is citrus and most other orchard tree crops. But not avocado.
When making a cross section of most trees, it's possible to see the growth rings – the growth increments that appear each year. The tree starts and stops growth each year and it's possible to clearly identified in what year there was more or less growth. In long lived trees like redwood, it's possible to identify years when certain events happened – the year of Lincoln's Gettysburg Address, for example. This growth habit is called ring porous.
In the case of avocado, it has a growth habit called diffuse porous. There is growth throughout the year and the rings are nor clearly delineated, if at all. It's because of this possible active growth occurring, that the avocado can often cover over damage that is quite extensive. After a fire, given time, mature avocado trees can summon up energy to recover to a great extent. It's not so true of young trees, however. Avocados still have a greater regenerative capacity than a lemon tree, and if the damage is to just one side of the tree, there's a very good chance of recovery.
But these young tree are severely impaired. They do have a chance of recovery, but the damage is extensive and the trunk is fully girdled. Only time will tell if they do recover. If the tree were only a year old, it would be a good idea to pull them and start over. But a number of these trees are three years old and have had a lot of investment in them besides their initial nursery cost – pruning, weeding, irrigation, fertilization, etc. It is heart breaking to see damage like this after so much attention has been paid to them.
And the best thing is to let the tree recover on its own. Use of pruning paint actually impairs tissue regeneration. The grower asked if a kaolin protectant like Surround might be used to provide some sun protection. Since that breathes, it might be a good idea. It might also be a good idea to apply some trunk wraps. These were taken off in order to prevent earwig and snail harbor which can cause significant damage to young trees. But they also provide protection from overly aggressive weed whackers. It is always a compromise when making these decisions.