- 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.
- Author: Ben Faber
Senior Public Information Officer
- UC Riverside,Plant materials that would otherwise become trash may be the key to solving two big problems: diminishing freshwater supplies for farms and diminishing effectiveness of antibiotics.
On average, agriculture accounts for 70% of global freshwater use. In California, which produces nearly half of all U.S.-grown fruits, nuts, and vegetables, that number rises to 80%.
The United Nations estimates food production will need to double by 2050. However, water supplies will not increase accordingly. Instead, due to climate change and drought, water resources are quickly shrinking.
One solution to the increasing need for farm water is to use treated municipal wastewater. There are roughly 16,000 wastewater treatment plants in the U.S., each of them capable of processing up to 10 million gallons every day.
“It's a huge amount of processed water that's mostly clean and can be used again, but there's a problem,” said Ananda Bhattacharjee, assistant project scientist at the U.S. Department of Agriculture's Salinity Laboratory, based at UC Riverside.
“This water can contain chemicals of emerging concern, like antibiotics, that are difficult to detect and treat without advanced and expensive instrumentation,” he said. “These instruments also require trained laboratory personnel to operate and maintain.”
Once exposed to the antibiotics in the water supply, soil bacteria immediately start developing resistance to the drugs because they want to survive. “Bacteria are amazing biological sensors,” he said. As the bacteria develop resistance, antibiotics stop working.
Once crops are irrigated with contaminated reclaimed water, plants that get harvested and come to our dinner tables may contain residual antibiotics, resistance genes, and resistant bacteria.
To correct this issue, Bhattacharjee is leading a new, $1 million project testing a low-cost technology to make the reclaimed water safer for agricultural re-use. Funded by the USDA's Agriculture and Food Research Initiative, the project will test how effectively biochar made from various types of discarded plant materials can “polish” the water.
Biochar is a charcoal-like substance made by burning organic material. Burning any organic matter, even wood chips, in limited-oxygen environments retains the mass of the burned substance. The remaining, charred substance is highly absorbent.
“It's like activated charcoal used in HEPA filters and HVAC systems. Biochar works on the same principal; it adsorbs chemicals present in reclaimed water and allows only clean water to pass through,” Bhattacharjee said.
Based on this principle, Daniel Ashworth, a soil scientist at the Salinity Laboratory, first built a bench-scale filtration system with biochar for the removal of antibiotics in synthetic wastewater. The results were very promising, with antibiotics removal efficiency of up to 98%.
“Encouraged by Dr. Ashworth's experiments, we will be designing the larger-scale biochar-based polishing systems for removing residual antibiotics in reclaimed water,” Bhattacharjee said.
Using biochar polishers could potentially remove the need to detect the antibiotics in reclaimed water, assisting treatment plants that do not have advanced detection or treatment technologies, and cannot afford them.
Affordability is one of the best features of the biochar system. “As engineers, we try to keep it simple. If we can build something for a dime, we don't want to have to spend a dollar,” Bhattacharjee said.
For this project, scientists from UC Riverside, the U.S. Department of Agriculture, US Salinity Laboratory, and the University of California's Agriculture and Natural Resources are teaming up to test biochar made from multiple kinds of plant materials left over from agricultural field production.
To start, they'll collect treated sewage sludge and plant materials such as pistachio shells and date palm leaves which would otherwise be thrown away. These materials will be turned into biochar for designing filtration systems that reclaimed water can pass through.
Ultimately, the team would like to develop a database of different, inexpensive biochar materials that can all be used for removing harmful compounds from reclaimed water for agricultural reuse, especially crop irrigation.
If the costs remain low and effectiveness remains high, the research team hopes growers will install biochar-based reclaimed water polishing systems on their farms. “That is the major goal of the project, taking this from bench scale to full field scale,” Bhattacharjee said.
Right now, the whole ecology of fields is changing due to residual antibiotics in irrigation systems. The reclaimed water gets into the soil, earthworms feed on organic matter in the soil, and they develop antibiotic resistance in their guts. Then they may release this resistance through their feces, making additional changes to soil microflora, which keeps the cycle of resistance going.
“We are slowly spiking our own agricultural fields with this resistance,” Bhattacharjee said. “Demonstrating this issue was our first project, Bacteria Wars: episode one. Now we have a technique to remove the antibiotics and resistant bacteria, reducing the antimicrobial resistance spread in agriculture. This is our episode two: Researchers Strike Back.”
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- Author: Ben Faber
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- Author: Ben Faber
La Fundación para la Investigación de la Agricultura Orgánica (OFRF por sus siglas en inglés) se complace en anunciar un nuevo curso asíncrono en línea que cubre la importancia de la salud del suelo para la producción agrícola. En este curso entraremos en el mundo del suelo y explicaremos cómo puedes promover la salud del suelo como parte de un ecosistema saludable. Los suelos saludables permiten aumentar la producción con menores costos, y hace que su negocio agrícola sea más productivo económicamente, a la vez que favorece la salud del medio ambiente, los animales, y los seres humanos. Analizaremos prácticas como el cultivo de cobertura, aplicación de enmiendas, la labranza y la rotación de cultivos, y proporcionaremos herramientas para ayudarle a decidir qué prácticas de gestión se adaptan mejor.
https://ofrf.org/online-courses/los-fundamentos-de-la-salud-del-suelo/
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- Author: Ben Faber
By Jules Bernstein | Photo by Stan Lim, UCR News
There is a curious buzz in Mark Hoddle's office. It is a figurative buzz, because of Hoddle's enthusiasm for controlling damaging pests with their natural insect enemies. But the buzz, at least today, is also literal. The sound is coming from long-nosed black palm weevils, flying in circles while tethered to an insect merry-go-round of sorts. The contraption is designed to test how far weevils can fly before they get tired.
“They are remarkably strong fliers,” Hoddle said. “On average, they can go about 25 miles in a day — 90 miles if they're feeling frisky.”
Given how far and how fast they can travel, there are fears they'll attack and kill the iconic palm trees throughout Southern California and wreck date crops in the Coachella Valley. So far, they've been mostly confined to San Diego County, where they've already destroyed tens of thousands of palms. In his role as director of UC Riverside's Center for Invasive Species Research, Hoddle is one of the people best qualified to keep the weevil threat at bay.
Working with insects is something Hoddle has always wanted to do. Growing up in New Zealand, he'd design houses out of toilet paper rolls for giant flightless grasshoppers called weta, and delight in figuring out their favorite foods. Then in college, he read about a lake in Papua New Guinea choking with an invasive water weed. By introducing a weevil that feasts on the weed, scientists eliminated the plant hazard.
“Their work made it so people could use the lake again safely, and it reduced people's exposure to mosquito-borne diseases. That was mind blowing! And it was a turning point for me,” Hoddle said.
During his undergraduate studies, Hoddle spent five years training in the New Zealand Army Reserves as an engineer. There he learned practical skills, like how to use chainsaws, lay explosives, clear booby traps and mines, lay lines for freshwater supplies, and build floating pontoon bridges.
“These are the skills that now help me trap insects in remote locations around the world,” Hoddle said. “I got used to pushing my way through prickly plants, having to be up to my waist in water, lying in cold mud when it was pouring with rain, tramping around all day digging holes, and looking for stuff with all my gear on. Doing this when looking for bugs isn't as big a deal for me because of the training I had.”
The hunt for Hoddle's holy grail — a solution to weevil invasions — has taken him and his entomologist wife Christina to Thailand, Vietnam, Cambodia, the Philippines, Indonesia, and Mexico. Previously, the pair traveled to Pakistan, working for up to three months at a time searching for an enemy of the Asian citrus psyllid, a citrus killer. Psyllid numbers have since been reduced by more than 70% in California because of a highly effective natural enemy they found.
Hoddle's Ph.D. pedigree and affinity for adventures in rough, foreign terrain have garnered him frequent comparisons to famed, fictional archaeology professor Indiana Jones. The incredible collection of artifacts from a wide variety of cultures in his office at UCR — carved wooden ceremonial masks, insect artwork, an ornate sake bottle — only enhances the sense you're in an adventurer's temple.