California agricultural employers, workers approach smoke concerns differently
UC Davis examines health and safety awareness around mounting threat
University of California - Davis
In 2018, California wildfires burned more than 1.8 million acres and caused smoke to drift hundreds of miles. As the frequency and intensity of wildfires increases with climate change, California agricultural workers are at greater risk of smoke exposure as they often have no option but to work outdoors.
A new study from researchers at the University of California, Davis, finds that while wildfires and smoke exposure are recognized by farmworkers and employers as a growing threat and safety concern, the means to address these concerns differs between the two groups.
"What stood out in this study is the substantial disparities between agricultural employers and farmworkers," said Heather Riden with the Western Center for Agricultural Health and Safety at UC Davis.
Riden, who led the research in partnership with the California Institute for Rural Studies, said that while growers and employers expressed concern about poor air quality at the time of the study in 2018, many had no clear plans or protocols for measuring air quality or managing workers in such conditions. While the public is advised to stay indoors due to poor air quality during a wildfire, agricultural work often continues.
The study also found that when farmworkers were offered protective masks, many found them difficult to use while working due to heat-related discomfort and chafing. Others believed wearing two bandanas over the mouth and nose would provide just as much protection.
Farmworkers' experience is compounded by economic need.
"Many farmworkers will continue working, even in unsafe conditions, to support their families. They don't have many other options," said Riden.
Last year, the state Division of Occupational Safety and Health, better known as Cal/OSHA, enacted an emergency regulation requiring employers to take measures to protect workers from wildfire smoke when the Air Quality Index reaches 151 or greater, which is considered unhealthy. Riden said as CAL/OSHA begins to craft permanent regulations, she hopes it takes the study's findings into consideration.
"This highlights the need for better awareness for both agricultural employers and farmworkers about the health risks associated with wildfire smoke," said Riden. "Employers also need training materials and concrete steps they can take to protect workers."
To assist agricultural employers with meeting the requirements outlined in the newly adopted regulation, the Western Center for Agricultural Health and Safety developed training materials and an employer checklist.
The study was based on interviews and focus groups with California agricultural employers and workers in the Salinas, San Joaquin and Imperial valleys. Support for the study came from the Centers for Disease Control and Prevention, and the National Institute for Occupational Safety and Health.
For the complete article and amazing pictures check out: https://www.ucdavis.edu/health/california-agricultural-employers-workers-approach-smoke-concerns-differently
This content was developed by the Western Center for Agricultural Health and Safety at UC Davis. For more information and to access their wildfire training materials, visit their wildfire training page: https://aghealth.ucdavis.edu/wildfires
A recent website just posted hopes to make research papers available to the general public. Many times these papers are locked away in archives or libraries and are hard to access. This website wants to change that. It is sponsored by various group0s, including USDA, University of Missouri, industry, Resource Conservative Districts and other entitites. It's a small data base at this point, but hopes to build over time. check it out:
There's a lot of distracting stuff at the site, but the guts are at
Other good ag websites are the USDA's National Ag Library:
USDA's ATTRA which is loaded with basic and detailed farming information:
USDA's Farming Information Center
It's a new year, READ ON!!!!
When reviewing possible problems your citrus might have, it's easy to jump to the conclusion that it is a virus. That's because viruses are a major problem around the world in citrus and the effects can be slow, chronic and debilitating or fast and deadly. Images get posted on the web, and if those symptoms look like something your tree has, then by golly you have a virus. Well, actually viruses are everywhere and in most plants, so you probably do have a virus or viruses, but not plant debilitating one. California, has had a pretty thorough nursery inspection procedure in place for many years and the likelihood of a virus causing a problem is less likely here than in many parts of the world.
In most cases viruses are difficult to eradicate in practice, so it is best to remove them before they get out in the field. The Citrus Clonal Protection Program (http://www.ccnb.info/page.php?s=2&c=3) weeds out citrus viruses before they get to wholesale nurseries and into the trade. That does not mean that we don‘t have debilitating viruses in the California industry. We do. Tristeza is in some of our orange orchards and that can lead to significant yield reductions and tree death (http://www.ipm.ucdavis.edu/PMG/r107101311.html.). Tristeza is spread by the melon aphid and is hard to control without good control of the aphid. In many older orchards there is exocortis and psorosis http://www.ipm.ucdavis.edu/PMG/r107100100.html; http://www.ipm.ucdavis.edu/PMG/r107100511.html). These are graft transmissible and why it is not good, in fact unlawful, to propagate trees with uncertified budwood.
In most cases in California if you are having symptoms of unhealthy in your trees it's most likely due to an irrigation problem (too much, too little, poor timing), a nutrient deficiency and possibly a fungal disease (most likely a root one such as armillaria or Phytophthora). Or in this day, it could be the start of Huanglongbing vectored by Asian Citrus Psyllid (http://www.ipm.ucdavis.edu/PMG/r107304411.html). Before jumping to the conclusion that there is a virus in your trees. Check out the most common problems for California citrus first (http://www.ipm.ucdavis.edu/PMG/C107/m107bpleaftwigdis.html). There are enough of those anyway.
Amazing. I was out with the contractor who has been doing the California Avocado Commission's annual acreage report. In the past, aerial photography was used and with painstaking accuracy the acreage was visually evaluated by hand. It was so expensive and took so long, that only parts of the California acreage were done each year. The company now uses satellite imagery and computer evaluation to do the whole avocado growing area each year and at much less cost. Now the contractor is going to try to estimate the amount of root rotted acreage that is out there. They will do this by canopy color and texture relative to healthy trees. We were out looking at the range of diseases out there that could be confused with root rot, such as bacterial canker, blight, black streak and crown rot. This will be amazing if they can distinguish amongst the diseases, but even if they can identify unhealthy groves that will be an amazing feat.
- Author: Ben Faber, University of California Cooperative Extension
- Author: Michael Spiers, HortResearch, Ruakura, New Zealand
Biological control of Phytophthora cinnamomi in avocado through the use of mulches was identified by an Australian grower and later described as the "Ashburner Method" by Broadbent and Baker. The technique uses large amounts of organic matter as a mulch along with a source of calcium. Control of avocado root rot in the Ashburner method was attributed to the presence of Pseudomonas bacteria and Actinomycetes. Multiple antagonists are more likely the cause of biological control, since no single organism has been found to be consistently associated with soils suppressive to P. cinnamomi.
The use of organic mulches has multiple effects, such as altered soil nutrient and water status and improved physical structure. Any improvements in plant status resulting from improvements in the growing environment can improve plant health. The effect of organic amendments on soil physical and chemical properties can vary considerably depending on soil texture and the environment. One of the most consistent effects of organic amendments is an increase in biological activity. Increases in organic substrate lead to increased fungal and bacterial populations. In numerous cases, this increase in biomass has been associated with disease suppression. This biological control can be ascribed to several mechanisms: competition, antibiosis, parasitism, predation and induced resistance in the plant.
The microbial biomass is responsible for release of enzyme products and polysaccharides in soils. The microbially-produced enzymes cellulase and glucanase have been demonstrated to have a significant effect on Phytophthora populations. This mechanism of antibiosis is possible because the microbes are releasing these enzymes to solubilize organic matter. Unlike other fungi, Phytophthora have cell walls that are comprised of cellulose and in the process of decomposing organic matter with enzymes, an environment is created that is also hostile to the pathogen.
In order to see if there might be potential differences in organic materials being better at combating avocado root rot, a little field trial was established with 23 different types of materials. The mulch materials were obtained from nearby hedges and chipped or obtained from commercial sources of mulch. Some of these materials would be difficult to get in large amounts, such as manuka (Leptospermum scoparium), but others are commercially available chipped greenwaste. The materials were then spread on the ground to a depth of five inches, in separate plots that were 36 X 36 inch squares. Decomposition was measured over a two year period and then cellulase was measured in the mulch, at the soil / mulch interface and at a two inch depth in the soil at the end of 2 years.
Since cellulase production is part of the decomposition process, the rate of decomposition should be a partial indicator of the amount of cellulase present. After a mulch application there is generally settling due to rainfall-caused compaction, but much of the decline by the second year is due exclusively to decomposition. The more recalcitrant materials, such as bark, wood chips and sawdust have barely lost half their depth after two years, while others such as shredded eucalyptus, manuka, avocado and willow are less than 20% of their initial depth. Much of the shredded/chipped material, such as eucalyptus had a significant fraction of leaves in the mulch. The wool disappeared a little after one year. The greenwaste + chicken manure compost is nearly the same depth as the wood chips, since it is a material that had gone through a decomposition process prior to its application and much of the easily digestible materials had already been decomposed.
The rate of decomposition has some bearing on the rate of cellulase production. Eucalyptus and manuka had the two greatest rates of decomposition and show the highest levels of cellulase production. The cellulase levels were consistent with all the different mulch materials. Using decomposition rate alone is not a complete indicator of cellulase production since, poplar, willow and avocado had high rates of decomposition, but their cellulase rates were half those of manuka and eucalyptus.
It is clear that the cellulase effect is limited to the layer of mulch and not to depth within the soil. There is some effect at the soil surface, but at 5 cm (2 inches) cellulase activity drops to background levels. There is earthworm activity at the test sites and one idea was that earthworm incorporation of organic matter would move the cellulase production into the soil. Maybe with further time this would occur. As it is, when mulches are applied to avocado, the roots tend to proliferate in the mulch, out of the soil where the cellulase activity is the least.
Something to keep in mind is that we do not know what levels of cellulase are necessary to control the root rot fungus. It may be that levels seen with pine bark are more than adequate. Also we have measured cellulase production at only one time in a two-year period and it is quite likely that this is not the best snapshot of what is happening before and after. A further reminder is that cellulase is only one of the many byproducts associated with decomposition and many of the antagonistic properties that are associated with the microbial biomass are not being measured in this trial. Having developed this screening procedure what needs to be done next is to take high, medium and low cellulase producing mulches and challenge the fungus to verify that this is a good way to evaluate mulches.