- Author: Ben Faber
Who a thunk it, but coffee can grow in coastal California, because our latitude approximates the climate found in high altitude coffee growing areas found in Central America. And now there is a "small" industry growing here. Along the coast from San Luis Obispo to San Diego, there are probably 50 growers with more than 100 plants. The largest with about 5 acres and rumors of someone putting in a much larger planting of 20 acres. Keep your eye open for other plantings going in.
Of all coffee species, Coffea arabica is considered to make the superior beverage. It accounts for more than three-quarters of the world production in spite of being prone to a devastating rust disease. C. arabica is indigenous primarily to the area around Kaffa in Ethiopia. For many years, this area was "closed", and the genetic breeding pool was limited to one seedling taken to Amsterdam in 1706 from a planting in the East Indies. The resultant inbreeding still may be a significant factor in what cultivars are presently available.
The first "coffee" drink was made from fermented fruit pulp. Not until the 15th century were dried "coffee" beans roasted, ground and a beverage extracted. In 1650 coffee from Arabia reached England, and by 1675 there were more than 3,000 forerunners of StarbucksTM.
C. arabica thrives and produces the most prized beans in the moderate (maximum of about 70o F) climates encountered at higher, frost-free elevations. Excellent coffee is produced near the equator up to 6000 feet. Growing conditions at this elevation correspond approximately to the coastal conditions at 34 degrees latitude (Santa Barbara and Ventura Counties). A good tasting coffee has been made from beans grown in Santa Barbara backyards.
Challenges facing production in California include adapting cultural techniques to California conditions, marketing California specialty coffees, and minimizing labor costs attendant with picking and grading without significantly degrading product quality.
We are still learning how to grow coffee and what conditions it likes. We know it doesn't like 115 deg. The following pictures are of coffee that survived two summer renditions that whacked avocados, citrus and even eucalyptus.
Coffee Heat Stressed in summer 2020
In the last weeks of February and early week of March 2022, we had temperatures that hovered around 33/35 degrees at night and one night dropped to 30 deg in Santa Paula where we have a planting. It toasted the tops of the plants, but they survived and will likely grow out of the damage. It will be interesting to see if they flower in the next month or so. Probably not, since a lot of the terminals were burned. A much larger planting in Santa Paula on a hillside escaped much of this cold damage.
Lots to learn yet.
Nine varieties of coffee, all neatly cold scorched in Santa Paula, March 2022
- Author: Ben Faber
Calls have come in - "What is the browning on the avocado leaves? Thrips damage? Salt damage? Dothiorella?" Nope, Frost Damage. From the end of February to the first week of March, Santa Paula had one night of 30 deg F, and 3 nights of 33 and a few nights around 35.. It wasn't cold cold, but cold enough that there was damage to the avocados there and more so the further east and up toward Ojai.It wasn't enough to defoliate the trees, although many were under stress from the flowering that is going on and a lot of the leaves were dropping from the flowering stress. The damage to the leaves is a darkening of the leaf both of the bottom surfaces. In many cases, the flower panicles got scorched. This is just the start of a big flower push and it looks like there's a lot of flowers that have not pushed that will be fine. It could still be a good avocado year. The coffee really got roasted.
- Author: Ben Faber
Translating the science of managing HLB
Your resource for learning about existing and new tools being developed by researchers to protect and manage citrus from the causative agent of huanglongbing (HLB).
Research Snapshots
See how scientists are working to control HLB by reading short snapshots about their research. Topics include:
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Click on the links below to explore the snapshots!
Questions?
We have the answers!
Growers and end-user audiences can use this PowerPoint presentation which has been tailored for their use. It provides general background on the genetics that are used to modify crops and information on state and national regulatory approaches and consumer attitudes.
Examples of the questions that are addressed:
- What are the general processes of genetically modifying plants and insects?
- When and where did huanglongbing (HLB) come from?
- What are some genetic approaches to controlling HLB?
- What is consumer response to engineered crops and foods?
- Author: Brad Buck, UF/IFAS
LAKE ALFRED, Fla. — Sometimes in science, a new perspective brings an “a ha!” moment. That's what one senior researcher at the University of Florida Institute of Food and Agricultural Sciences believes happened with his latest research on Huanglongbing (HLB), or citrus greening.
HLB is worldwide, devastating citrus disease caused by Candidatus Liberibacter asiaticus (CLas), a bacterium that settles into the tree's phloem — its interior vascular system — eventually killing the tree. Since first found in Florida in 2005, it has infected virtually every grove in Florida and cost the citrus industry billions of dollars.
UF/IFAS' Nian Wang's most recent research describes in detail how HLB causes damage to citrus trees and presents the case that HLB is a pathogen-triggered immune disease. A pathogen-triggered immune disease is a disease that results from the activation of an organism's immune cells fighting a pathogen (a virus, bacteria, or parasite) that invades an organism, in this case, the citrus plant.
This is the first time that this explanation of HLB symptoms as pathogen-triggered immune responses has been presented and defended. Seeing HLB in this new context may mean finding new solutions to the disease, faster. Pathogen-triggered immune diseases have not been reported in the world of plants that includes over 250,000 species but are common in humans.
Scientists don't fully understand how the pathogen that causes HLB damages infected citrus plants because it has not been cultured in artificial media. With this new evidence that supports a premise that HLB is an immune-mediated disease, researchers can see new light on how to manage HLB.
Through his research Wang, has shown HLB infection stimulates systemic and chronic immune responses in phloem tissue, especially overproduction of reactive oxygen species (ROS), which are part of the plant's immune response. Chronic and excessive ROS production is responsible for systemic cell death of phloem tissues, which in turn causes HLB symptoms. This supports the hypothesis that HLB is an immune-mediated disease.
Antioxidants and immunoregulators are commonly used to treat human immune-mediated diseases. They halt or reduce the process that results in cell death. In citrus, the researchers tested whether growth hormones like gibberellin acid (GA) and antioxidants (uric acid and rutin) could impact cell death triggered by the infection and, therefore, block or reduce HLB symptoms.
The researchers found the GA and uric acid had an encouraging positive impact on infected trees. This has also been supported by other research in process at the UF/IFAS Citrus Research and Education Center.
“Our findings allow us to control HLB by mitigating ROS with integrated horticultural measures, genetic improvements of citrus varieties with antioxidant enzymes, generating non-transgenic HLB resistant/tolerant citrus varieties by editing key genes required for CLas-triggered ROS production, and using CTV-mediated expression of antioxidant enzymes and silencing of key genes required for CLas-triggered ROS production,” said Wang, a professor of microbiology and cell science at UF/IFAS.
Wang's research also tested existing grove management practices that integrate antioxidants, micronutrients (activating antioxidant enzymes), gibberellin (mitigating ROS, regulating immune response, and promoting new growth) and optimized fertilization and irrigation (reducing ROS production) that are available in Florida. All the products tested, except the antioxidants, have already been registered for citrus production, thus can be easily adopted by citrus growers.
Wang's research has also identified the RBOHD gene to be the main producer of CLas-triggered ROS. With this, the researchers can now “edit (using CRISPR technology)” or “silence” RBOHD or specific receptor gene(s) responsible for RBOHD activation and the resulting cell death of phloem tissues and HLB symptom development. It is expected these approaches will allow economic and efficient citrus production in HLB endemic citrus production regions such as Florida and Texas and provide the long-term solution against HLB for all citrus production regions of U.S. (including California) in case that HLB becomes endemic in the future.
Read the whole story:
Key Points About Plant "Immunity"
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Unlike vertebrates, plants do not have an adaptive immune system. Nonetheless, plants can launch specific, self-tolerant immune responses and establish immune memory.
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To promote virulence, pathogens inject effector molecules that target conserved immune signalling hubs into the plant cell. In response, plants have evolved resistance (R) proteins that detect effector-induced perturbations in these hubs, providing the potential to specifically recognize a large number of pathogens with similar infection strategies through a smaller number of R proteins.
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Intraspecific and interspecific plant crosses suggest that autoimmunity can arise from self-reacting R proteins, illustrating the threat of uncontrolled R protein activity. Dynamic transcriptional and post-transcriptional regulation of R protein levels is thought to minimize the risk of autoimmunity in plants.
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Pathogen-infected tissues generate a mobile immune signal consisting of multiple proteins as well as lipid-derived and hormone-like molecules. These signal molecules are transported to systemic tissues, where they induce systemic acquired resistance (SAR). SAR is associated with the systemic reprogramming of thousands of genes to prioritize immune responses over routine cellular requirements.
- Author: Ben Faber
New ‘Candidatus Liberibacter' Pathosystems Focus Issue from APS (American Phytopathological Society) |
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Read the great review of the bacteria that causes Citrus Huanglongbing and then the abstracts of the articles in this edition of Phytopathology. The review itself is pretty comprehensive, however you can't read the full articles contained in the editon without paying. But this gives you an idea of the extent of work being done, even though the language may be quite technical. The 18 articles in this Phytopathology Focus Issue showcase the enormous research efforts made by the scientific community, giving rise to major advances and achievements in a short time often through multidisciplinary approaches applied to the bacterium, psyllid vector, and plant host. Preview two editors' pick below or see the full Focus Issue. |
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Transcriptome Profiling of ‘Candidatus Liberibacter asiaticus' in Citrus and Psyllids |
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Alves et al. explored Huanglongbing (HLB) presence and absence over 13 years in citrus orchards in Brazil and compared two hierarchical Bayesian modeling approaches to link climatic factors to the spatial distribution of HLB prevalence. They found an inverse relationship between HLB prevalence and mean temperature during the dry season, but wind speed, rainfall, and proximity of other HLB contributed to HLB prevalence. The results further our understanding of environmental factors associated with disease distribution and spread and assists policymakers in defining regions at risk of HLB outbreaks to help guide monitoring strategies that mitigate further spread of HLB. |
HLB symptoms
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