- Author: Ben Faber
The recent Huanglongbing Conference in Orlando, FL was chock full of people and ideas. Some of the ideas were still in the fermentation state and some were in practice on farm. One of the ideas that has been put into practice is the use of antibiotics, such as tetracycline and streptomycin to control the bacteria, Candidatus Liberibacter asiaticus (CLas), which causes HLB or citrus greening. This is somewhat disturbing since the rise of antibiotic resistant bacteria which affects humans has been affected by the wide-spread use in animal production facilities. This has led to some food companies to discontinue the sourcing of meat from animals treated with antibiotics for non-health reasons.
Antibiotics are molecules that limit the growth or reproduction of bacteria. They come under the umbrella of bactericides which include antibiotics, but also disinfectants like bleach and copper sulfate and antiseptics like peroxide, iodine and alcohol. Antibiotics when properly used will not harm human tissue and can be derived from bacteria, fungi and synthetically and will often act directly on the bacteria that is causing the disease. Some of these molecules can be simple assemblages of amino acids called peptides (etymology “to digest”) or strings of peptides called proteins. And sometimes they do not work on the bacteria itself, but on steps that lead up to processes that make the bacteria effective at its job.
At the conference, several papers were presented that illustrated this type of antibiotic effect. One of these papers was presented by Robert Shatters for his group. The peptide they are looking at actually inhibits the movement of the CLas bacteria in the gut of the insect, reducing or possibly preventing the transmission of the bacteria to the host plant – citrus.
The following is an abstract from the paper.
Identification of gut epithelium binding peptides that reduce systemic movement of ‘Candidatus' Liberibacter asiaticus within the Asian citrus psyllid vector
Robert G. Shatters, Jr1, Dov Borovsky1, El-Desouky Ammar1, David Hall1, Kasie Sturgeon2, EricaRose Warwick2, Marc Giulianotti3, Radleigh G Santos3 and Clemencia Pinilla4
1USDA, ARS, USHRL, Fort Pierce, FL USA; 2University of Florida, CREC, Lake Alfred, FL USA; 3Torrey Pines Institute for Molecular Studies, Port St Lucie, FL USA; Torrey Pines Institute for Molecular Studies, San Diego, CA USA.
Non-Technical summary: The Asian citrus psyllid is the only known vector of the bacteriumthat causes citrus greening disease. This insect acquires CLas from an infected citrus tree while feeding as a nymph. Transmission to uninfected trees occurs when infected adults emerge and fly off and feed on uninfected trees. Our current understanding of the CLas-psyllid interaction suggests that adults become competent for transmission only after the bacterium moves from the insect gut into the hemolymph and then to the salivary glands. We have identified a set of small peptides that when fed to the psyllid, bind the gut membranes and reduce the ability of the citrus greening bacterium to move from the gut to the salivary glands. These peptides are now being tested to determine if they can be used as an effective way of reducing the spread of citrus greening disease.
This and other paper abstracts will soon be available at: http://irchlb.org/files/33373ab0-7df3-4117-9.pdf
photo: HLB Symptoms

- Author: Jeannette E. Warnert
Three citrus trees that produce inedible fruit at the UC Lindcove Research and Extension Center in Visalia may be a game-changer for the citrus industry, reported Ezra David Romero on Valley Public Radio.
The trees are thought to be resistant to huanglongbing, a severe disease of citrus that has devastated the Florida industry and could become a serious problem in California. The citrus-saving potential of the three 34-year-old trees was outlined in an article by UC Agriculture and Natural Resources writer Hazel White in the most recent issue of California Agriculture journal.
UC Riverside citrus breeder Mikeal Roose collected seed from the trees and will test seedlings as soon as they are large enough.
"So what (breeders) have to do is cross this with some edible varieties and eventually create something that has the gene for resistance, but also the genes for good fruit," said Beth Grafton-Cardwell, Lindcove director and research entomologist.
Huanglongbing disease has cut citrus production in Florida by more than half. It's been found in residential citrus trees in Southern California, but hasn't reached the state's vast commercial orchards yet. Grafton-Cardwell said she expects the disease will arrive in 4 or 5 years.
Yeah!!!!

- Author: Ben Faber
Topics in Subtropics
January - March Topics in Subtropics 2017
In this issue:
- Revisiting an old study on high density citrus orchards
- Shoot and Twig Dieback in Citrus
- Alternative Crops or ......
- Referendum Comments Citrus Research Board


- Author: Ben Faber
On a recent trip to Florida we saw a dog in action locating avocado trees that had been attacked by the Redbay ambrosia beetle which carries the fungus Raffalea lauricola which is a similar pest/disease complex that is found in California with the Polyphagous/Kuroshio Shot Hole Borer and Fusarium Euwallacea that leads to Fusasrium Wilt in avocado. The fungus gives off a certain odor that the dog is trained to smell and along with the human trainer goes around the orchard to identify infected trees. The trees can then be removed so that they don't act as a reservoir of infection that can be spread to other trees by the beetle. The dog seemed to work pretty fast. Depending on the acreage covered, the handler says they charge $150 per acre to find diseased trees. This can happen before more advanced symptoms show up that humans can see. This technology could be used in identifying other tree diseases, such as Huanglongbing, citrus canker and Phytophthora, along with others.
Dog has found a laurel wilt infected tree that will soon be removed. (Tim Spann).

- Author: Ben Faber
The latest National Agricultural Statistics Service (NASS) results are out for the citrus crop. These are results that are collected by the USDA to gauge production in the different growing areas of the country. From this most recent data, it is clear that citrus production is diminishing with time, most likely the effect of Huanglongbing. This is about a 60% decline from 2015.
The impact of this reduced production has reached out to not just growers, but also the juice industry they support, or are supported by. There's been a decline in the number of juice plants since 2014 which are reliant on volume to stay in business. If plants close, growers have fewer options for their juice citrus. http://www.theledger.com/news/20140705/at-least-one-juice-processor-expected-to-close
Most commercial crop production figures are collected by state and summarized on a state basis with the Agricultural Census every 10 years - https://www.agcensus.usda.gov/. The last was done in 2012.
Daily market prices for these different commodities can be seen on a wholesale basis by city, at USDA's Market News Service - https://www.marketnews.usda.gov/mnp/fv-home . This gives current prices and archived prices for products sold in different markets. It gives a general idea of what the grower will be paid for a given crop.
All of these sources are helpful for deciding where crop prices and markets are going. If you have time check them out.
