Stopping Fruit Mould - Without Pesticides

How many times have you purchased a package of beautiful, red, ripe strawberries from the grocery store only to have them spoiled by grey fuzz a day or two after you get them home?

That unappetizing fuzz is called grey mould, and it’s caused by the fungal pathogen Botrytis cinerea. Other common fungal diseases of strawberry include powdery mildew and anthracnose. These diseases pose big problems for growers, who traditionally apply fungicides to control them. And many fungicides are not even an option for organic producers.

Fortunately, USDA Agricultural Research Service (ARS) scientists are on the case, looking for ways to keep strawberries mould free without fungicides.

Ultraviolet-C (UV-C) irradiation has been studied as a way of killing microbes by damaging their DNA, but at effective doses, it damages leaves and fruit. ARS scientists Wojciech Janisiewicz and Fumiomi Takeda discovered a way to sidestep this problem. They demonstrated that UV-C irradiation of strawberry plants—followed by a period of darkness—resulted in drastic kill of the Botrytis pathogen, the powdery mildew fungus, and anthracnose. In fact, the technique increased UV-C’s killing power 6- to 10-fold, depending on the pathogen, with no damage to the leaves, flowers, or fruit.

A bonus? The treatment also reduced spider mite infestations, and that could mean less pesticide use, too.

The scientists think the dark period following the UV-C treatment deprives the pathogens of the light needed to activate their DNA-repair mechanisms. They’ve filed a patent application on the technology, which is now called PhylloLux and includes applications of two beneficial yeasts. They have also automated the technology for large-scale applications. The scientists are working with an industry partner to develop a robot that can treat a field of strawberry plants at night on commercial farms.

Janisiewicz and Takeda work at the ARS Appalachian Fruit Research Station in Kearneysville, West Virginia. Their method for controlling fungal plant pathogens, and even spider mites, would greatly reduce product loss to strawberry growers and processors and reduce pesticide use. It will also benefit consumers who lose strawberries to mould before they can consume the entire package.—By Sue Kendall, ARS Office of Communications.

Another smart example of the role of precision horticulture now expanding around the globe.

Detecting Citrus Greening Disease with Dogs

The article below is demonstrating a very smart plant disease detection methodology.  While this disease is not in Australia it is still showing a very smart new and relevant option and maybe could be applied to other diseases as well.

Trained Dogs Are the Most Efficient Way to Hunt Citrus Industry's Biggest Threat

By Kim Kaplan
February 3, 2020

FORT PIERCE, Florida, Feb. 3, 2020—Dogs specially trained by Agriculture Research Service (ARS) scientists have proven to be the most efficient way to detect huanglongbing—also known as citrus greening—according to a paper just published in the Proceedings of the National Academy of Sciences.

Currently, the only solid hope of curtailing the spread of citrus greening is to eliminate trees with the disease as quickly as possible to prevent further spread. Early detection of the citrus greening pathogen is crucial because trees can be infected and act as a source to spread the disease months or years before showing symptoms that are detectable by the naked eye.

ARS plant epidemiologist Timothy R. Gottwald with the U.S. Horticultural Research Laboratory in Fort Pierce, Florida, discovered that dogs can be trained to sniff out the presence of Candidatus Liberibacter asiaticus, the bacteria that causes citrus greening, with greater than 99 percent accuracy. 

"We found that, once trained, these dogs were able to identify infected trees within two weeks of the trees being inoculated," Gottwald said. "The dogs also were able to distinguish the citrus greening pathogen from a variety of other citrus bacterial, viral, fungal, and spiroplasma pathogens, including closely related Liberibacter species.

During testing, the citrus greening detector dogs had total of 4 to 15 false negatives and false positives on 950 to 1,000 trees per dog. Occasionally, the dogs alerted on clean trees that were in the same spot where an inoculated tree had been placed in previous tests due to residual scent.

In contrast, the only currently USDA-approved method for confirming the presence of the citrus greening pathogen—a DNA-based assay called a polymerase chain reaction (PCR) test detected less than 3 percent of infections at 2 months, 16 of 30 inoculated trees at 16 months, and 20 out of 30 in 17 months.

PCR tests also require considerable time, financial and human resources for sampling, processing and laboratory work. They are very expensive to use as a general surveillance tool.

The training is similar to that of explosives sniffing dogs, in which the dogs are taught to recognize a particular odor and to sit down next to the source once found. The dogs are rewarded with play time with a toy.  However training is more extensive and specific because the dogs are trained to detect a bacteria infecting a plant, and the two cannot be separated.

So far, Gottwald's program has trained 19 dogs obtained from European breeders of detection canines because of their keen abilities and drive. (Watch a video)

"When we ran epidemiological models, we found canine detection combined with infected tree removal would allow the citrus industry to remain economically sustainable over a 10-year period, compared to using molecular assays or visual inspection combined with tree removal, which failed to suppress the spread of infection," Gottwald explained.

Citrus green sniffing dogs have been deployed for 9 months in California and northern Florida.

In the past decade, huanglongbing has caused more than 70 percent decline in the production of oranges for juice and the fresh fruit market in Florida and threatens other states, making it the largest economic threat to the $3.35 billion U.S. citrus industry. It was first found in the United States in 2005, citrus greening has spread to Florida, Texas, California, Georgia, and Louisiana.

Genetic Fix to Manage Bee Colony Collapse Disorder

Colony Collapse Disorder caused the loss of an estimated 40 per cent of honey bee colonies in the US last year. Now researchers have genetically engineered a bacterium that lives in the gut of honey bees, to boost their ability to fight off pathogens that are often responsible for colony collapse. 

The researchers from the University of Texas first identified that honey bees carry a particular beneficial gut bacterium called Snodgrassella alvi, and then genetically engineered that bacterium to produce RNAi — RNA interference — in the gut of the bee. 

That RNAi is then able to suppress the expression of the deformed wing virus, and also kills the parasitic Varroa mite.

RNA interference [RNAi]  is a biological process in which RNA molecules inhibit gene expression or translation, by neutralizing targeted mRNA molecules. Historically, RNAi was known by other names, including co-suppression, post-transcriptional gene silencing (PTGS), and quelling. 


 appeared originally as Scientists modify honey bee gut bacterium to fight colony collapse-causing Varroa mite and deformed-wing virus in  ABC News (Science) - 31 January 2020
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Late Monsoon Season for Australia

Mid January 2020 and still no monsoon arrival.  Getting quite late but not yet the latest date recorded.

However, it could be some time away  with a few of the global weather drivers looking decidedly dodgy ie not especially positive for a monsoon burst anytime soon.

Read the current Tropical Climate Note from earlier this week  [http://www.bom.gov.au/climate/tropical-note/ ] and note the eastwards movement of the MJO away from our region, usually negative for rain across N Australia.

Today's weather reports refer to hot and drier conditions across the north over the next few days, although there may be storms.

Please continue to wait.......and wait...........and wait.

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3 February 2020 - UPDATE - now coming .........the monsoon onset!!   Latest ever for Darwin and even now it is still not quite here YET.  Maybe in a few days still.  While a monsoonal low is moving west several hundred kms  SW of Darwin, officially not yet for Darwin! 

Eyes in the Sky - Drones for Post Fire Hydrologic Assessment

A very topical article appeared in the recent edition of Stormwater Magazine based on US usage but would seem highly relevant for use in Australia right now.

A post grad student used drone flights and various software programs to assess the landscape following fire, in California but this seems highly useful for eastern and south eastern Australia right now in early 2020 to assess our burnt landscapes.

The emphasis was on how the landscape patterns have been changed and how this has influenced how the hydrology of the area has been impacted. 

The link is below and should be readily available.

Seems a very timely application, now that some rain seems to be arriving which may quench a number of the fires.

Link is:

https://www.stormh2o.com/erosion-control/article/21117902/eyes-in-the-sky?utm_source=EC+Weekly+Newsletter&utm_medium=email&utm_campaign=CPS200114039&o_eid=0996E9426678A4U&rdx.ident%5Bpull%5D=omeda%7C0996E9426678A4U&oly_enc_id=0996E9426678A4U