Cucumber Green Mottle Mosaic Virus (CGMMV)
By LEN TESORIERO, PCA Director and Senior Plant Pathologist NSW DPI
A new R&D project has commenced to investigate CGMMV in Australia.
This virus was first recorded in 2014 on watermelon crops near Katherine in the NT and subsequently on cucumbers grown under protected cropping near Darwin.
It has been present in Europe for many years where it can cause a serious disease on susceptible greenhouse cucumber varieties.
In recent years it appears that an aggressive strain of CGMMV emerged that has spread around the world with infected seed.
There have been new reports of this disease from countries including Israel, Canada and the USA just prior to the detection in Australia.
The R&D project is a collaboration of scientists from across Australia and is led by Dr Lucy Tran-Nguyen from the NT Department of Primary Industries and Fisheries (who incidentally was awarded Vegetable Researcher of the Year at the recent national horticulture convention on the Gold Coast).
Funding has been provided by the Australian vegetable industry levy but in future may also draw on funds from the newly established Australian melon industry levy.
These levy funds are matched by the Australian Government through Horticulture Innovation Australia.
Symptoms on young leaves are vein clearing and crumpling may be visible, while mature leaves may show mottling or mosaic patterns, or look pale, yellow, or bleached. Young seedling symptoms may be indistinct or difficult to recognise as being caused by a virus. In severe infections, embryonic leaves may become yellow, but symptoms may not be apparent until more mature leaves emerge.
The project has five broad areas of activity:
1. Identify the weed host and non-host plants. This will be important to determine if the virus is spread with weed seeds and therefore to inform the industry on management of the spread of the disease.
2. Determine how long the virus can persist in soil and plant debris. Again this is critical knowledge to manage the disease in fields or substrates where CGMMV was previously shown to occur.
3. Develop more sensitive CGMMV detection techniques. As most imported cucurbit seed must now be tested either overseas or in Australia it is important that the detection methods are validated and sensitive enough to pick up low infection levels. In-field detection methods may also help to determine if the virus is in weeds and soils.
4. Field cucurbits rely upon bee pollinators and there is some preliminary evidence that CGMMV may be transmitted by them. Research is required to confirm this occurs, and will link with current studies led by Dr Aviv Dombrovsky in Israel.
5. An extension and capacity-building component will keep growers and industry stakeholders informed about the research findings and management options. Detection of this exotic disease in Australia exposed an uncontrolled biosecurity pathway of infection via untreated and untested imported seed.
A testing regime is now in place to mitigate this risk.
More importantly the Australian melon industry now has an R&D levy to fund relevant R&D as well as a Biosecurity Levy component to assist with any future incursions. This includes a provision to compensate affected growers for financial losses.
PCA will keep you informed on the progress of this project which has broader implications than simply the melon and cucurbit industry.
CMV-infected plants are more alluring to bumble bees
Bumble bees have a thing for tomato plants, especially if they’re harbouring a destructive virus. That’s the curious finding of a new study, in which researchers released the insects into spaces that contained either normal tomato plants or those infected with the cucumber mosaic virus (CMV).
CMV alters the gene expression of the tomato plants it infects, stunting their growth and distorting their leaves, and it can cause severe losses of crops worldwide. It also causes the plant to emit a different scent than noninfected tomatoes, researchers report today in PLOS Pathogens.
The scent appears to make a difference; the bees were more likely to visit infected plants than noninfected plants, and they spent more time buzzing around them. That preference likely keeps the virus going in tomato plants, according to a mathematical model the team developed. The team says further research could lead to ways to increase bee pollination of important crops.
Source: Science Magazine
The safety harness of an EPPRD, R&D levy and a biosecurity levy
by ROBERT HAYES PCA Chair
Let us hope that the CGMMV disease is controlled and hopefully eliminated before it causes a major problem for the cucumber and melon industries elsewhere in Australia.
I can only hope that the key players in the Australian greenhouse tomato industry are watching this event unfold.
The tomato industry needs to learn from this experience and look at applying a similar approach to their biosecurity vulnerability by implementing at the very least, a biosecurity levy and signing up an Emergency Plant Pest Response Deed (EPPRD).
Further, it needs to be lobbying the government to ensure that imported tomato seeds are treated and tested against the various potentially disastrous diseases lurking overseas.
Is it too much to suggest, once again, that the largest horticultural industry by value in Australia needs to consider implementing an R&D and Biosecurity levy?
This would attract matching government dollars to invest preemptively in being prepared for an almost inevitable incursion, rather than find itself reacting to a disaster after the event.
PCA is prepared to assist and facilitate this process, as it has done on two previous occasions.
PCA is the only national industry representative body with a direct interest in the protected cropping tomato industry.
However, as a voluntary organisation PCA is not resourced to pursue the agri-political activities involved in lobbying the Federal Government and the various arms of bureaucracy.
Neither is it resourced to be involved in the biosecurity monitoring and management process.
Despite this, PCA is prepared to assist where it can to facilitate a third, and hopefully more successful attempt to implement a Tomato Levy.
Recent developments in other horticultural IRB’s and the new independence of HIA from them, mean that the pathways to establishing a statutory R&D and Biosecurity levy are probably now a little less obstructive than they have been in the past.
The PC tomato industry needs to take a good hard look at its risk profile into the future.
It needs to figure out whether it is prepared to continue risking the massive capital investment it has made and continues to make, whilst walking a biosecurity high wire without the safety harness of an R&D Levy, an EPPRD and a Biosecurity Levy.
The smaller segments of the PC tomato industry have long supported such an approach.
It is the larger players, who actually have far more to lose, that need to take the lead on this. The real question is this – will they stand up and be counted?