Botrytis
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| Chemical
Fungicides
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| Biological
Control
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| Research
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| LifeCycle
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"Bunch Rot" of grapes, caused by the fungus Botrytis cinerea, is a significant problem for the wine industry world-wide. The disease, also know as "grey mould", is arguably the most important disease problem confronting the New Zealand wine industry.
[Healthy grapes, inset Botrytis infected grapes]
The most favourable conditions for development of the fungus are warm temperatures and high humidity. The disease can occur on grapes at any time during the growing season but it’s most destructive patterns occur after there is rainfall accompanied by warm temperatures either at flowering or late in the growing season. The disease spreads easily late in the season via airborne spores that are produced in abundance from infected berries. The fungus develops as a moist rot on the berries and other fleshy parts of the vine and at its latest stages is visible as a grey felt-like mat of spores.
Limited or controlled Botrytis infection can result in a non-destructive stage of the disease known as “noble rot” which can be managed in order to make “noble” or “botrytised” wines. More usually, the fungus continues to penetrate the grapes on the vine causing them to rot, making winemaking difficult.
 Botrytis developing in grapes |
Grapes from most large vineyards are mechanically harvested rather than hand-picked. This means that grapes infected with "bunch rot" cannot practicably be separated from healthy grapes. So even where the proportion of Botrytis-infected grapes within a bunch is low, the volume, quality, taste and value of the whole bunch, and ultimately the wine made from it, is reduced.
“Bunch Rot” caused by Botrytis has been estimated to seasonally cost the New Zealand wine and grape growing industry up to $25 million in lost grape sales and disease control costs and up to a further $40 million in lost wine sales. Given that New Zealand represents a fraction of 1% of world-wide wine production, the cost of Botrytis infection to the grape growing industry world-wide is enormous.
Chemical fungicides either kill the fungus itself (fungicidal products) or stop its growth (fungistatic products). In both cases, the fungicide attacks the biological structure (for example, the cell wall) or function (for example, protein synthesis) of the fungus. Over time, natural selection frequently occurs, with resistant strains of the fungus surviving and eventually replacing the strains that are susceptible to the fungicide. The fungicide becomes progressively less effective and must eventually be either modified or replaced by an entirely new fungicide.Historically chemical fungicides have proved they can be non-specific and therefore can act on organisms other than the target fungus, including other naturally occurring beneficial organisms. Because of their chemical nature, they may also be toxic and non-biodegradable. Chemical residues can build up in the soil and throughout the food chain.
Consumers world-wide are increasingly conscious of the potential environmental and health problems associated with the build-up of toxic chemicals, particularly in food products. This has resulted in growing consumer pressure to reduce the use of chemical pesticides. As a result, “organic” products or those resulting from sustainable production programmes – produced without the aid of chemicals - are increasingly perceived as more healthy, more desirable and of premium value. BOTRY-Zen is entirely compatible with all the requirements of current sustainable agriculture objectives with the active ingredient in BOTRY-Zen being a naturally occurring organism. The excipients in the product are organic compounds approved in the United States and Europe for use in the food and pharmaceutical industries and it is considered that BOTRY-Zen will be an attractive alternative Botrytis control product for grape growers who want to be able to describe their crops as sustainably grown
The use of a biological control agent for fungus diseases such as Botrytis can help avoid dependence on chemicals and is therefore perceived to be a “natural” alternative to chemical fungicides.BOTRY-Zen is a substance containing a non-pathogenic saprophytic fungus that acts as a biological control agent by competing for the same biological niche as Botrytis cinerea. It aggressively occupies the same physical space and out-competes Botrytis for the nutrients in the dead and senescent vegetative material on the vines. BOTRY-Zen is non-invasive and will not cause harm to live plant tissue. With this mechanism of action it is highly unlikely that resistance to BOTRY-Zen will develop.
A biological control agent is therefore likely to remain effective for a longer period than a chemical fungicide without needing modification or replacement and without contributing to the environmental and health problems perceived by consumers to be associated with the application of chemicals.
The use of biological control agents, rather than chemical fungicides, is one of the horticultural practices that enable growers to describe their food crops as “organic”. There is growing consumer preference for “organic” food products and it is this consumer demand that has created a demand by grape growers and wine makers for an organic alternative to chemical control of Botrytis infection.
HortResearch scientists screened many naturally occurring saprophytic fungi from a range of plant types and successfully isolated an aggressive and successful competitor of Botrytis cinerea. HortResearch then applied for a patent relating to the use of the saprophytic fungus as a biological control agent and subsequently deposited isolates of the fungus in the Australian Government Analytical Laboratories for the purposes of complying with the patent application procedure.The discovery and underpinning research was undertaken and funded by HortReseach. Subsequent developmental research was jointly funded by HortResearch and by the Wine Institute of New Zealand Incorporated and the New Zealand Grape Growers Council whose commercial arms, Winegrowers of New Zealand Limited and New Zealand Grape Growers Limited formed a joint venture called Winegrape Tech. Winegrape Tech has the right to commercially exploit the HortResearch patent rights and other intellectual property rights associated with the saprophytic fungus organisms themselves and has granted to Botry-Zen Limited an exclusive licence of those rights in all countries that are parties to the Patent Co-operation Treaty. The research was also partially funded by the Foundation for Research Science and Technology through a Technology Business Growth grant.
BOTRY-Zen trial site.
Extensive laboratory tests and field trials have now established that the novel saprophytic fungus isolate is an effective control agent for Botrytis cinerea and Sclerotinia Sclerotiorum – diseases that affect a number of horticultural crops in New Zealand and around the world.
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