谈一谈葡萄Esca病

近日从国外网站上看到一条新闻，说今年有关葡萄Esca病发生情况的报道在法国西南部葡萄产区急剧增加，该病害在Bordeaux,、Gascony以及 Charente等地的日益流行正在显现出来。

据该文章介绍说，尽管该病害对葡萄酒的影响已经遍布全世界，但是对这种病害的来源、如何传播以及有可能呈级数增加却知之甚少。

出于从事葡萄病虫害专业的敏感性，我专门去网上查阅了有关的文献报道，对该病害有了一个基本的了解。

葡萄Esca病是由真菌引起的葡萄病害，除了叫葡萄Esca病以外，它还有其它的名称，如葡萄幼树衰退病、黑麻疹病（black measles）、葡萄中风病以及葡萄癌症等，它是一种至少由三种病原真菌引起的真菌性病害。目前已知的病原（无性阶段）有Phaeoacremonium aleophilum、Phaeoacremonium inflatipes、Phaeoacremonium chlamydosporum以及Phaeomoniella chlamydospora 。有性阶段已经发现三种：Togninia minima、T. californica以及T. fraxinopennsylvanica。

这种病害通常发生在8到10年树龄甚至更老的葡萄树上，也会在葡萄幼树上发生，并引起幼树的衰退。

该病害主要侵染葡萄的维管束组织，造成木质部导管变黑和堵塞，症状有轻有重，另外还造成叶片褪绿枯黄、葡萄落叶以及阻碍葡萄生长发育等，有时候在葡萄生长季节中期发病，甚至会导致葡萄树或者葡萄主蔓突然萎蔫和死亡（中风），尤其是在天热的气候条件下。

附国外对该病害的介绍以及原始新闻来源：

一、GrapeMeasles (Esca)

Pathogen: Nine species of fungi in the genus Phaeoacremonium. The perfect stage has been found for three: Togninia minima, T. californica, and T. fraxinopennsylvanica SYMPTOMSAffected leaves display small, chlorotic interveinal areas that enlarge and dry out. Foliage symptoms are frequently called "esca." In red varieties dark red margins surround the dead interveinal areas. Severely affected leaves may drop and canes may dieback from the tips. Symptoms may occur at any time during the growing season but are most prevalent during July and August. On berries, small, round, dark spots, each bordered by a brown-purple ring, may occur. These spots may appear at any time between fruit set and ripening. In severely affected vines the berries often crack and dry on the vine or are subject to spoilage.

COMMENTS ON THE DISEASEMeasles are caused by several species of Togninia, a fungus that produces perithecia on grapevines in old, rotted vascular tissue. Ascospores are released from fall and winter into spring with rainfall; temperatures do not seem to be limiting for spore release. Ascospores reinfect the vine through pruning wounds. Wounds remain susceptible up to 16 weeks after pruning with susceptibilty declining over time. The pathogen enters the current season's vascular tissue and it is believed that symptoms are expressed in the same year that new infections occur. Symptoms are caused by a toxin produced in the vascular tissue and include both leaf striping and fruit spotting. Other symptoms that appear in May are shoot tip dieback and tendril dieback.
Another species of fungus, Phaeomoniella chlamydospora, that causes the disease is closely related to the species of Togninia listed above and is also an endophyte in grapevine. This fungus overwinters as pycnidia in 3-5 year-old pruning wounds and releases pycnidiospores with rainfall from fall through spring. The pathogen also infects the vine through current year pruning wounds and produces symptoms.

With both pathogens, there can occur a 50% reduction in shoot growth.

Early measles leaf symptomsLeaf severely infected with measles fungus. The peculiar berry spotting gives black measles its name
Berries dry up or rot on vines severely infected with measles. Photo by Jack Kelly ClarkSome berries in bunch affected by black measles are cracked and shriveled

MANAGEMENT

Measles is more prevalent in areas with consistently high summer temperatures, such as the Central Valley, and in areas with heavy spring rainfall. Generally, plantings that are 10 years of age or older are affected, although measles has been seen on fruit and foliage on younger vines. Control can be achieved with use of liquid lime sulfur. However, it is important that the product get into the cracks and crevices of the vine because that is where the fungal fruiting bodies reside. Other treatments include use of wax or tree tar to fill the holes on the vine. Though still experimental, there would be no way for the fungus to reinfect the vine if these holes are plugged up.

二、Fatal fungus threatens vines across southwest France

September 4, 2008

Jane Anson in Bordeaux

A fatal fungus that attacks vines is becoming increasingly prevalent across the wine regions of Bordeaux, Gascony and the Charente, it has emerged.
The disease, a fungus called Esca (known more commonly as vine measles, or vine cancer), attacks the woody parts of the vine, eventually killing the entire plant.

Very little is known about its origin, how it spreads, or its likely progression. Although it affects vines all over the world, this year there has been a sharp rise in reported cases of Esca in southwest France.

There are calls for an agricultural emergency to be declared in the area, and demands for state aid to replant the affected vines.

'You can literally see the vines withering before your eyes,' a winemaker in Gascony told a local newspaper. 'We are going to need to pull up and replant vines that are scarcely 15 years old.' Auch, a large town in the area, is due to hold a demonstration on September 15, demanding government assistance.
Winegrowers in Bordeaux, Cognac and Champagne have also reported widespread problems, with some estimating the disease is affecting up to 20% of all vines in France.

Chris Foss, senior wine lecturer at Plumpton agricultural College in the UK, told decanter.com the disease was almost unstoppable.
'The disease can be treated with sodium arsenite, but the product has been banned since 2001 because of public health concerns,' he said. 'All wood diseases are an absolute nightmare because they are so difficult to treat, and they seem to be getting more prevalent.' （注：本文来自Decanter杂志，现题目是作者后改过来的，开始作者因为外行的原因将Esca说成是一种病毒性病害）

读者浏览后的评论：

Chris Foss is correct when he says that sodium arsenite is the only effective chemical defence to Esca. Esca has two forms of attack; Phellinius igniarius and Stereum hirsutum. The first is contamination by basidiospores which causes a necrotising within the woody cell walls and which is then compounded by mycelium which degrade the cellulose and lignin. Infection often occurs when such surfaces are exposed to the air in the form of 搊pen wounds?which are commonly and inevitably caused by pruning or by battering from mechanical harvesters. In the light of a European ban on sodium arsenite the risk can be limited whilst pruning by ensuring that secateurs are thoroughly washed and cleaned at every opportunity and by timing the work so that the vine is just awakening from its overwintering, dormant state. Should pruning take place whilst dormant the spores will over winter in the cut and thus cause infection. However by timing the work so that the sap is rising the vine will weep and so is more likely to expel any contamination. For the same reason pruning in the rain should also be avoided (much to the relief of those working in the vines) as any spores will wash into these wounds and not, as might be thought, simply wash away or dilute the contamination. This then leaves mechanical harvesting which by its nature is a brutal process and causes damage through which such spores can gain entry. The risk of infection is greater at harvest time as the sap is likely to be descending rather than rising. It is perhaps interesting to note that whilst certainly not free from contamination those vineyards which harvest by hand appear to have a lower incidence of infection, especially those run organically. However, presumably because of the lower prices achieved in Charente and Gascony the vast majority of vineyards use mechanical harvesters and those are often first or second generation machines which are much more damaging that the latest models. These actions compound the problem and infection is spread ever wider. Another argument for the hands on, organic approach, maybe? Stephen Eggerton
Yes, esca is hard to stop in the vineyard, particularly if there are wounds that are not protected as soon as they are made. Hot water treatment of dormant cuttings (30 min at 50 degrees)will reduce the titre of the fungi involved and thus reduce the chances of planting a vineyard that has a latent infection. I refer you to papers by Morton, Fourie, Mugnai, Edwards, Pascoe and others. For a review of hot water treatment see my recent paper in Phytopathologia Mediterranea, Waite, H & L.Morton 2007. Hot water treatment, trunk diseases and other critical factors in the production og high-quality grapevine planting material, Phytopathologia Mediterranea, 46, 5-17 Helen Waite There is a good deal of scientific information and research on Esca. A good deal of this research was printed in the scientific journal "Plant Disease". Also, you can speak with Dr. Doug Gubler and his staff at the University of California-Davis as they have done some of this research as well as groups in South Africa.
As a viticulturist and plant pathologist, I manage several large vineyards which have vines with Esca that are over 20 years old and continue to produce both excellent fruit and vineyard designate wine. We deal with the Esca in a variety of ways, the last of which is replanting. They include double pruning, removal of infected vines, arms and cordons as soon as they are identified, switching from spur pruning to cane pruning (less pruning wound surface area) to name a few. In most cases you can identify Esca before it infects the entire vines, unless the original planting material was injected.
Now I admit that as I live and work in Napa, California I am not completely familiar with the situation is southwest france, but the idea that this disease is "unstoppable" sounds a bit like dramatic license. Didn't people way the same thing about powdery mildew, downy mildew, phylloxxera, various viruses, as well as botrytis bunch rot and Eutypa? How could this disease be unstoppable if it has been managed in these vineyards producing high quality fruit for 15-20 years, and most likely longer. This disease has been around for a very, very long time in europe as well as california, south africa and australia.
The internal wood-decay fungi are difficult to treat and deal with, as control is more related to preventing infection in the first place, as opposed to eradication of the disease after infection has occurred. I also know that there is research currently on-going to find and develop fungicidal materials to protect pruning wounds from injection.
I would think a little more research by the authors and editors should have been done in this case. Thank you. Anon
It is interesting (a coincidence?) that this article on Esca appeared on the final day of the 6th conference of the ICGTD (International Council on Grapevine Trunk Diseases) in Florence, Italy.
Contrary to the assertion that "very little is known about its origin, how it spreads...", research is being done on all over the world on this disease and related ones, especially over the past 10 years. There is a wealth of information in the Proceedings of the ICGTD conferences, published in special editions of Phytopathologia Mediterranea. In France, Esca research is spearheaded by Dr. Philippe Larignon (philippe.larignon@itvfrance.com).
Stephen Eggerton is correct about the basidiomycete fungi involved in Esca. However, the initial fungal pathogen, which paves the way for wood-rotting basidiomycetes to infect the vine, is Phaeomoniella chlamydospora. When basidiomycetes are present as well, the disease is called Esca. P. chlamydospora alone, or in combination with some species of Phaeoacremonium, is now termed Petri Disease.
P. chlamydospora is a water-borne fungus which can infect vines through wounds such as from pruning. Through this pathway, it typically takes many years for Esca to kill a vine. But P. chlamydospora also can be present in rootstocks of newly grafted vines from nurseries. Infected baby vines may become debilitated and are less likely to withstand the stresses of planting and producing grapes, leading to stunting or even death. In California, the massive replanting required to replace AXR1 with phylloxera-resistant rootstocks in the 1980's and '90's led to a huge increase in new vines infected at grafting with P. chlamydospora, and many of them died in the first few years after planting. Until renamed Petri Disease, the phenomenon was known as "young vine decline" or "black goo" (because the vine's response to the fungus is a dark, sticky exudate that clogs the xylem vessels).
It would be worthwhile to investigate the routes of infection in the sick French vines, to determine if P. chlamydospora is entering those vines predominantly from pruning wounds (in which case the scion will be infected but the fungus will seldom cross the graft union into the rootstock), or if some vines arrived in the vineyard with rootstocks already infected and thus were more susceptible from the beginning to intrusion by basidiomycetes from the field. Lisa Van de Water, Vinotec Group