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Remarks (public):For a complete description including images see www.cababstractsplus.org/dfb 
Remarks (internal):The fungus is usually referred to as the imperfect state and the literature on Botrytis cinerea is extensive, not only because of the wide host range of the fungus, but also because of its popularity for studies on fungal physiology and for use as a bioassay organism in fungicide screening tests. However, an up to date comprehensive review of the many diseases caused by B. cinerea is lacking. The fungus grows well on many different kinds of artificial media, but is variable in culture. Growth and sporulation are effected by UV light (53, 1231). The optimum temperature for growth, sporulation and spore germination is around 25°C (50, 1604). The fungus produces pectolytic enzymes (41, 191), organic acids and a polysaccharide toxin (42, 449) which are responsible for symptom expression in the host.
The incidence of grey mould is greatest during cool moist conditions which allow profuse sporulation of the pathogen and the production of high inoculum levels. Relatively long periods of free moisture are necessary for successful infection and this may be related to the release of organic substances from the host tissue into the infection drop. Any wounding of the host epidermis markedly increases susceptibility, and the provision of exogenous nutrients by, for example, pollen grains in the infection drop also increases infection (47, 3350). The following are notes on some of the more important diseases caused by B. cinerea.
(a) Fruit: Dry eye rot of apples and pears (41, 317) may commence as a flower infection (39, 116) which spreads to the calyx area of the fruit during wet summer weather causing a dried brown circular lesion which progresses as a post harvest rot. Grey mould of strawberries (33, 737) may also commence as a blossom blight. Fruit is most readily infected where it touches the ground or is closely sheltered by foliage. On raspberries the disease may also cause a cane blight and on gooseberries can cause a general dieback which may kill the bush (UK Ministry of Agriculture Advisory Leaflet 204). Grey mould of grapes (16, 437) may also commence as a flower infection and remain dormant until ripening (53,1483). Some grey mould infection of grapes is desirable in the production of certain sweet wines. Recent work on grey mould of grapes has been reviewed (49, 3421). On citrus, the fungus can cause twig blight, gummosis and fruit rot. Lemons are most susceptible and a flowerblight with reduced fruit set may occur.The fungus is also responsible for a tip end rot of bananas (11, 728), warty berry of coffee (20, 59), fruit drop in apricots (26, 344) and similar diseases on many other fruit species.
(b) Vegetables: Grey mould of lettuce (13, 599) causes damping-off of young plants, basal stem rot and leaf blight (UK Ministry of Agriculture Advisory Leaflet No. 539).On legumes, the disease can cause stem, leaf and pod blight of Phaseolus beans, peas and chickpea (Cicerarietinum). Leaf damage to cabbage and globe artichoke and rots of onion, potato, beet and carrot may cause large losses intransit or store.On tomato, the disease may cause a leaf and stem blight, but 'ghost spotting' of the fruit (17, 633) is the commonest symptom.
(c) Other crops: In forestry, B. cinerea may cause losses to seedling trees and dieback of young conifer shoots (41, 414, 682). On flax the fungus causes an important seed-borne disease which causes damping-off and stem blight (35, 452; 38,209).On ornamentals, grey mould blight of buds and flowers can cause large losses to the horticultural industry during wet weather. Control of grey mould disease varies with the crop but generally the prevention of predisposing conditions by adequate spacing and pruning to promote ventilation and careful handling to prevent wounding, and the removal of inoculum sources by adequate phytosanitation are most beneficial. Storage in SO2 or acetaldehyde (53, 48, 1467) controls grey mould on harvested grapes and other fruits. Various soil or seed dressing fungicides have been used,
e.g. captan, thiram, chlorinated nitrobenzenes to control grey mould of lettuce and flax, but some resistance to these has been noted (51, 1101). Griseofulvin has also been widely used. On strawberries and tomatoes sprays of dichlofluanid and benomyl have produced good results, although strains resistant to benomyl have been noted (51,366). Varieties vary in their resistance to grey mould and some useful resistance occurs in soft fruit (45, 3028).
 
Description type:Non-original description 
Description:Sclerotinia fuckeliana (de Bary) Fuckel, Symbolae mycologicae Wiesbaden: 330, 1870.
Conidial state: Botrytis cinerea Pers., 1801.
Colonies grey or greyish brown. Sclerotia production, size and shape on natural substrata and in culture extremely variable; in culture some strains form no sclerotia, in others they are abundant; sclerotia black, usually smaller and thinner than those of Sclerotinia sclerotiorum. Conidiophores frequently 2 mm or more long, mostly 16-30 µm wide, branched, often with a stipe and a rather open head of branches, smooth, clear, brown below, paler near the apex, with the ends of the branches often hyaline. Conidia ellipsoidal or obovoid, often with a slightly protuberant hilum, hyaline to pale brown, smooth, (6-) 8-14 (- 18) x (4-) 6-9 (-11) µm [1/b ratio 1:35-1:5].
Hosts: Occurs both as a parasite and a saprophyte on a very wide range of host plants.
Disease: Causes 'grey mould' or 'botrytis disease', a blight or rot of immature, fleshy or senescent tissues. Lesions develop as tan or brown water soaked areas, which may become greyish on drying out. The profuse grey brown sporulation of the fungus on old diseased tissue is characteristic. Rotting of perishable plant produce at harvest or in store causes large losses; can be particularly severe on soft fruit such as strawberries and grapes and vegetables such as cabbage, lettuce etc. Damping-off and basal leaf and stem rot result in severe damage to lettuce and flax. Blights of buds, blossom, leaves and stems may also occur on a wide range of hosts and the fungus has been implicated in dieback and canker formation on woody plants.
Geographical distribution: World wide, but most prevalent as a disease in humid temperate or sub-tropical areas.
Physiological specialization: Isolates of the fungus vary widely in many characters. Strains have been grouped according to sporulation, sclerotial formation and mycelial characters (8, 528) and pectolytic enzyme activity (51, 3211), but the occurrence of definite pathotypic strains is complicated by heterocaryosis and variation in the nuclear content of spores (51, 3837). Forms have been proposed for the fungus on coffee (20, 60), flax (9, 246), grapevine and some ornamentals (10, 274; 44, 119, 548), but the utility of these is doubtful.
Transmission: Conidia are air-borne, but may be carried on the surface of rain splash droplets (41, 436). Diseased plant parts, on which sporulation is profuse in wet weather, are important sources of inoculum in disease epidemics. The fungus overwinters as sclerotia or as mycelium in old plant debris and may be seedborne as spores or mycelium on
e.g. flax (37, 720).
Literature: Paul, Transactions of the British Mycological Society 14: 118-135, 1928 (strains); Baker, Plant Disease Reporter 30: 145-155, 1949 (hosts); Jarvis, Annals of Applied Biology 50: 569-575, 1962 (strawberry and raspberry); Marsh, Nature, UK 202: 341-312, 1961 (diseases).

 
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