230:
release ascospores (teleomorphic phase) although these are not a very significant source of primary inoculum for infection. The sclerotia are capable of continuous and prolonged production of conidia thus resulting in a huge amount of primary inoculum. The conidia and ascospores then go on to produce primary infection on leaves causing leaf blights. Conidia are produced in the necrotic tissues that act as sources of dissemination and secondary inoculum. Towards maturity, Sclerotia are produced in the leaves and necks of infected bulbs (blackened appearance) that overwinter and germinate the following spring. Sclerotia can survive up to 21 months at a depth greater than 15 cm from the soil surface.
209:
33:
54:
255:) plants. It is important to discard damaged and diseased onions at harvest. Dithiocarbamates have been identified as the most effective protectant fungicides. Weather forecasting is generally used to aid in limiting the number of sprays per cropping season. It has also been observed that ground spraying is much more effective than aerial spraying. The optimal frequency has also found to be one spray every 7–10 days.
188:. The lesions start out as whitish streaks and take on a yellow tinge as they mature. They cause yield losses up to 30%. This fungus is endemic to the USA and has also been reported in Europe, Asia, and Australia. Typical management of this disease includes chemical fungicides with significant efforts being made to establish a means of biological control.
200:
spp. The first symptom of the disease occurs in the leaves 24–48 hours after initial exposure to the pathogen, appearing as long white lesions 1–5 mm in length surrounded by a greenish-white halo. The tissue then turns soft due to pectolytic enzymes produced by the pathogen and the center of the
229:
As mentioned earlier, the pathogen makes sclerotia that overwinter in the field debris (infected leaves, bulbs) and cull piles and germinate in the spring. As a result of this germination, conidiophores arise that produce conidia (anamorphic phase). Apothecia also arise out of the sclerotia and
238:
The optimum temperature for the disease development has been reported to be 15-20 °C, the first symptom seen after 6 hours of leaf wetness, with the lesion development decreasing with increasing periods of dryness. At temperatures between 9-25 °C, lesion development increases with
201:
lesion takes on a straw-color. Complete blighting can be seen about 12 days after initial infection. Symptoms towards the later stages also include leaf tip dieback and necrosis. These necrotic spots are the sites of secondary
180:) is a fungus that causes leaf blight on onion (often termed ‘blast’) that is distinctly characterized by the two stages – leaf spotting followed by blighting. The pathogen is an ascomycete that belongs to the family
239:
increasing temperature and leaf wetness. Based on studies conducted in controlled environments, sporulation on dead leaves has been found to occur with an increase in temperature until 30 °C and leaf wetness.
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have been reported so far. Cultural controls include avoiding cull piles and 2–3 years of rotation with non host (species other than
318:
Carisse, Odile (2011). "Management of
Botrytis Leaf Blight of Onion: The Quebec experience of 20 years of continual improvement".
703:
32:
53:
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Chemical and cultural controls are the two most practiced ways of control. No commercial varieties resistant to
754:
454:
Alderman, S.C. (1984). "Influence of temperature and moisture on growth and sporulation of
Botrytis squamosa".
356:
Sutton, John (1983). "Relation of weather and host factors to an epidemic of
Botrytis leaf blight in onions".
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486:"Influence of leaf position and maturity on development of Botrytis squamosa in onion leaves"
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562:"Timing initial fungicide application to control Botrytis leaf blight epidemics on onions"
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Taxonomy, physiology, and pathogenicity: A guide to the literature
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586:
422:"Survival of sclerotia and conidia of Botrytis squamosa"
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This pathogen only affects onion, garlic and leek –
595:
385:"Sources of primary inoculum of Botrytis squamosa"
526:Cooperative Extension Service, Purdue University
543:"Onion-Botrytis Leaf Blight(Botrytis squamosa)"
16:Species of fungus which can damage onion crops
8:
280:"Pathogen of the Month - Botrytis squamosa"
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537:
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31:
20:
522:"Diagnosis and Control of Onion Diseases"
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287:The Australasian Plant Pathology Society
547:Vegetable MD online, Cornell University
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714:62c36e34-9ee0-452c-847f-0a338c5705bb
750:Fungal plant pathogens and diseases
358:Canadian Journal of Plant Pathology
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52:
1:
776:
456:Canadian Journal of Botany
420:Ellerbrock, L.A. (1977).
383:Ellerbrock, L.A. (1977).
370:10.1080/07060668309501607
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49:Scientific classification
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484:Alderman, S.C. (1984).
332:10.1094/PDIS-11-10-0797
221:
505:10.1094/phyto-74-1461
211:
441:10.1094/Phyto-67-219
404:10.1094/Phyto-67-363
178:Botryotinia squamosa
304:. pp. 249–319.
300:Korf, R.P. (1973).
222:
43:on an onion plant
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736:
722:Open Tree of Life
597:Botrytis squamosa
589:Taxon identifiers
499:(12): 1461–1463.
462:(12): 2793–2797.
213:Botrytis squamosa
192:Host and symptoms
173:Botrytis squamosa
169:
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158:Botrytis squamosa
41:Botrytis squamosa
25:Botrytis squamosa
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140:B. squamosa
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569:Phytopathology
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493:Phytopathology
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435:(2): 219–225.
429:Phytopathology
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398:(3): 363–372.
392:Phytopathology
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364:(4): 256–265.
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184:in the order
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176:(teleomorph:
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149:Binomial name
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96:Leotiomycetes
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660:iNaturalist
249:B. squamosa
234:Environment
218:Allium cepa
744:Categories
575:: 409–414.
259:References
186:Helotiales
164:J.C.Walker
106:Helotiales
86:Ascomycota
82:Division:
134:Species:
72:Kingdom:
66:Eukaryota
686:MycoBank
678:11119306
634:Fungorum
612:Q2132442
606:Wikidata
340:30731952
203:conidial
127:Botrytis
112:Family:
62:Domain:
727:1010990
665:1072221
652:2583474
122:Genus:
102:Order:
92:Class:
711:NZOR:
704:139640
691:278697
639:278697
338:
253:Allium
198:Allium
673:IRMNG
565:(PDF)
489:(PDF)
425:(PDF)
388:(PDF)
283:(PDF)
76:Fungi
699:NCBI
647:GBIF
626:MQPG
336:PMID
621:CoL
501:doi
464:doi
437:doi
400:doi
366:doi
328:doi
215:on
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