The mode of penetration of Alternaria porri into onion leaves

Fahim, M. M.; El-Shehedi, A.-A. A.

doi:10.1016/s0007-1536(66)80037-2

Cited by 7 publications

(8 citation statements)

References 3 publications

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“…Conidia of A. linicola germinated mainly to produce germ tubes like conidia of most Alternaria species (Fahim & El-Shehedi, 1966;Allen et al, 1983). However, occasionally secondary conidia were formed directly, as with A. brassicae (Tsuneda & Skoropad, 1977) and A. alternata (Skidmore, 1976) conidia.…”

Section: Discussionmentioning

confidence: 99%

“…Penetration of leaf tissue was mostly through epidermal cells, although indirect penetration through stomata was observed rarely. There are contradictory reports on the mode of penetration of other Alternaria species with entry via stomata, wounds or directly (Walker, 1952;Changsri & Weber, 1963;Fahim & El-Shehedi, 1966).…”

Section: Discussionmentioning

confidence: 99%

“…dryness) (Rotem, 1994). Penetration of host tissues by different Alternaria species can occur either directly through the epidermal cells or indirectly through stomata (Fahim & El-Shehedi, 1966;Tsuneda & Skoropad, 1977). This paper describes experiments to investigate the effects of temperature, leaf wetness, light regime and their interactions on conidial germination of A. linicola and the mode of penetration of linseed leaf tissues by the pathogen.…”

Section: Introductionmentioning

confidence: 99%

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**Germination of Alternaria linicola conidia on linseed: effects of temperature, incubation time, leaf wetness and light regime**

1996

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Conidia of Alternaria linicola germinated on both water agar and linseed leaves (detached or attached) over a wide range of temperatures (5-258C) by producing one to several germ tubes. At temperatures between 108C and 258C and under continuous wetness in darkness, germination started within 2 h after inoculation and reached a maximum (100%) by 8 to 24 h, depending on temperature. At 58C, the onset of germination was later and the rate of germ tube elongation was slower than that at 10-258C. During germination, conidia of A. linicola were sensitive to dry interruptions of wet periods and to light. Short (2 h) or long (12 h) dry interruptions occurring at any time between 2 and 6 h after inoculation stopped conidial germination and germ tube elongation. With continuous wetness, light periods 2 to 12 h long immediately after inoculation inhibited conidial germination, which was resumed only when a dark period followed subsequently. However, germination and germ tube elongation of A. linicola conidia stopped and the viability of the conidia was lost during exposure to dry light periods immediately after inoculation with spore suspensions. Penetration of leaves by A. linicola was evident after 12 h and occurred mainly through epidermal cells (direct) with or without the formation of appressoria.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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**Germination of Alternaria linicola conidia on linseed: effects of temperature, incubation time, leaf wetness and light regime**

1996

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“…Onion leaves are subject to infection by Alternaria porri , which causes purple leaf blotch (PLB) of Allium spp. ( Fahim & El–Shehedi, 1966; Aveling et al ., 1994 ). PLB is an important disease of Allium spp.…”

Section: Introductionmentioning

confidence: 99%

“…Alternaria porri forms appressoria prior to penetration through stomata and epidermal cells ( Fahim & El–Shehedi, 1966; Aveling et al ., 1994 ). Penetration of onion leaves by S. vesicarium is also via stomata and epidermal cells ( Aveling & Snyman, 1993).…”

Section: Introductionmentioning

confidence: 99%

Infection of onion leaves by Alternaria porri and Stemphylium vesicarium and disease development in controlled environments

Suheri¹,

Price²

2000

Plant Pathology

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Infection of onion by Alternaria porri and Stemphylium vesicarium was investigated under a range of controlled temperatures (4±258C) and leaf wetness periods (0±24 h). Conidia of A. porri and S. vesicarium germinated within 2 h when incubated at 48C. Terminal and intercalary appressoria were produced at similar frequencies at or above 108C. The maximum number of appressoria was produced after 24 h at 258C. Penetration of leaves by both pathogens was via the epidermis and stomata, but the frequency of stomatal penetration exceeded that of epidermal penetration. There was a strong correlation (R 2 . 90%) between appressorium formation and total penetrations at all temperatures. Infection of onion leaves occurred after 16 h of leaf wetness at 158C and 8 h of leaf wetness at 10±258C, and infection increased with increasing leaf wetness duration to 24 h at all temperatures. Interruption of a single or double leaf wetness period by a dry period of 4±24 h had little effect on lesion numbers. Conidia of A. porri and S. vesicarium separately or in mixtures caused similar numbers of lesions. Alternaria porri and S. vesicarium are both potentially important pathogens in winter-grown Allium crops and purple leaf blotch symptoms were considered to be a complex caused by both pathogens.

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Pathogens of Monocotyledon Crops

Dixon

1981

Vegetable Crop Diseases

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The mode of penetration of Alternaria porri into onion leaves

Cited by 7 publications

References 3 publications

**Germination of Alternaria linicola conidia on linseed: effects of temperature, incubation time, leaf wetness and light regime**

**Germination of Alternaria linicola conidia on linseed: effects of temperature, incubation time, leaf wetness and light regime**

Infection of onion leaves by Alternaria porri and Stemphylium vesicarium and disease development in controlled environments

Pathogens of Monocotyledon Crops

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