Leaf Spots Induced by Ascochyta pisi and Mycosphaerella pinodes

Heath, Michèle C.; Wood, R. K. S.

doi:10.1093/oxfordjournals.aob.a084314

Cited by 43 publications

(36 citation statements)

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“…Dense crop canopies allow free water to remain on leaf surfaces longer and prevent drier air and fungicide applications from penetrating the canopy. Under high humidity, lesions develop more quickly on young leaves than on older ones (Heath and Wood 1969). This contradicts field observations where larger lesions almost always appear on the older tissue near the base of the plant.…”

Section: Discussioncontrasting

confidence: 64%

Impact of seeding rate and depth on mycosphaerella blight and seed yield of field pea

Hwang¹,

Conner²,

Chang³

et al. 2006

Can. J. Plant Sci.

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. 2006. Impact of seeding rate and depth on mycosphaerella blight and seed yield of field pea. Can. J. Plant Sci. 86: 845-853. Mycosphaerella blight (Mycosphaerella pinodes) occurs throughout western Canada and can severely reduce field pea (Pisum sativum) seed yield. Field trials were conducted at two sites (Edmonton, AB, and Morden, MB) from 2001 to 2003 to assess the impact of seeding rate and seeding depth on blight severity. Mycosphaerella blight severity in the canopy was greater at higher seeding rates; treatments seeded at 30 plants m -2 had lower levels of disease than those seeded at more than 100 seeds m -2 . However, yield potential was reduced at low seeding densities. Depth of seeding did not affect seedling density, disease severity, yield or final seed weight. In addition, field trials were conducted at Edmonton to quantify yield losses associated with mycosphaerella blight in Alberta. In trials inoculated with M. pinodes, application of a foliar fungicide (chlorothalonil) increased yield by about 20% over the unprotected control. , les auteurs ont effectué des essais sur le terrain à deux endroits (Edmonton, en Alberta, et Morden, au Manitoba) en vue d'établir l'incidence de la densité et de la profondeur des semis sur la gravité de la maladie. Le feuillage est plus atteint par l'anthracnose quand la densité des semis est plus élevée; ainsi, les parcelles ensemencées à raison de 30 plants par mètre carré sont moins atteintes que celles ensemencées à raison de 100 graines au mètre carré. Une densité de semis plus faible débouche cependant sur une réduction du rendement potentiel. La profondeur des semis n'affecte pas la densité des plantules, la gravité de la maladie ni le poids final des semences. Les auteurs ont aussi effectué des essais sur le terrain à Edmonton afin de quantifier les pertes de rendement associées à l'anthracnose en Alberta. Dans les parcelles inoculées avec M. pinodes, l'application d'un fongicide foliaire (chorothalonil) accroît le rendement d'environ 20 % par rapport à celui de la parcelle témoin non traitée.

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Section: Discussioncontrasting

confidence: 64%

Impact of seeding rate and depth on mycosphaerella blight and seed yield of field pea

Hwang¹,

Conner²,

Chang³

et al. 2006

Can. J. Plant Sci.

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“…Asochyta fabae was also observed to invade intercellular spaces between epidermis and mesophyll of susceptible faba bean lines within the area of the lesion (Maurin et al 1993). In contrast, intra-as well as intercellular hyphae in the palisade mesophyll 24 h after inoculation were visible in pea leaves inoculated with M. pinodes resulting in a rapid disorganisation and browning of the contents of invaded cells and those adjacent to intercellular hyphae beyond the necrosis (Heath and Wood 1969). The second phase of infection consists of aggressive mycelium extension which coincides with the diffusion of toxins, enzymes and/or suppressors allowing rapid fungal progression in dead tissues by removing physical barriers (toxins and enzymes) and delaying or suppressing the host defense responses (suppressors).…”

Section: Infection Processmentioning

confidence: 98%

“…Epicotyl penetration typically occurred through an appressorium which Roger et al (1999a) also observed for leaf infections by this pathogen. Subsequent colonization by A. pisi was characterized by an initial phase of subcuticular development followed by intercellular spread which resulted in the collapse and death of the host cells, beyond which no hyphae were detected (Brewer and MacNeill 1953;Heath and Wood 1969). Asochyta fabae was also observed to invade intercellular spaces between epidermis and mesophyll of susceptible faba bean lines within the area of the lesion (Maurin et al 1993).…”

Section: Infection Processmentioning

confidence: 99%

Comparison of the epidemiology of ascochyta blights on grain legumes

2007

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Asochyta blights of grain legumes are caused by fungal pathogens in the genus Ascochyta. Different species infect the different legume species, and in pea three species including Phoma medicaginis var. pinodella have been implicated in ascochyta blight. The impact of the diseases varies between crops, countries, seasons and cropping systems, and yield loss data collected under welldefined conditions is scarce. However, ascochyta blights are considered major diseases in many areas where legumes are grown. Symptoms appear on all aerial parts of the plant, and lesions are similar for most of the species, except for M. pinodes and P. medicaginis var. pinodella. Infected seed, stubble and/or air-borne ascospores are major sources of primary inoculum. Their importance varies between species and also between regions. All Ascochyta spp. produce rain-splashed conidia during the cropping season which are responsible for the spread of the disease within the crop canopy. Only in pea are ascospores involved in secondary disease spread. Limited data suggests that Ascochyta spp. may be hemibiotrophs; however, toxins characteristic for necrotrophs have been isolated from some of the species. Modelling of ascochyta blights is still in the developmental stage and implementation of such models for disease forecasting is the exception.

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“…Un appressorium et une hyphe pénétrante interviennent également dans l'attaque de la cuticule (Heath et Wood, 1969). Selon Kerling (1949) (Bateman et Basham, 1976;Bateman, 1976 (Deverall et Wood, 1961), soit avec une modification dans le temps de la structure secondaire de la paroi (Kuc et al, 1967;Nevins et al, 1968 (Paxton, 1981).…”

Section: Macules éVolutives Dues à M Pinodesunclassified