Abstract
Abstract A description is provided for Peronospora hyoscyami f. sp. tabacina . Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: Naturally infected: Capsicum annuum, Nicotiana alpina, N. acuminata, N. attenuata, N. benthamiana, N. bigelowii, N. caesia, N. glauca, N. glutinosa, N. langsdorffi, N. longiflora, N. mesophila, N. nodiflora, N. nudicaulis, N. paniculata, N. quadrivalvis, N. repanda, N. rustica, N .x sanderae, N. stocktoni, N. suavolens, N. sylvestris, N. tabacum, N. tomentosa, N. trigonophylla, N. wigandioides, Solanum lycopersicum, S. melongena, S. nigrum .Infected experimentally: Capsicum frutescens, Dunalia ramiflora, Hyoscyamus muticus, H. niger, Nicotiana alata, N. affnis, N. cavanillesii, N. fragrans, N. gossei, N. goodspeedii, N. ipomopsifolia, N. maritima , N. megalosiphon, N. raimondii, N. tomentosifolius, Lehmania otophora, Physalis alkekangi, P. lanceifolia, P. peruviana, Petunia × hybrida, Schizanthus pinnatus . DISEASE: Blue mould of tobacco plants (48, 3141; 61, 2664) (commercial and ornamental varieties are affected); the fungus is an obligately biotrophic plant pathogen. Chlorotic leaf spots develop on leaves of susceptible seedlings, which become deformed. Undersurfaces of leaves become covered with a layer of sporophores, producing a diagnostic blue-grey felt. Rapid generalized light-brown tissue necrosis follows and the apical meristem ceases growth. Disease symptoms may not appear immediately after infection, however, or during sporophore production. If the fungus encounters any barrier to its growth through the plant tissues (because of a physiological response, high temperature or fungicides), then the infection becomes wholly systemic, being confined to an area close to the veins, or to a necrotic area if the plant is genetically resistant. Similar symptoms develop on mature plants in the field and the entire plant may be destroyed within 3-4 weeks, leaving only a blackened stem. The fungus attacks leaves and stems of tobacco seedlings and mature plants in Europe and Australia, but only leaf tissues in the USA, where weather conditions confine it to being a seedling disease in most years. GEOGRAPHICAL DISTRIBUTION: First reported in Australia in 1891, now worldwide; see CMI Distribution Maps of Plant Diseases 23. TRANSMISSION: By airborne spores, which can remain viable for 2 months at 20-40% RH, and have been reported to be transported over distances of 1, 600 km. Most favourable conditions for sporulation are an average temperature of 20°C and a period of relatively high humidity (95% RH) for at least 3 h. Spore liberation is dependent on a rise in temperature, a decrease in relative humidity and an increase in insolation. There is some evidence for soil-borne transmission by oospores in infected plant debris in the USA, since blue mould appears more often in seedbeds which have previously contained infected tobacco. Although mycelium can survive and overwinter in plant tissues, there are no reports of transmission by a systemic route.
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Claims 16
Claim · model-written summary
Capsicum annuum is listed as naturally infected.
- Taxon
- Capsicum annuum
Capsicum annuume0 - Outcome
- Naturally infectede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Naturally infected: Capsicum annuum”
t0“Peronospora hyoscyami f. sp. tabacina”
Claim · model-written summary
Nicotiana tabacum is listed as naturally infected.
- Taxon
- N. tabacum
Nicotiana tabacume0 - Outcome
- N. tabacume0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“N. tabacum, N. tomentosa, N. trigonophylla”
t0“Peronospora hyoscyami f. sp. tabacina”
Claim · model-written summary
Susceptible tobacco seedlings develop chlorotic leaf spots and deformity.
- Taxon
- tobacco plantsNicotiana tabacumt0
- Organ / stage
- leaves of susceptible seedlingse0
- Outcome
- Chlorotic leaf spotse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Chlorotic leaf spots develop on leaves of susceptible seedlings, which become deformed”
t0“Blue mould of tobacco plants”
t1“Peronospora hyoscyami f. sp. tabacina”
Claim · model-written summary
A diagnostic blue-grey sporophore layer covers leaf undersurfaces.
- Taxon
- tobacco plantsNicotiana tabacumt0
- Organ / stage
- Undersurfaces of leavese0
- Outcome
- diagnostic blue-grey felte0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Undersurfaces of leaves become covered with a layer of sporophores, producing a diagnostic blue-grey felt”
t0“Blue mould of tobacco plants”
t1“Peronospora hyoscyami f. sp. tabacina”
Claim · model-written summary
Tissue necrosis follows and apical meristem growth stops.
- Taxon
- tobacco plantsNicotiana tabacumt0
- Outcome
- Rapid generalized light-brown tissue necrosise0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Rapid generalized light-brown tissue necrosis follows and the apical meristem ceases growth”
t0“Blue mould of tobacco plants”
t1“Peronospora hyoscyami f. sp. tabacina”
Claim · model-written summary
Disease symptoms can be delayed after infection.
- Taxon
- tobacco plantsNicotiana tabacumt0
- Outcome
- Disease symptoms may not appear immediatelye0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Disease symptoms may not appear immediately after infection”
t0“Blue mould of tobacco plants”
t1“Peronospora hyoscyami f. sp. tabacina”
Claim · model-written summary
Mature field plants can be destroyed within 3-4 weeks.
- Taxon
- tobacco plantsNicotiana tabacumt0
- Outcome
- entire plant may be destroyede0
- Value
- 3-4 weekse0
- Setting
- fielde0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Similar symptoms develop on mature plants in the field and the entire plant may be destroyed within 3-4 weeks”
t0“Blue mould of tobacco plants”
t1“Peronospora hyoscyami f. sp. tabacina”
Claim · model-written summary
The fungus attacks tobacco leaves and stems in Europe and Australia.
- Taxon
- tobaccoNicotiana tabacume0
- Interactor
- The funguse0pathogen
- Outcome
- attacks leaves and stemse0
- Setting
- Europe and Australiae0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The fungus attacks leaves and stems of tobacco seedlings and mature plants in Europe and Australia”
Claim · model-written summary
In the USA the fungus attacks only tobacco leaf tissues.
- Taxon
- tobacco plantsNicotiana tabacumt0
- Outcome
- only leaf tissuese0
- Setting
- USAe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“but only leaf tissues in the USA, where weather conditions confine it to being a seedling disease in most years”
t0“Blue mould of tobacco plants”
t1“Peronospora hyoscyami f. sp. tabacina”
Claim · model-written summary
The pathogen is now worldwide.
- Taxon
- tobacco plantsNicotiana tabacumt0
- Outcome
- now worldwidee0
- Setting
- Australiae0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“First reported in Australia in 1891, now worldwide”
t0“Blue mould of tobacco plants”
t1“Peronospora hyoscyami f. sp. tabacina”
Claim · model-written summary
Airborne spores can remain viable for two months at 20-40% relative humidity.
- Taxon
- tobacco plantsNicotiana tabacumt0
- Outcome
- airborne spores, which can remain viablee0
- Value
- 2 monthse0
- Qualifier
- 20-40% RHe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“By airborne spores, which can remain viable for 2 months at 20-40% RH”
t0“Blue mould of tobacco plants”
t1“Peronospora hyoscyami f. sp. tabacina”
Claim · model-written summary
Spores have reportedly been transported 1,600 km.
- Taxon
- tobacco plantsNicotiana tabacumt0
- Outcome
- transported over distancese0
- Value
- 1, 600 kme0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“have been reported to be transported over distances of 1, 600 km”
t0“Blue mould of tobacco plants”
t1“Peronospora hyoscyami f. sp. tabacina”
Claim · model-written summary
Sporulation is favored by 20°C and 95% RH for at least 3 h.
- Taxon
- tobacco plantsNicotiana tabacumt0
- Outcome
- sporulatione0
- Qualifier
- an average temperature of 20°C and a period of relatively high humidity (95% RH) for at least 3 he0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Most favourable conditions for sporulation are an average temperature of 20°C and a period of relatively high humidity (95% RH) for at least 3 h”
t0“Blue mould of tobacco plants”
t1“Peronospora hyoscyami f. sp. tabacina”
Claim · model-written summary
Spore liberation depends on rising temperature, falling humidity and greater insolation.
- Taxon
- tobacco plantsNicotiana tabacumt0
- Outcome
- Spore liberatione0
- Setting
- rise in temperaturee0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Spore liberation is dependent on a rise in temperature, a decrease in relative humidity and an increase in insolation”
t0“Blue mould of tobacco plants”
t1“Peronospora hyoscyami f. sp. tabacina”
Claim · model-written summary
Previously infected tobacco seedbeds are associated with more blue mould.
- Taxon
- tobaccoNicotiana tabacume0
- Outcome
- blue moulde0
- Direction
- more oftene0
- Setting
- seedbedse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“blue mould appears more often in seedbeds which have previously contained infected tobacco”
t0“Peronospora hyoscyami f. sp. tabacina”
Claim · model-written summary
No systemic transmission has been reported despite mycelium overwintering in plant tissue.
- Taxon
- tobacco plantsNicotiana tabacumt0
- Outcome
- no reports of transmission by a systemic routee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Although mycelium can survive and overwinter in plant tissues, there are no reports of transmission by a systemic route”
t0“Blue mould of tobacco plants”
t1“Peronospora hyoscyami f. sp. tabacina”