Phoma Exigua Var Research Articles

ChemInform Abstract: ADDITION OF METHANOL TO PHOMENONE, A PHYTOTOXIN FROM THE FUNGI PHOMA EXIGUA VAR. INOXYDABILIS‐ STRUCTURE OF METHOXYDESOXYPHOMENONE

Chemischer InformationsdienstVolume 7, Issue 47 Natural Products ChemInform Abstract: ADDITION OF METHANOL TO PHOMENONE, A PHYTOTOXIN FROM THE FUNGI PHOMA EXIGUA VAR. INOXYDABILIS- STRUCTURE OF METHOXYDESOXYPHOMENONE M. DEVYS, M. DEVYSSearch for more papers by this authorJ.-P. FEREZOU, J.-P. FEREZOUSearch for more papers by this authorA. GAUDEMER, A. GAUDEMERSearch for more papers by this authorJ.-F. BOUSQUET, J.-F. BOUSQUETSearch for more papers by this authorM. BARBIER, M. BARBIERSearch for more papers by this author M. DEVYS, M. DEVYSSearch for more papers by this authorJ.-P. FEREZOU, J.-P. FEREZOUSearch for more papers by this authorA. GAUDEMER, A. GAUDEMERSearch for more papers by this authorJ.-F. BOUSQUET, J.-F. BOUSQUETSearch for more papers by this authorM. BARBIER, M. BARBIERSearch for more papers by this author First published: November 23, 1976 https://doi.org/10.1002/chin.197647350Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume7, Issue47November 23, 1976 RelatedInformation

Host control of scopolin accumulation in infected potato tissue

Three fungal pathogens of potato, Phytophthora infestans, Fusarium solani f. coeruleum and Phoma exigua var. foveata, activated identical populations of fluorescent coumarin-accumulating cells in the tubers of Craigs Alliance. P. infestans also activated a similar population of cells in tubers of another clone 6003(ab)33. Similar amounts of scopolin accumulated in these cells in both clones in response to invasion by the first two pathogens. Thus while invasion may activate synthesis, the number of cells in which fluorescent coumarins accumulate and the amounts accumulated appear to be a property of the host which is not subject to modification by the invading pathogen.

Stress metabolite production in potato tubers infected by Phytophthora infestans, Fusarium avenaceum and Phoma exigua

The stress metabolites rishitin, phytuberin, desacetylphytuberin and solavetivone were found in eight different cultivars of potato tuber inoculated with Phytophthora infestans, Fusarium avenaceum and Phoma exigua var. foveata. Concentrations of up to 83 μg rishitin, 409 μg phytuberin, 545 μg desacetylphytuberin and 333 μg solavetivone/g dry weight of infected tissue were found, although not all compounds were detectable in each interaction. Extracts from infected tissue were treated with diazomethane prior to mini-column chromatography which removed interfering apolar compounds including fatty acid methyl esters. Eluates were subjected to analytical gas chromatography on a 10% OV210 column which enabled simultaneous measurement of all four compounds due to a greatly improved resolution compared to the published gas chromatographic procedure for potato stress metabolites. Anhydro-β-rotunol and lubimin, if present in the extracts, could also be quantitatively measured.

Factors affecting the assessment of resistance of potatoes to gangrene (Phoma exigua var. foveata)

SUMMARYThree experiments designed to elucidate the effects and interactions of different inoculation methods, inoculation positions, strains of Phoma exigua var. foveata and clones of potato tubers inoculated were analysed using as data dimensions of the lesions and a more general surface score. The assessment of susceptibility was affected by all these factors. The ranking of varieties for resistance altered considerably depending upon whether the surface area or the depth of lesions was considered. Derivation of more complex scores combining these measurements reduced the relative genetic component and hence would be of no value to potato breeders.

Cytochalasins A and B from Strains of Phoma exigua var. exigua and Formation of Cytochalasin B in Potato Gangrene

Cytochalasins A and B from Strains of Phoma exigua var. exigua and Formation of Cytochalasin B in Potato Gangrene

The effect on gangrene incidence of dusting seed potatoes with benomyl at time of planting

SUMMARYIn 1 out of 2 years' field trials benomyl applied as a dust treatment at time of planting seed potatoes resulted in an increase in potato gangrene in the progeny of both gangrene‐free tubers planted in land contaminated with Phoma exigua var. foveata and gangrene‐diseased tubers planted in clean land. Gangrene‐infected seed tubers treated with benomyl also produced more stems infected with var. foveata than untreated tubers. Two hypotheses are presented to account for this increase in gangrene which does not occur in seed potatoes treated shortly after lifting.In all cultivars tested an organo‐mercury dip‐treatment increased total numbers of tubers in the seed and chat‐size grades without increasing total weight whereas benomyl dust increased the numbers in these grades in Majestic only. The treatment of gangrene‐diseased seed with benomyl dust affected neither total weight nor total number of tubers.

The effect of soil‐ and tuber‐borne inoculum on the incidence of potato gangrene

SUMMARYUnder optimum growing conditions neither tuber‐ nor soil‐borne Phoma exigua var. foveata inoculum appreciably affected stand or yield of the subsequent potato crop. Seed tubers with gangrene rots caused high levels of stem and tuber symptoms when planted in var. foveata contaminated or uncontaminated land; contaminated seed tubers with no rots also produced progeny with a high gangrene potential.Sufficient soil‐borne inoculum was carried over in land that produced a gangrene affected crop in the previous year to override the effect of tuber disinfection. Effective gangrene control was achieved by a combination of tuber disinfection shortly after harvest over successive years with a 1 in 5 yr potato crop rotation.Gangrene rots usually developed through injuries to the tuber periderm, rots in other tubers being associated with pustules of powdery scab (Spon‐gospora subterranea).

Phoma herbarum var. medicaginis . [Distribution map

Abstract A new distribution map is provided for Phoma herbarum [Phoma exigua var. exigua] West. var. medicaginis West, ex Rab. Hosts: Lucerne (Medicago sativa). Information is given on the geographical distribution in AFRICA, Libya, Malawi, Rhodesia, Zambia, ASIA, Afghanistan, Israel, Japan, Lebanon, USSR, AUSTRALASIA & OCEANIA, Australia, New Zealand, EUROPE, Britain, Bulgaria, Czechoslovakia, Denmark, France, Germany, Greece, Ireland, Norway, Poland, Portugal, Romania, Sweden, USSR, Yugoslavia, NORTH AMERICA, Canada, Mexico, USA, CENTRAL AMERICA & WEST INDIES, Guatemala, SOUTH AMERICA, Argentina, Chile.

Study of Phoma exigua Populations in the field

Strip-baits, consisting of filter-paper disks sandwiched between plastic tapes, were exposed in potato crops in 1968 and 1969. The frequency of isolation of Phoma exigua var. foveata and P. exigua var. exigua from the disks was related to the height of exposure of strip-baits above the soil, to the date of their exposure and to their position in the crop. Isolation of both varieties was high from strip-baits exposed 15 cm above the soil surface; wax. foveata was isolated most frequently from strip-baits exposed near potato plants grown from gangrene-diseased seed tubers while var. exigua was isolated most frequently outside the potato crop at the north end of the field. In comparison with 1968, the frequency of isolation in 1969 ofvar. foveata was almost halved whilst that of var. exigua increased almost threefold. In both years, following the harvest of the potato crop, the frequency of isolation of var. foveata tended to decline whereas that of var. exigua remained high for several months.

The infection of potatoes by Phoma exigua

SUMMARYThe pathogenicities of Phoma exigua var. foveata and P. exigua var. exigua were compared by determining the relationship between incidence of infection of whole tubers or tuber pieces and various inoculum levels in soil. In natural soil var. foveata was more pathogenic than var. exigua, but in sterilized soil there were no clear differences between the two. Both varieties were isolated from some lesions derived from inoculum to which only one variety had been added indicating either natural contamination of soil or latent infection in tubers; the proportion of such lesions increased at the lower inoculum concentrations.In studies where potato plants were grown in infested soils, the incidence of stem disease and tuber disease increased at increased inoculum concentrations of var. foveata; var. exigua was not added to the inoculum but was isolated from some lesions, the proportions of such lesions again increasing at lower inoculum concentrations. The infectivity of the infested soil, assessed by a tuber‐baiting method, declined soon after planting but increased prior to harvest.Laboratory studies indicated that in natural soil the infectivity was highest after 2–3 months and lowest after 10 months incubation, but in sterilized soil infectivity was highest after 5 months and lowest after 7 months incubation.

The effects of temperature on the development of gangrene following laboratory inoculation of potato tubers with Phoma exigua var. foveata

Potato tubers were inoculated with cores taken from agar cultures of Phoma exigua var. foveata. The relationship between the size of subsequently formed gangrene rots and time of incubation typically showed a point of inflexion. The relationship was influenced by incubation temperature possibly through two conflicting factors, fungal growth and tuber resistance. Both factors increase with temperature from 0 to 20 °C producing an acceleration of the early stages of rotting over the range 0 to 10 °C, an earlier limitation of rotting with rise in temperature, and increased variability at 15 and 20 °C. Some apparently conflicting results of temperature effects on rotting reported by other workers can be explained by this relationship. A seasonal effect was found in that the time of testing differently affected rotting at 5 and 10 °C with a fixed incubation period of 28 days. Rotting was favoured by the lower temperature initially (July) and by the higher one later in the storage season (February). Tuber resistance declined with storage and the relationship between this and the differential rotting effect is discussed. The results are related to temperature relationships observed in agricultural practice and to tests of susceptibility to gangrene.

Epidemiology of Stem Blight of Vinca minor Incited by Phoma exigua var. exigua

Epidemiology of Stem Blight of Vinca minor Incited by Phoma exigua var. exigua

Control of potato gangrene and skin spot diseases by fumigation of tubers with sec-butylamine.

FUNGAL diseases of potato tubers can cause considerable losses in the United Kingdom every year. At present in Scotland the most serious is gangrene, a rot of tuber flesh caused by Phoma exigua var foveata. Skin spot, caused by Oospora pustulans, is also important, but in this case the organism does not rot tuber flesh: small pustules appear on the surface and, more importantly, eyes may be killed and sprouting affected.

Ascochyta phaseolorum . [Descriptions of Fungi and Bacteria

Abstract A description is provided for Ascochyta phaseolorum [Phoma exigua var. exigua] . Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: On Canavalia ensiformis, Glycine max, Lablab (Dolichos) niger, Phaseolus acutifolius, P. atropurpureus, P. aureus, P. calcaratus, P. lathyroides, P. limensis, P. lunatus, P. mungo, P. nanus, P. richardianus, P. trilobus, P. vulgaris, Vigna catjang', V. coerulea, V. sesquipedalis, V. sinensis, V. unguiculata, Voandezia subterranea . Also by inoculation on Althaea rosea, Cannabis sativa, Capsicum annuum, Fagopyrum sagittatum, Gossypium spp., Hibiscus esculentus, Lycopersicon esculentum, Malva verticillata, Nicotiana tabacum, Solanum melongena, Vicia sativa (Crossan, 1958; Zherbele, 1958). DISEASE: Leaf spot (or blotch) of bean. Young leaf spots are irregularly circular with grey to brown centres surrounded by a border of light green-yellow tissue. Other spots are light to dark brown and frequently zonate, marginal, terminal or discrete, cracking in the centre when the dead tissue finally drops out, 3-5 cm diam. Lesions common on pulvini result in considerable defoliation. Ascochyta phaseolorum causes target-spot lesions on several genera in the Leguminosae . Such symptoms on Phaseolus spp. are indistinguishable from the drab, zonate lesions of A. boltshauseri , but are distinct from those of A. pinodella L. K. Jones which are purplish-brown, indistinctly zonate and irregular, and A. pisi Lib. which are not zonate but light brown with a darker distinct margin. Also destructive on pods, stems and roots of seedlings. GEOGRAPHICAL DISTRIBUTION: Africa (Congo, Ethiopia, Kenya, Malawi, Rhodesia, Sudan, South Africa, Tanzania, Uganda, Zambia); Asia (China, India, Japan, Malaya, North Borneo, Pakistan, Sarawak), Australasia & Oceania (New Guinea, Solomon Is.); Europe (Denmark, Great Britain, Czechoslovakia, Netherlands, Sweden, U.S.S.R.); North America (U.S.A.); South America (Peru). TRANSMISSION: Seed borne, persisting in a viable condition for 24 years (26: 276). Viability and virulence also unimpaired after storage in culture at 1°C or 10-12°C for 20-25 months (41: 374). The pathogen may spread by infected haulms and by spores disseminated by splashing rain drops from infected seedlings. Also spread in pods of harvested plants stored in stooks in the field in cool, moist, weather (Hubbeling, 1955).