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Showing papers on "Leaf spot published in 1985"


Journal ArticleDOI
TL;DR: Frequency of infection (number of lesions/cm² leaf area) and percentage defoliation varied greatly within each section and species.
Abstract: When 96 accessions of wild A. spp. were evaluated against C. personatum [Mycosphaerella berkeleyi], lesions were formed on leaflets of all accessions but were small and nonsporulating on all those of sections Erectioides, Triseminalae, Extranervosae, Rhizomatosae, and Caulorhizae. Spp. in section Arachis had lesions 0.16-1 mm diam.; 15 accessions had no sporulating lesions, while in the others, sporulation was slight to extensive. Frequency of infection (number of lesions/cm² leaf area) and percentage defoliation varied greatly within each section and species.

45 citations


Journal ArticleDOI
TL;DR: A survey conducted during 1979–81 in Bangladesh revealed 20 rice diseases, including two viral, two bacterial, 13 fungal, two nematode and one micronutrient deficiency problem, which were common to all regions.
Abstract: A survey conducted during 1979–81 in Bangladesh revealed 20 rice diseases, including two viral, two bacterial, 13 fungal, two nematode and one micronutrient deficiency problem. Of these diseases. 16 appeared as major during the period under report. The number of diseases were 17, 16 and 16 during the Boro. Aus and transplant Aman seasons, respectively, with 12 common in all three seasons. Thirteen diseases including bacterial blight, bacterial leaf streak, sheath blight, sheath rot, blast, brown spot, grain spot, stem rot and leaf scald were classified as major; and tungro, bakanae, cercospora leaf spot and zinc‐deficiency were classified as either major or minor, and were common to all regions. Diseases not common in all regions were stack burn, root knot, and ufra classified as major or minor, and false smut, seedling blight. Yellow dwarf and damping off which were always classified as minor. Diseases which were typical for Boro. Aus and transplant Aman seasons were seedling blight and damping ...

38 citations



Journal ArticleDOI
TL;DR: Number of lesions was influenced greatly by resistance to early leaf spot, were chosen environment and therefore was an unreliable means to evaluate these genotypes in the greenhouse and ranking of genotypes for latent period was consistent with two methods of measuring latent North Carolina State University.
Abstract: artist's airbrush at about 0.6 kg/cm 2 air Ricker, M. D., Beute, M. K., and Campbell, C. L. 1985. Components of resistance in peanut to pressure so that the leaves were wetted Cercospora arachidicola. Plant Disease 69:1059-1064. without droplet runoff. Seventeen peanut breeding lines and Twenty genotypes of peanut (Arachis hypogaea) were tested in the greenhouse and ranked in the commercial cultivars Florigiant, NC increasing order of resistance to early leaf spot (Cercospora arachidicola) for each of the following 2, and NC 5 were obtained from J. C. components of rate-reducing resistance: number of lesions per leaf, lesion diameter, latent period, Wynne, North Carolina State University. time until leaflet defoliation, and sporulation. With the exception of lesion diameter, differences These genotypes, representing a range of among genotypes were found for all components. Number of lesions was influenced greatly by resistance to early leaf spot, were chosen environment and therefore was an unreliable means to evaluate these genotypes in the greenhouse. after evaluation in small field plots at Ranking of genotypes for latent period was consistent with two methods of measuring latent North Carolina State University. Plants period: time until at least two lesions sporulated and time until 50% of the lesions sporulated. Genotypes with longer latent periods and fewer sporulating lesions generally had a longer period f each genotype were grown either from until leaflet defoliation. Genotype NC 3033 showed the greatest overall resistance to early leaf spot. seed or from shoot cuttings taken from

27 citations


Journal ArticleDOI
TL;DR: In glasshouse experiments, Cylindrocladium quinqueseptatum was associated with outbreaks of leaf spot and shoot blight in a young plantation of Eucalpytus microcorys in north Queensland during the 1982 and 1983 autumns and Mancozeb was more effective at controlling the disease than benomyl, captan or copper oxychloride.
Abstract: In glasshouse experiments, Cylindrocladium quinqueseptatum, which was associated with outbreaks of leaf spot and shoot blight in a young plantation of Eucalpytus microcorys in north Queensland during the 1982 and 1983 autumns, was pathogenic on seedlings of E. microcorys and caused varying degrees of leaf spot and shoot blight in ten species of Eucalyptus from major taxonomic groupings of the genus, When the outbreaks occurred, the weather was unusually showery with minimum temperatures above 16°C. In vitro studies showed that free water was essential for conidial germination, which occurred between 14–32°C. The optimum for mycelial growth was 28.5°C. In vivo studies showed that leaf penetration. by germinated conidia was via the stomata. Mancozeb was more effective at controlling the disease than benomyl, captan or copper oxychloride. The potential importance of C. quinqueseptatum and options for control in young Eucalyptus plantations are discussed.

26 citations



Journal Article
TL;DR: The prevalence and incidence of the virulent strain of blackleg increased tenfold in standing crops of rapeseed in Saskatchewan between 1978 and 1981, but the overall yield loss from basal stem cankers was slight.
Abstract: The prevalence and incidence of the virulent strain of blackleg (Leptosphaeria maculans) increased tenfold in standing crops of rapeseed (Brassica napus and B. campestris) in Saskatchewan between 1978 and 1981, but the overall yield loss from basal stem cankers was slight. Virulent blackleg was most prevalent in northeastern and central areas (crop districts (C.D.) 6b an 8). occurring in over 40% of the in only 1.5% of the fields. Damping-off and seedling blight, caused primarily by Rhizoctonia solaniwere severe in 1979. Footrot (R. solaniand Fusarium roseumf affected 81% of the fields that year with a mean incidence of 16%. White rust (staghead) declined in importance on B. campestris over the 4 years, but a different race of Albugo candida became more prevalent on B. juncea. Grey leaf spot or altarnaria black spot (A. brassicae and A. raphand was often widespread, but rarely severe. White leaf spot and grey stem (Pseudocercosporella capsellad, pod drop (cause unknown) and aster yellows were generally of minor importance. "Hybridzation nodules" on the roots of rape plants were prevalent in dry areas in 1979.

16 citations


Journal ArticleDOI
01 Sep 1985-Heart
TL;DR: The aim of breeding trials is to improve leaf production, erect leaf attitude, resistance to Septoria leaf spot and to bolting, and a higher dry matter and digoxin content.
Abstract: After the second world war Marshall Aid funds were used to establish a cooperative organisation for growing, drying, and selling Digitalis lanata (and other medicinal, aromatic, and culinary herbs) in the Netherlands. The crop is sown in mid April and the fully mechanised harvest of the leaves takes place from September to late November. The leaves are dried for 10-12 hours at 50 degrees C maximum. The aim of breeding trials is to improve leaf production, erect leaf attitude, resistance to Septoria leaf spot and to bolting, and a higher dry matter and digoxin content.

14 citations


Journal ArticleDOI
TL;DR: None of the tested cultivars of lettuce was found resistant to Stemphylium leaf spot, a common disease in Israel, and resistance is apparently controlled by two genes: one dominant and one recessive.
Abstract: None of the tested cultivars of lettuce was found resistant to Stemphylium leaf spot, a common disease in Israel. Within a Lactuca saligna population collected in wild lettuce in Israel, resistance was traced. Interspecific crosses of L. saligna x L. sativa were made and the mode of inheritance of resistance to this disease was studied. Resistance is apparently controlled by two genes: one dominant (Sm1) and one recessive (sm2).

13 citations


Journal ArticleDOI
TL;DR: P. brassicae was not found on any of the common cruciferous weeds present in vegetable brassica crops in the Pukekohe district and tests indicated that the disease was not seed-transmitted.
Abstract: This paper discusses the role of a pothecia of Pyrenopeziza brassicae Sutton & Rawlinson in the disease cycle of light leaf spot of brassicas. Apothecia survived for up to 27 weeks on the soil surface under a weed canopy but for less than 4 weeks when buried in the soil. Apothecia stored for up to 50 weeks on dry cauliflower residues in the laboratory discharged ascospores when wetted. Ascospores discharged on to glass slides remained viable for up to 8 weeks at about 20°C and 70% RH. Less than 1% of conidia incorporated into unsterilised volcanic loam remained viable after 10 days as determined by direct counts, but bioassay showed that some conidia remained viable for up to 10 weeks. Seeds from severely diseased cauliflower seedheads contained the pathogen but tests indicated that the disease was not seed-transmitted. P. brassicae was not found on any of the common cruciferous weeds present in vegetable brassica crops in the Pukekohe district. Only summer-grown plants of oilseed rape were susce...

10 citations



Journal ArticleDOI
TL;DR: The current status of sesamum diseases in India is reviewed in this article, where the authors present a review of the most destructive diseases in the country and the most important fungal diseases.
Abstract: Current status of sesamum diseases in India is reviewed. Sesamum phyllody is the most destructive disease in India. Leaf curl is also responsible for heavy losses when it infects at early growth stages of the crop. Bacterial leaf spot, Pseudomonas sesami causes considerable yield reduction whenever it infects the sesamum crop. Bacterial blight, Xanthomonas sesami is serious during the monsoon and to young plants. Among the fungal diseases, leaf blight, Alternaria sesami leafspot, Cercospora sp., and leaf blight. Phytophthora parasitica are important. Charcoal rot, Macromophomina phaseolina is widespread and destructive but difficult to control. Mildew is not a serious disease. A number of organisms have been reported to cause this disease. Reports on the occurrence of several minor diseases have also been listed.


Journal ArticleDOI
S.J. Roberts1
TL;DR: In pathogenicity tests on Philadelphus and other plant species, isolates of Pseudomonas syringae from leaf spots on Philadelphia spp.
Abstract: Roberts, S.J. 1985. Variation within Pseudomonas syringae pv. philadelphi, the cause of a leaf spot of Philadelphius spp. Journal of Applied Bacteriology59, 283–290 In pathogenicity tests on Philadelphus and other plant species, belonging to ten genera in seven families, isolates of Pseudomonas syringae from leaf spots on Philadelphus spp. in England did not produce symptoms on any plants other than Philadelphus. It is therefore proposed that these isolates should be designated a distinct pathovar of Ps. syringae with the name Pseudomonas syringae pv. philadelphi. Isolates of this new pathovar varied in their reactions to 6 of 57 biochemical tests. In phage typing tests isolates also varied in their sensitivity to five of seven bacteriophage strains. Four of the six biochemical tests (aesculin hydrolysis, utilization of DL-homoserine L-leucine and sorbitol) and all five of the phages (P11, Pls, P2, A15, and A26) were used to separate the isolates into seven groups. These groups had some relation to their geographical origin, species of Philadelphus from which they were originally isolated, and relative virulence on P. coronarius and P. x purpureo-maculatus. They may represent ecotypes of this new pathovar.

Journal ArticleDOI
TL;DR: Three new species of Mycovellosiella, M. malvacearum and M. trijugae are described, which cause leaf spot diseases on Desmodium pulchellum, Kydia calycina and Schleicher a trijuga respectively.
Abstract: Three new species of Mycovellosiella, M. desmodiicola, M. malvacearum and M. trijugae are described. They cause leaf spot diseases on Desmodium pulchellum, Kydia calycina and Schleicher a trijuga respectively.

Journal ArticleDOI
S.J. Roberts1
TL;DR: Results of infectivity titrations were compared for attached and detached leaves of Berberis gagnepainii and B. vulgaris inoculated with Pseudomonas syringae pv.
Abstract: Results of infectivity titrations were compared for attached and detached leaves of Berberis gagnepainii (evergreen) and B. vulgaris (deciduous) inoculated with Pseudomonas syringae pv. berberidis. In B. vulgaris results for attached and detached leaves were not comparable because of difficulties in maintaining detached leaves in a viable state. In B. gagnepainii infection of detached leaves occurred following inoculation with as few as 1.1 cfu. The slopes (b) of probit response/log dose curves were < 2 suggesting that cells of Ps. syringae pv. berberidis act individually and independently of each other following inoculation, which is further supported by values obtained for response time (RT50) and their distributions. No significant differences (P = 0.05) were found between attached and detached leaves of B. gagnepainii, for values of RT50, ED50 or b, suggesting that detached leaves of B. gagnepainii might be useful for the study of this leaf spot disease.




Journal Article
TL;DR: Daconil 2787 4.17F and 75W (chlorothalonil) controlled leaf spot on photinia (Photinia fraseri) caused by Entomosporium maculatum in 2 tests under commercial nursery conditions as mentioned in this paper.
Abstract: Daconil 2787 4.17F and 75W (chlorothalonil) controlled leaf spot on photinia (Photinia fraseri) caused by Entomosporium maculatum in 2 tests under commercial nursery conditions. Manzate 200 80W (ma...





Journal ArticleDOI
TL;DR: The phytotoxicity and biological activities of thesephytotoxins produced by Phoma betae were reported and only aphidicolin has been isolated as an antiviral compound from Cephalosporium aphidICola.
Abstract: Phoma root rot and leaf spot disease caused by the fungus Phoma betae Fries is an important disease of sugar beet (Beta vulgaris L.) in Japan1). This fungus, which attacks seedlings and foliage, can also damage mature roots. It produces a superficial dry rot on the root and large round spots showing concentric rings on the leaves. Recently Ichihara et al.2-4) reported that seven metabolites were isolated from the culture filtrate of Phoma betae and all of them suppressed the growth of root elongation in lettuce seedling. The fungus was grown on potato-sucrose medium by surface culture for 15 days at 25C. The culture broth was filtered and the mycelium was extracted with acetone. Water was added to the extract for further extraction with ether. On the other hand, the filtrate was acidified with acetic acid to pH 5.5-6.5, and also extracted with ethyl acetate. The extract from the filtrate was combined with that from the mycelium. After removing the solvents, the dark brown residue was chromatographed on a silica gel column which was eluted with chloroform-methanol (9:1, v/v). The active fractions which inhibited the root elongation on lettuce seedlings were further purified by repeated chromatography as described previously4). The chemical structures of these phytotoxins were identified as betaenone A, betaenone B, betaenone C, aphidicolin, 3-deoxyaphidicolin, aphidicolin-17-monoacetate and aphidicolin-3, 18-orthoacetate (Fig. 1) by X-ray analysis. Among these toxins, only aphidicolin has been isolated as an antiviral compound from Cephalosporium aphidicola5). This paper reports the phytotoxicity and biological activities of these phytotoxins produced by Phoma betae. The phytotoxicity test was carried out as described previously6). These toxins were

01 Jan 1985
TL;DR: There are many diseases of mango caused by fungi, bacteria viruses, phanerogamic parasites and nutritional deficiencies as discussed by the authors, the number and severity of diseases vary as to cultivars.
Abstract: There are many diseases of mango caused by fungi, bacteria viruses, phanerogamic parasites and nutritional deficiencies. The number and severity of diseases vary as to cultivars. The major diseases are mango malformation, anthracnose, bacterial leaf spot, scab, fruit rot, sooty-mold black mildew, collar rot, brown felt, thread blight, pink disease, shoestring root, leaf spots, blight, powdery mildew, and red rust. Market diseases of mango are caused by a number of pathogens. The major diseases are stem end rot, black mould rot, soft rots, alternaria rot, dry rot, black spot, brown spot, phomispsis rot, bacterial soft rot and bacterial rot. Diseases caused by nutritional deficiencies and black tip, little leaf, and mango decline, Two important genera of phanerogamic parasites are Dendropthoe and Viscum which cause considerable damage to mango plants.