Tomato Leaf Mold Research Articles

Gypsy-class retrotransposon sequences in organisms related to the leaf mould fungus, Cladosporium fulvum

Gypsy retrotransposons are a major branch of retroid elements and have been found in a wide diversity of eukaryotic organisms including CfT-1 in the tomato leaf mould pathogen, the fungus Cladosporium fulvum (syn. Fulvia fulva). We have examined organisms that are either ecologically or phylogenetically related to C. fulvum, for elements related to CfT-1. Using PCR and Southern hybridisation, similar sequences were found only in the co-genic fungus Cladosporium cladosporioides. This finding confirms the apparent ubiquity of retroelements, suggests that the phylogeny of retrotransposons is consistent with the phylogeny of their hosts and argues against frequent horizontal gene transfer.

The Tomato Cf-2 Disease Resistance Locus Comprises Two Functional Genes Encoding Leucine-Rich Repeat Proteins

In plants, resistance to pathogens is frequently determined by dominant resistance genes, whose products are proposed to recognize pathogen-encoded avirulence gene ( Avr) products. The tomato resistance locus Cf-2 was isolated by positional cloning and found to contain two almost identical genes, each conferring resistance to isolates of tomato leaf mould (C. fulvum) expressing the corresponding Avr2 gene. The two Cf-2 genes encode protein products that differ from each other by only three amino acids and contain 38 leucine-rich repeat (LRR) motifs. Of the LRRs, 20 show extremely conserved alternating repeats. The C-terminus of Cf-2 carries regions of pronounced homology to the protein encoded by the unlinked Cf-9 gene. We suggest that this conserved region interacts with other proteins involved in activating plant defense mechanisms.

Plant disease resistance genes: unravelling how they work

Resistance (R) genes confer on a plant the ability to defend itself following microbial attack. Each R gene exhibits an extreme specificity of action and is only effective against a microbe that has the corresponding functional avirulence (Avr) gene. This article reviews the strategies and experimental approaches deployed to understand the molecular events underlying the specificity of action of various tomato Cf resistance genes that results in incompatibility to the fungal pathogen Cladosporium fulvum. Topics covered include the clustering of Cf genes, the biology of Cf-dependent incompatibility, the map-based and transposon tagging approaches used to clone the Cf-2 and Cf-9 genes, respectively, identification by mutagenesis of other plant loci required for full Cf-9 mediated resistance, the expression of a functional Avr9 gene in planta and its lethal consequences to Cf-9 containing plants, the physiological and molecular host responses to C. fulvum and AVR elicitor challenges and some genetic approaches to ascertain the crucial components of the defense response. Key words: Cladosporium fulvum, Lycopersicon esculentum, tomato leaf mold, Cf resistance genes, fungal avirulence genes, plant defense responses.

Induction of polyacetylenic phytoalexins in Lycopersicon esculentum after inoculation with Cladosporium fulvum (syn. Fulvia fulva)

After inoculation with Cladosporium fulvum (syn. Fulvia fulva), the causal agent of tomato leaf mold, tomato fruits and leaves accumulate the polyacetylenic phytoalexins cis-heptadeca-l,9-diene-4,6-diyne-3,8-diol (falcarindiol) and probably cis-heptadeca-l,9-diene-4,6-diyne-3-ol (falcarinol); in addition fruits also accumulate the novel compound, cis-tetradeca-6-ene-1,3-diyne-5,8-diol. Maximal concentrations of falcarindiol and cis-tetradeca-6-ene-1,3-diyne-5,8-diol were 5 to 10 μ g−1 fresh wt. Complete mycelial growth inhibition of Cladosporium fulvum and Cladosporium cucumerinum in vitro occurred with about 6 and 18 μg ml−1 falcarindiol and cis-tetradeca-6-ene-1,3-diyne-5,8-diol, respectively. To our knowledge this is the first report on the occurrence of polyacetylenic phytoalexins in Solanaceae.

Effect of Polyoxin fractions on leaf mold of tomato by a brief method of the field screening test

Effect of Polyoxin fractions on leaf mold of tomato by a brief method of the field screening test

Evaluation of systemic fungicides for use in the glasshouse industry

AbstractThe primary evaluation of ten fungicides for the control of cucumber powdery mildew (Sphaerotheca fuliginea), tomato leaf mould (Cladosporium fulvum) and tomato grey mould (Botrytis cinerea) indicated that nine of them were systemically active against one or more of the pathogens when applied as soil drenches. Benomyl, thiophanate, thiophanate‐methyl, thiabendazole and Cela W52A showed activity against all three diseases, but dimethirimol, triarimol and dodemorph were more specific and mainly active against cucumber powdery mildew. An in vitro bioassay generally indicated that fungitoxicity was not translocated from sprayed to unsprayed leaves, and though toxicity to B. cinerea, following soil drenches of benomyl, thiophanate and thiophanate‐methyl, was detected by bioassay in leaf sap and calyces it was not detected in fruit. Furthermore, extended evaluation of benomyl for the control of grey mould on cropping tomotoes showed that in the presence of abundant B. cinerea inoculum, benomyl soil drench treatment effectively controlled flower and leaf infection but not fruit ghost‐spotting.

Hansfordia sp.: A Parasitic Pathogen of Dematiaceous Plant Pathogenic Fungi in Puerto Rico.

Hansfordia sp. was found parasitizing papaya black rust and tomato leaf mold in the field in Puerto Rico and on Cladosporium cladosporioides in the laboratory. The fungus was first detected on the margins of lesions spreading towards the lesions' centers. Black rust and leaf mold colonies became completely covered and decolorized by the hyperparasite. Growth of Hansfordia sp. was greatest on black rust and least on C. cladosporioides. The fungus did not grow on corn meal agar but grew and sporulated on malt yeast and potato dextrose agars. Although Hansfordia did not grow on corn meal agar alone, it did grow sparingly on C. cladosporioides growing on corn meal agar. Hansfordia sp. reduced radial growth of C. cladosporioides 25,10, and 0% on potato dextrose, corn meal and malt yeast agars, respectively. On potato dextrose agar, parasitism of Hansfordia sp. on C. cladosporioides reduced production of viable conidia by over 90%. Besides having potential importance in the biological control of leaf blights by dematiaceous fungi, this Hansfordia sp. may be an important tool in studying fungal melanin degradation.

Tomato leaf mould: its assessment and effects on yield

SUMMARYWhen the natural incidence of Cladosporium fulvum Cooke, occurring at a relatively late stage of cropping, was controlled with fungicides, comparisons with unsprayed control plants showed that there was an interval of c. 6 weeks between the incidence of severe infection, when the fungus was colonizing at least 50 % of the host's leaf area, and fruit yield decreases.Eye estimates made on separate leaves usually over‐estimated the percentage of infection. Correction factors were derived from the regression of eye estimates on infected areas calculated from leaf tracings. Whole‐plant infection indices were obtained by averaging corrected values of percentage infection separately assessed on leaves immediately above each fruit truss.Although dichlofluanid and tank‐mixed zineb decreased the incidence of C. fulvum more than captan sprays, tomato yields (including green fruit) were increased similarly by all three fungicides from 2·99 to an average of 3·51 kg/plant during c. 3 months' picking. Decreasing the intervals between successive sprays from 21 to 7 days greatly decreased leaf mould infection but did not significantly affect yields. Restricting applications to plant tops (namely foliage from the fourth‐youngest truss to the mainstem apex) gave yield benefits equal to those gained from sprays applied to whole plants.

Effect of some fungicides on leaf mold of tomato, especially on the conidia of the causal fungus formed on the lesions

Effect of some fungicides on leaf mold of tomato, especially on the conidia of the causal fungus formed on the lesions

Influence of temperature and air-humidity on the development of leaf mold and early blight of tomato in the vinyl house

Influence of temperature and air-humidity on the development of leaf mold and early blight of tomato in the vinyl house

Effects of some fungicides on leaf mold and early blight of tomato

Effects of some fungicides on leaf mold and early blight of tomato

Effects of some fumigants on the conidial germination of leaf mold and early blight of tomato

Effects of some fumigants on the conidial germination of leaf mold and early blight of tomato

Dispersion of conidia of leaf mold and early blight fungus of tomato in the vinyl house

Dispersion of conidia of leaf mold and early blight fungus of tomato in the vinyl house

Effects of Dichlone-rod for the control of powdery mildew of cucumber and leaf mold of tomato in vinyl houses

Effects of Dichlone-rod for the control of powdery mildew of cucumber and leaf mold of tomato in vinyl houses

CLADOSPORIUM FULVUM RACE 10 AND RESISTANCE TO IT IN TOMATO

A new race of Cladosporium fulvum Cke., the tomato leaf mold pathogen, appeared on the tomato lines Purdue 38 and Purdue 135 in commercial greenhouses in the vicinity of Cincinnati, Ohio, in the fall of 1962. These lines incorporate from L. hirsutum the gene Cf4, which confers immunity to races 1 to 9. Greenhouse inoculations indicate that race 10 is similar to race 1 in pathogenicity against Cf1, Cf2, and Cf3. Varieties such as Vetomold, Tucker's Forcing, and Manalucie, which contain Cf2, are accordingly immune from race 10.

THE EFFECTS OF POLYBUTENE EMULSIONS ON GREENHOUSE TOMATOES AND THE CONTROL OF LEAF MOLD

Polybutene emulsion sprays effectively controlled tomato leaf mold in the greenhouse. A spray of 0.25% H-35 emulsion applied weekly controlled mold effectively but significantly reduced the yield of tomatoes. Applications at 2-week intervals resulted in a moderate infection. The latter gave the greatest yield and a marketable yield only 3% less than the standard Manzate treatment. The emulsifier also reduced mold severity. Weekly applications of H-35 emulsion left an objectionable sticky residue on the fruit. Residues of lower viscosity polymers (L-100 and L-50), although less sticky, were still undesirable owing to their content of the viscous polymer H-100.

TOMATO LEAF MOULD: SPRAYING TRIALS IN LANCASHIRE AND YORKSHIRE, 1949–52

Plant PathologyVolume 3, Issue 1 p. 21-25 TOMATO LEAF MOULD: SPRAYING TRIALS IN LANCASHIRE AND YORKSHIRE, 1949–52 A. Beaumont, A. Beaumont National Agricultural Advisory Service, LeedsSearch for more papers by this author A. Beaumont, A. Beaumont National Agricultural Advisory Service, LeedsSearch for more papers by this author First published: March 1954 https://doi.org/10.1111/j.1365-3059.1954.tb00679.xCitations: 2AboutPDF 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 onFacebookTwitterLinked InRedditWechat Citing Literature Volume3, Issue1March 1954Pages 21-25 RelatedInformation

PHYTOPHTHORA INFESTANS (MONT.) DEBARY AND CLADOSPORIUM FULVUM COOKE ON VARIETIES OF TOMATO AND POTATO AND ON GRAFTED SOLANACEOUS PLANTS

SUMMARYExperiments are described which are concerned with the possibility of an increase or decrease in susceptibility to pathogenic fungi, induced or transmitted by grafting. Two diseases are investigated, namely, potato blight, caused by Phytophthora infestans (Mont.) dc By., and tomato leaf mould, caused by Cladosporium fulvum Cke.Preliminary inoculation experiments were carried out on eleven large‐fruited varieties of tomato, eight varieties of potato, various small‐fruited tomatoes, and other Solanaceous plants, with the following results: Phytophthora infestans. All the varieties of potato were equally susceptible, but certain varieties only of tomato, viz. Giant Red, Golden Queen. Detached leaves of the currant tomato were also infected. Cladosporium fulvum. Only tomato varieties and certain smail‐fruited tomatoes were susceptible. Giant Red and Golden Queen were particularly susceptible, Stirling Castle and Maincrop were relatively resistant. The currant tomato (Lycopersicum racemigerum Lange or L. pimpinellifolium Dun.) was immune. No support can be given to Schmidt's suggestion that immunity depended on the presence of a substance termed “prohibitin”, capable of inhibiting spore germination. It is suggested that the identity of Schmidt's cultures was mistaken.About fifty grafts were made involving various combinations of resistant and susceptible plants. The grafts were inoculated, in most cases, after new growth had developed from stock and scion. Without exception, the results of these experiments were the same as on the ungrafted material, both stock and scion retaining their characteristic reaction to infection unaltered. Although negative results cannot be conclusive in themselves, they indicate that resistance and susceptibility are either genotypic properties of the protoplasm or else are due to some factor that is not, as such, transmissible from stock to scion or vice versa.

Oil Fuel for Horticultural Purposes

THE seventeenth annual report (1931) of the Ches-hunt Experimental and Research Station contains a short account of a test with an automatic heating installation using oil fuel. A thermostat in the tomato greenhouse controls the action of a crude oil burner which gives heat to a special hot-water heating boiler. The account is quite short and the experiment incomplete, but the results show that an enhanced yield can be expected from the increased night temperature. Moreover, the fungus disease known as tomato leaf mould was kept in check by the higher temperature.

Experiments on the Control of Tomato Leaf Mould (Cladosporium Fulvum) By Fungicides and Fumigants

Summary.1. Experiments have been made on the control of tomato leaf mould (Cladosporium fulvum) by fungicides and fumigants. The results showed that most fungicides gave better control of the disease when Agral I was added as a spreader instead of saponin. Effective control was obtained on pot plants sprayed with ammonium copper carbonate, colloidal sulphur A, and salicylanilide. Preliminary trials on commercial nurseries showed that ammonium copper carbonate and colloidal sulphur A were suitable fungicides for use on glasshouse tomato crops. Further work showed that ammonium copper carbonate was useful for spraying diseased tomato crops.2. The disease was controlled by the fumigants ethylene dibromide, quinone, and thymol, in laboratory experiments, and by quinone in trials made in a small glasshouse. Further work is necessary to ascertain if quinone fumigation is practicable for the control of tomato leaf mould in large glasshouses.3. Fumigation with Campbell's sulphur vaporiser protected only the upper side of the leaves from the disease and also failed to kill the spores on the under side of diseased leaves. Experiments made to determine on which leaf surface infection occurs under natural conditions were not successful, but inoculation tests showed that infection may occur on either side of the leaf.4. It has been shown that large empty glasshouses may be practically freed from infection by fumigation with formaldehyde or sulphur dioxide.