Phoma Betae Research Articles

Scanning Electron Microscope Examination of Sugarbeet Flowers and Fruits Infected with Phoma Betae

Scanning Electron Microscope Examination of Sugarbeet Flowers and Fruits Infected with Phoma Betae

Competition for nutrients between epiphytic micro-organisms and germination of spores of plant pathogens on beetroot leaves

When different numbers of leaf micro-organisms were applied in droplets to non-sterile beetroot leaves inhibition of germination of Botrytis cinerea conidia was positively correlated with uptake of amino acids. Of the micro-organisms tested two isolates of Pseudomonas and an isolate of Sporobolomyces were most effective at inhibiting germination and removing amino acids from droplets at comparatively low cell densities. Leaves bearing a natural microflora needed to be wetted for 24 h before appreciable uptake of amino acids occurred and conidia of B. cinerea were inhibited from germinating. Negligible quantities of 14C-labelled amino acids or glucose, added to droplets placed on the surface of sterile beetroot leaves, were taken up by the leaf. Most of the 14C label lost from sterile 14C-labelled beetroot leaves was detected in droplets shortly after placing them on the surface of the leaves. Germination of conidia of Phoma betae and Cladosporium herbarum was greatly inhibited on beetroot leaves in the presence of a leaf surface bacterium, Pseudomonas sp. isolate 14, and there was a close relationship with uptake of amino acids by the bacterium on leaves. Percentage germination of conidia of Colletotrichum dematium f. sp. spinaciae was not inhibited by the bacterium but length of germ tubes was reduced. Presence of the bacterium stimulated development of appressoria.

PENICILLIUM CLAVIFORME: SUGAR BEET PATHOGEN AND ANTAGONIST OF BOTRYTIS CINEREA

Sugar beet storage rot caused by Botrytis cinerea was completely inhibited by a storage rot isolate of Penicillium claviforme in sugar beet tissue. Storage rot caused by Phoma betae was not inhibited. Growth of B. cinerea was inhibited 50–100% in liquid cultures containing diluted filtrates of P. claviforme. Differing reports as to the prevalence of B. cinerea as a storage rot pathogen may be due to this antagonism.

Some observations on assessing Phoma betae infection of sugar‐beet seed

SUMMARYNear‐ultraviolet or ‘black’ light applied continuously from the start of incubation, facilitates tests for Phoma betae on sugar‐beet seed by stimulating the production of pycnidia and restricting mycelial growth of P. betae and other fungi. Pretreatment of the seed with dilute sodium hypochlorite decreases the number of seeds with P. betae by removing superficial infection, but some of this is of significance in the field. Rubbing beet seed also decreased counts of P. betae in the laboratory and increased field emergence, primarily by removing the fungus.Griseofulvin sprayed on beet‐seed plants either 2 wk or 2 days before harvest significantly decreased seed infection with P. betae, but not to a level at which further seed treatment could be omitted.

Seed-borne Phoma betae as influenced by area of sugarbeet production, seed processing and fungicidal seed Treatments

Seed-borne Phoma betae as influenced by area of sugarbeet production, seed processing and fungicidal seed Treatments

Peroxidase, polyphenoloxidase, and endopolygalacturonate transeliminase activity in different tissues of sugar beet infected with Phoma betae

The storage rot pathogen Phoma betae normally attacks the exposed stem pith of harvested sugar beets (Beta vulgaris L.) before invading adjacent stem and taproot tissues. A comparison of rotted and sound tissues of nonselected roots showed that increased polyphenoloxidase activity occurred in rotted stem tissue, but peroxidase decreased. Endopolygalacturonate transeliminase (endoPGTE) was more active in rotted pith tissue compared with other rotted tissue. Comparison of rotted tissue from resistant and susceptible inbreds showed the greatest difference in oxidase activity occurred in resistant taproot tissue. Higher polyphenoloxidase activity was associated with resistant stem tissue of nonselected roots when catechol was the substrate rather than chlorogenic acid. Phoma betae growth in liquid culture was inhibited more by oxidation products of catechol than by those of chlorogenic acid. Peroxidase activity was associated with resistance only in stem and taproot tissue of inbreds. Endo PGTE activity was low in infected resistant tissue. When isolated cell walls of nonselected sugar beets were used as the carbon source, P. betae grew more and endo PGTE activity was greater on cell walls from pith than cell walls from adjacent stem or taproot tissue after 6 days incubation.

A Selective Medium for the Enumeration and Isolation of Phoma betae from Soil and Seed

A Selective Medium for the Enumeration and Isolation of Phoma betae from Soil and Seed

Survival of Phoma betae in Soil

Survival of Phoma betae in Soil

Interference by common leaf saprophytic fungi with the development of Phoma betae lesions on sugarbeet leaves

SUMMARYWhen sugarbeet leaves were inoculated simultaneously with the parasitic Phoma betae and the saprophytic Aureobasidium pullulans or Torulopsis Candida, the development of expanding lesions caused by P. betae was curtailed. Two other common saprophytes, Sporobolomyces pararoseus and Cladosporium cladosporioides, also decreased numbers and sizes of expanding lesions in the presence of pollen. The numbers of saprophyte cells applied to inoculum areas were similar to those occurring naturally on sugarbeet leaves in the summer.Lesion development was not affected by a mixture of heat‐killed cells of the four saprophytes.

Pectolytic enzyme production by Phoma betae

Phoma betae from decayed sugar beet storage root tissue grew most rapidly in culture at 15C but produced more polygalacturonase (PG) at 20C. When the fungus was supplied with six different nitrogen sources, it produced the most PG on (NH4)2SO4.Assays of dialyzed culture filtrates using sodium polypectate and pectin or cell wall material from storage roots as the carbon sources showed the production of exopolygalacturonase (exo-PG) and endopolygalacturonate trans-eliminase (endo-PGTE). No pectin methyl esterase was detected. Exo-PG and endo-PGTE also were present in decayed sugar beet tissue. Only endo-PGTE was detected within 3 mm of tissue surrounding the rotted area.In culture, cell wall material from the susceptible variety A58 induced more endo-PGTE formation than the resistant 2B. But 2B induced more exo-PG formation than A58. It is suggested that endo-PGTE plays a major role in cell wall degradation because pH 7.5 was optimum for tissue maceration and pH 8.5 for enzyme activity and the advancing margins of rotted tissue contained only endo-PGTE.

Attempts to define and mimic the effects of pollen on the development of lesions caused by Phoma betae inoculated onto sugarbeet leaves

SUMMARYExpanding lesions resulted when conidia of Phoma betae Frank, mixed with rye pollen, were inoculated on to sugarbeet leaves by a standard technique. Conidia without pollen generally caused non‐expanding necrotic spots; these could be made to spread later by covering them with pollen or orange juice, but not with water.Germ‐tube growth was quicker on water agar than on sugarbeet leaves. Pollen extract stimulated germ‐tube growth on leaves 10 h after inoculation and resulted in the production of knots of hyphae overlying areas where intercellular hyphae could be discerned and where expanding lesions developed.Some inorganic salts mimicked the stimulatory effect of pollen on germtube growth on agar slides, but only a mixture of hexose sugars with boric acid reproduced the effect of pollen on both numbers and size of expanding lesions caused by P. betae on sugarbeet leaves, and numbers of expanding lesions caused by Botrytis cinerea Pers. ex Fr. on bean leaves.

The effect of pollen on the fungal leaf microflora of Beta vulgaris L. and on infection of leaves by Phoma betae

Studies were made on the leaf-inhabiting fungus flora of two plots of flowering sugarbeet. Flowers were removed from plants of one plot as they appeared. Changes in the numbers of micro-organisms on leaves were recorded by leaf washing and leaf homogenization techniques, and were found to follow closely the changes in numbers of pollen grains seen on cleared leaf discs. The main colonizers, grouped into pink yeasts, white yeasts,Cladosporium spp. andAureobasidium pullulans, were all influenced by the natural presence of pollen and reached high numbers on leaves in the plot bearing flowers. Rainfall was not found to influence numbers of pollen grains or micro-organisms greatly, but high temperature led to isolation of smaller numbers of pink and white yeasts. Recovery of populations was swift after hot weather, and may be linked with the high contamination of fieldcollected sugarbeet pollen by components of the microflora. The spectrum of fungi growing from washed leaf discs differed qualitatively from assessments made by washing and homogenization.

The Incidence of Sugar Beet Seedling Diseases and Effects of Seed Treatment in England

SUMMARYOn average, 180 samples of sugar beet seed grown in England between 1958 and 1970, and examined before being steeped in ethyl mercuric phosphate (EMP), had 39 per cent of clusters infected with Phoma betae. However, the fungus damaged few seedlings in commercial crops because this treatment controlled it. In 1969, Aphanomyces sp. was unusually prevalent in sugar beet crops. Treating EMP‐steeped seed with a protectant fungicide did not, on average, significantly increase seedling emergence or final plant stand.

Hot water treatment for elimination of seeelborne Phoma betae and other microbial contaminants from sugarbeet seed

Hot water treatment for elimination of seeelborne Phoma betae and other microbial contaminants from sugarbeet seed

Nullification of Antagonism of Phoma betae by Bacillus subtilis var. niger in Soil and in a Simulated Rhizosphere

Nullification of Antagonism of Phoma betae by Bacillus subtilis var. niger in Soil and in a Simulated Rhizosphere

Pleospora bjorlingii . [Descriptions of Fungi and Bacteria

Abstract A description is provided for Pleospora bjorlingii [Pleospora betae] . Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: On Beta spp. DISEASE: Black leg of sugar beet and mangold. Also root rot and leaf rot or heart rot (45, 1243), storage decay (41: 188) and clamp rots (45, 2655). GEOGRAPHICAL DISTRIBUTION: Africa (north & south); Asia, Australasia, Europe, N. America. (CMI Map 427, Ed. 1, 1967). TRANSMISSION: On seeds and in decayed host material or soil.

Effects of Vapors of Aromatic Chemicals on Fungi

The in vitro antifungal properties of the vapors of 196 aromatic chemicals were tested against growing cultures of four fungi. The data presented indicate that 63 per cent of the vapors inhibited the growth of at least one of the test organisms. Phoma betae was found to be the most vulnerable. In general, the vapors of the groups of chemicals were found to possess the following order of decreasing antifungal activity: acids, aldehydes, alcohols, ethers, miscellaneous, ketones, esters, lactones, and acetals.

FURTHER EXPERIMENTS ON BLACK‐LEG DISEASE OF SUGAR‐BEET SEEDLINGS

Soaking sugar beet seed for 20 min. in ten times its weight of water containing 40 p.p.m. ethyl mercury phosphate to control seed‐borne Phoma betae gave better seedling emergence than surface treatments with commonly used organo‐mercury dusts or with Panogen (methyl mercury dicyandiamide), thiram, Granosan M (ethyl mercury p‐toluene sulphonanilide), captan, Dow 9B (zinc trichlorophenate) or Cerenox (acylphenylhydrazone). In 4 years' field trials, soaking seed in ethyl mercury phosphate solution followed by dusting with an insecticidal dust, compared with a routine mercury‐plus‐insecticidal dust, increased seedling emergence at fifty‐three of fifty‐nine sites by an average of 10% under good emergence conditions and by 20–30% under adverse conditions. Final plant stand was increased each year by an average of 5.8, 3.4, 1.8 and 0.6%, respectively.

EXPERIMENTS ON BLACK LEG DISEASE OF SUGAR‐BEET SEEDLINGS

Phoma betae was usually the predominant pathogen attacking sugar‐beet seedlings in the field in eastern England, but Pythium spp. sometimes predominated when the seedlings were very young. Fusarium spp. were associated with acid soil conditions. Rhizoctonia solani only occasionally caused severe losses.Black leg, caused chiefly by Phoma betae, was most prevalent at low soil temperatures when, in stands from untreated seed, up to 45 % of the seedlings were attacked. Disease decreased by 0·8 to 2·4 diseased seedlings per 100 in stands from untreated seed per 1° F. rise in soil temperature. Seed treated with Panogen,* thiram and ethyl mercury phosphate regularly gave better stands in small‐scale trials than seed treated with Ceresan or Agrosan. In large‐scale experiments average increase in seedling emergence following treatment with Panogen, thiram and Agrosan varied in different years between + 6·4 and + 19·2 %. Average response to BHC soil dressing was + 4·2 and + 8·6 %. Response to seed dressings increased as the time taken for emergence increased and as percentage emergence decreased; when emergence was 50 % of the possible, dressing gave on average 20 % more seedlings. Response to dressing increased as soil became more acid or alkaline than the optimum for beet, and was lower on heavy soils and on soils dressed with farmyard manure.Maximum emergence varied from year to year between 2100 and 2700 seedlings per oz. seed; minimum between 690 and 1050. Emergence of both treated and untreated seed varied greatly and was related to time taken for emergence, suggesting that effects of soil moisture, temperature or texture are important. Emergence WM not correlated with pH, but when the pH was below 6·5 or above 8·7 it was not more than 75 % of that at pH 7·0–7·4. In 2 out of 3 years emergence was increased by 32 and 84 seedlings/oz. seed by each extra cwt. per acre of inorganic fertilizer (N, P, K). Seed rate, cultural operations and drill type had no consistent effect.A 1 % increase in seedling stand increased the final plant population on average by 0·2%.

TREATMENT OF SUGAR BEET “SEED” TO PREVENT SEEDLING DISEASES

Summary. The organisms responsible for Blackleg in sugar beet seedlings have been referred to and the damage that they do considered. It has been shown that treatments used to disinfect the “seed” may be harmful, they may exert no influence, or they may be of considerable value. The present trials have shown the beneficent effects of an organic compound containing mercury. This material increased the “plant” in the majority of cases, and this increase varied between 12 per cent, under some conditions and in increasing amounts up to 193 per cent, under more favourable conditions. An increase in the vigour of young plants was noted occasionally. Quantitative tests showed an increase in both the green and dry weight per seedling as the result of treatment. The beneficial action of treatment is not due to the influence of water. The organic compound containing mercury was the most effective in reducing diseased growths during laboratory tests; the proprietary dust was nearly as efficient. Steeping in a f per cent, solution of carbolic for half‐an‐hour was ineffective. Treatment of the clusters with 60 per cent, sulphuric acid did not appreciably improve “plant” establishment, but this treatment followed by the mercury treatment increased the number of plants considerably. Field trials conducted for one season on a field scale have not shown an increase in the percentage of sugar as a result of the treatment of “seed,” but a slight increase in yield and in the total number of roots per acre was noted as the result of treatment with the organic compound containing mercury. The proprietary dust was not noted as being responsible for reducing the “plant” in the field. Its beneficent action was not as uniformly apparent as that of the mercury material. Carbolic acid at a strength of per cent, was definitely injurious when used for steeping purposes. Furthermore, trials show no benefit from a modified form of this treatment in which a 3| per cent, solution is sprinkled on the “seed.” Other materials tested were found to be of doubtful value. Certain samples of commercial “seed” as supplied treated with a mercury material were found to be infected to a considerable extent by Phoma Betae. Such “seed” it was found could be efficiently re‐disinfected by careful re‐treatment with marked beneficial results. In conclusion it is desired to thank those who gave assistance. Among these are Mr Alfred Eastham, Director of the Official Seed Testing Station, Cambridge, Dr Van Poeteren, Wageningen, Mr G. R. Clarke, Advisory Chemist, and Dr N. Cunliffe, Advisory Entomologist both of Oxford, Mr W. A. Stewart and Mr W. R. Seward, Dr Pethybridge and the officials of many beet sugar factories who lent a helping hand.