Didymella Applanata Research Articles

Peroxidase involvement in the defense response of red raspberry to Didymella applanata (Niessl/Sacc.)

Peroxidase activity of red raspberry canes was dependent on the cultivar and influenced the subsequent lignification. After inoculation with Didymella applanata, responsible for the spur blight cane disease, the activity of soluble cytoplasmic enzyme increased in the moderately resistant ‘Latham’ and susceptible ‘Malling Promise’, similarly for syringaldazine and guaiacol as hydrogen donors. Systemic induction found in ‘Latham’ was recognized as a symptom of defence mechanism responsible for fungal restriction. Locally enhanced peroxidase activity in the ‘M.Promise’ tissues was related to the local lignification and/or may be associated with the loss of cell integrity caused by pathogen penetration. Pathogen-induced changes of cell wall peroxidases were similar in both cultivars mentioned above. No influence of the infection was found in the high susceptible Zeva cultivar. Using native-PAGE analysis and horizontal starch electrophoresis of soluble fraction five constitutive acidic isoperoxidases were detected in ‘Latham’ and three in ‘M. Promise’. The infection process was accompanied by the appearance of two new anodic isoforms.

Establishment of pioneer litho-microorganisms on chalk rocks after a severe forest fire in Israel

Three and a half years after a forest fire in the Carmel Mountains, Israel, we observed, on chalk rocks, ascocarps of the non-lichenized ascomycete Didymella applanata which is considered to be the first visible pioneer on such rocks following a forest conflagration. Four years after the fire, we observed unicellular green algae on burnt surfaces of the rocks, probably Trebouxia sp., colonizing small holes 30–50 μm in diameter, and clusters of ascospores of the lichens Caloplaca aurantia and Xanthoria parietina located in small rock depressions. Young thalli of the lichen Xanthoria parietina colonized fissures on the rock surfaces. The first thalli of crustose lichens which were observed on rocks 4 years after the fire were Caloplaca aurantia.

The effect of temperature on the response of canes of red raspberry cv. Mailing Jewel to infection by Didymella applanata

SUMMARYA single population of container‐grown red raspberry plants cv. Mailing Jewel was divided and grown in two environments prior to wound inoculating young canes with Didymella applanata in late July. The plants were then sub‐divided and held in one of three contrasting post‐inoculation environments. Various assessments were made to examine the effect on spur blight of the different environmental treatments.Inoculation of internodes showed that D. applanta produced longer lesions and more pseudothecia on canes grown in spring in an unheated glasshouse than on canes grown outside, but post‐inoculation conditions had little effect on these aspects of disease. Petiole inoculations showed that dwarfing of axillary buds in the first season and lateral shoot failure in the year after infection were most serious on canes grown outside in spring but held at relatively high temperatures in August and September after inoculation. The results indicate that spur blight may have the potential to cause higher yield losses in areas with warmer spring and autumn conditions than those usually experienced in north‐east Scotland.

Common resistance in red raspberry to Botrytis cinerea and Didymella applanata, two pathogens occupying the same ecological niche

SUMMARYComparisons were made between Botrytis cinerea and Didymella applanata, which occupy the same ecological niche on canes of red raspberry. Isolates of B. cinerea from diverse localities within the British Isles were pathogenic to the SCRI selection M30 when internodal wounds on young canes were inoculated. A single inoculation frequently caused the buds at several nodes to fail the following spring. Differences in the lengths of the stem lesions that formed indicated differences in isolate pathogenicity, but these were not related to isolate origin. Bud suppression and lateral shoot failure also occurred when petioles of cvs Mailing Orion, Mailing Jewel and Glen Clova were wound inoculated with B. cinerea up to late August.The relative resistance of seven cultivars to three isolates of each pathogen was determined. Principal components analysis of data from five estimates of resistance to each pathogen showed that 40% of the variation described a common resistance to the two diseases.Further analysis showed that cvs Chilcotin and Meeker had the strongest common resistance and that cvs Glen Prosen and Mailing Jewel had the weakest. The remaining variation described cultivar differences in relative bud length after petiole inoculation with either pathogen, and differences in the relative importance of spring and autumn symptoms. Only 7% of the variation indicated independent resistance to the two pathogens and this was not influenced by cultivar differences.

The influence of cultivar and isolate on the susceptibility of red raspberry canes to Didymella applanata

SUMMARYThe internodes of young canes of a single red raspberry selection were inoculated in the field with 32 isolates of Didymella applanata from diverse localities throughout the British Isles. All isolates were pathogenic but differed in virulence estimated by lesion length; their origin and virulence were not related.Four petioles on young canes of seven cultivars were inoculated in the glasshouse with 13 of the isolates. The axillary buds at treated nodes were shorter and the emergence of lateral shoots was substantially less than at non‐inoculated nodes in all seven cultivars. Although there were significant cultivar × isolate interactions, these were small in comparison to the effects of inoculation, cultivar and position of the treated node.The cultivar × isolate interactions between eight cultivars and 14 isolates were also studied in the field by inoculation of petioles and the internodes of young canes. Joint regression analysis of bud and lesion lengths revealed significant cultivar × isolate interactions but no discontinuous variation in the expression of disease was found. A principal components analysis using % nodes infected, % reduction in bud length and % lateral shoot failure confirmed the relationship between these variates and gave three vectors. The first (83.3% of variation) named the ‘resistance’ vector described the relative resistance or susceptibility of cultivars, the second ‘tolerance’ vector (13.4%) described the variation due to relative tolerance or intolerance of these genotypes and the third a ‘bud response’ vector accounted for only 3.3% of the variation.

Phenolic Compounds and the Polyphenoloxidase and Peroxidase Activity in Callus Tissue Culture‐Pathogen Combination of Red Raspberry and Didymella applanata (Niessl.) Sacc.

AbstractThe content of phenolic compounds as well as the activity of polyphenoloxidase and peroxidase in the red raspberry callus tissue after D. applanata infection were investigated. Two red raspberry cultivars: Latham — relatively resistant and M. Promise — susceptible were used.In the M. Promise cultivar the amount of phenols, especially o‐diphenols, decreased after infection and stayed more or less on the same level in Latham cultivar. The activity of polyphenoloxidase increased in both of the investigated cultivars, however in the tissue of Latham cultivar this rise was more pronounced than in the M. Promise one. The changes in peroxidase activity after infection were inconsiderable.The relation between the changes observed after infection in the phenolic metabolism and the differentiated susceptibility of callus tissue to D. applanata of the investigated cultivars was discussed.The obtained results explain partially the browning of infected callus tissue of one of the investigated cultivar i.e. M. Promise which had already been observed in the earlier investigations.

Polyderm, a Barrier to Infection of Red Raspberry Buds by Didymella applanata and Botrytis cinerea

A histological study was made of the axillary region of raspberry canes infected naturally by Didymella appianata (Niessl) Sacc. and Botrytis cinerea Pers. : Fr. The outer suberized phellem layer of the polyderm and a primary protective layer of suberized and lignified cells across the adaxial cortex of the petiole precluded infection of the axillary buds by hyphae growing from a saprophytic base in the leaf. No protective layer formed through the abaxial cortex at the petiole base; consequently both fungi colonized the epidermis, primary cortex and outermost non-suberized phelloid cells of the polyderm beneath the node.

Effects of spur blight (Didymella applanata) and premature defoliation on axillary buds and lateral shoots of red raspberry

SUMMARYNodal lesions typical of natural infections of Didymella applanata were produced on young raspberry canes when wounded petioles were inoculated with mycelium. The buds which developed in the axils of these inoculated petioles were smaller and less likely to produce lateral shoots than those in the axils of delaminated or undamaged petioles, but only when the petioles were inoculated in the field before the end of July. This effect was more pronounced in cv. Mailing Jewel than in cv. Glen Clova which suggests that the latter is more tolerant of D. applanata.Sprays to control D. applanata in the cropping region of canes will probably be effective in Scotland only if applied before the end of July.

Further evidence on the effects of gene H, which confers cane hairyness, on resistance to raspberry diseases

Gene H determines cane hairyness in raspberries and was reported to facilitate escape from infection by Botrytis cinerea and Didymella applanata. However, experiments with mycelial inoculations of wounded canes showed that it conferred a form of resistance which was evident for a long period after the establishment of infections by these pathogens. The gene also contributed to the resistance of fruit to B. cinerea and of canes to Leptosphaeria coniothyrium. Alternative hypotheses to explain these observations are discussed: two based upon its possible genetic linkage with a gene or genes for resistance and one based upon its possible pleiotropic effects.

Resistance to Didymella applanata in red raspberry and some related species

SUMMARYWhen raspberry canes were inoculated in summer with a mycelial inoculum of Didymella applanata resistant genotypes developed relatively small lesions which produced few fruiting bodies in the following spring. Scores of the frequency of these fruiting bodies provided the best discrimination between genotypes. Very strong resistance was found in R. pileatus, R. occidentalis and R. coreanus and in hybrids of these species with red raspberry. Hybrids with R. crataegifolius were less resistant. Resistance was also found in Malling 1473/35, a derivative of red raspberry cv. Chief, and in red raspberry segregates with gene H which determines cane pubescence. Both the expression of resistance and the ranking of resistance sources for their resistance was similar for D. applanata to that reported for Botrytis cinerea.

Fungicide programmes for the control of spur blight, powdery mildew and grey mould on raspberry

SUMMARYFive sprays of dichlofluanid (0–1% a. i.) reduced spur blight (Didymella applanata) on canes and powdery mildew (Sphaerotheca macularis) on fruit more than five sprays of captan (0–1% a. i.). Omission of the first three applications resulted in little increase in disease but when the fourth (full bloom) application also was omitted the incidence of disease was comparable with that on untreated plants. The final (fruitlet stage) application did not further reduce disease incidence. Five sprays of dichlofluanid reduced grey mould (Botrytis cinerea) on stored fruit more than five sprays of captan. There was an increase in grey mould with progressive reductions in the number of sprays. Incidence on canes was slight and was unaffected by treatments.A programme of five dichlofluanid sprays applied at 14‐day intervals until c. 2 wk before harvest and supplemented by a single early full bloom spray of either dinocap (0–025% a. i.), binapacryl (0–05% a. i.), triforine (0–025% a. i.), benomyl (0–025% a. i.) or replaced by benomyl (0–025% a. i.) all halved both the number of fruits infected by powdery mildew and the number of spur blight lesions on canes, compared with unsprayed controls.Six applications of any of the following fungicides at 7‐day intervals from 23 May until 29 June 1977 reduced powdery mildew incidence on fruit, the last fungicide being particularly effective: dinocap (0–0125%), dichlofluanid (0–075%), binapacryl (0–025%), triforine (0–0125%), bupirimate (0–0075%), ditalimfos (0–01875%) and fenarimol (0–0036%). Only triforine and bupirimate reduced the incidence of mildew on shoots. Dichlofluanid, binapacryl, triforine and fenarimol all reduced the amount of spur blight on canes. The largest fruit occurred on plants sprayed with bupirimate, ditalimfos and fenarimol, and late ripening was associated with triforine treatments.

Fungus diseases of raspberry (Rubus idaeus L.) in Finland

During 1978—1981 a total of nearly 200 raspberry cane samples were investigated originating mainly from southern and eastern Finland. The samples consisted of young and already fruited canes injuried to different degrees. Phoma sp., the conidial stage of Didymella applanata (Niessl) Sacc., causer of raspberry spur blight, was most common of the isolated fungi; the perfect stage did not develope until afer preservation in cold. The peak of pycnospore release on raspberry canes was in July 1981. Other weak wound pathogens were isolated: Fusarium avenaceum (Cda. ex Fr.) Sacc., which occurred in 22 % of the transfers, F. culmorum (W. G. Sm.) Sacc., Botrytis cinerea Pers. ex Fr. and the secondly most common Phoma species, P. exigua Desm. v. exigua Maas. The fungi mentioned above were mainly obtained from different depths of the raspberry stem tissues, the least on an average from the pith. Alternaria alternate (Fr.) Keissl. was the most common ’surface fungus’, Phialophora spp., wood rotting saprophytes, common also in the pith. Leptosphaeria coniothyrium (Fckl.) Sacc., the most strong of the pathogens, was rare in the samples. The occurrence of Cylindrocarpon destructans (Zinssm.) Scholten in root samples changed 8-70 %. The cv. Muskoka is more susceptible to spur blight than cv. Ottawa. On the other hand, the larvae of raspberry cane midge (Resseliella theobaldi (Barnes)) produced plenty of injuries in Ottawa-samples originating from Mikkeli in 1980 and thus increased also the fungal damage.

Fungus diseases of cultivated arctic bramble (Rubus arcticus L.) in Finland

During 1975 and 1977—1979 studies were carried out on the fungus diseases of experimentally cultivated arctic bramble (Rubus arcticus L.). The most common pathogenic or weakly pathogenic fungi isolated from the diseased clones were Cylindrocarpon destructans (Zins.) Scholten and Fusarium avenaceum (Cda ex Fr.) Sacc. Some other Fusarium species and Botrytis cinerea Pers. ex Fr. were rather uncommon. Didymella applanata (Niessl) Sacc. and plenty of pycnidia of Phoma spp. were established on nearly withered clones; among the isolates were P. exigua Desm. var. exigua Maas, Phoma spp. and Coniotbyrium fuckelii Sacc. (con. st. of Leptosphaeria coniotbyrium (Fuck.) Sacc.). Isolates of little significance were identified in the whole from 26 fungal genera.

The effect of sprays of thiophanate–methyl on cane diseases and yield in red raspberry, with particular reference to cane blight (Leptosphaeria coniothyrium)

SUMMARYSpur blight (Didymella applanata), cane botrytis (Botrytis cinerea) and cane blight (Leptosphaeria coniothyrium) were studied in two consecutive seasons in unsprayed raspberries and in plots sprayed with thiophanate‐methyl in the first season alone, (a) twice pre‐harvest, (b) twice post‐harvest, or (c) twice pre‐ plus twice post‐harvest. Pre‐harvest, but not post‐harvest sprays, gave moderate control of both spur blight and cane botrytis; both diseases occurred mainly on the lower halves of canes, the latter being the less common.Cane blight occurred at the base of canes where they were wounded by old cane stubs. In the first year it was severe; 37% of canes died before harvest in the unsprayed plots. The three spray programmes all decreased cane death due to cane blight and they all increased yield by c. 45% even in those plots sprayed post‐harvest where spur blight was severe and not controlled. Clearly this last disease, despite its high incidence, had no effect on potential yield in this experiment. In the second year cane blight was common but less severe and the incidence of its lesions was reduced similarly by all programmes, but only 4% of canes died in control plots.Analysis of the potential yield and the sizes of lesions caused by L. coniothyrium in canes inoculated at fortnightly intervals in the previous year showed that potential yield loss occurred only when lesions girdled canes. A bimodal distribution in the lesion sizes, measured by length or girdling, indicated some endogenous control of lesion development which might explain the marked differences in the effect of cane blight on potential yield in two seasons.

Effects of Didymella applanata and Botrytis cinerea on axillary buds, lateral shoots and yield of red raspberry

SUMMARYThe viability of axillary buds and the growth and potential yield of lateral shoots at nodes of red raspberry (Rubus idaeus) infected naturally by Didymella applanata or Botrytis cinerea were measured on excised nodes, decapitated nursery canes or on canes from fruiting plantations. In comparison with lesion‐free nodes, buds at infected nodes were smaller and fewer of them were capable of growth when excised and ‘forced’, although the difference in growth between infected and uninfected nodes decreased during late winter. After February, those buds at infected nodes which were capable of forced growth did so as early and with a similar growth rate as those at lesion‐free nodes. In April, 70% of buds at infected nodes were capable of growth compared with 94% of those at lesion‐free nodes.When nursery canes of cv. Mailing Delight were decapitated above infected nodes the emergence of lateral shoots from the terminal infected node did not differ significantly from that at lesion‐free nodes. On a range of farm sites in Scotland the emergence of shoots at infected nodes in the cropping region of canes was significantly poorer than from uninfected nodes but substantially better at infected nodes of cv. Glen Clova than at those of cvs Mailing Jewel and Mailing Orion. It is suggested that cv. Glen Clova is relatively tolerant of spur blight and cane botrytis. The length and potential yield of laterals which developed at infected nodes in the cropping region of canes in these three cultivars did not differ significantly from those at lesion‐free nodes. In all tests there was no significant difference in growth at nodes infected by D. applanata and B. cinerea which may indicate a common mechanism for suppression of buds.

Effects of Benomyl on Yield Components of Red Raspberry (Rubus Idaeus) in Relation to the Incidence of Spur Blight (Didymella Applanata) and Cane Botrytis (Botrytis Cinerea)

SummaryBenomyl was applied to red raspberry cv Glen Clova on three occasions in June (Programme A) or in conjunction with additional benomyl sprays earlier in the year (Programme B). Programme A had no effect on cane botrytis (Botrytis cinerea) and usually none on spur blight (Didymella applanata). Programme A always decreased the incidence of spur blight and, on occasion, also that of cane botrytis. Compared with the unsprayed controls Programme B always increased fruit yield, but in general Programme A did not. The higher yields resulted from increases in berry size and usually also in berry numbers; benomyl did not increase the number of canes ha−1 or the number of laterals per cane. On one occasion Programme A increased yield without decreasing the incidence of spur blight and Programme B, although decreasing spur blight, did not increase yield beyond that given by Programme A. It is suggested that the yield increases which can follow the use of benomyl may be unrelated to the control of spur blight.

Development of perithecia and pycnidia of Didymella applanata (causing spur blight) on raspberry canes

The development of perithecia and pycnidia of Didymella applanata (Niessl) Sacc. was studied microscopically in whole mounts and tissue sections. Perithecia and pycnidia occurred together on the same stems. Perithecial initials were first seen in mid-August; development continued throughout the winter, and perithecia reached maturity by early April. Pycnidia were initiated from November onwards, and reached maturity between April and mid-November. Pycnidiospores were apparently released over a long period, with a peak in July and August.

Field observations on disease susceptibility, yield and agronomic character of some new raspberry cultivars

SummaryA trial on replicated plots of Mailing Jewel, Mailing Delight, Mailing Orion, Glen Clova and seedling 1318/27, and data from unreplicated plots of Mailing Admiral and Mailing Leo, showed that cane botrytis (Botrytis cinerea) increased only slightly during six years of observations, whereas spur-blight (Didymella applanata) increased from nil in the first year to more than 50% buds infected in the sixth year. Mailing Orion and Mailing Delight were more susceptible to both diseases than Mailing Jewel; 1318/27 was susceptible to spur-blight but resistant to cane botrytis. Mailing Orion was less susceptible than Mailing Jewel to powdery mildew (Sphaerotheca macularis) on foliage; all cultivars except Glen Clova had fewer infected fruits than Mailing Jewel. Mailing Delight, Glen Clova and 1318/27 all showed more crown gall (Pseudomonas tumefaciens) than Mailing Jewel. All new cultivars had larger fruit, cropped more heavily and grew taller than Mailing Jewel, Mailing Delight being outstanding in both fruit size and yield. Mailing Orion, Mailing Admiral and Glen Clova produced more new canes than Mailing Jewel.

Vigour control, an integrated approach to cane, pest and disease management in red raspberry (Rubus idaeus)

SUMMARYThe first flush of young canes of red raspberry (Rubus idaeus) was removed at different dates in spring, using the contact herbicide dinoseb. In comparison with untreated plots, cane removal increased fruit yield, controlled excessive cane vigour, and improved the health status of vegetative canes in a plantation infested by raspberry cane midge (Resseliella theobaldi). At the end of the growing season vegetative canes on treated plots were shorter and thinner, and sustained less physical injury than those on untreated plots. Access to the fruit at harvest was also improved. Reduced competition between fruiting and vegetative canes increased yield in the year of treatment by an average of 35%. Yield was not affected by date of cane removal, but growth of replacement cane was reduced below optimum when first flush cane was removed after mid‐May.The later the canes were removed, the less was the incidence of pest and diseases. Cankers and lobate vascular lesions (‘patches’) resulting, respectively, from the feeding of first and second generation midge larvae (with associated fungi) affected fewer canes in treated than in untreated plots. Significantly fewer live larvae of R. theobaldi were recovered in the following winter from soil in plots treated on or after 11 May than from untreated plots. The main effect of vigour control on R. theobaldi and midge blight was that replacement canes provided fewer egg‐laying sites (natural splits) than did the first flush canes on untreated plots. The incidence of spreading vascular lesions (‘stripes’) attributed to Leptosphaeria coniothyrium infecting either physical wounds (cane blight) or midge feeding wounds (midge blight) was substantially less in treated than untreated plots. Cane botrytis (Botrytis cinerea) and spur blight (Didymella applanata) were also less common in treated plots.Interactions between vigour control and pest and disease incidence are discussed in relation to the efficient management of cv. Glen Clova in eastern Scotland.

Rubus coreanus as donor of resistance to cane diseases and mildew in red raspberry breeding

Strong resistance to the cane diseases Elsinoe veneta, Didymella applanata and Botrytis cinerea, and to Sphaerotheca macularis, occurred in F1 and BC1 derivatives of an accession of Rubus coreanus. Resistance to cane spot (E. veneta) was polygenic.