摘要:

AbstractForty‐fourCorynebacterium fasciansstrains from different geographical origins and host plants were characterized by their phytopathological capacity towards different host plants together with 206 morphological, biochemical and physiological features.The numerical analysis of the phenotypic features utilizing the SSMsimilarity coefficient and the average unweighted pair‐group clustering method revealed that allCorynebacterium fasciansstrains form a rather homogeneous cluster: over 80%, SSMexists between the44Corynebacterium fasciansstrains from phenon II. From the present results the reclassification ofC. fasciansasRhodococcus rhodochrousis not obvi

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1984.tb03396.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

AbstractHypobaric pressures prevented the ripening of avocado fruit discs and the development ofColletotrichum gloeosporioidesinfection on them. The same condition did not prevent the growth ofC. gloeosporioideson potato dextrose agar. Using this system it was shown that the resistance of unripe avocado fruit discs does not originate in the lack of subsrate for fungal growth.

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1984.tb03397.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

AbstractAlternaria macrosporawas isolated from seeds only after the natural opening of the bolls and exposure of seeds to an environment in which the fungus was present. The fungus lacks the ability to penetrate the boll wall and reach the seed site. Attempts to isolate the pathogen from seeds of immature bolls at different developmental stages failed. Internal infection by slow injection resulted in seed infection and partial shedding of the injected plant parts which was high in buds and decreased with the ripening to mature bolls. Severity of seed infection was not dependent on either inoculum level, boll physiological age or even if the boll itself was not diseased. Infection of flowers under field conditions caused flower shedding. Naturally infected seeds or inoculated seeds with inoculum levels of 100 spores/ml and above resulted in diseased cotyledons, the incidence of which was, for inoculated seeds, positively correlated with inoculum level. A small difference was observed between cultivars in susceptibility to artificial inoculation at the cotyledon stage.A. macrosporasurvived on commercial cotton seeds and on post‐season plants left growing at the field edges. Survival in plant debris under field conditions was minimal and may only have a minor effect on field reinfestatio

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1984.tb03398.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

AbstractConidia ofVenturia inaequalisgerminated and formed appressoria on all leaves independently of age and origin within the first 15 hours after inoculation. On the youngest expanded leaves of the apple variety Golden Delicious 80% of the conidia developed stromata within the first 24 hours, sporulation occurred after 8 days. On the second leaf (counted from the top of the twig) stroma formation was slowed down compared to the first and sporulation occurred after 10 days only. On the third leaf the fungus rarely formed stromata and never sporulated. The fourth leaf already showed complete ontogenetic resistance. In the diploid variety Priscilla the gene Vf, which confers resistance against scab to apple leaves, was expressed as reduced stroma formation without sporulation, as in the case of ontogenetic resistance. In the triploid variety Sir Prize with the gene Vf, stroma formation was retarded and colonization and sporulation occurred later on the first leaf, similarly to the reaction of the second leaf of variety Golden Delicious.

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1984.tb03399.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

AbstractThe Hyp content was studied in cell wall of alfalfa susceptible and resistant strains on the 3rd, the 7th and on the 14th day after inoculation withVerticillium albo‐atrumorCorynebacterium michiganensepv.insidiosum.The changes of Hyp content after inoculation with both pathogens were markedly expressed in alfalfa roots.Resistant plants of R 337 strain responded to inoculation withV. albo‐atrumorC. michiganensepv.insidiosumby the decrease of Hyp content mainly on the 3rd and on the 7th day. On the 14th day after inoculation Hyp content practically did not differ from that of the control. Susceptible plants of S 354 and S 321 srains responded to inoculation with wilt pathogens by the slight decrease of Hyp content at the 3rd day after inoculation. A significant increase of Hyp content was found on the 7th and mainly on the 14th day after inoculation in comparison with control plants.The cell wall Hyp content was also determined with 7 R‐strains and 7 S‐strains at 120 days after inoculation with both pathogens. In each R and S strain two categories of plants were used for chemical analyses: Wilt‐free plants (0 to 1 classes) and diseased, wilted plants (2 to 6 classes). In the resistant alfalfa strains no differences in Hyp content between the wilt‐free and diseased plants were found. In the susceptible alfalfa strains the Hyp content was significantly higher in roots of diseased plants comparing with the wilt‐free ones.Only negligible changes in Hyp content were registered in the overground parts of all inoculated al

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1984.tb03400.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

AbstractA foliar disease, causing necrotic spots and severe defoliation ofElaeagnus angustifolia, was detected in Tuscany, Italy, in 1979. The causal agent was identified asSeptoria elaeagni.It was not pathogen toE. umbellata, E. pungens, E. multiflorum, andHippophae rhamnoides.Ultrafiltrates from liquid cultures showed toxicity againstE. angustifoliaand some herbaceous species, non hosts of the pathogen.Disease was significantly more severe in an overhead irrigation system than when water was delivered to the soil alone.

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1984.tb03401.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

AbstractSeveralAgropyronspecies were tested for new sources of resistance to barley yellow dwarf virus (Bydv) and wheat streak mosaic virus (WSMV). With BYDV strain PAV, 11 of the 17 Agropyron species showed no virus transmission when plants were given access feed by viruliferousRhopalosiphum padi.Similar trials with BYDV strain RMV (vectored byR. maidis) indicated that all plants, except susceptible control plants, remained virus free. Virus status was confirmed by enzyme‐linked immunosorbent assays. When plants were mechanically inoculated with WSMV, 11 Agropyron species failed to express symptoms, while five other species showed a segregating response or had some accessions segregating and some resistant. Test results suggest that resistance to BYDV and WSMV inAgropyronspecies does not appear to be correlated with any specific genome ofAgropyronspecies although most of the Agropyron species containing S genome were resistant to BYDV and WSM

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1984.tb03402.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

AbstractCorn stunt spiroplasma (CSS) was transmitted by the leafhopper vectorEuscelidius variegatus(Kirschbaum) and produced symptoms on four dicotyledonous plant species,Sinapis albaL. (mustard),Pisum sativitmL. (pea),Raphanus sativusL. (radish) andSpinacia oleraceaL. (spinach). The vectors became infective by microinjection with a broth culture of CSS. This insect also acquired CSS from infected mustard plants and transmitted it to healthy ones.

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1984.tb03403.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

AbstractThe presence of virus having mixed coats has been demonstrated serologically in tomato plants cross‐protected with a mild strain (M 11–16) against the severe (UI) strain of tobacco mosaic virus (TMV). The proportion of virus having mixed coats remained constant throughout at ca. 40% even in top leaves where severe symptoms caused by the challenge virus (U1) first appeared.The symptoms caused by the U1 in doubly‐inoculated plants occurred in the leaves where:(a)the amout of total virus (irrespective of the type of coat) protein was 52% that of U1 strain in singly inoculated plants,(b)the multiplication of the severe U1 strain was reduced to only 9% as compared with the leaves singly inoculated with U1,(c)the ratio of severe to mild strain was increased to near equality although there was a significant reduction in the multiplication of U1in these leaves,(d)the amount of infective U1RNA started to inc

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1984.tb03404.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

AbstractTissue‐cultured plantlets which were derived from meristems of a sour cherry plant infected by prune dwarf virus were examined by enzym‐linked immunosorbent assay (ELISA). The virus could be detected with sufficient reliability in 17‐week‐old rooted plant‐lets still growin

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1984.tb03405.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY