摘要:

SUMMARYLongidorus attenuatusproduces galls at the tips of roots of field crops, including sugar beet, growing in alkaline, sandy soils in eastern England.L. elongatusproduces similar, but often larger, galls on the roots of sugar beet and other crops in sandy soils in the W. Midlands and in Fen peats.Trichodorusspp. cause ‘stubby root’ of sugar beet and can feed on many field crops. Seven species ofTrichodoruswere found in sandy soils in eastern England.L. attenuatus, L. elongatusandTrichodorusspp. aggregate around roots and stunt sugar beet and other crop plants.L. attenuatusis commoner below plough depth than in the topsoil, whereasT. cylindricus, T. pachy‐dermusandT. anemonesare more abundant in the topsoil. These nematodes cause some forms of ‘Docking di

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1970.tb05502.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

SUMMARYThirty‐three gal D–D or chloropicrin/acre (371 l/ha) injected during winter into well‐drained, sandy soils controlledLongidorus attenuatus, Trichodorusspp. and other migratory root‐parasitic nematodes and resulted in greatly increased yields of sugar beet for at least 3 years; 2 years of bare fallow was less effective than soil fumigation.Trichodorusspp. multiplied more on sugar beet than on barley, whereasL. attenuatusmultiplied more on barley and clover than on sug

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1970.tb05503.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

SUMMARYSmaller amounts of D–D (6–12 gal/acre) (68–135 1/ha) or ethylene dibromide (9 gal/acre) (100 1/ha) than are customarily used to disinfest field soils killed many root‐parasitic nematodes (Trichodorus, Pratylenchus, TylenchorhynchusandLongidorus attenuatus) when injected 6–8 in (15–20 cm) deep during early autumn in rows 10 in (25 cm) apart in well‐drained sandy soils. They also increased the yield of sugar beet grown in fields infested withTrichodorusorLongidorus attenuatus, without affecting sugar percentage or juice purity of the roots, and in some places increased the yield of barley grown after the beet. D–D was much less effective when injected 8–12 in deep during late autumn or winter. Increasing nitrogen dressings to the seedbed from 1·5 to 3 cwt/acre (188 to 376 kg/ha) increased sugar beet yield in one field, decreased it in another and decreased juice purity in both. In two other experiments extra nitrogen did not affect sugar beet yield.Even smaller amounts of the nematicides ‘placed’ in the rows, before or after sowing sugar beet in them, killed many of the nematodes and also increased sugar yield. Phytotoxic nematicides can be placed in the rows during autumn, winter or spring but placement is simpler during spring, when the treated rows are indicated by the position of the marks of the tractor wheels left when the nematicide was applied. When applied during autumn or winter, the rows need to be indicated by d

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1970.tb05504.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

SUMMARYMany populations ofHeterodera rostochiensismostly from the main potato growing areas of England and Wales, were tested with eelworm‐resistant potato varieties (andigenahybrids). Except in the Eastern Region, where resistant varieties were planted alongside commercial varieties in infested fields, tests were done in pots inoculated with a standard number of cysts extracted from a single soil sample from each field. The tests showed that England and Wales could be divided into areas according to the percentage of cysts(70%) produced on the resistant compared with a commercial non‐resistant variety. On the peat soils of the East Anglian fens and in Bedfordshire, Essex and Kent (area A) most populations produce few cysts on resistant varieties. In much of the East Midlands and Yorkshire (area D), populations produce many cysts on resistant varieties which behave much as ordinary susceptible potatoes. Populations in the rest of England and Wales (areas B, C) vary and in many districts every field must be tested separately.If the pathotypes occurring in Britain had separate origins in South America, the present distribution in England and Wales is probably due to chance introductions dispersed with seed and following the patterns of trade in seed potatoes. As all commercial varieties, before the release of eelworm‐resistant ones, were about equally susceptible to the different pathotypes, the varieties themselves probably played little part in determining the present distribution of pat

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1970.tb05505.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

SUMMARYThe proportion of larvae from ten populations ofHeterodera rostochiensisWoll. that became female was determined on five potato clones containing genes for resistance derived fromS. tuberosumssp.andigena., on three with genes fromS. multidissectumand on four with genes for resistance from both sources. Variations in the resistance of the clones bred fromandigena, especially to two of the populations, suggest the presence of more than one gene for resistance.

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1970.tb05506.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

SUMMARYPotato mop‐top virus (PMTV) was transmitted by inoculation of sap to twenty‐six species in the Solanaceae or Chenopodiaceae and toTetragonia expansa;species in eleven other plant families were not infected. The virus was cultured in inoculated leaves ofNicotiana tabacumcv. Xanthi‐nc or inN. debneyi.Diagnostic local lesions were produced inChenopodium amaranticolor.In winter, ten solanaceous species were slowly invaded systemically but the first leaves infected were those immediately above inoculated leaves. When transmitted to Arran Pilot potato by the vectorSpongospora subterranea, PMTV induced all the main types of shoot and tuber symptoms found in naturally infected plants. Isolates of PMTV from different sources differed considerably in virulence.PMTV‐containing tobacco sap lost infectivity when heated for 10 min at 80 °C, diluted to 10‐4, or stored at 20 °C for 14 weeks. Infectivity was partially stabilized by 0·02% sodium azide. When sap was centrifuged for 10 min at 8000 g, infectivity was mainly in the sediment. Infective sap contained straight rod‐shaped particles about 20 nm wide, with lengths up to 900 nm and crossbands at intervals of 2·5 nm. Many of the particles were aggregated side‐to‐side, and the ends of most seemed damaged. The slight infectivity of phenol‐treated leaf extracts was abolished by pancreatic ribonuclease. The present cryptogram of PMT

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1970.tb05507.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

SUMMARYPlants exposed for 24–72 h to light of different wavelengths differed in their subsequent susceptibility to virus infection. French bean leaves were less susceptible to infection by tobacco necrosis virus andNicotiana glutinosaleaves were less susceptible to infection by tobacco mosaic virus when previously exposed to blue or red light than when exposed to green light. These differences were most pronounced at low energy levels. Leaves exposed to each kind of light were less susceptible than those kept in darknes

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1970.tb05508.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

SUMMARYSeventy‐four viruses were tested for survival after lyophilization of infective sap and subsequent storage in vacuum‐sealed ampoules at room temperature. Fifty‐seven viruses survived at least i year and 19 of them over 10 years. The best results were obtained from host plants not containing inhibitors of infection or potent phenol oxidase systems. Purified preparations were also lyophilized. Lyophilization offers many advantages for maintaining a culture collection of sap‐transmissible

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1970.tb05509.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

SUMMARYDifferent types of cocoa were compared for their resistance to infection and tolerance of infection with the virulent strain A of cocoa swollen‐shoot virus, inoculated either by mealybugs or manually. The method of infection did not affect the ranking of the cocoa types for resistance, except at high percentages of infection, or for tolerance. In comparison with other methods, manual inoculation simplifies the screening of cocoa types for resistance and tolerance to virus infection, and provides a more sensitive test for resistanc

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1970.tb05510.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

SUMMARYThe resistance and tolerance to infection with cocoa swollen‐shoot virus (virulent strain A) of forty‐five and thirty‐eight cocoa progenies respectively was estimated using a manual inoculation method. Resistance was estimated from the proportion of inoculated seedlings which developed symptoms, and tolerance from the severity of these symptoms during a 4‐month period. Resistance was found among Nanay, Iquitos and Scavina, all Upper Amazon types; and an inter‐Nanay cross was outstandingly resistant and offers scope for improvement by breeding. Some Amazon‐Amazon and Trinitario‐Amazon progenies snowed tolerance, especially those with Trinitario T9/21 as a parent. Some progenies seem sufficiently promising for field testing to select varieties suitable for planting in those areas in Ghana where swollen‐shoot dise

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1970.tb05511.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY