摘要:

SUMMARYAn isolate of pea early‐browning virus from Britain (PEBV (B)) has tubular particles most of which are either about 103 or 212 mμ long with sedimentation coefficients of 210 and 286Srespectively. Both types show cross‐banding at intervals of 2.5 mμ. Virus preparations containing only the shorter particles were not infective.PEBV (B) was transmitted to pea seedlings by both adult and juvenileTrichodorus primitivus(de Man) (Nematoda) and persisted for 32 days inT. primitivuskept without plants. In two experimentsT. primitivusfailed to transmit a Dutch isolate (PEBV (D)), which is distantly related serologically to PEBV (B). PEBV (B) was transmitted by nematodes to cucumber roots more readily in soil at 20d̀ than at 24d̀ C., and more readily at 24d̀ than at 29d̀ C.When transmitted by inoculation of sap, PEBV (B) and PEBV (D) caused similar symptoms in some pea varieties but differed in virulence towards others. Thirty‐one varieties resistant to natural infection with PEBV in The Netherlands were susceptible to PEBV (B) when manually inoculated with sap or when grown in naturally infested soil from one site; twenty‐six of these varieties did not become infected in soil from a second site, in which several other varieties that are susceptible in The Netherlands were infected. Varieties should therefore be tested for resistance by growing them on many infested fields. All but one of the pea varieties resistant to PEBV in The Netherlands became infected with the English form of tomato black ring virus when grown in soil containing infectiveLongidorus att

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1966.tb06872.x

出版商:Blackwell Publishing Ltd    

年代:1966

数据来源: WILEY

摘要:

SUMMARYPurified virus preparations made from nettlehead‐diseased hop plants, or fromChenopodium quinoa, to which the virus was transmitted by inoculation of sap, contained polyhedral virus particles of 30 mμ diameter which were identified serologically as arabis mosaic virus (AMV). There were serological differences between AMV isolates from hop and from strawberry, and also differences in host range and in symptoms caused inC. quinoaandC. amaranticolor.AMV was always associated with nettlehead disease. The nematodeXiphinema diversicaudatumoccurred in small numbers in most hop gardens, but was numerous where nettlehead disease was spreading rapidly.Preparations from nettlehead‐affected hops also contained a second virus, serologically related toPrunusnecrotic ringspot virus (NRSV), in mild and virulent forms which infected the same range of test plants but showed some serological differences. Mild isolates did not protectC. quinoaplants against infection by virulent isolates. Hop seedlings inoculated with virulent isolates of NRSV developed symptoms indistinguishable from those of split leaf blotch disease. Latent infection with NRSV was prevalent in symptomless hop plants. Nettlehead disease is apparently associated with dual infection of AMV and virulent isolates of NRSV.An unnamed virus with rod‐shaped particles 650 mμ long was common in hop and was transmitted by inoculation of sap to herbaceous plants. Cucumber mosaic virus was obtained from a single plant ofHumulus scand

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1966.tb06873.x

出版商:Blackwell Publishing Ltd    

年代:1966

数据来源: WILEY

摘要:

SUMMARYHealthy and streak‐virus‐infected cocksfoot plants of a single genotype were examined over a 2‐year period. In the first year infection decreased tillering by about 40%, but in pot‐grown plants individual tiller weights were 30% higher so dry‐matter yield was decreased by only 10%. In the second year the larger tiller weights compensated completely for decreased tillering. No similar compensation was observed in field‐grown plants.The virus had the largest effects when soil fertility was highest, healthy plants producing significantly greater responses to nitrogen effects, but potassium, at certain times of the year, produced larger tiller weights in infected than in healthy plants. Infection decreased dry‐matter yield more in frequently than in infrequently cut plants.Infection greatly decreased the number of vegetative but not of fertile tillers. Infected plants tended to flower earlier and produced fewer, slightly smaller,

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1966.tb06874.x

出版商:Blackwell Publishing Ltd    

年代:1966

数据来源: WILEY

摘要:

SUMMARYSmall experimental swards of three types‐healthy, 50% and 100% streak‐virus‐infected‐were established from single tillers of randomly selected cocksfoot genotypes. In these swards 44% of infected plants died within 2 years compared with 21% of healthy plants. Mortality of infected plants was not increased by the presence of healthy plants in the same sward. In swards containing both healthy and infected plants, increased growth of healthy plants compensated for the low yield of infected ones only when the swards were frequently defoliated. Infrequent cutting apparently allowed infected plants to check the growth of healthy ones, and 50% infected swards yielded little more than 100% infected swards. This difference in response was attributed to differences in the growth habits of healthy and infected plants. Few initially healthy plants became infected during 2 years of the exp

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1966.tb06875.x

出版商:Blackwell Publishing Ltd    

年代:1966

数据来源: WILEY

摘要:

SUMMARYIrish perennial rye‐grass plants infected with barley yellow dwarf virus (BYDV) showed inconspicuous leaf symptoms but were more stunted and yielded less total herbage, but more early spring herbage, than healthy plants. During a period of 2 years, infection did not decrease plant survival; infected plants produced more tillers and gave a higher ratio of vegetative to fertile tillers than healthy plants. BYDV caused a greater loss of yield in simulated rye‐grass swards cut twice a year than in those cut four times. Swards in which half the plants were infected gave yields intermediate between those of healthy and infected swards. Infected plants tended to dominate healthy ones in swards cut four times, but in those cut twice a year the initialstatus quowas maintained. In swards containing rye‐grass and white clover, the clover yielded more for most of the year when with BYDV‐infected than with healthy rye‐grass, but this trend was reversed in spring.The different effects of barley yellow dwarf virus on rye‐grass plants and of cocksfoot streak virus on cocksfoot seem reflected by the different effects of the viruses on the competition between infected grass, healthy grass and white clover plants, when these are grown in different c

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1966.tb06876.x

出版商:Blackwell Publishing Ltd    

年代:1966

数据来源: WILEY

摘要:

SUMMARYIn a field trial, three varieties each of oats and barley were infected with barley yellow dwarf virus (BYDV) either at growth stage I or at growth stage 8 (Feekes scale), using a virulent isolate of BYDV transmitted by the ‘plum‐grain’ aphid (Rhopalosiphum padi L.). Early infection decreased yields of the susceptible varieties, Blenda oats and Proctor barley, by 97% and 93% those of the more tolerant oat varieties, Albion and CI 7488, b31% and 12%, but had no effect on the yield of the two tolerant Ethiopian barleys, CI 2325 and CI 7224. Late infection decreased grain yield only in Blenda. Mature straw height was decreased by early infection in all three oat varieties and by late infection in Blenda oats and in the barley variety CI 7224. The number of fertile tillers, number of grains per ear and Iooo‐grain weights were decreased in parallel with the decreases in yield, except that early infection increased the number of ear‐bearing tillers in CI 7488 and increased rooo‐grain weight in Albion. The lower yield resulting from late infection in Blenda was not accompanied by a decrease in number of gra

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1966.tb06877.x

出版商:Blackwell Publishing Ltd    

年代:1966

数据来源: WILEY

摘要:

Book reviewed in this article:Ecology of Soil‐borne Plant Pathogens. Prelude to Biological Control. Edited by K. F. BAKER and W. C. SNYDER.Handbook of Physiology, Section 4. ‘Adaptation to the environment.’ Published by the American Physiological Society. Section editor D. B. DILL.Plant Nematology, 2nd ed. Edited by J. F. SOUTHEY.The Wood‐Pigeon. New Naturalist Special Volumes. By R. K. MURTON.Multivariate Statistical Analysis for Biologists. By H.

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1966.tb06878.x

出版商:Blackwell Publishing Ltd    

年代:1966

数据来源: WILEY