摘要:

SUMMARYVertical sticky cylinder traps were as useful as a volumetric trap for detecting seasonal changes in numbers ofErysiphespores from barley crops. Changes in spore catches by both traps also resembled changes in numbers of pustules developing on initially healthy barley seedlings exposed in the same crop. Seasonal changes in catches on cylinders exposed at some distance from any crop differed from those on cylinders just above barley crops.Cylinder traps are cheap, simple and quicker to scan than volumetric traps and seem likely to be acceptable alternatives to them for much work on cereal mildew and other air‐dispersed pathogens, particularly for rautine trapping at many site

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1974.tb01366.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

SUMMARYIn two experiments, on Julia and Zephyr spring barley, evidence was obtained that the development of powdery mildew in sprayed plots depended very much on their proximity to unsprayed crop. The effective period of control achieved with one spray was greater where plots were well separated from unsprayed crop than where they were surrounded by or very close to unsprayed crop. There is probably a risk that small plot experiments may not only underestimate the potential effectiveness of fungicides in agricultural practice, but also give misleading information on optimal spray timing.

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1974.tb01367.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

SUMMARYThree aphid‐transmitted viruses, tulip breaking, lily symptomless and cucumber mosaic, were obtained from lilies in Britain. Tulip breaking virus was detected by the leaf mottle produced inLilium formosanum, cucumber mosaic virus by inoculation of sap toNicotiana clevelandiiandChenopodium quinoa, and lily symptomless virus by electron microscopy of crude leaf extracts from symptomlessL. formosanum.Liiy symptomless virus was transmitted byMyzus persicae, Macrosiphum euphorbiae, Aulacorthum solaniandAphis fabae. M. persicae, which in a small experiment appeared a more efficient vector thanA. fabae, transmitted the virus in a non‐persistent manner. This conflicts with the original report of transmission in a persistent manner byA. gossypiibut no transmission byM. persicae.The possibility that there are two distinct viruses with similar pathological effects is discussed. Tulip breaking and lily symptomless viruses spread to bait plants ofL. formosanumwithin a field planting of lilies in Scotland especially during July to September; lily symptomless virus was the more prevalent. No spread of cucumber mosaic virus was detec

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1974.tb01368.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

SUMMARYBothTrichodorusspp. andLongidorusspp. damage roots of sugar‐beet seedlings in sandy soil, causing Docking disorder. Trials in infested fields between 1969 and 1972 tested the effects of fumigation along the rows with different amounts of D‐D or Telone applied either two weeks before sowing or immediately before sowing, application of the systemic nematicide aldicarb (Temik) in the furrow with the seed during sowing, and top‐dressing with nitrogen. Seedling establishment was often decreased by fumigation immediately before sowing, especially when followed by excessive rainfall, but only rarely by earlier fumigation or by aldicarb; differences in numbers of roots harvested were smaller because hand‐singling removed excess seedlings. There was usually little difference between the yield increases given by the most effective treatments, which were aldicarb at 1·12 kg active ingredient/ha and 2·2–6·6 ml D‐D or Telone/m of row at either time of application. Nitrogen top‐dressing never affected sugar yield significantly.Longidorusspp. andTrichodorusspp. were both controlled well in the fumigated row but much less well at 13 cm, and not at all at 25 cm from the row (i.e. mid‐way between

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1974.tb01369.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

SUMMARYFourteen cultivars of north temperate, Australian, Mexican and Rhodesian origins, were grown in eight treatments: 2‐day‐lengths (10 h and 14h) × two temperature regimes (18/13 °C and 25/20 °C) × two seed vernalization treatments (unvernalized and 28 days at 1–2 °C). Numbers of days to 50 % ear emergence, leaf numbers and spikelet numbers of the main shoots were recorded.The north temperate cultivars were the most sensitive to daylength: in long days their mean spikelet number was 15 and they headed in 40–50 days, while in short days they had a mean of 24 spikelets and failed to head in 100 days. The Rhodesian cultivars were the least sensitive, but nevertheless headed 20–30 days earlier and had three to five fewer spikelets per ear in long days.The effects of vernalization on the tropical cultivars were related to maturity class: they ranged from negligible in early cultivars such as Sonora 64 and Devuli to decreases of 20 days to heading and seven spikelets in late cultivars such as Mexico 120 and Cajeme 71 in long days.The effects of temperature varied with cultivar and with vernalization treatment. Early cultivars and vernalized late cultivars headed earlier and had fewer spikelets in the warmer regimes while unvernalized late cultivars tended to have more spikelets and headed later. It is suggested that some vernalization of these late cultivars took place in the cooler regime.The significance of the results for the understanding of the physiological basis of the adaptation of wheat cultivars to different climatic zone

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1974.tb01370.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

SUMMARYCarrot seeds which had been imbibed or germinated and were then sown in a gel extruded through standard coulters emerged five days earlier than dry seeds sown with a conventional drill and gave higher yields after 64 days although not after 77 days. There was no difference in mean time to emergence or in final plant stand between lettuces grown from dry seeds and those from seeds imbibed for 24 h and sown in a gel, but the duration of the emergence period of the latter was halved in one of the two experiments. Celery seeds, the light requirements of which had been satisfied during germination in optimum conditions in the laboratory before they were sown in the field in a gel, gave a 60% plant stand as compared with a stand of 2% from dry seeds.

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1974.tb01371.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

SUMMARYCarbon dioxide exchange of the developing hop cone was measured in field and laboratory experiments. Older cones showed a clear response of CO2exchange to light intensity, indicating photosynthetic activity, but this rarely exceeded respiratory loss. Cones therefore made little photosynthetic contribution to their growth. Young cones showed no response of CO2exchange to light intensity and therefore possessed negligible photosynthetic activity. The initiation of photosynthesis was sudden and coincided with the onset of rapid cone growth and with the response of water loss to light intensity. It is suggested that the maturation of stomata is linked with the initiation of gas exchange.

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1974.tb01372.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

SUMMARYPest damage to sugar beet, including that by birds, has been recorded since 1957. During that time damage by rooks has decreased almost to nil, but some other bird damage has greatly increased, most probably as a result of changing agronomic practices, especially the extensive use of herbicides, the introduction of monogerm seed, and the increasing practice of ‘planting‐to‐a‐stand’. The most severe bird damage in the spring is grazing by several species, and in early summer localized felling of plants by pheasants. Observations in the mid–1960's of causes of seedling and plant losses suggested that birds were then of minor importance; the British Sugar Corporation currently consider that birds are the most serious pest of sugar beet. The distribution of the reported damage does not seem to follow any national pattern. In small‐plot field trials possible repellent materials such as anthraquinone, methiocarb or thiram, applied to seed or foliage, did not decrease the exte

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1974.tb01373.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1974.tb01374.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1974.tb01375.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY