摘要:

SUMMARYThe mushroom sciarid was found to develop on a plant‐derived diet of oat or soya meal. Details of simple rearing techniques and insecticidal assays of treated casing are given. In laboratory tests using ten chemicals, chlorfenvinphos and pirimiphosethyl showed persistent activity against larvae when used at 15 ppm and are suggested as suitable for incorporation in peat‐chalk casing mixtures to give protection throughout cropping. The low figures obtained for phytotoxicity and residues in the crop suggest this technique would be acceptable in commerce. Diazinon remained active in casing for only a short t

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1973.tb01316.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

SUMMARYIn controlled temperature, light and relative humidity,Metopolophium dirhodumandSitobion avenaemultiplied more on young Proctor barley than on Blenda oats, and less on Cappelle wheat.Rhopalosiphum padiincreased in number fastest on barley and slowest on oats. More survived, and generation lengths seemed shorter, on barley forM. dirhodumandS. avenaeand on wheat forR. padi.Tests with young cereals outdoors generally agreed with those in controlled conditions. On mature plants, there were moreM. dirhodumon barley, moreR. padion wheat and moreS. avenaeon oats than on the other cereals.Given a free choice in large cages outdoors, most aphids were found on barley. When allowed to choose between grasses, moreM. dirhodumwere onDactylis glomerata, Poa pratensisandFestuca pratensis, moreR. padionLolium perenneandF. pratensis, and moreS. avenaeonD. glomerataandL. perenne.Most aphids of all species combined were onF. pratensis, LoliumandPhleum, and fewest onFestuca rubraandHolcus mollis.

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1973.tb01317.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

SUMMARYProgeny from different honeybee queens that were reared in, and foraged from, the same colony sometimes differed in their floral preferences, confirming that these are to some extent innately determined.

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1973.tb01318.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

SUMMARYPathogens damage potatoes in so many ways and at so many stages of cropping, transport and storage that it is difficult to estimate their total effect. This paper describes methods used to measure how fungal pathogens affected crop health and yield, and experiments that measured how much the yield lost through gaps was compensated by extra growth of neighbouring plants.Some tubers in stocks were diseased, so healthy controls were not available and contrasts could be made only by selecting grades differing in symptom severity. The differences measured represented only part of the damage because many infections are symptomless, and vigorous plants compensate for the small yields of weak or absent neighbours.Plots gapped randomly to varying degrees at emergence or flowering showed that yields were decreased by 0–332 (± 0–129) %and“833 (± 0–094) % respectively, for every 1 % of plants removed. When up to 24 % of plants were removed the regression of percentage gaps on yield did not become significantly n

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1973.tb01319.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

SUMMARYKing Edward and Majestic seed potatoes selected as ‘clean’ (macroscopically symptomless), moderate and severe according to the extent of skin spot were planted in field experiments at Rothamsted between 1964 and 1968. Usually crops from ‘clean’ and moderately infected seed did not differ detectably in growth or yield. Plants from severely infected seed tubers emerged more slowly, had fewer stems and yielded less (King Edward 20 %, Majestic 13 %). Seed infection also affected tuber size distribution; severely infected seed of King Edward yielded almost 4 tons/acre less of 1 1/4‐2 1/4 in tubers and Majestic, 1 ton/acre less of these and 2 tons/acre less 2 1/4‐3 1/4 in tubers. However, the total yield from diseased seed stocks was only slightly less (King Edward, o‐6 ton/acre and Majestic o‐8 ton/acre) than the yields from the ‘clean’ tubers selected from them. Seed severely infected byOospora pustulansoften increased infection of the progeny tubers, and usually decreased their infection byRhizoctonia solaniand sometimes byHelmintho‐sporium solani.Another series of experiments compared King Edward seed tubers classified according to the number of live eyes showing in March. Seed with one, two, three and more live eyes yielded equally. About half the tubers without live eyes in March eventually produced plants, but late, with few stems and giving only half the yield of seed with three or more live eyes. Surprisingly, the progeny tubers from seed without live eyes were least infected byO. pustulans, R. solaniandH. solani.Progenies of King Edward and Majestic seed from a common source grown on seven widely separated farms were infected more in 1963 than in 1964, but in each year infection differed widely between farms. Often whereO. pustulanswas common,R. solaniwas scarce and vice versa. By contrast, when King Edward stocks very differently infected byO. pustulanswere grown at Rothamsted their progenies were almost uniformly infected byO.

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1973.tb01320.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

SUMMARYThe formation of microsclerotia ofPyrenochaeta lycopersiciSchneider&Gerlach was observed in culture, in isolated tomato root segments and in roots of intact tomato plants. In culture microsclerotia formed in the aerial mycelium, and submerged in the agar; in tomato roots they formed in single cells of the outer cortex.The microsclerotium ofP. lycopersiciis structurally unspecialized and has cell walls of similar thickness throughout. Microsclerotia are thought to have powers of long survival in soil. In isolation the microsclerotia of P.lycopersicimaintained viability over 2 years with consistently high germinability. Transverse hyphae were never seen in sections of microsclerotia, suggesting that germ‐tubes arise from the outermost layers of cell

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1973.tb01321.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

SUMMARYAcyrthosiphon pisumwas a more efficient vector thanMyzus persicaeof bean leaf roll virus (BLRV), but the two species transmitted pea enation mosaic virus (PEMV) equally well and much more often thanMegoura viciae. M. viciaedid not transmit BLRV, andAphis fabaedid not transmit BLRV or PEMV.BLRV and PEMV were transmitted more often by nymphs ofA. pisumthan by adult apterae or alatae that fed on infected plants only as adults, but both viruses were readily transmitted by adults that had developed on infected plants. The shortest time in which nymphs acquired BLRV was 2 h, and 50 % transmitted after an acquisition period of 4 days. Some nymphs acquired PEMV in 30 min and 50% in 8 h. The shortest time for inoculation of BLRV by adults was 15 min, but some transmitted PEMV in probes lasting less than 1 min. The median latent periods of BLRV and PEMV in aphids fed for 12 h on infected plants were, respectively, 105 and 44 h.Clones ofA. pisumdiffered in their ability to transmit BLRV and PEMV, and efficiency in transmitting the two viruses seemed to be unrelated. Some aphids that fed successively on plants infected with each virus transmitted both viruses, and infectivity with one virus did not seem to affect transmission of the other.

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1973.tb01322.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

SUMMARYBean leaf roll virus (BLRV) and pea enation mosaic virus (PEMV) were each transmitted byAcyrthosiphon pisum(Harris) to fifteen of thirty species of legumes in the glasshouse; eleven species were susceptible to both viruses. The only biennial or perennial species infected by BLRV were hop trefoil(Medicago lupulinaL.), lucerne(M. sativaL.) and red clover(Trifolium pratenseL.), but naturally infected sainfoin(Onobrychis viciifoliaScop.) and white clover(T. repensL.) were found. The only perennial species infected with PEMV in the glasshouse was kidney vetch(Anthyllis vulneraria L.).Eggs ofA. pisum, which seems to be the main vector of BLRV and PEMV in England, were found in winter on several species of cultivated perennial legumes, most on lucerne, fewest on white clover. In spring, more viviparae ofA. pisumwere found on lucerne than on other perennial legumes, and many on lucerne, but few on red or white clover, were infective with BLRV. Lucerne is probably the main overwintering source of BLRV in areas where lucerne is common, but elsewhere red and white clovers are probably as important. No aphid collected from perennial legumes between 1965 and 1968 was infective with PEMV, but this virus can overwinter in common vetch(Vicia sativaL.).Lucerne infected with BLRV was usually symptomless or showed only transient mild yellowing of young leaves. Lucerne plants showing vein‐yellowing, similar to that previously reported as a symptom of BLRV, were possibly infected with an aberrant strain of BLRV but more probably with BLRV and another aphid‐transmitted agent. Inoculations from lucerne with vein‐yellowing symptoms sometimes caused vein‐yellowing, and sometimes typical BLRV‐symptoms, in crimson clover(Trifolium inca

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1973.tb01323.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

SUMMARYQuintozene is the only chemical used successfully in practice to control soil‐borneStreptomyces scabies, the cause of potato common scab. However it may be carcinogenic, and the aim of this work was to find a substitute for it.About 100 chemicals, most of which had known fungitoxic action or were related to such chemicals, were tested in the glasshouse by growing potato plants in soil with which the chemicals had been mixed, usually at 50 ppm. Many of the chemicals failed to decrease the incidence of scab, or decreased the yield of tubers, or both. The most effective chemical was captafol, which was as effective as quintozene and, unlike quintozene, did not decrease yield. Captan and folpet, which are very closely related to captafol, were ineffectiv

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1973.tb01324.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

SUMMARYIncorporated in silt or peat loam top‐soil in spring before susceptible potatoes were planted, three carbamoyl oximes, aldicarb, Tirpate (2,4‐dimethyl‐2‐formyl 1‐1,3‐dithiolane oxime iV‐methylcarbamate) and Du Pont 1410 (S‐methyl i‐(dimethylcarbamoyl)‐N‐((methylcarbamoyl) oxy) thioformimidate) and one organophosphate, Nemacur (O‐ethyl‐O‐(3‐methyl‐4‐methylthiophenyl)‐isopropylamidophosphate) all at n‐2 kg a.i./ha greatly increased the yield of tubers and effectively controlled potato cyst‐nematode(Heterodera rostochiensisWoll.). At the same dosage thionazin was as effective in the peat loam but was ineffective in the silt loam; phorate and Mocap (O‐ethyl S,S‐dipropyl phosphorodithioate) were less effective and chlorfenvinphos, diazinon and a coarse granule formulation of fensulphothion were inef

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1973.tb01325.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY