ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1973.tb07295.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

SUMMARYDetailed observations were made of the behaviour ofPhytoseiulus persimiliswhile searching for, identifying and feeding on eggs ofTetranychus urticae.A theory is proposed to explain howP. persimilismay identify prey eggs and distinguish them from non‐prey objects. The existence of a water‐soluble feeding stimulant on prey eggs is postulated.The effect of residues of captan, dinocap and malathion on the feeding behaviour ofP. persimiliswas investigated. Residues of the fungicide dinocap on the eggs of the prey did not affect acceptance by the predator, but captan had a marked repellent effect. Malathion had an even stronger repellent effect.It is suggested that, by making the prey eggs less acceptable to the predator, the use of certain fungicides could render more difficult the prediction of population interactions on which biological control depends.We wish to thank Dr N. W. Hussey of the Glasshouse Crops Research Institute for helpful comments and for supplying predatory mites. Mr Jackson wishes to thank the Overseas Development Administration for financial support during this w

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1973.tb07296.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

SUMMARYWinter eggs ofPanonychus ulmifrom six orchards in Kent showed a range of 3 weeks in the dates of 50 % hatch at field temperatures. From the effects of the duration and temperature of chilling, and the temperature of incubation, it was concluded that samples varied in their chilling requirement, and not in threshold temperatures for development. Diapause was terminated most effectively by chilling initially at ooC (for late‐hatching strains) or 5 followed by 9 for the last month or two. Heritable variation in diapause intensity is discussed in relation to heat sums and the forecasting of hatch, and to phenolog

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1973.tb07297.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

SUMMARYIn 1970‐1,Metopolophium dirhodum, Rhopalosiphum padiandSitobion avenaewere the commonest alatae trapped from April/May to August, with most in July and early August. The first alatae appeared in the Rothamsted survey suction trap 0–34 days before aphids were found on the cereals, but during May and June no relationship was found between the numbers trapped and the number on the crop. Most species occurred first near the sheltered edge of the crop, butM. dirhodumwas widespread over the field. Most infestations were quickly dispersed by the movements of older morphs; adults only stayed in one place for about 2 days. AlateM. dirhodummoved more often than apterae, but both morphs ofS. avenaemoved equally often and more frequently between larvipositions than did those ofM. dirhodum.Apterae deposited more nymphs in a ‘group’ than alatae, andM. dirhodumdeposited more thanS. avenae.Few ‘groups’ persisted for more than a week. AlthoughM. dirhodumoccupied the crop area faster thanS. avenae, all 0–3 m lengths of row sampled being infested within 2–5 wk of their first appearance, most or all of the tillers were colonized only in

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1973.tb07298.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

SUMMARYWhere haulm was left on the soil surface the mycelium ofMycosphaerella pinodeswent through cycles of active saprophytic growth, followed by inactive phases during the earlier parts of the year. Burial at either 15 or 25 cm brought about a decrease in survival with time. The majority of the mycelium was on the outer portions of the stem pieces, with only a small amount of penetration into the plant remains. Experiments on root surface colonization showed that mycelium ofM. pinodeswas capable of growing saprophytically on the host roots in competition with the normal soil microflora.

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1973.tb07299.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

SUMMARYTwo morphologically similar viruses isolated from maize in East Africa induced two distinct symptom types in maize. One, designated maize stripe virus (MSV), showed broad yellow stripes or a yellowing of the entire leaf, acute bending of the shoot apex and severe stunting. The second, maize line virus (MLV), induced continuous, narrow yellow lines along the leaf veins and did not cause apical bending or stunting. MSV and MLV were both transmitted byPeregrinus maidis(Delphacidae), but not byCicadulina mbila(Jassidae) or by sap inoculation.Both viruses were purified by extracting systemically infected leaves in 0–5 M sodium citrate buffer and clarifying with 7 ml n‐butanol/100 ml extract, followed by differential, and finally sucrose density gradient, centrifugation.Partially purified preparations of both viruses contained isometric viruslike particles of two sizes: MSV particles were 35 and 40 nm in diameter with sedimentation coefficients (so2o, w)I09anI0o respectively; MLV particles were 28 and 34 nm in diameter. Antisera prepared against MSV and MLV had dilution end points of 1/128 and 1/64 respectively in agar‐gel diffusion tests.In tests with low‐titre antisera, MSV did not react with MLV antiserum and MLV did not react with MSV antisreum; in the presence of antiserum containing antibodies to both MSV and MLV, the two viruses formed precipitin bands which crossed in the pattern of non‐identity. Maize streak virus and maize mottle virus showed no serological relationship with MSV or MLV.On the basis of particle size and serology MSV and MLV are shown to be two distinct and possibly unrelated viruses.MSV and MLV apparently are dissimilar from any characterized viruses of the

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1973.tb07300.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

SUMMARYBenomyl, pyrazophos (HOE 2873), triarimol, triforine and the non‐systemic fungicide diethyl phthalimidophosphonothionate (Dowco 199) were sprayed atc.200 gal/acre (2250 1/ha) at 14‐day intervals from pink bud (late April/early May) on seven apple cultivars including Cox's Orange Pippin, Golden Delicious and Jonathan. Compared with binapacryl or dino‐cap (and with elemental sulphur on the sulphur‐tolerant cv. Golden Delicious), these compounds were more phytotoxic without substantially or consistently improving the control ofPodosphaera leucotricha;fruit russet was increased and the crop and fruit size of some cultivars were reduced in some trials. In 1969 the inclusion of bis(dimethylthiocarbamoylthio)‐methylarsine (44 ppm) as Urbacid(R)in the sprays reduced russeting by benomyl and Dowco 199 so that these fungicides became as safe as captan on several cultivars; Dowco 199 was also safened by captan (500 ppm). Urbacid(R)(88 ppm a.i.) safened benomyl and triarimol on fewer cultivars in 1970 when russet was less severe. The addition of Urbacid(R)did not prevent yield losses caused by sprays in either year.The crop is most sensitive to spray damage from pink bud until late June. This is a crucial period for the control of mildew, and unless new fungicides are less phytotoxic, palliatives may become necessary

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1973.tb07301.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

SUMMARYA new portable insect suction sampler, powered by a small petrol engine, is described. It has been in use for three seasons, and examples given of samples taken from oil‐seed rape demonstrate that the suction method is more informative than visual counts or sweep‐net sampling for assessing blossom beetle populati

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1973.tb07302.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

SUMMARYWettable powder and emulsifiable concentrate formulations of endosulfan and azinphos‐methyl and an emulsifiable concentrate of malathion were sprayed on oil seed rape in full flower to assess their relative toxicities to foraging honeybees. Endosulfan was very much safer to honeybees than the two organophosphate insecticides, but there was little difference between the two types of formulatio

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1973.tb07303.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

SUMMARYDuring 1970 and 1971 six systemic fungicides were compared as seed dressings and sprays against foliage and root diseases of cereals. The fungicides differed greatly in effectiveness against mildew, loose smut, rusts and eyespot but none controlled take‐all. Effects were also noted on germination, seedling growth and leaf‐surface microfl

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1973.tb07304.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY