摘要:

SUMMARYIn laboratory studies, treating ‘Butternut’ squash (Cucurbita pepo) seeds with ascospores of Chaetomium globosum NRRL 6296 and 6297 reduced oviposition by the bean seed fly Hylemya platura (Meigen), and reduced seed rot caused by Pythium ultimum and P. aphanidermatum. Treatment of seeds with thiram or captan increased oviposition by the bean seed fly. In the field, treatment of snap bean seeds with C. globosum NRRL 6296, or a commercial seed treatment mixture containing captan, diazinon, and streptomycin sulphate, resulted in significantly less damage by bean seed fly larvae than a treatment with thi

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1978.tb02602.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

SUMMARYA technique has been developed for the rapid determination of some species of prey consumed by mites and insects. The method detects prey enzymes within the gut of a predator by polyacrylamide gradient gel electrophoresis and subsequent staining for esterase activity. It is sufficiently sensitive to detect fruit tree red spider mite (Panonychus ulmi) esterases within the gut of a single predacious mite (Typhlodromus pyri) for at least 31 h after feeding. The method has been used to demonstrate feeding relationships among a range of insect and mite predator and prey species in the laboratory and in the field.

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1978.tb02603.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

SUMMARYThe effects of feeding site of Sitobion avenae and Metopolophium dirhodum on grain weight, number and nitrogen content were investigated in the laboratory and in the field. When the latter species was confined to particular leaves in a growth room, grain weight reductions occurred only when the aphid fed on the flag leaf; reductions in percentage grain protein, but not grain weight, followed lower leaf feeding. Leaves which had borne aphids had a higher proportion of nitrogen at death than control leaves, but this explained little of the shortfall in grain nitrogen, which was mainly due to direct removal during aphid feeding.Multiple regressions of grain weight on aphid species/feeding site in the field confirmed the lack of grain weight effects when lower leaves were colonised; because grain size was greatly reduced by aphid feeding, percentage grain nitrogen increased with increasing aphid density in one cultivar and in others was unchanged. Successive comparison of control grain weights with those from tillers bearing an increasing range of aphid densities resulted in a significant reduction in weight with tillers bearing 21 to 25 aphid units on their ear and flag leaf combined, one unit comprising one adult or fourth‐instar aphid or three of earlier instars. These and other factors affecting the nature and extent of cereal aphid damage are discusse

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1978.tb02604.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

SUMMARYThe presence of the internal parasite (Aphidius matricariae) of the aphid Myzus persicae can be identified by electrophoresis, and staining of several enzyme systems, of which malate dehydrogenase is recommended as the most reliable. It is suggested that the technique could be extended to other small insects, and that pest populations can be screened for percentage parasitism as an adjunct to insecticide and integrated control field trials.

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1978.tb02605.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

SUMMARYThe supercooling distribution curves of Myzus persicae varied in response to feeding position, diet and age. Unfed instar I aphids supercooled to temperatures lower than –20 °C. Feeding aphids supercooled to higher temperatures, the earlier instars on subsidiary veins supercooling to lower temperatures than the late instars and adults on the main veins. Starvation decreased supercooling ability in some adult aphids. The supercooling ability of aphids feeding on sucrose solutions through a Parafilm membrane decreased in response to an increasing concentration, the position being reversed on 25% sucrose. Varying the amino acid concentration had no effect. The possible effects of this variable supercooling ability on the winter survival of the aphid are discuss

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1978.tb02606.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

SUMMARYWater‐soluble carbohydrate (WSC) and total nitrogen (N) contents of leaves of field‐grown barley plants were measured in 1966 and 1967. Consistent differences were found between cultivars.The susceptibility of cultivars to leaf blotch was correlated negatively with WSC content and positively with N content at G.S. 10.4. Application of nitrogen fertiliser (which increased N and decreased WSC) also increased the severity of leaf blotch.The occurrence of primary lesions on seedlings does not seem to be affected by their WSC and N contents and the relation between WSC and N contents of leaves and severity of leaf blotch possibly depends on differences in growth and sporulation of the pathogen on substrates containing different amounts of carbohydrate and nitro

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1978.tb02607.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

SUMMARYPlants of two cultivars of winter wheat were inoculated with Pseudocercosporella herpotrichoides at Growth Stage 4 and with Septoria nodorum at Growth Stage 9 or 10.5. Significantly higher levels of S. nodorum developed on the leaves of eyespot infected plants but there was no significant interaction in terms of grain yield. Eyespot infection markedly predisposed the developing seed to infection by S, nodorum.The significance of these results is discussed with reference to the epidemiology of S. nodorum and in relation to the strategy for fungicide control of cereal diseases.

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1978.tb02608.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

SUMMARYOf 43 fungicides tested in vitro, 19 showed strong, seven moderate and 17 weak inhibition of germination of conidia and ascospores of Microcyclus ulei. The formation of lesions on Hevea brasiliensis leaf discs was also suppressed by the first category of fungicides as well as by the five adjuvants tested. Ascospores were not released when perithecia were treated with urea, thiabendazole or alcoholic mercury chloride at 10.00, 0.10, 1.00 g/1 respectively; other fungicides had no such inhibitory effect.In field trials, thiophanate methyl (0.07% a.i.) and benomyl (0.025% a.i.) were most effective in controlling leaf infection, followed by chlorothalonil (0.15% a.i.) and mancozeb (0.32% a.i.). Benomyl suppressed conidial sporulation, whereas one application of thiophanate methyl (0.14% a.i.) to perithecia inhibited ascospore release; half of this concentration applied to conidial lesions or pycnidia caused the perithecia formed subsequently to abort. Thiophanate methyl thus shows promise for SALB control and elimination and benomyl may be valuable as a supplement in later rounds of spraying to control conidial sporulation.After 6 days of showery rain (2 mm for 17 min per day), water collected from sprayed leaves still gave complete inhibition of spore germination. However, inhibition was markedly reduced after 6 days of heavy rain (over 8 mm for 24 min per day).

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1978.tb02609.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

SUMMARYNo spontaneous mutation for tolerance to the fungicide carbendazim was detected in C. 108conidia from each of eight carbendazim‐sensitive field isolates of Botrytis cinerea. Conidia of B. cinerea were highly insensitive to u.v.‐irradiation, although after severe irradiation treatments mutant strains showing the same levels of tolerance as two groups of carbendazim‐tolerant field isolates were selected at frequencies of between 10‐9and 10‐6of survivors. Mutants with low levels of tolerance (ED50>10 μg ml‐1carbendazim; ‘partially‐tolerant’) were selected from irradiated conidia obtained from sensitive field isolates and a further series of mutants capable of growth on 10 000 μg ml‐1carbendazim (‘fully‐tolerant’) were selected from irradiated conidia from either partially‐tolerant mutants or from partially‐tolerant field isolates. Both mutation steps were confirmed in similar experiments in which tolerance to an unrelated fungicide, 2, 6‐dichloro‐4‐nitroaniline (DCNA), was incorporated as a

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1978.tb02610.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

SUMMARYWhen benomyl, drazoxolon, thiabendazole or zineb were applied as soil drenches to established grassland drazoxolon reduced the incidence of rhizoplane fungi. Benomyl and thiabendazole significantly increased yield at one harvest but only benomyl had a significant effect on total yield. When benomyl was applied at monthly intervals from March to July significant increases in total yield were obtained with the June applications which also significantly increased yield at the first harvest in the following year. Repeated applications from March to July also had a significant residual effect on total yield. Yield increases were not significantly affected by increasing the benomyl level from 2.5 to 5.0 g/m2.

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1978.tb02611.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY