摘要:

SUMMARYDepending on their stage of development, treatment of mature larvae ofEphestia kühniellawith a synthetic juvenile hormone resulted in the production of super larvae (which invariably prolonged larval life) and larval‐pupal intermediates. When migrating last‐instar larvae were treated with the juvenile hormone analogues (JHA) ethyl‐3,7, n‐trimethyldodeca‐2,4‐dienoate (ZR512) and isopropyl ii‐methoxy‐3,7, ii‐trimethyldodeca‐2,4‐dienoate (ZR515), larval‐pupal intermediates and pupal mortality were induced. However, when applied topically, ZR515 appeared more effective than ZR512. Both analogues prevented adult emergence when topically applied to the migrating larvae at doses between 28–52 ng. One‐day‐old pupae were most susceptible while older individuals became less sensitive with age. When larvae pupated in corrugated cardboard rolls were treated with ZR512 those of bothE. cautellaandE. kiihniellafailed to emerge. At an estimated dose of 179 ng cm‐2, ZR515 prevented 77‐6%E. cautellaand 100%E. kühniellalarvae from emerging as adults. The control ofEphestiaby JHA treatment

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1975.tb01614.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

SUMMARYGymnosporangium juniperi‐virginianae, the incitant of cedar apple rust, induced the greatest number of lesions (flecks, pycnial lesions, aecial lesions) on 6‐ and 8‐day‐old leaves of single‐shoot potted apple plants inoculated and incubated under controlled conditions. The largest pycnial lesions developed on 2‐ and 4‐day‐old leaves and the largest aecial lesions on 6‐day‐old leaves. The number of lesions was positively correlated with the concentration of basidiospores in the inoculum, but lesion size was constant at different inoculum levels. Elevated inoculum concentrations failed to induce pycnia on cv. McIntosh which normally bears only flecks; very low concentrations induced the development of pycnia but not aecia on cv. Rome Beauty, which normally bears aecia. An ‘infection rating’, log10(10nd2), wherenis the highest number of pycnial lesions per leaf anddis the largest mean diameter of pycnial lesions on any leaf, calculated for four cultivars in greenhouse tests showed a positive correlation with a ‘susceptibility rating’ developed from observations of natural infection of t

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1975.tb01615.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

SUMMARYTen organic amendments were added to unsterile soil which was contaminated 14 days later withCorticium praticolaand sown with lettuce seeds. Substantial increases in final stands of seedlings were obtained with grass meal, bran and wood cellulose. Corn and barley meal, linseed cake and fish meal decreased final stands; molassine meal, potato starch and peptone had relatively little effect. Seedlings grown with wood cellulose were very chlorotic and stunted.Up to 30% of lettuce seeds sown in soil which, 180 days earlier, had been amended with corn meal and contaminated withC. praticolabecame colonized by the fungus. None was colonized in unamended soil or in soil amended with grass meal. Ninety days after amendment and contamination fewer seeds were colonized in soil amended with grass meal than in unamended soil. The amendment of soil with grass meal was as effective as thiram seed treatment in protecting lettuce seedlings againstC. praticolaand grass meal was particularly effective in reducing both the numbers of seedlings attacked and the survival of the fungus in the soil.

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1975.tb01616.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

SUMMARYThe influence of ryegrass mosaic virus (RMV) on yield of perennial ryegrass swards was examined under two harvesting frequencies and at two levels of nitrogen fertilizer, in a field trial planted with a clone of ryegrass, cv. S 321, using small plots established with proportions of healthy and infected plants.RMV reduced the height and the number of tillers of plants grown in pots and reduced the height also of plants in the field.The swards were planted in August and at a harvest 8 wk later RMV reduced the yield from 2–12 to 1–52 t dry matter (d.m.)/ha. In the first full harvest year, RMV caused only a small reduction in yield where no N fertilizer was applied and the application of a very small amount of fertilizer would have recouped the loss. On the other hand RMV severely restricted the increase in yield resulting from heavy dressings of the fertilizer. Thus where 400 kg N/ha was applied, RMV reduced the total annual yield from 18‐6 to 13‐8 t d.m./ha. The effect of the virus was especially great both in the Spring, the period of maximum herbage production, and when the level of fertilizer w

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1975.tb01617.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

SUMMARYThe virulent strain A of cocoa swollen‐shoot virus (CSSV) severely decreased the growth and yield of Amelonado cocoa(Theobroma cacao)trees kept free of capsids(Distantiella theobromaandSahlbergella singularis)and the dieback fungus(Calonectria rigidiuscula)in Ghana. Fifteen per cent of graft‐inoculated Amelonado trees showed symptoms within 4 months, and 48, 80 and 100% within 6, 12 and 20 months, respectively. Infected trees, whether shaded or unshaded, began to decline 6 months after infection, and deteriorated rapidly during the next 27 months by which time 16 % had died and most others were moribund; fertilizer applications had no significant effect on the rate at which infected trees deteriorated. Yields of pods and dry cocoa were greatly reduced 2 yr after infection and were very low after 3 yr; yields were significantly reduced by virus infection but there were no significant further effects of applying fertilizer. These results confirm that CSSV strain A alone is very damaging and often eventually lethal to Amelonado trees in Ghana, and indicate that the conflicting results obtained previously in Ghana and Nigeria were probably due to differences in the virulence of the CSSV strains tested.In contrast, the virus had much less effect on cocoa trees of the Amazon type; only 3% of graft‐inoculated Amazon trees showed symptoms within 4 months, and 43, 84 and 97% after 1, 2 and 3 yr, respectively. Slight deterioration of tree canopies was first detectedc.15 months after infection and, although it continued slowly during the next 21 months, the decline was much less severe than that of Amelonado trees. Yields of both unshaded and shaded trees were apparently reduced by virus infection, but yield losses were much smaller than those of Amelonado trees. These results support the present objectives of controlling the spread of CSSV in Ghana by roguing infected trees, and selecting cultivars with greater tolerance to infection for futur

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1975.tb01618.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

SUMMARYA particle with morphology characteristic of the rhabdovirus group was found in leaf‐dips and thin sections of symptomlessLoliumspp. from several places in Britain. The particle was not transmitted mechanically nor by a number of groups of possible arthropod vectors.Despite the lack of conclusive evidence for the viral nature of the particle its morphology and intracellular localization strongly suggest that it is a member of the rhabdovirus group. This is the first report of such a particle inLoliumspp. and in Gramineae in Britain. The presumed virus is tentatively called ryegrass bacilliform virus (RBV

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1975.tb01619.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

SUMMARYCucumber mosaic (CMV) and alfalfa mosaic (AlfMV) viruses were eradicated or their concentrations greatly diminished when infected meristem tips were grown in static or shake culture at 32 or 34oC. Similar cultures grown at 22oC remained infected. Tobacco mosaic virus (TMV) was not eradicated from shake cultures at 32oC and the concentration of TMV in such cultures at 32oC was sometimes higher than at 22oC.The concentration of CMV and AlfMV was considerably less in cultured tissues than in infected leaf material, but that of TMV was similar. Cultures infected with CMV or TMV grew more slowly than healthy cultures. Growth of AlfMV infected and healthy cultures was similar.

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1975.tb01620.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

SUMMARYA number of bis‐[(i‐formamido‐2,2,2‐trichloro)ethylamino]‐alkanes and their dioxy and dithio analogues were examined for direct and systemic antifungal activity. All compounds showed very lowin vitrofungitoxicity and only slight protectant anti‐mildew activity when applied as a foliar spray. Certain diamino and dioxy derivatives were, however, systemically active against powdery mildew fungi when applied as a root drench to seedlings of wheat or cucumber; the dithio analogues were inactive. The level of systemic activity shown by these compounds was markedly influenced by the nature of the hydrocarbon ‘br

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1975.tb01621.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

SUMMARYA method is described by which a mist of thiabendazole (TBZ) is applied to potato tubers using an ultra low volume sprayer set over rotating rollers. The fungicidal solution (2 % a.i. TBZ) is applied at 2 1/t of potatoes moving through the mist at 50 kg/min.Effective control of gangrene in storage was achieved in laboratory and farm trials.

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1975.tb01622.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

SUMMARYFoliar sprays of benomyl partially protected potted black currant plants from infection with gall mites, whilst soil applications gave complete protection. Soil applications of benomyl, carbendazim and thiophanate‐methyl all gave significant protection against mites under field conditions. Entry of mites into new buds was not affected by these treatments, nor was the transmission of Reversion virus. The main effect of the benzimidazole fungicides is probably on the survival of mites after entry into buds and before gall formation begin

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1975.tb01623.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY