摘要:

SUMMARYIn 1968 when conditions were favourable for the spread of infection (rainfall 243 mm June‐August), halo‐blight of beans initiated from 0.38% primary infection produced 33.8% infected pods but in 1969 (rainfall 112 mm June ‐August+38 mm irrigation water), a similar level of primary infection resulted in only 3.2% infected pods. In both years plant and pod infection were reduced by approximately 90% by sprays of streptomycin sulphate or copper oxychloride (0.1% a.i. 60 gal/acre (675 l/ha)) applied every 10 days from seedling emergence to flowering

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1972.tb04704.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

SUMMARYIn the period from late spring to leaf‐fall (May‐November)Gloeosporium albumOsterw. was regularly isolated from leaves of the apple variety Cox's Orange Pippin affected by the disorder called ‘Cox‐spot’. The fungus grew epiphytically on healthy apple leaves, producing a network of mycelium which developed sporulating pustules when in contact with damaged or moribund tissues.Both the imperfect and perfect stages of the fungus were found on overwintered leaves; isolates from ascospores and conidia proved pathogenic on wood

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1972.tb04705.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

SUMMARYAnalyses of disease progress curves of lettuce drop, caused bySclerotinia minor, indicate that early infected plants sometimes provide inocula for later secondary spread within the crop, there sometimes being evidence of plant‐to‐plant spread. It is suggested that primary infections are attributable to aerially dispersed ascospores, produced by germinating sclerotia which are soil‐borne, and that secondary plant‐to‐plant spread is associated with mycelia

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1972.tb04706.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

SUMMARYGlasshouse experiments are reported, in which the development of young wheat and barley plants was examined following inoculation withOphiobolus graminis(Sacc.) Sacc. The dry weight, leaf area, tiller number and water content of the shoot were reduced by infection. Reductions were equally severe in wheat and barley. The seminal root system of both was severely attacked and its growth retarded. Inoculated plants, however, translocated a greater proportion of their total assimilates to the root system and produced more adventitious roots than healthy plants. As a result there was an increase in both the number and proportion of healthy roots on these plants following the initial infection of their root systems. This effect was more pronounced in barley than in wheat. It is suggested that this may in part account for the reported relative tolerance of barley to take‐all attack under field condition

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1972.tb04707.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

SUMMARYPlant debris, naturaiiy infested with the take‐all fungus (Ophiobolus graminis), was washed from soil and added to a leached sandy loam, deficient in nitrate nitrogen (NO3‐N) and magnesium. Nutrient solutions containing potassium and phosphorus, with and without magnesium, were added to the amended soil unsupplemented, or with either NO3‐N, ammonium nitrogen (NH4+‐N), or both. Nitrification of NH4+‐N was inhibited by 2–chloro‐6–(trichloromethy1)‐pyridine (N‐Serve). After 38 days at 19°C, fewer plants had take‐all with N (75 or 100 mg/kg soil) than without and root systems were most discoloured and had most diseased axes when nutrients were not added. Plants given NH4+‐N developed less take‐all when magnesium was present. A comparison of forms of N in the presence of added magnesium showed that take‐all was least with a mixture of both forms of N, intermediate with NO3‐N alone and worst with NH4+‐N alone. The most extensive lesions on individual root axes occurred on plants given NH4+‐N. It is suggested that take‐all will be least when the amounts and ratio of NH4+‐N and NO3‐

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1972.tb04708.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

SUMMARYFrom a study of forty compounds related to the systemic fungicideN,N'‐bis(1–formamido‐2,2,2–trichloroethyl)‐piperazine, known as triforine (CELAW524), it was found that a new compound,N‐(2,2,2–trichloro‐1–methoxyethyl)‐formamide, controlsErysiphe graminison wheat when applied to the roots in sand. A number ofN‐(2,2,2–trichloro‐1–aryloxyethyl)‐form‐amides and alkylN‐(2,2,2–trichloro‐1–arylaminoethyl)‐carbamates protect broad beans againstUromyces fabaeand wheat againstErysiphe graminis; some of these formamides show sl

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1972.tb04709.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

SUMMARYWhen dried on leaves, aqueous suspensions of copper oxychloride and of kaolin damaged the leaves similarly. With both, the damage was correlated with the rate the leaves lost water, which increased as the size of the suspended particles of copper oxychloride decreased. The damage seemed to arise mainly from a physical effect of the particles and not from copper reacting chemically.

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1972.tb04710.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

SUMMARYThe life‐histories of four enchytraeid worms,Lumbricillus rivalis, Enchy‐traeus coronatus, E. buchholzi, andE. albiduswhich occur in sewage percolating filters, were studied under laboratory conditions at8, 15 and 20°C.The number of ova per cocoon varied from 0 to 50 (L. rivalis), 0 to 33 (E. coronatus), 1 to 9 (E. buchholzi) and 0 to 22 (E. albidus). The mean number of ova per cocoon was highest at 15°C for all species exceptE. coronatuswhich had a highest mean value at 8°C. The number of ova in cocoons was correlated with cocoon length (P<0.001) for all species.Cocoon production usually increased with temperature ranging from 0.8 cocoons per adult per week at 8°C to 2.0 at 20°C forL. rivalis, and from 1–4 to about 2.6 forE. coronatusandE. buchholzi.The total number of ova produced by eachE. coronatus(350 at 8°C to 550 at 20°C) was similar to that produced by eachL. rivalis(600 at 8°C to 350 at 20°C) and was about five times greater than the total numbers produced by the other two species. Cocoon and ova production and the number of ova per cocoon varied with the age of the adult, usually reaching a peak soon after maturity.Hatching success was low and generally 40–50%of ova failed to develop; subsequent mortality among immature worms was about 10–20%.Growth was more rapid at the higher temperatures;L. rivalismatured in about 26 days at 20°C, the clitellum forming when the worm was 13–14 mm long; data for the other species are 13 days and 5–6 mm (E. coronatus);16 days and 3–4 mm (E. buchholzi);28 days and 13–14 mm (E. albidus). The maturation period at 8°C was at least twice that at 20°C.The generation period (cocoon to cocoon) was about a month at 20°C for all species exceptE. albidus(2 months), but as some species had longer reproductive periods than others the actual number of generations per year was highest inE. buchholzi, 7.0 per year, and lowest inE. albidus, about 3.3 per year, At 8°C all four species had between 1.4 and 2.8 generations a year.A comparison of expected and observed population densities ofL. rivalisandE. coronatusin a sewage percolating filter showed that neither achieved values approaching their potential summer densities although ample food was apparently available.Of the four species studied onlyE. buchholziprod

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1972.tb04711.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY