bluuebunny/crossref_metadata_2025 huggingface dataset:
Etiology of a gall disease of cocoa in Ghana caused by Calonectria rigidiuscula (Berk. & Br.) Sacc.
Authors: BRUNT A. A. F. , WHARTON A. L.
Published: February 2008

A form or strain of Calonectria rigidiuscula (Berk. & Br.) Sacc. has been shown to be the cause of a gall disease of cocoa (Theobroma cacao L.) in Ghana. Galls were formed only when the pathogen was inoculated into buds, and the disease is not systemic.

Seed is highly susceptible to infection, symptoms usually appearing 12–14 days after inoculation, and a rapid seed inoculation method for testing the pathogenicity of isolates from gall tissue is described. Galls on trees may not develop until many months after inoculation and the full extent of the latent infection period is not known.

Using the same methods of inoculation, the disease could not be reproduced by isolates of the same fungus commonly associated with the disease‐complex referred to as ‘cocoa dieback’.
Fungicidal activity and chemical constitution XI*. The activity of n‐alkyl guanidine acetates
Authors: BYRDE R.J.W. , CLIFFORD D.R. , WOODCOCK D.
Published: February 2008

Thirteen n‐alkyl guanidine acetates were prepared and tested against conidia of Venturia inaequalis. Maximum fungistatic activity was associated with a chain length of 12–15 carbon atoms. Selected members of the series were also tested against conidia of Nectria galligena and in a greenhouse assay against apple mildew, caused by Podosphaera leucotricha. These fungi proved in general more tolerant of the guanidines than was V. inaequalis, but were markedly checked by the n‐dodecyl homologue (dodine acetate).

For comparison, ten n‐alkylamine hydrochlorides were also tested against V. inaequalis, and found to be generally less toxic.
Toxicological studies on a beetle, Alphitobius laevigatus (F.)
Authors: HEWLETT P.S.
Published: February 2008

As a first stage in obtaining information basic to full interpretation of experiments involving topical dosage of insects, relations between quantal response and two dose factors, concentration of toxicant and volume of solution, have been examined.

The test insects, lesser mealworm beetles, Alphitobius laevigatus (F.), were dosed with solutions of n‐valeryl 1,3‐indandione (n‐valone), DDT, dieldrin, and allethrin in a non‐volatile mineral oil, Shell Risella 17. Drops of 0.02‐0.10μl. were shot on to the mesoscutella of the beetles by an improved form of the air‐pulse micro‐drop applicator described by Hewlett (1954a); the beetles were positioned by means of a micromanipulator designed for the purpose. Control over the drop size was better than that by the previous applicator, as shown by an improved version of the immersion method of drop measurement used before. Beetles retained their doses satisfactorily, though transfers of minute quantities of solution between dosed beetles caged together, were shown to be possible. The toxicants appeared to act by contact only. Under certain conditions, which were avoided, the responses of individual beetles dosed with dieldrin or allethrin and caged together were not independent, probably because active beetles disturbed those affected.

The toxicants differed markedly in the signs of poisoning that they produced and in speed of action, though none induced appreciable hyperactivity of the beetles. However, for investigating dose‐response relations, ‘end‐point mortalities’ or a near‐equivalent were determined. Planes for regression of probit response on log concentration and log volume fitted the data satisfactorily. For DDT and allethrin the coefficient for regression on log concentration was significantly higher than that on log volume; for dieldrin the difference was not significant, and for n‐valone the results were variable. The estimate of the LD50 for DDT, in terms of μg. DDT per beetle, was about 50% higher when the DDT was applied in 0.08 μl. of solution than when in 0.02 μl.; the corresponding figure for allethrin was about 30%. The greater toxicity of the more concentrated solutions is discussed.

Houseflies, Musca domestica (susceptible strains), appear to be more susceptible than A. laevigatus to DDT, dieldrin and allethrin.
The absolute efficiency of insect suction traps
Authors: TAYLOR L. R.
Published: February 2008

The ways in which insect size, sampling rate and velocity, and wind speed affect the efficiency of suction traps were measured and an expression obtained to give total efficiency for most insects caught in most traps at most wind speeds. Tables converting log. catch per hour directly into log. density per 106 cu.ft. air, corrected for changes in volume of air sampled and for losses in efficiency under various working conditions, are given for 9, 12, 18, and 30 in. traps.

In an appendix, a net is described that samples isokinetically in high winds and works efficiently as a whirligig trap in low winds.
Insecticidal control of paedogenetic cecid larvae in mushroom beds
Authors: HUSSEY N.W. , WYATT I.J.
Published: February 2008

Loss of about 10% in mushroom yield was demonstrated through infestation by large larval populations of Heteropeza pygmaea Winn., following infestation of the beds soon after spawning.

Experiments are described in which γ‐BHC and aldrin were used to prevent such attacks. These insecticides were tested by incorporation at different rates in the casing and compost, and also by applying emulsions to the surface of the casing on cropping beds. The most successful method was mixing γ‐BHC at 50 p.p.m. in the casing before its application to the beds.
The epidemiology of apple scab (Venturia inaequalis (Cke.) Wint.)
Authors: HIRST J.M. , STEDMAN O.J.
Published: February 2008

The prevalence of Venturia inaequalis ascospores in orchards was compared both in terms of the number of spores per volume of air (dose) and the number produced per area of dead leaf (productivity). The two parameters often gave divergent estimates, probably because dose depends on total leaf per unit area of ground whereas productivity does not. Differences in the amount of dead leaf surviving until bud‐burst in different orchards or years were enough to explain the anomalies and suggested that because earthworms often removed over 90% of the fallen leaves by spring, they exercised an important control of ascospore number.

Assessments of fruit surface scabbed, an accepted way of judging scab control, were not related to ascospore productivity the following spring, but estimates on the percentage of all leaves infected at leaf‐fall were. Other natural variables, like the dates when leaves were formed or fell, seemed of minor importance, especially when compared with effects of earthworms or chemicals. Applying dinitro‐ortho‐cresol to dead leaves in spring decreased the number of ascospores liberated by at least 90% and there is evidence of a similar effect from broadcast ammonium sulphate. The spring and summer spray programmes were also important. Measurements in several orchards during an 8‐year period showed that dose and productivity both declined to less than a hundredth of the highest levels, but in a single wet year productivity in sprayed orchards increased several times and by 40‐fold on unsprayed trees. Ways to prevent high ascospore doses occurring are discussed, together with possible causes of past severe attacks of apple scab at Wisbech.
Some components of the air‐spora in Jamaican banana plantations
Authors: MEREDITH D. S.
Published: February 2008

The air in several Jamaican banana plantations was sampled from July 1960 to September 1961 with an automatic volumetric spore trap. In dry weather, many fungi showed typical diurnal periodicity. Group I fungi (Deightoniella, Nigrospora, Cordana, Corynespora, Zygosporium and Zygophiala) first appeared shortly after 06.00 hr., reached a peak before 09.00 hr. and then showed a rapid fall. Group II fungi (Cladosporium, Alternaria, Curvularia, Cerebella, Pithomyces, Periconiella, Memnoniella, Ustilago and others) and pollens had peak concentrations between 09.00 and 14.00 hr. Groups I and II formed the majority of the spore catch during daylight, but they were practically absent between 20.00 and 06.00 hr. Group III fungi (represented chiefly by ascospores, especially of Leptosphaeria spp., basidiospores and splash‐dispersed types) first appeared near 20.00 hr., attained a maximum between midnight and 06.00 hr. and a minimum during daylight. In dry weather, Cladosporium conidia accounted for 23% of the total catch; coloured fusiform spores for 18%; coloured basidiospores for 16%; unclassified minute spores (including Sporobolomyces) for 14%; and Deightoniella only 0.2%.

During rain, the typical dry‐air‐spora decreased and was replaced to varying extents by group III ascospore types and splash‐dispersed spores. When, after rain, the plantation dried out during daylight, group III fungi decreased while groups I and II briefly reappeared before the typical night‐time flora developed. When rain was continuous during daylight, groups I and II were rare; ascospores and splash‐dispersed spores dominated the traces. All fungi occurred in low concentrations during heavy rain, periods of drought and strong wind. With rain or under‐tree irrigation or both, the following days had varying increases of all group I fungi and certain group II fungi, probably because favourable humidity conditions caused increased sporulation.
Effects on subsequent generations after γ‐irradiation of larvae of Lyctus brunneus (Steph.) (Coleoptera, Lyctidae)
Authors: BLETCHLY J.D.
Published: February 2008

The effects of a single irradiation at 4000 roentgens on larvae of the powder‐post beetle Lyctus brunneus (Steph.) are described. These included a reduced and delayed emergence of the first generation. The number of beetles produced per female returned to normal in subsequent generations. The vigour of emerged beetles as judged by their average weights did not appear to be much affected. Irradiation at a sublethal dosage thus seems unlikely to be a practical method of employing γ‐radiation for the treatment of infestations by wood‐boring insects. One of the chief limiting factors in the employment of lethal dosages for such treatments is the mass of screening required, hence a technique enabling lower dosages to be used would be of value.
The etiology of tulip‐root disease in susceptible and in resistant varieties of oats infested by the stem nematode, Ditylenchus dipsaci (Kühn) Filipjev
Authors: BLAKE C.D.
Published: February 2008

The number of pre‐adult larvae of Ditylenchus dipsaci which invaded seedlings of the oat variety Sun II growing in sand was linearly related to the number of larvae in the inoculum. In seedlings growing on pads, invasion rates were higher but were limited to about 200 nematodes per plant. The respective numbers of larvae invading the susceptible varieties Sun II and Powys and the resistant varieties Manod and Pennant were not significantly different after 3 days. Reproduction occurred in the susceptible varieties, and after 28 days the number of nematodes per plant in the susceptible varieties was about double that in the resistant ones.

When the resistant variety Manod was infested at germination, 32.5% of the seedlings were killed after 14 days compared with 45% of the susceptible variety, Sun II, and this difference was significant at the 5% level. Oat and lucerne seedlings were invaded by larvae of both the lucerne and oat races of D. dipsaci but only in the compatible host did reproduction occur. More larvae invaded the pseudostems of oats than the root systems and this difference was significant at the 0.1% level. The nematode reproduced only in the pseudostems.

A method for classifying plants attacked by stem nematodes is proposed based on the reaction of the tissues and the multiplication of the nematode within them.
The etiology of tulip‐root disease in susceptible and in resistant varieties of oats infested by the stem nematode, Ditylenchus dipsaci (Kühn) Filipjev
Authors: BLAKE C.D.
Published: February 2008

Ditylenchus dipsaci caused cells to enlarge and separate in tissues of the susceptible oat variety, Sun II. Cytoplasm was withdrawn from the cells, the walls of which collapsed to form a cavity around the nematodes. In the resistant variety Manod, separation and hypertrophy were slight, but cytoplasm was withdrawn and cavities formed similar to those in Sun II; hyperplasia or necrosis was not seen.

The body and gonads in nematodes from Manod plants were shorter than from Sun II, but the de Man ratios and the ratio of males to females were the same. Fourth‐stage larvae matured to adults more slowly in Manod seedlings. Nematodes grew by a series of steps caused by alternating periods of slow growth before an ecdysis and rapid growth afterwards. In Manod, D. dipsaci grew more slowly but the form of the growth curve was as in Sun II. Gonads lengthened rapidly and continuously during the late fourth larval and early adult stages and especially during the period before the fourth ecdysis when body length stopped increasing.
Some factors affecting rhododendron bud blast and its control
Authors: HOWELL P.J. , WOOD R.K.S.
Published: February 2008

In studies of the relationship between rhododendron bud blast, caused by Pycnostysanus azaleae, and the leaf hopper Graphocephala coccinea, laboratory experiments provided no conclusive evidence that the fungus entered the bud tissues through the wound produced by oviposition. The primary brown necrotic lesions of the disease were frequently found to contain the insect's eggs.

In the field healthy buds which had been enclosed in muslin to exclude the insect did not become infected. Buds enclosed with the fungus but not the insect showed very few infections. Most infections occurred when both insects and diseased material had been enclosed with the bud. Although the muslin was found not to impede the passage of P. azaleae spores, fewer buds became infected when the insect was enclosed without the diseased material. The possibility that the insects may be contaminated by spores is discussed.

Field trials in 1956/57 and 1957/58 showed that the disease could be reduced both by certain fungicides and by a DDT insecticide. A colloidal sulphur spray was the most effective on Rhododendron var. Prince of Wales in both years and had no apparent phytotoxic effects. Some phytotoxicity was shown by Bordeaux mixture and phenyl mercury acetate sprays.
Mechanical transmission of cocoa swollen‐shoot virus to and from cocoa and other hosts
Authors: BRUNT A.A. , KENTEN R.H.
Published: February 2008

Cocoa swollen‐shoot virus, hitherto transmitted only by mealybugs and grafting, was transmitted mechanically to cocoa from cocoa and eight other hosts. The virus was more readily transmitted from Adansonia digitata L. and Bombax brevicuspe Sprague than from the other hosts and most readily from B. brevicuspe. Transmission rates varied from 0 to 46% and rarely exceeded 5%. With a single exception, infective slurries were prepared only when the extracting fluid (pH 8‐8.5) contained a reducing agent (cysteine, ascorbate, thioglycollate or sulphide) in addition to phosphate.

Only cocoa half‐beans and A. digitata seedlings have been infected mechanically; of these, cocoa half‐beans were the more convenient test material.
The toxicity to rainbow trout of spent still liquors from the distillation of coal
Authors: HERBERT D.W.M.
Published: February 2008

From a survey of the literature on the toxicity of ammonium salts, phenol, cyanide and sulphide to rainbow trout, and from determinations of the toxicity of sodium thiocyanate and sodium thiosulphate, it is postulated that the toxicity of spent still liquors from the distillation of coal should be due mainly to their content of ammonia and monohydric phenols. This is confirmed by experiments showing that the toxicity of an equivalent mixture of ammonium chloride and phenol is nearly as great as that of a spent liquor from a gas works, and that phenol is almost as toxic as mixtures of the monohydric phenols known to be present in such liquors.

Experiments on the effect of pH value, hardness, dissolved‐oxygen concentration and temperature on the threshold concentration of monohydric phenols are described and compared with similar data for ammonia.

Experiments with ammonia and phenols suggest that a mixture of these substances is at its threshold concentration when AS/AT+PS/PT= 1, AS and PS being the concentrations of un‐ionized ammonia and monohydric phenols in solution and AT and PT being the threshold concentrations of these substances when tested individually in the same dilution water. The effect of dissolved‐oxygen concentration on the toxicity of an ammonia‐phenol mixture is examined and compared with the effect of this variable on the individual toxicities of ammonia and phenols.

A method based on these experiments for predicting the toxicity of ammonia‐phenol mixtures from the chemical composition of their solutions is described, and evaluated against laboratory determinations of the toxicity of spent liquors from a coke oven, and against the death or survival of trout held captive in a stream polluted with spent liquor from a gas works. It is concluded that the correspondence between the predicted and observed toxicities is good enough for the method to be used as a basis for assessing whether trout could live in a stream to which a particular spent still liquor was discharged, or when deciding what treatment the effluent should receive to make it safe for such fish after discharge.
Studies on parsnip canker
Authors: CHANNON A. G.
Published: February 2008

Two main types of canker on the shoulders and crowns of parsnips are described, (a) black canker, caused by Itersonilia or Phoma, or both together, and (b) orange‐brown canker, of unknown cause. Black canker is the more common.

A large number of isolates of Itersonilia were obtained from diseased parsnip roots and leaves and from the air within parsnip crops in widely separated localities. The dicaryophase only of these isolates was studied. The majority possessed many chlamydospores and agreed with the descriptions by Olive and by Sowell & Korf of isolates obtained from and pathogenic to parsnips. Although these authors identified such isolates as I. perplexans, the writer considers that they should be regarded as a new species, I. pastinacae. The remainder of the isolates from these sources and a number from other hosts possessed few or no chlamydospores and more closely resembled I. perplexans Derx. Tests showed that I. pastinacae was pathogenic to parsnip roots and leaves, but not to chrystanthemum flowers, while an isolate of I. perplexans pathogenic to chrysanthemums, did not attack parsnips. Of the other isolates resembling I. perplexans, only those obtained from cankered roots were pathogenic to parsnip roots.

A Phoma sp. causing black canker was isolated from parsnips in four out of thirteen localities. In laboratory pathogenicity tests it attacked only parsnips (both seedlings and mature roots), and may thus be different from other Phoma spp. Parsnip foliage was readily infected artificially, but natural leaf infection has not been observed in the field.

Attack by both I. pastinacae and Phoma sp. was enhanced by wounding of the parsnip roots.
Potato haulm resistance to Phytophthora infestans
Authors: LAPWOOD D. H.
Published: February 2008

Haulm susceptibility to Phytophthora infestans (Mont.) de Bary of fourteen widely differing potato varieties was compared in laboratory and field tests with the maincrop variety Majestic as a standard. These two tests gave similar results except that the early varieties Viola and Arran Pilot were more resistant in the laboratory than in the field.

The sequence of infection within the crop canopy was the same in susceptible and resistant varieties, starting first mainly on the lowest leaves on the stem, then the middle and finally the uppermost. This sequence was lost when haulm became prostrate. Varieties differed in the rate that infection spread and leaves were destroyed, some being attacked more rapidly, and others more slowly, than Majestic.

In the field the fungus spored on different varieties as in the laboratory test; the annulus was wide and sporulation intense on susceptible varieties, but narrow and sparse on resistant ones.
A comparison of competitive effects of some common weed species
Authors: WELBANK P. J.
Published: February 2008

In a series of four pot experiments single plants of kale and sugar beet or wheat were grown alone and with sixteen plants of several different weed species for from 7 to 11 weeks. Two levels of nitrogen were included.

The effects of different weeds on dry‐weight growth of the crop plants were used as a measure of their competitive abilities. The results from each experiment were corrected on the basis of the effects of Chenopodium album, which was included as a standard in all experiments. The order of competitive abilities obtained was: with kale, first Sinapis arvensis, then Polygonum convolvulus and Alopecurus myosuroides, then Chenopodium album, Polygonum uviculure and P. persicaria, followed by Matricaria maritima ssp. inodora, and finally Stellaria media, Capsella bursa‐pastoris, Veronica perszca and Anagallis arvensis; with wheat, a similar order, but Polygonum convolvulus had less competitive ability than Alopecurus and about the same as Chenopodium and P. aviculure, and Matricaria had about the same value as Veronica.

The effect of nitrogen on kale and on sugar beet was statistically significant, but on wheat it was significant in only one experiment. Weed effects generally were not significantly decreased by high nitrogen; the effects of Sinapis on kale, and of Chenopodium on wheat were increased, The leaf nitrogen percentage of kale and sugar beet was greatly increased by high nitrogen, but usually only slightly affected by weeds; nitrogen deficiency seems not to have been the sole cause of the weed effects. In two experiments with wheat, although high soil nitrogen increased the leaf nitrogen percentage of plants with weeds, it had little effect on their leaf dry weight, so that competition for nitrogen appeared non‐effective. In a third experiment Alopecurus and Sinapis both appeared to compete with wheat for nitrogen.

In spite of the greater number of weeds per pot, their yields were usually decreased by adding a single indicator plant to their pots. Those weeds were least affected which themselves most reduced the growth of the indicators.

The method used is judged to give results similar to those that might be found in the field, and to have advantages over alternative methods for estimating the relative importance of weeds as competitors of crops.
The response of the feral pigeon when offered the active ingredients of commercial repellents in solution
Authors: DUNCAN C. J.
Published: February 2008

This paper describes the response of the feral pigeon to solutions of the active ingredients of commercial repellents. Among the repellents tested, marked rejection of solutions of β‐naphthol was found.

It is suggested that some commercial repellents may operate by an irritant action rather than by true gustatory repellency.

When offered many of the solutions, the pigeons demonstrated a surprisingly high degree of discriminatory ability.
Eyespot (Cercosporella herpotrichoides) and other factors influencing yield of wheat in the six‐course rotation experiment at Rothamsted (1930‐60)
Authors: GLYNNE MARY D.
Published: February 2008

Yeoman wheat, in the six‐course rotation experiment (potatoes, rye, sugar beet, barley, clover, wheat) at Rothamsted between 1937 and 1960 averaged 34% of straws at harvest infected, 19% severely, with Cercosporella herpotrichoides, the cause of eye‐spot. In different years infected straws ranged from 2 to 99%, which included 1–81% with severe lesions. Straws severely infected increased by about 7% in each succeeding 6‐year cycle, presumably because the amount of infectious material steadily increased. The small amount of eyespot at the beginning of the experiment can be explained by the few cereal crops taken on the land before the experiment began.

The fungus survived 5 years between wheat crops partly on spring‐sown barley and autumn‐sown rye, which (1952‐60) each averaged 8% infected straws, only 2% severely, while wheat had 45 % infected, 27 % severely.

Other factors that probably influenced yield in some years include lodging (which occurred in 10 years, when straw yield or severe eyespot were above average), other diseases and pests, notably wheat bulb fly, weeds and differences in cultivations and treatments.

Mean yield of grain in the 30 years was 28·5 cwt./acre, the maximum 41·1, minimum 18·7. In a neighbouring field, Yeoman wheat, unharmed by soil‐borne diseases and pests and given the same amount of nitrogen (0·6 cwt./acre) yielded about 40 cwt./acre with a year‐to‐year variance of only 5 cwt./acre compared with a range of 19·1 cwt./ acre in the six‐course wheat in the same period (1952‐58), the same weather having different effects on healthy and diseased wheat.

The number of straws per foot row (adjusted to 7 in. spacing) averaged annually 21·3 (maximum 28·0, minimum 14·8). Regression analyses showed that 18% of the variance in grain yield was accounted for by the number of straws and that when the number with severe eyespot lesions was included as a depressing factor, together they accounted for 48%. These figures further indicate that severe infection of all straws would almost halve the yield, and that the mean loss attributable to severe eyespot lesions at harvest (1942‐60) was about 12%.
The predaceous activity of nematode‐trapping fungi added to soil
Authors: COOKE RODERIC C.
Published: February 2008

Predaceous activity of different species of nematode‐trapping fungi introduced into non‐sterile soil varies in both intensity and duration. In some cases free‐living nematode populations increase after the addition of mycelium of these fungi to the soil and in other cases decrease.

Evidence suggests that fungi forming the constricting ring type of trap are more efficient in reducing soil nematode populations than fungi forming adhesive reticulate traps,
Populations of stem‐boring Diptera in leys and in subsequent winter wheat and the effects of aldrin and phorate
Authors: HEARD A. J. , HOPPER M. J.
Published: February 2008

In 1957‐61 stem‐boring larvae were removed for identification from grasses shortly before ploughing in October and from the subsequent crop of wheat. At Hurley populations of up to 700 larvae per sq.yd. including up to 400 Meromyxa spp., 270 Oscinella vastator and 250 O. frit agg. were found in the leys and up to forty larvae per sq.yd. of all species were found in the wheat. Migration of the larvae from the buried grasses into the wheat was associated with soil temperatures above 7·2°C. at 4 in. depth. The larvae occurred in the wheat mainly in February and March.

A survey of twenty‐nine leys in the southern half of England gave an average of eighty larvae, including twenty‐three larvae of O. frit agg., per sq.yd. In wheat grown after the leys there was an average of only two larvae per sq.yd.

Attempts were made to kill the migrating larvae by applying aldrin and phorate dusts to the grassland before ploughing and by applying aldrin granules to the soil surface after establishing the wheat. To ensure different levels of infestation the larval population was doubled on some plots by ploughing in a double layer of turf. The aldrin dust treatment of the grassland killed 70% of the migrating larvae. The aldrin granules and the phorate were less, if at all, effective.
Withertip disease of limes (Citrus aurantifolia) in Zanzibar
Authors: ROBERTS MARGARET F. , MARTIN J. T.
Published: February 2008

Lime leaves (Citrus aurantifolia) of different ages were examined chemically to ascertain the relationship between cuticle development and susceptibility to withertip disease. Marked differences were found in the contents of waxes and cutin between the young susceptible and the older resistant leaves. The rapid rate of deposition of cutin, and the exceptionally high level of deposition attained, indicated that cuticle development was an important factor in the resistance of the older leaves to infection.
Further studies on the biological activity of bulbiformin
Authors: VASUDEVA R. S. , SINGH PRITAM , GUPTA P. K. SEN , MAHMOOD M. , BAJAJ B. S.
Published: February 2008

Amendment of soil with roots of certain leguminous crops, molasses and oil cakes markedly increased the antibiotic production by Bacillus subtilis. A soil amendment consisting of a combination of groundnut cake and molasses was about five times more effective than a dextrose amendment in increasing the production of bulbiformin and also favoured its persistence in the soil. The antibiotic was found to act systemically and to be non‐phytotoxic when taken up by the roots of pigeon pea (Cajunus cajan).

In a pot experiment, inoculation of B. subtilis into autoclaved soil amended with molasses, sweet clover roots and groundnut cake brought about a reduction of 88% in the incidence of pigeon pea wilt caused by Fusarium udum.
The uptake of copper by fungal cells
Authors: SOMERS E.
Published: February 2008

Using 64Cu a quantitative study has been made of the factors influencing the uptake of copper, from buffered solutions of pH 5·6, by conidia of Neurospora crassa. The initial uptake is probably an ion‐exchange reaction which is followed by permeation throughout the cell; there was no evidence of an adsorption process. Copper is considered to be accumulated passively by the spores by unspecific reaction with cell constituents; the process is complicated by the high uptake of dead cells which results in a variable response by the spore population. The apparent activation energy of the initial exchange has been calculated and the competitive effect of other metal ions shown. A small proportion of the copper uptake was inhibited by respiratory poisons whilst increased copper uptake was observed under anaerobic conditions.

The distribution of accumulated copper in disrupted conidia of Alternaria tenuis, N. crassa, and Penicillium italicum has been found to vary with fungal species. Cell walls, particularly of A. tenuis and P. italicum, had a much greater avidity for copper than has been previously supposed. The copper‐binding sites on A. tenuis were more accessible to acid washing, chelation by EDTA, and to radioactive exchange than those on N. crassa. High levels of copper uptake are required for fungicidal action against both these species of fungi and it is suggested that there are different sites of action for the fungistatic and fungicidal processes.
Investigations on fungicides
Authors: WAIN R. L. , SOBÓTKA W. , SPENCER D. M.
Published: February 2008

A series of thiocarbamoylthionitroparaffins of the general formula XC(S)SCH(CCl3)CHRNO2 (where X is a secondary amino grouping and R is hydrogen or methyl), together with other related compounds, were prepared and examined for their ability to inhibit the germination of spores of Botrytis cinerea in vitro. Some of these compounds were notably fungistatic and the two most active were selected for further examination in tests against six other fungi. Their protectant fungicidal activity was also assessed against B. fabae and Uromyces fabae on broad bean and against Erysiphe graminis on wheat and compared with that of two established commercial fungicides. They were found to possess low phytotoxicity and good fungicidal properties and may find specific uses in crop protection.
Changes in the capsule of Papaver somniferum between flowering and maturity
Authors: BUNTING E. S.
Published: February 2008

The changes occurring during ripening in the seed and capsule of Papaver somniferum were examined at Oxford in each of the years 1948‐60.

The percentage content of dry material in the seed increases at a fairly uniform rate and in average seasons reaches a maximum of 85–90 about 7 weeks after flowering. The dry weight of the seed and the content of oil and protein are maximal at least a fortnight before a minimum water content is attained.

The capsule increases very rapidly in size and weight during the first 2 weeks and the volume, fresh weight and dry weight are maximal within 3 weeks of flowering. Subsequently, there is a significant reduction, not only in volume and fresh weight but also in dry weight. When the capsule has a minimum water content the dry weight is 10–15% below the previously recorded maximum. The percentage dry matter content of the capsule shows little increase until 4–6 weeks after flowering; it then falls very rapidly and the maximum percentage value of 80–85 is reached at the same time as in the seed.

The dry and ripe capsule readily absorbs or loses water with changes in ambient conditions, whereas the contained ripe seed exhibits little such variation.

Morphine is accumulated in the capsule until about 6 weeks after flowering but later the content declines. When conditions during ripening are warm and dry the water content of the seed and capsule is nearly minimal when the morphine content in the capsule is maximal. In wet seasons, more than half of the morphine previously accumulated in the capsule may be lost by the time a minimum water content is reached.

Different varieties behave similarly during ripening, but there are marked variations from year to year in the maximum amount of morphine accumulated in the capsule. Although morphine content is usually greater when warm, dry conditions prevail during ripening, there are exceptions, and the complex interrelationships between environment and morphine production need further elucidation.
Post‐treatment effects of sublethal doses of dieldrin on the mosquito Aedes aegypti L
Authors: DUNCAN JOHN
Published: February 2008

Sublethal doses of dieldrin were topically applied to individuals of the mosquito Aedes aegypti L., and the effects on feeding, egg laying and mortality observed. The highest dose of dieldrin (0·0075 μg./insect) stopped the feeding of 2‐ to 3‐day‐old blood‐fed females. Egg laying continued up to 96 hr. after treatment but then dwindled and finally stopped. Lower doses induced diminished responses and the lowest amount of insecticide applied (0·0016 μg./insect) had no effect.

Females (1–2 days old) were treated with 0·0060 μg./insect. Of the survivors, very few fed on subsequent days and only a small number of eggs were laid by them. Dieldrin apparently had no effects on the viability of the progeny from the treated adults.

It is concluded that the insecticide primarily affects feeding; egg laying and longevity suffer as a consequence.
Toxicological studies on a beetle, Alphitobius laevigatus (F.)
Authors: HEWLETT P. S. , GOSTICK K. G.
Published: February 2008

The influence on the toxicity of insecticides of the site of topical application on the insect's body has been studied, with Alphitobius laevigatus beetles as the test insects. Four toxicants, n‐valone (2‐n‐valeryl 1,3‐indandione), DDT, dieldrin, and allethrin were used in solution in a non‐volatile mineral oil, Shell Risella 17 (R17).

To facilitate the interpretation of the results of the toxicity tests, the spread of oil after application to different sites was followed. R 17 oil was marked with a fluorescent material and its spread over beetles was observed under ultra‐violet light. Doses of 0·05 μl. spread over considerable areas of cuticle from most of the sites of application, though doses of 0·02 μl. spread rather less. The greatest spread occurred after dosage between the front coxae, and the least after that on the pronotum. Although the areas of wetted cuticle overlapped following application to different sites, there were possibly quantitative differences in distribution not detectable with the method used. For experimental work applications to the mesoscutellum and hind coxae were the easiest.

Toxicity tests for nine sites of application were done, using fixed doses. During and after treatment on the pronotum, elytron, or tarsi, beetles were held in wire loops to prevent their shedding any of the dose. After treatment on the other sites, the beetles were kept in groups running freely within containers. The site of application influenced slightly but significantly the toxicity of n‐valone DDT, and allethrin, but scarcely at all that of dieldrin. Generally the first three toxicants were most toxic when applied on or near the prothorax.

The toxicities of the applications made to the mesoscutellum and hind coxae were examined in more detail, varying the doses. Pairs of parallel probit‐log‐dose lines fitted satisfactorily responses for the two sites, concentration of toxicant and volume of solution being varied in respective experiments with each toxicant. Combining these results with those from the first paper of this series indicates that the respective probit planes in log‐concentration and log‐volume for the two sites were parallel.

From the toxicity experiments as a whole, it appeared that the toxicant was at most about 1·9 times as effective on the ‘most sensitive’ site as on the ‘least sensitive’.
Field tests of experimental and commercial soil sterilants against the potato‐root eel worm, Heterodera rostochiensis Woll
Authors: PEACHEY J. E. , RAO G. N. , CHAPMAN MARGARET R.
Published: February 2008

Five experiments were made on sandy loam containing 12% clay, infested with potato‐root eelworm. Methyl bromide at 89 g./10 sq.ft. killed most eelworms, induced most increase of ammonia‐nitrogen and gave the largest yield of ware potatoes. Metham‐sodium diluted and mixed into the soil at normal dose (35 ml. active material/10 sq.ft.) and half dose, dazomet at 29 g. active material/10 sq.ft. mixed into the soil and methyl isothiocyanate injected at 23 ml. active material/10 sq.ft. were more effective than injected metham‐sodium or D‐D, except when D‐D was applied at 70 ml./10 sq.ft. to soil at 20° C. Methyl bromide, metham‐sodium, dazomet and methyl isothiocyanate controlled weeds in the weeks immediately following treatment.

Assays of live eggs, hatched larvae, larvae in roots or cysts formed on the root‐mat of potato indicator plants and counts of nematodes free in the soil all selected the same treatment as the most effective. More new cysts formed in the treated plots than in untreated controls because intensive eelworm attack in untreated plots limited root growth and prevented larvae developing into cysts. To produce a good yield of ware potatoes it was necessary to reduce the eelworm population by 90%.

None of the commercial treatments damaged the haulms or tainted the tubers, though spring treatment 7 weeks before planting may have depressed yields slightly. Of many experimental compounds tested, only 1,2,3,‐tribromopropane and chloro‐bromopropene (CBP‐55) were promising.
Fruit‐spot (‘speckle’) of Jamaican bananas caused by Deightoniella torulosa (Syd.) Ellis
Authors: MEREDITH D. S.
Published: February 2008

The severity of banana fruit‐spot (‘speckle’), caused by Deightoniella torulosa, in plantations having abundant leaf trash was greater than in relatively trash‐free plantations. Experimental de‐trashing reduced disease severity to a level at which it ceased to be of commercial importance. Aerial application of fungicides did not control disease, but direct spraying of bunches was effective. Plastic bags put on bunches shortly after ‘shooting’ also provided good control of speckling. Relative costs of various control measures are discussed and associated practical difficulties pointed out. De‐trashing two or three times a year appears to be the cheapest and most practical method.
Stump protection against Fomes annosus
Authors: RISHBETH J.
Published: February 2008

Inoculation of pine stumps with oidia of Peniophora gigantea directly after felling gives good protection against Fomes annosus. With the largest inoculum of F. annosus spores likely to occur naturally, a dosage of 1 × 104oidia suffices for stumps having a wood‐diameter of 16 cm. P. gigantea enters the lateral roots of inoculated stumps and tends to check advance of F. annosus in any tissues infected at the time of felling; it also replaces this fungus to some extent, Lignin is rapidly decomposed and sporophores are generally produced within a year. Suspensions may conveniently be applied by a compressed air sprayer. Owing to the selectivity of freshly cut stumps, contamination of the suspension is not a serious hazard.

If widely used, the method would necessitate large‐scale production of suitable inoculum sources. For most of the experimental work undertaken the inoculum was derived from wood‐block cultures of P. gigantea stored in polythene bags, but for routine use a more compact source would be preferable. A method is described for preparing tablets which, when dissolved in IOO ml. water, yield suspensions containing up to 1 × 106viable oidia per ml.: if kept at 10° C. they should each provide inoculum for more than a hundred stumps over a storage period of 10–20 weeks.

The relative merits of inoculation and chemical treatment for control of F. annosus in pine stumps are briefly discussed and other possible applications of stump inoculation are outlined.
Bacterial canker of stone‐fruits
Authors: CROSSE J. E.
Published: February 2008

Most leaf‐scar infections of cherry trees are caused by bacteria washed from the leaf surfaces in rain. In estimates made from three young orchards in four different seasons the numbers of Pseudomonas mors‐prunorum on the leaf surfaces of the cherry variety Napoleon during the autumn were consistently higher than those on the more resistant variety Roundel, the ratio on occasion exceeding three to one. The amount of leaf surface inoculum and the number of cankers on each variety increased progressively with the age of the trees, but both were unrelated to the severity of leaf‐spot infection, which fluctuated widely from year to year. The possibility of epiphytic growth by the pathogen and the relationship between inoculum potential and ‘field’ resistance of the varieties are discussed.
The effects of nitrogen, phosphorus, potassium and gibberellic acid on leaf area and cell division in Majestic potato
Authors: HUMPHRIES E. C. , FRENCH S. A. W.
Published: February 2008

Potato plants in a factorial experiment with nitrogen, phosphorus and potassium were sprayed with gibberellic acid. Leaf areas were determined at a‐week intervals and cell numbers in some leaves determined. Total leaf area of main‐stem leaves was affected more by nitrogen than by gibberellic acid. The effects of nitrogen and gibberellic acid on maximum size of main‐stem leaves increased acropetally. Mineral nutrients affected lateral‐stem leaves more than main‐stem leaves, because laterals developed after the soil had been depleted of nutrients.

Leaf discs from main‐stem leaves nos. 7, 11 and 15 were macerated with pectinase and ethylene‐diamine‐tetraacetic acid and cells counted. Cell size decreased from leaf to leaf up the stem. Gibberellic acid but none of the mineral nutrients increased cell size. Cell size accounts for only part of the increase in leaf area caused by gibberellic acid, because cell number also increased.

In contrast to its effect in an earlier experiment, gibberellic acid increased dry matter of tubers, perhaps because larger pots were used. Potassium increased total dry matter and net assimilation rate.

In absence of nitrogen gibberellic acid increased the integral of leaf area and time (the leaf‐area duration) but this increase was not associated with increase in yield. With nitrogen most of the difference in leaf‐area duration caused by mineral nutrition was associated with lateral‐stem leaves. There was a linear relationship between leaf‐area duration and dry‐matter yield, and regression coefficients indicated that I g. dry matter was produced by a leaf‐area duration of 3 or 4 dm.2weeks.
Weed populations on arable land after four‐course rotations and after short leys
Authors: HEARD A. J.
Published: February 2008

Using a point‐quadrat, measurements were made of the frequency of the weeds in the stubbles of winter wheat grown after various 3 1/2‐year leys and after two four‐course arable rotations barley, fodder‐beet and barley undersown with a 1‐year ley. The most frequent broad‐leaved weeds were Matricaria maritima var. inodora, Stellaria media and Polygonum aviculare. The total frequency of broad‐leaved weeds was 10% after the arable rotations and 18% after the 3 1/2‐year leys. The corresponding figures for Poa annua were 16 and 25%. These differences probably occurred because the weeds were abundant and set seed during the years of establishment of the 3 1/2year leys.

Some grasses and clovers sown in the leys were common weeds of the wheat. Lolium multiflorum, Trifolium pratense and T. repens showed frequencies of 14–30% after leys in which they had seeded. Lolium perenne re‐established vegetatively; its average frequency was 15% after ryegrass leys. Dactylis glomerata was more easily killed by ploughing.

Defoliation and nitrogen manuring treatments of the leys affected the control of S. media, P. aviculare, T. repens, L. perenne, P. annua and Agropyron repens. The frequency of A. repens was 15% after the arable rotation, whereas after 34‐year leys it was 15% after hayed leys and only 4% after cut leys not receiving nitrogen and after some grazed leys.
Stem‐pitting in Coffea arabica
Authors: SHEFFIELD F. M. L.
Published: February 2008

Although stem‐pitting in Coffea arabica resembles conditions caused by virus infection in some other trees, experiments suggest that in coffee it is not caused by a virus but may be induced by factors that favour rapid growth.
The epidemiology of tomato mosaic III. Cleaning virus from hands and tools
Authors: BROADBENT L.
Published: February 2008

10% Teepol, 2% citric acid, 1% tannic acid, 3% NaH2PO4, 3% Na2HPO4, 0·1%, 0·5%, 1 and 3% Na3PO4 and Diversol (a chlorinated Na,PB, plus bromine) solutions were mixed with tomato sap infected with tomato mosaic virus (TMV) and inoculated to Nicotiana glutinosa, after standing for different lengths of time. Fewest lesions were caused by mixtures with tri‐sodium orthophosphate or Diversol at concentrations over 1%.

It was found difficult to free sap‐cngrained hands from TMV: the best treatment was to wash in a 3% solution of tri‐sodium orthophosphate and then to scrub well with soap and water, but this did not always free under the nails from virus.

The best way to prevent contamination from TMV‐infected tools, other than heat sterilization, was to dip them in 3% tri‐sodium orthophosphate solution and not to rinse this off.
The use of nematicides to control the spread of arabis mosaic virus by Xiphinema diversicaudatum (Micol.)
Authors: HARRISON B. D. , PEACHEY J. E. , WINSLOW R. D.
Published: February 2008

Field experiments on three soil types in southern Britain showed that applying dichloropropane‐dichloropropene (D‐D) or methyl bromide at 2 lb./100 sq.ft. in summer killed over 99% of X. diver sicaudatum in soil and almost stopped the infection of strawberry crops with arabis mosaic virus (AMV). Both chemicals killed X. diversicaudatum down to 28 in., the greatest depth sampled. D‐D at 1 lb./100 sq.ft. gave variable results when applied in summer but was more effective when left in the soil through the winter. At the doses used, dazomet, methyl isothiocyanate, metham‐sodium, dibromochloropropane and tetramethyl thiuram disulphide killed too few X. diversicaudatum to control the spread of AMV.

Incidence of AMV in crops planted on treated land was closely related to the number of surviving X. diversicaudatum. Larvae and adults seemed equally susceptible to the chemicals. In some experiments, other species of plant‐parasitic nematodes were sometimes less affected by D‐D than X. diversicaudatum.

In untreated soil planted with strawberries, numbers of X. diversicaudatum tripled in 2 years, most of the increase coming in the second year. In D‐D treated soil, the few survivors appeared to increase even more slowly than this. A nematicidal treatment that brings the X. diversicaudatum population to fewer than one nematode per 2 1. of soil should not need repeating for several years.