bluuebunny/crossref_metadata_2025 huggingface dataset:
Screening of bacteria for the suppression of Botrytis cinerea and Rhizoctonia solani on lettuce (Lactuca sativa) using leaf disc bioassays
Authors: FIDDAMAN P J , O'NEILL T M , ROSSALL S
Published: July 2006

Two leaf disc bioassays were developed for screening bacteria as putative biological control agents of Botrytis cinerea and Rhizoctonia solani on lettuce. Aerobic spore and non‐spore forming bacteria were isolated from the phylloplane, rhizoplane and rhizosphere of symptom‐free lettuce plants grown in the presence and absence of chitin or composted bark soil amendments. Bacteria, previously isolated from other plants, were also included in the primary screen initially against B. cinerea. One hundred and twenty‐seven of 700 isolates reduced botrytis rotting of lettuce leaves by more than 50% in the primary screen. Following a secondary screen against B. cinerea, the lead 50 isolates were also tested for suppression of R. solani infection. Four isolates significantly reduced both botrytis and rhizoctonia leaf rotting. Eleven and five isolates gave control of botrytis and rhizoctonia, respectively, equal to that given by the standard fungicides Rovral WP (iprodione) and Basilex (tolclofos methyl). The two most effective isolates against B. cinerea and R. solani were both identified as Bacillus subtilis. Use of soil amendments did not increase the proportion of efficacious isolates recovered. Effective isolates were originally recovered from roots of oilseed rape and lettuce leaves. In general, it was found that bacteria which controlled one disease effectively did not control the second disease nearly as well. The bioassay protocols developed in this study were used successfully in screening a large number of bacterial isolates in a short time.
Evaluation of methods of screening strawberry cultivars for resistance to crown rot caused by Phytophthora cactorum
Authors: EIKEMO H , STENSVAND A , TRONSMO A M
Published: July 2006

Four methods were evaluated in measuring resistance of strawberry cultivars to crown rot caused by Phytophthora cactorum. Meristem propagated plants grown in vitro were inoculated with mycelial discs. Four to five days after inoculation, it was possible to distinguish between cultivars with large differences in susceptibility to the disease. Ten days later, all plants were totally necrotic making it impossible to distinguish between cultivars. When detached leaves were inoculated by inoculating a plug of mycelium into the petiole, disease symptoms developed more slowly in resistant cultivars, but leaf age greatly affected the rate of symptom development. When plug plants (not cold stored) were lightly wounded in the rhizome with a scalpel and inoculated with either zoospores or mycelium, differences in disease development between cultivars were mainly as would be expected from previous information on susceptibility, but both age and size of plants influenced the rate of disease development. Unwounded, inoculated plants did not develop symptoms. When cold‐stored plug plants were either unwounded or lightly wounded with a scalpel in the rhizome and inoculated with zoospores, the relative rates of disease development consistently reflected the susceptibility to crown rot. At the time of final assessment, disease was much more severe in wounded plants, but the relative susceptibility of cultivars was not affected by the wounding.
The measurement of multiple spray deposits by sequential application of metal chelate tracers
Authors: MURRAY R A , CROSS J V , RIDOUT M S
Published: July 2006

Chelates of the transition metals copper, cobalt, manganese and zinc, available as foliar feeds, were identified as the most suitable spray tracers for comparisons of deposits arising from up to four sequential applications to a single target. Their use minimised many of the disadvantages associated with other commonly used tracers such as visible and fluorescent dyes, and it was possible to quantify each tracer when present on the target in ratios of up to 100:1. Each spray solution contained a single chelate at a metal concentration of 1 g litre−1. The recovery of metal chelates from plant tissue may not be quantitative, as a consequence of absorption or adsorption by leaves for example. The food colorant tartrazine, at a concentration of 10 g litre−1, was shown to be a suitable internal standard for estimation of percentage recovery. Combined spray deposits were recovered readily from apple leaves and fruit by aqueous extraction and analysed by atomic absorption spectroscopy. The spray deposit of each metal tracer was calculated from the raw analytical data using procedures for generating calibration curves designed to optimise the accuracy of the analysis.
Molecular characterisation and differential diagnosis of a necrotic PVY isolate in tomato
Authors: ROSNER A , LACHMAN A , PEARLSMAN M , MASLENIN L , ANTIGNUS Y
Published: July 2006

A PVY isolate which causes strong necrotic lesions in tomato was isolated and characterised. It did not infect potato and did not react with antiserum specific to the N‐strain of PVY. Restriction endonuclease cleavage patterns of PCR products derived from the 5′‐end of the virus genome (Hinc II and Rsa I) clearly distinguished the tomato, pepper and potato strains. Additional sequence analysis indicated that the tomato and pepper isolates were closely related, while both markedly differed from the necrotic strains of potato. Hence, it was concluded that the necrotic tomato isolate is uniquely specific for tomato.
Suppressing spread of alfalfa mosaic virus in grazed legume pasture swards using insecticides and admixture with grass, and effects of insecticides on numbers of aphids and three other pasture pests
Authors: JONES R A C , FERRIS D G
Published: July 2006

Field experiments were sown with alfalfa mosaic virus (AMV)‐infected or healthy seed of burr medic (Medicago polymorpha) and grazed by sheep. Seed‐infected plants acted as primary sources for virus spread by naturally occurring aphids. Admixture with annual ryegrass (Lolium rigidum), a non‐host of AMV, and different insecticides were used in attempts to suppress virus spread. Sowing swards to provide the ratios 1: 4 and 1: 13 of medic:ryegrass plants diminished AMV spread in medic plants by 23% and 45% respectively. Applications of organophosphorus (demeton‐s‐methyl), carbamate (pirimicarb) and newer generation synthetic pyrethroid (alpha‐cypermethrin) insecticides, all significantly decreased final AMV incidence. Alpha‐cypermethrin was the most effective, suppressing AMV incidence by 87% (two sprays), 79% (one late spray) and 65% (one early spray). Two sprays of demeton‐s‐methyl decreased incidence by only 36%, while two and 2 weekly applications of pirimicarb diminished it by 29–65% and 35–70% respectively. AMV infection of medic seed harvested decreased by up to 76% in sprayed plots. Insecticide treatment did not prevent winged aphids from landing but numbers of wingless Acyrthosiphon kondoi colonising swards were suppressed by up to 92% by spraying with pirimicarb and up to 96% by alpha‐cypermethrin. A. kondoi were much slower to recover with alpha‐cypermethrin than with pirimicarb, the former still significantly diminishing its numbers 35 days after spraying. Alpha‐cypermethrin was also very effective at suppressing Halotydeus destructor and Penthaleus major but not Sminthurus viridis. Greater effectiveness of insecticides in controlling spread of AMV in pasture than has been found previously with non‐persistently aphid‐transmitted viruses in annual crops seems due to the key role played by wingless aphids as virus vectors.
Studies on the local dispersal of the New Zealand flatworm, a predator of earthworms, in Edinburgh between 1993 and 1999
Authors: GIBSON PETER H , COSENS DEREK J
Published: July 2006

The flatwormArtioposthia triangulatawas found, from studies using weighted down plastic sheeting, to move predominantly through the soil rather than over it and to use earthworm burrows. Under compost‐filled plastic sacks the flatworm was most active at night although its numbers were similar to those during the day. The transfer of specimens into an area covered with weighted plastic sheeting had no lasting effect on their numbers. The flatworm was regularly removed over 6 years from under paving stones, sheets of newspaper and cardboard placed on the ground in a garden. The rise and fall of the numbers of the flatworm under this debris suggest a predator‐prey periodicity between the flatworm and earthworms of 3 years.
Susceptibility of the pine processionary caterpillar Thaumetopoea pityocampa (Lepidoptera: Thaumetopoeidae) toward δ‐endotoxins of Bacillus thuringiensis under laboratory conditions
Authors: SHEVELEV A B , BATTISTI A , VOLYNSKAYA A M , INOVIKOVA S , KOSTINA L I , ZALUNIN I A
Published: July 2006

A series of natural crystal proteins from B. thuringiensis subsp. Alesti 12–25, caucasicus, galleriae 11–67, galleriae 6–96, kenyae, and shondungensis and spore‐crystal preparations from finitimus 11–66 and from a recombinant strain of B. thuringiensis subsp. kurstaki expressing Cry 1 Ga1 only, were assessed as a toxic agent for the pine processionary caterpillar, Thaumetopoea pityocampa. Some preparations had a thoroughly investigated composition and contained Cry1Aa, Cry1Ab2, Cry1Ab7, Cry1D, Cry1F, Cry 1 Ga1, Cry9Aa, Cry26 crystal proteins, whereas crystals of B. thuringiensis subsp. caucasicus, kenyae, and shondungensis harboured predominantly unidentified toxins distant from commonly used prototypes.

Bioassays were based on the simultaneous assignment of each treatment to groups of 20 full sibling first‐instar larvae, obtained from broods of a population from North‐western Italy. The toxin was applied to pine needles by the leaf dipping method and the effect was registered in both feeding inhibition and mortality. B. thuringiensis subsp. caucasicus, kenyae, galleriae 6–96, alesti, and galleriae 11–67 gave the best results in terms of both feeding inhibition and larval mortality. Broods tested in B. thuringiensis bioassays showed a substantial variation in susceptibility to the toxins, suggesting the potential development of resistance in the population.
Effects of gamma irradiation on the life stages of yellow flower thrips, Frankliniella schultzei (Trybom) (Thysanoptera: Thripidae)
Authors: YALEMAR JULIANA A , HARA ARNOLD H , SAUL STEPHEN H , JANG ERIC B , MOY JAMES H
Published: July 2006

Irradiation at a minimum absorbed dose of 250 Grays (Gy) has been approved by the USDA as a quarantine treatment for certain fruits in Hawaii to control four species of tephritid fruit flies. Subsequent research must determine whether this dose is sufficient to control other quarantine pests, such as mealybugs, thrips, mites, beetles, moths, and scale insects, on other commodities with export potential that are approved for irradiation treatment for fruit flies. This study demonstrated that irradiation at 250 Gy caused non‐emergence of eggs and pupae, failure of larval development, and sterility of adults of yellow flower thrips, Frankliniella schultzei (Trybom). Adults were the most resistant stage tested, with 100% mortality at 57, 36 and 30 days post‐treatment for the 250, 350 and 400 Gy treatments, respectively. Untreated adults survived up to 66 days. After receiving an irradiation dose of 250 Gy, no one‐ to two‐day old eggs hatched successfully, while 3–4‐day old eggs hatched but did not develop beyond the larval stage. Of the controls, 96.0% of 1–2‐day old eggs and 75.9% of the 3–4‐day old eggs hatched and survived through pupation. No first or second instar larvae treated with a target dose of 250 Gy were able to pupate. When pupae were irradiated at 250 Gy, 37% emerged as adults and all were sterile compared to 88.3% emergence of controls.
Broccoli growth parameters and level of head infestations in simple and mixed plantings: Impact of increased flora diversification
Authors: HOOKS CERRUTI R R , JOHNSON MARSHALL W
Published: July 2006

The impacts of interplanting broccoli, Brassica oleracea var. italica L., with chili pepper, Capsicum annuum L., or yellow sweetclover (YSC), Melilotus officinalis L., on broccoli growth parameters and levels of lepidopteran head infestations were studied during two field seasons (winter & summer). During both seasons, several broccoli growth characteristics (e.g. plant vertical area, whole plant biomass, etc.) were significantly reduced in broccoli‐YSC habitats. However, broccoli heads in broccoli‐YSC habitats did not differ significantly in size from other treatment habitats. Additionally, these heads contained the lowest mean lepidopteran contaminants per broccoli crown during the winter season. During this period, the average number of lepidopteran contaminants per broccoli head was more than twice that in monoculture and pepper intercropped broccoli than in broccoli‐YSC habitats. During the summer experiment, the average number of lepidopteran contaminants per broccoli head was greater in pepper intercropped broccoli than in both monoculture and YSC interplanted broccoli. Potential causes of broccoli growth differences and their relationship to lepidopteran ovipositional behavior are discussed.
Minor modifications to the cry1Ac9 nucleotide sequence are sufficient to generate transgenic plants resistant to Phthorimaea operculella
Authors: BEUNING L L , MITRA D S , MARKWICK N P , GLEAVE A P
Published: July 2006

Minor modifications were made sequentially to the nucleotide sequence of truncated cry1Ac9 to produce cry1Ac9A (one nucleotide change) and then cry1Ac9B (seven nucleotide changes). The derivative genes under the control of the CaMV 35S promoter were transformed into Nicotiana tabacum in order to determine whether these modified genes conferred resistance on the resulting transgenic tobacco plants to larvae of the potato tuber moth (Phthorimaea operculella). Over two trials with PTM larvae on the transgenic plants expressing the cry 1Ac9b gene, lower larval growth, development and survival was evident for most of the lines compared to the control plants. In the second trial, for four of these lines (7, 25, 26 and 28) larval growth rates were very low (0.28, 0.3, 0.42 and 0.28, respectively) compared to the control growth rate (4.18) and leaf damage was minimal. Northern analysis and RT‐PCR analysis showed that higher levels of cry 1Ac9 mRNA were present in the transgenic tobacco lines containing cry 1Ac9b than in the tobacco lines containing cry 1Ac9a. These results suggest that certain minor modifications to the nucleotide sequence of cry 1 Ac9 are sufficient to improve the stability of its mRNA when expressed in tobacco and that this increase in steady state mRNA is sufficient to confer significant resistance to PTM larvae.
Host selection and utilisation of Sonchus oleraceus (Asteraceae) by Helicoverpa armigera (Lepidoptera: Noctuidae): A genetic analysis
Authors: GU H , CAO A , WALTER G H
Published: July 2006

The cotton bollworm (Helicoverpa armigera) prefers the common sowthistle (Sonchus oleraceus L.) to cotton (Gossypium hirsutum L.), sorghum (Sorghum bicolor L.) and maize (Zea mays L.) for oviposition in the field in Australia. Using the common sowthistle and cotton as host plants, we carried out this study to evaluate genetic variation in both oviposition preference and larval growth and genetic correlation between maternal preference and larval performance. There was a significant genetic component of phenotypic variation in both characters, and the heritability of oviposition preference was estimated as 0.602. Helicoverpa armigera larvae survived slightly better and grew significantly faster on common sowthistle than on cotton, but genetic correlation between maternal preference and larval growth performance was not detectable. Instead, larval growth performance on the two hosts changed with families, which renders the interaction between family and host plant significant. As a result, the genetic correlation between mean values of larval growth across the two host species was not different from zero. These results are discussed in the context of the relationship between H. armigera and the common sowthistle and the polyphagous behaviour of this insect in general.
Distinguishing the effects of light and temperature variations on the growth, development, multiplication potential and ex vitro survival rates of in vitro cassava
Authors: JORGE M A B , ROBERTSON A I , MASHINGAIDZE A B , KEOGH E
Published: July 2006

Dissemination of cassava tissue culture plantlets is difficult in the arid tropics due to low eux vitro survival rates. Increased in vitro light intensity has been reported to induce high ex vitro survival rates. The results from earlier experiments suggested that it would be worthwhile to analyse the separate effects of in vitro light and of temperature on the in vitro growth pattern as well as differentiate its relation to ex vitro survival. Accordingly, analysis of a range of in vitro light intensities from 0 to 369 μmol−1 m−2 photosynthetic photon flux density (PPFD) was conducted both with and without fans to control the heat. Temperature proved stable at low PPFD levels but increased above 204 μmol s−1 m−2 when no fans were used. Increased PPFD levels induced larger fresh and dry masses as well as stem thickness. PPFD levels affected the developmental index (senescent leaf numbers) in vitro when it rose above 204 μmol s−1 m−2 PPFD. Raised temperature ranges increased the multiplication index (node numbers) in vitro and ex vitro. It increased root number and leaf development (lobe anatomy). As in vitro temperatures of up to 40°C improve multiplication rates and PPFD levels above 101 μmol s−1 m−2 were detrimental for ex vitro survival (as low as 60%), it is suggested that simpler and less costly laboratories with low light levels and a wide range of temperature tolerance could be successfully established in the tropics for in vitro cleaning and rapidly multiplying crops like cassava.
Impact of soil suppressiveness on various population densities of Heterodera schachtii
Authors: WESTPHAL A , BECKER J O
Published: July 2006

Infectivity of second‐stage juvenile (J2) populations of Heterodera schachtii was assayed with radish.The numbers of J2 in three‐day‐old seedlings were proportional to the numbers of J2 in two differently textured soils.In a microplot trial with a known H.schachtii‐supprcssivc soil, half of the plots contained untreated suppressive soil, the other half contained the same soil, but methyl iodide‐fumigated and therefore conducive.Both soils were infested with cysts introducing the equivalents of 0, 30, 60 or 120 H.schachtii eggs g‐1 soil, kept moist for 2 months, and then planted to Swiss chard.The numbers of J2 in radish roots were proportional to the numbers of H.schachtii eggs introduced into the microplots, at a low level of detection in suppressive soil and at a high level in conducive soil.Growth of Swiss chard was not different at increasing infestation levels in suppressive soil, but growth was reduced in conducive soil proportionally to increasing nematode infestation level.
The incidence of viruses in wild Brassica nigra in Dorset (UK)
Authors: THURSTON M I , PALLETT D W , CORTINA‐BORJA M , EDWARDS M‐L , RAYBOULD A F , COOPER J I
Published: July 2006

Using enzyme‐linked immunosorbent assays, the frequency of occurrence of six viruses was determined in Brassica nigra collected from five coastal sites in Dorset, spanning approximately 24 km. During 1998–2000, the viruses detected were: Turnip mosaic virus (genus Potyvirus) (TuMV), Turnip yellow mosaic virus (genus Tymovirus) (TYMV), Turnip crinkle virus (genus Carmovirus) (TCV), Turnip rosette virus (genus Sobemovirus) (TRoV), Beet western yellows virus (genus Polerovirus) (BWYV) and Cauliflower mosaic virus (genus Caulimovirus) (CaMV). Multiple infections were detected in some individuals (48/447). TuMV was detected infrequently over the three‐year period (5/597). A representative isolate of each virus was tested for its effects on glasshouse‐grown individuals from different half‐sib families of B. nigra from four of the sites. Whether inoculated manually or via aphids (Myzus persicae), TuMV caused a rapid (within 10 days) lethal systemic necrosis in the B. nigra seedlings except when they were near flowering at the time of inoculation. Each of the other viruses invaded systemically but were not lethal. Indeed, BWYV systemically invaded 13/19 glasshouse‐grown B. nigra seedlings but did not produce any visible symptoms. Otherwise, the isolates tested differed in their pathogenicity and in the symptoms they produced in infected B. nigra. With TYMV or TCV viral antigen concentration was closely linked to pathogenicity; for TRoV or CaMV, there was little or no difference in virus concentration between plants with and without symptoms. Substantial and reproducible differences were observed in sensitivity/susceptibility among B. nigra genotypes from different sites in Dorset challenged with the same virus isolate.
Mini‐plot field experiments on slug control using biological and chemical control agents
Authors: JIGLESIAS By , CASTILLEJO J , CASTRO R
Published: July 2006

In three field experiments, the rhabditid nematode Phasmarhabditis hermaphrodita was applied one or more times at the standard rate (3 × 109 ha−1) or half the standard rate to protect crops from slug damage under experimental conditions. Expt 1 was done in a field planted with the ornamental Polygonatum japonica. The treatments were: infective juveniles of the nematode at the standard field rate, metaldehyde pellets at the recommended field rate, and ioxynil (a herbicide with molluscicidal properties) at 90 mg m−2. The treatments were repeated every 2 wk. Arion ater agg. caused most of the damage to P. japonica. There were no significant differences in damage between treatments during the 3 wk after first application, but plants on plots treated with metaldehyde or nematodes had significantly less damage than plants on untreated plots in the fourth and fifth weeks. Expts 2 and 3 were done on the same site, the first with leaf beet and the second with lettuce. The treatments in these experiments were: nematodes applied to the planted area at the standard field rate 3 days prior to planting, with or without previous application of cow manure; nematodes at half standard rate applied twice, 6 days apart, to the planted area or to the surrounding area; metaldehyde pellets and iron phosphate pellets, both applied at the recommended rate to the planted area immediately after planting. In both experiments, the two chemical molluscicides and nematodes applied once to the planted area at the standard field rate without previous application of cow manure, or twice at half standard rate, were able to reduce slug damage. Nematodes applied after manure did not reduce slug damage. None of the treatments reduced the numbers of slugs contaminating the harvested plants. Slug populations were assessed by means of soil sampling before and after Expts 2 and 3. Only after Expt 3 was there a significant effect of treatment on slug numbers, with significantly fewer in metaldehyde treated plots than in untreated plots.
Gene effects for specific leaf area and harvest index in three crosses of groundnut (Arachis hypogaea)
Authors: NIGAM S N , UPADHYAYA H D , CHANDRA S , RAO R C NAGESWARA , WRIGHT G C , REDDY A G S
Published: July 2006

Groundnut productivity is low in the semi‐arid tropics mainly because of drought caused by low and erratic rainfall. Genotypes that have ability to use limited available water efficiently are required to enhance productivity of the crop. In groundnut, water use efficiency (WUE) is correlated with specific leaf area (SLA). The latter can be used as a surrogate trait for selecting for WUE. Partitioning of assimilates as measured by the harvest index (HI) has the greatest effect on pod yield. In order to improve SLA and in turn WUE and HI, a good knowledge of genetic systems controlling the expression of these traits is essential for the choice of an efficient breeding procedure. This study was conducted to investigate inheritance of SLA and HI in three crosses involving Chico, TMV 2 NLM, and ICGV 86031 groundnut genotypes. The study included parents, F1, F2, and backcross generations. Generation means analysis indicated that the additive effects were more important than the dominance effects in the expression of SLA and HI. In addition to additive and dominance effects, additive × additive type of epistasis, which can be fixed in groundnut (a self pollinated crop), was also significant for SLA in all the three and for HI, in two crosses. The selection for SLA and HI can be effective in early generations in some crosses and to exploit the additive × additive type of interaction, it can be done in large populations of later generations.
Discrimination amongst Alliums using an electronic nose
Authors: ABBEY L , AKED J , JOYCE D C
Published: July 2006

Pyruvic acid content determination and, to lesser extents, thiosulphinates determination and organoleptic tests are used for assessing the eating characteristics of onions and other Allium spp. Each of these methods has inherent limitations, especially when large numbers of samples are to be evaluated. With a view to developing a more convenient quality evaluation method, an electronic nose was used to discriminate flavour and aroma characteristics amongst garlic, leek, shallot, bulb onion and spring onion. Differences in relative sensor response to headspace volatiles over macerated samples of these five different Allium types were recorded. Principal Component Analysis (PCA) showed some separation among the five types. PCA and Mahalanobis' D2 statistic suggested similarities in headspace volatiles for shallot, spring and bulb onions and differences for leek and, especially, garlic. Multiple linear regression analyses (Y =α+β1X1+β1X2; N(x, Y)=5) of the first two principal component values (PCA 1 [X1] and PCA 2 [X2]) accounted for not less than 90% of the total variation in pyruvic acid concentration (Y1), total soluble solids content (Y2) and percentage dry matter content (Y3) of the Allium types. These relationships suggest that electronic nose discrimination was on the basis of quality characteristics that relate to Allium flavour. This work has shown that the electronic nose has potential for flavour characteristic‐based discrimination amongst Allium types. Future work will explore this potential within a single Allium spp.
Genetic variation in native and introduced populations of the ‘New Zealand flatworm’, Arthurdendyus triangulatus
Authors: DYNES C , FLEMING C C , MURCHIE A K
Published: July 2006

The internal transcribed spacer regions (ITS1 and ITS2) including the 5.8S region of the ‘New Zealand flatworm’,Arthurdendyus triangulates, are 1004 base pairs in length. Restriction fragment length polymorphism analysis of PCR products (PCR‐RFLP) was conducted onA. triangulatesspecimens from 45 locations in Northern Ireland, Scotland, England and New Zealand. Seven restriction endonucleases(Alu I, Rsa I, Sau3A I, Cfo I, Nde I, Dde I, and Mbo I)were used to reveal intraspecific variation. Analysis of molecular variance revealed the presence of population genetic substructuring, with most genetic heterogeneity present between populations rather than between individuals or geographical regions. No distinct differences were found between Northern Irish and Scottish populations but phylogenetic analysis supports the hypothesis of multiple introductions from New Zealand. There was no significant relationship between genetic distance and geographic distance, as would be expected for natural spread, indicating that this species is largely anthropochorous, even in parts of New Zealand.
Phenological stages of the quince tree (Cydonia oblonga)
Authors: MARTÍNEZ‐VALERO R , MELGAREJO P , SALAZAR D M , MARTÍNEZ R , MARTÍNEZ J J , HERNÁNDEZ FCA
Published: July 2006

As in other temperate species, the quince tree (Cydonia oblonga) shows different phenological stages throughout its vegetative growth period in response to changing temperatures. Two cultivars were studied, and 15 phenological stages were identified during their annual cycle, starting at bud dormancy and ending at leaf fall a year later. The different phenological stages were classified according to the BBCH General Scale and Fleckinger's code. The length of all the stages was measured in days and as cumulative day degrees. This study of the quince tree might aid to prevent and deal with any potential physiological and pathological disorders.
Effects of temperature on germination and hyphal growth from ascospores of A‐group and B‐group Leptosphaeria maculans (phoma stem canker of oilseed rape)
Authors: HUANG Y J , TOSCANO‐UNDERWOOD C , FITT B D L , TODD A D , WEST J S , KOOPMANN B , BALESDENT M H
Published: July 2006

Ascospores of both A‐group and B‐group Leptosphaeria maculans germinated at temperatures from 5–20°C on distilled water agar or detached oilseed rape leaves. After 2 h of incubation on water agar, some A‐group ascospores had germinated at 10–20°C and some B‐group ascospores had germinated at 5–20°C. The percentages of both A‐group and B‐group ascospores that had germinated after 24 h of incubation increased with increasing temperature from 5–20°C. The observed time (Vo50) which elapsed from inoculation until 50% of the spores had germinated was shorter for B‐group than for A‐group ascospores. Germ tube length increased with increasing temperature from 5–20°C for both ascospore groups. Germ tubes from B‐group ascospores were longer than germ tubes from A‐group ascospores at all temperatures tested, but the mean diameter of germ tubes from A‐group ascospores (1.8 μm) was greater than that of those from B‐group ascospores (1.2μm) at 15°C and 20°C. The average number of germ tubes produced from A‐group ascospores (3.8) was greater than that from B‐group ascospores (3.1) after 24 h of incubation at 20°C, on both water agar and leaf surfaces. Germ tubes originated predominantly from interstitial cells or terminal cells of A‐group or B‐group ascospores, respectively, on both water agar and leaf surfaces. Hyphae from A‐group ascospores grew tortuously with extensive branching, whilst those from B‐group ascospores were predominantly long and straight with little branching, whether the ascospores were produced from oilseed rape debris or from crosses between single ascospore isolates, and whether ascospores were germinating on water agar or leaf surfaces.
The effect of date of haulm destruction and harvest on the development of dry rot caused by Fusarium solani var. coeruleum on potato tubers
Authors: CARNEGIE S F , CAMERON A M , HADDON P
Published: July 2006

Over 3 yr, the development of dry rot, caused by Fusarium solani var. coeruleum, and the efficacy of treating potato tubers with imazalil was examined in relation to the date of haulm destruction and harvest, and the interval between haulm destruction using diquat dibromide and harvest. The effect of these factors on skin set was also assessed.

Planting inoculated seed tubers bearing small rots produced more dry rot on the daughter tubers than planting naturally contaminated seed tubers in 1992. The incidence of dry rot was higher on daughter tubers wounded by a standardised method than on those passed over a reciprocating riddle (riddling). The relationship between the two assessment methods was significantly (P<0.05) correlated in 2 out of 3 yr. Overall, the interval between haulm destruction and harvest had less effect on the incidence of dry rot on daughter tubers after riddling than the date of harvest. In 2 out of 3 yr, the incidence of dry rot on riddled tubers was least on those harvested in August and was much greater on September‐harvested tubers. On tubers harvested in October, the pattern was variable, with the incidence declining in 1 yr but increasing in the other. In the third year, the development of dry rot was similar on August‐ and September‐harvested tubers and was least on those harvested in October. Dipping tubers in imazalil gave significant reductions in dry rot although the amount of the reduction was variable and not affected by time of treatment or the amount of fungicide deposited within the range 6.7 to 19.4 mg imazalil kg−1.

Skin set at harvest, as measured by skin strength or the amount of scuff damage, increased the later the tubers were harvested but did not appear to be affected by the interval between haulm destruction and harvest.
Hypersensitive response, cell death and histochemical localisation of hydrogen peroxide in host and non‐host seedlings infected with the downy mildew pathogen Sclerospora graminicola
Authors: KUMUDINI B S , VASANTHI N S , SHETTY H S
Published: July 2006

Hypersensitive response, cell death and release of hydrogen peroxide as measures of host and non‐host defense mechanisms upon inoculation with the downy mildew pathogen Sclerospora graminicola were studied histochemically at the light microscopy level. The materials consisted of coleoptile tissues of the highly susceptible (cv. HB3), highly resistant (cv. IP18293) and induced resistant pearl millet host seedlings and non‐host sorghum (cv. SGMN10/8) and cotyledon of french bean (cv. S9). Resistance up to 80% protection against the downy mildew pathogen was induced in the highly susceptible HB3 cultivar of pearl millet by treating the seeds with 2% aqueous leaf extract of Datura metel for 3 h. Time course study with the pathogen inoculated highly resistant pearl millet cultivar revealed the appearance of hypersensitive response in 20% of seedlings as necrotic spots as early as 2 h after inoculation. In contrast, a similar reaction was observed in the highly susceptible pearl millet cultivar only 8 h after inoculation with the pathogen. In induced resistant seedlings, appearance of hypersensitive response was recorded 4 h after inoculation. Delayed hypersensitive response was observed in both the non‐host species at 10 h after inoculation. Hypersensitive response in the seedlings of the highly resistant pearl millet cultivar 24 h after inoculation showed 100% hypersensitive response, which was not observed in susceptible and non‐host species, although the induced resistant seedlings showed 90% hypersensitive response after that period of time. Cell death in the tissues of the test seedlings was also observed to change with time. Statistical analysis revealed that the tissues of highly resistant pearl millet seedlings required 2.9 h to attain 50% cell death. Tissues of induced resistant and highly susceptible pearl millet seedlings required 4.65 and 6.50 h respectively. In non‐hosts, 50% cell death was not recorded. Quantification of hydrogen peroxide in the tissue periplasmic spaces of the test seedlings revealed 2.94 h as the time required for 50% hydrogen peroxide accumulation in the tissues of highly resistant pearl millet seedlings. Tissues of induced resistant and highly susceptible pearl millet seedlings needed 3.76 and 5.5 h respectively. Fifty percent hydrogen peroxide localisation in non‐hosts could not be recorded. These results suggested the involvement of hydrogen peroxide, cell death and hypersensitive response in pearl millet host defense against S. graminicola.
Strong resistance to potato tuber necrotic ringspot disease in potato induced by transformation with coat protein gene sequences from an NTN isolate of Potato virus Y
Authors: RACMAN DARJA STANIČ , MCGEACHY KARA , REAVY BRIAN , ŠTRUKELJ BORUT , ŽEL JANA , BARKER HUGH
Published: July 2006

The potato cv. Igor is susceptible to infection withPotato virus Y(PVY) and in Slovenia it has been so severely affected with NTN isolates of PVY causing potato tuber necrotic ringspot disease (PTNRD) that its cultivation has ceased. Plants of cv. Igor were transformed with two transgenes that contained coat protein gene sequence of PVYNTN. Both transgenes used PVY sequence in a sense (+) orientation, one in native translational context (N‐CP), and one with a frame‐shift mutation (FS‐CP). Although most transgenic lines were susceptible to infection with PVYNTNand PVYO, several lines showed resistance that could be classified into two types. Following manual or graft inoculation, plants of partially resistant lines developed some symptoms in foliage and tubers, and virus titre in the foliage, estimated by ELISA, was low or undetectable. In highly resistant (R) lines, symptoms did not develop in foliage and on tubers, and virus could not be detected in foliage by ELISA or infectivity assay. Four lines from 34 tested (two N‐CP and two FS‐CP) were R to PVYNTNand PVYOand one additional line was R to PVYO. When cv. Spey was transformed with the same constructs, they did not confer strong resistance to PVYO.
An investigation of biological attributes that may contribute to the importance of Phytophthora capsici as a vegetable pathogen in Florida
Authors: PLOETZ RANDY , HEINE GREGOR , HAYNES JODY , WATSON MARI
Published: July 2006

During the 1999–2000 and 2000–2001 seasons, 19 commercial squash fields in the vicinity of Homestead, Florida (USA) were examined for diseases caused by Phytophthora capsici. In each of the six fields in which two or more isolates of P. capsici were recovered, both the Al and A2 mating types were present, and both mating types were recovered from the same plant five times. Insensitivity to mefenoxam was common among isolates, with EC50s ranging from 5 μg mefenoxam ml−1 to more than 60 μg ml−1. Of 15 weed species that were examined as possible alternative hosts of the pathogen, only common purslane, Portulaca oleracea, was infected by P. capsici. Few or no oospores of the pathogen formed in a glasshouse (c. 28°C) when artificially inoculated pepper plants were covered with plastic bags or kept under continuous mist. In studies in the laboratory (c. 22°C) with detached pepper leaves, no oospores were formed on wire screens over water reservoirs. Consistent production of oospores occurred only when leaves were in constant contact with water. Maximum production occurred at 18°C, and production also occurred at 14°C, 20°C, 24°C and 26°C, but not at 6°C, 12°C, 30°C and 32°C.
Inhibition of the growth of apple pollen tubes by EDTA, surfactants and fungicides
Authors: KÖPCKE D , BAUR P , SCHÖNHERR J
Published: July 2006

The effects of EDTA (ethylene diamine tetraacetic acid), Kresoxim‐methyl, Wettable Sulphur 80 WP and the surfactants Triton X‐100, Triton X‐114, Dehydol TA 5 and Dehydol TA 29 on pollen tube growth of Malus domestica, Borkh. cvs ‘Golden Delicious’ and ‘Mondial Gala’ were determined by image analysis. The ED50 ‐ and ED90 ‐ values (effective doses giving 50% and 90% reduction of growth) of the chemicals, except for the surfactants, were determined.

The selected test substances showed an inhibiting effect on pollen tube growth, with Kresoxim‐methyl being the most active. Surfactants are components of pesticides and they also caused inhibition of pollen tube growth but only at application rates more then 10‐fold higher than typically recommended. Pollen of both apple cultivars were almost equally sensitive to the chemicals.
The effect of genetic transformations for pest resistance on foliar solanidine‐based glycoalkaloids of potato (Solatium tuberosuni)
Authors: BIRCH AN E , GEOGHEGAN I E , GRIFFITHS D W , McNICOL J W
Published: July 2006

Foliage of potato cv. Desiree was harvested from glasshouse‐cultivated plants of five experimental transgenic lines expressing three different insecticidal proteins (snowdrop lectin, Galanthus nivalis agglutinin (GNA); jackbean lectin, Concanavalin A (Con A), cowpea trypsin inhibitor; (CpTi)), tissue‐cultured control plants and standard control (non‐tissue cultured) plants. The foliage was subdivided into stems, upper, middle and lower leaves and analysed separately by HPLC for the solanidine‐based glycoalkaloids a‐solanine and a‐chaconine. The results demonstrate that one or more stages in the plant transformation process (i.e. insecticidal‐ and marker‐gene insertions, gene expression and tissue culture) resulted in a lower level of leaf glycoalkaloids than that found in either the tissue‐cultured controls or standard controls, based on the selected potato lines transformed for insecticidal protein expression. However, the distribution of glycoalkaloids throughout the plant foliage was unaffected by genetic transformation and tissue culture, with the highest glycoalkaloid levels being observed in the top third of the plant. The importance of investigating unexpected effects of genetic engineering on plant secondary metabolism is discussed from an ecological viewpoint.
Phenological growth stages of olive trees (Olea europaea)
Authors: SANZ‐CORTÉS F , MARTINEZ‐CALVO J , BADENES M L , BLEIHOLDER H , HACK H , LLACER G , MEIER U
Published: July 2006

This paper describes the phenological growth stages of olive trees using the BBCH (Biologische Bundesanstalt, Bundessortenamt, Chemische Industrie) scale. Eight principal growth stages for bud, leaf and shoot development, inflorescence emergence, flowering, fruit development, fruit maturity and senescence and 32 secondary growth stages are described. Advantages of the BBCH scale over other methods are discussed.
Effect of Cercospora zeae‐maydis infested maize residue on progress and spread of grey leaf spot of maize in central Uganda
Authors: ASEA G , BIGIRWA G , ADIPALA E , OWERA SAP , PRATT R C , LIPPS P E
Published: July 2006

The spread of grey leaf spot caused by Cercospora zeae‐maydis from infested maize residue on the soil surface and progress over time were studied under tropical conditions at two locations in central Uganda, Kabanyolo and Namulonge, using a susceptible local cultivar, LP16. Infested maize residue collected the previous season was used as the inoculum source in varying amounts; 80% coverage, 40% coverage and 0% soil coverage were used to simulate no tillage, minimum tillage and maximum tillage with complete burial of residues. In all the seasons, disease spread was adequately described by a power law model, whereas disease progress over time was equally well represented by both Gompertz and logistic models. The time factor was highly significant (P < 0.05) for disease development, indicating both increases in disease intensity over time and change in gradients with time. The amount of infested residue on the soil surface in the maize planting was highly significant (P < 0.05) for slope (b) and intercept (a) of the linearised disease gradient. The gradient parameter (b) based on the average for the four directions from the residue source ranged from −0.96 to −0.08 in the second cropping season of 1999, from −2.16 to −0.01 and from −0.87 to −0.03 in the first and second seasons of 2000, respectively. The distance from the infested residue significantly affected foliar disease, but the direction from the residue inoculum source did not, nor was the distance by direction interaction significant. However, interactions between amount of residue and distance were significant. Percentage leaf area affected by grey leaf spot, the areas under disease progress curves and disease intercepts decreased with distance at both locations, but rate of disease increase (r) was generally constant with distance from residue source at Kabanyolo, but not at Namulonge. The relationship between disease severity and amount of residue cover appeared to be affected by the level of background inoculum. At Kabanyolo, where little background inoculum was present, differences were detected in disease severity parameters between the no‐residue plots and residue plots, whereas at Namulonge, where high background levels existed, there was no effect of residue on disease.
Potato cyst nematodes in England and Wales ‐ occurrence and distribution
Authors: MINNIS S T , HAYDOCK P P J , IBRAHIM S K , GROVE I G , EVANS K , RUSSELL M D
Published: July 2006

Potato cyst nematodes (PCN) have been known to occur in the UK for nearly a hundred years. They are the most problematic pests of potatoes and can cause severe yield losses. Previous work has shown the two species, Globodera rostochiensis and G pallida, to be distributed throughout the UK. This paper reports the results of the first structured and statistically unbiased survey undertaken to assess their occurrence and distribution in the potato growing land of England and Wales. The survey showed that PCN were present in 64% of sites sampled. Of the populations found, 67% were G pallida, 8% were G rostochiensis and 25% contained both species. The results show an increase in the incidence of PCN since previous studies were completed and confirm the perceived shift towards G pallida as the predominant species. Of the infestations found, 62% had a population density of less than 10 eggs g−1 soil.
The effect of fungicides, irrigation and plant density on the development of Peronospora sparsa, the cause of downy mildew in rose and blackberry
Authors: O'NEILL T M , PYE D , LOCKE T
Published: July 2006

Downy mildew of rose (Rosa spp.) and blackberry (Rubus fructicosus), caused by Peronospora sparsa, can cause significant losses in production. In a series of experiments, fungicides with different modes of action to the commonly used phenylamide‐based products were examined for efficacy on both crops. Cymoxanil + mancozeb + oxadixyl and fluazinam gave good downy mildew control on both rose and blackberry. On outdoor, container‐grown rose, high volume sprays of fosetyl‐aluminium were also effective, but on young micropropagated blackberry plants, application as a drench treatment was better than as a spray. Good control was also achieved on blackberry with chlorothalonil and with metalaxyl in formulation with either thiram or mancozeb. There was no evidence of loss of control with phenylamide fungicides due to resistance. Irrigation regimes were also examined on blackberry and sub‐irrigation of plants in propagation on a sand bed led to significantly lower disease levels than those found where plants had been irrigated by overhead sprinklers. Reducing the density of container‐grown rose plants had a measurable effect on the progress of downy mildew, though this was small and temporary when compared with the effect of fungicide treatment. Fungicide programmes which gave season‐long control of rose downy mildew resulted in significantly improved extension growth.
The circulative pathway of begomoviruses in the whitefly vector Bemisia tabaci— insights from studies with Tomato yellow leaf curl virus
Authors: CZOSNEK HENRYK , GHANIM MIRIAM , GHANIM MURAD
Published: July 2006

Our current knowledge concerning the transmission of begomoviruses by the whitefly vector Bemisia tabaci is based mainly on research performed on the Tomato yellow leaf curl virus (TYLCV) complex and on a number of viruses originating from the Old World, such as Tomato leaf curl virus, and from the New World, including Abutilon mosaic virus, Tomato mottle virus, and Squash leaf curl virus. In this review we discuss the characteristics of acquisition, transmission and retention of begomoviruses by the whitefly vector, concentrating on the TYLCV complex, based on both published and recent unpublished data.

We describe the cells and organs encountered by begomoviruses in B. tabaci. We show immunolocalisation of TYLCV to the B. tabaci stylet food canal and to the proximal part of the descending midgut, and TYLCV‐specific labelling was also associated with food in the lumen. The microvilli and electron‐dense material in the epithelial cells of the gut wall were also labelled by the anti TYLCV serum, pointing to a possible virus translocation route through the gut wall and to a putative site of long‐term virus storage. We describe the path of begomoviruses in their vector B. tabaci and in the non‐vector whitefly Trialeurodes vaporariorum, and we follow the rate of virus translocation in these insects. We discuss TYLCV transmission between B. tabaci during mating, probably by exchange of haemolymph. We show that following a short acquisition access to infected tomato plants, TYLCV remains associated with the B. tabaci vector for weeks, while the virus is undetectable after a few hours in the non‐vector T. vaporariorum. The implications of the long‐term association of TYLCV with B. tabaci in the light of interactions of the begomovirus with insect receptors are discussed.