East Mailing Research Articles

Overwintering of Venturia inaequalis the causal agent of apple scab in relation to weather

SUMMARYApple leaves collected at East Mailing and bearing colonies of Venturia inaequalis were exposed outdoors from November 1978 to May 1979 at 12 United Kingdom sites. Pseudothecial development and abundance were recorded from samples returned to East Mailing every 2 wk. Pseudothecia matured most rapidly with high rainfall in November and high temperatures in spring. Mature pseudothecia were most abundant with low temperatures in November and low rainfall in spring. In 1979‐80 a cross‐over experiment, in which scabbed leaves spent either November‐January or February‐April at a common site, and the other half of the winter at one of five sites, demonstrated the separate effects of weather following leaf‐fall and in the spring. Equations for forecasting the time to pseudothecial maturity, but not the numbers of mature pseudothecia, were obtained.Experiments in controlled environments demonstrated the importance of low temperature and high moisture for initiation and early development of pseudothecia, but a controlled increase of temperature in the spring did not result in faster rates of maturation compared with lower temperatures outdoors. Ascospore production from leaves kept in controlled environments in spring was consistently lower than from leaves kept outside.

Raspberry bushy dwarf virus and field infection of Mailing Jewel

Plant PathologyVolume 32, Issue 3 p. 357-359 Raspberry bushy dwarf virus and field infection of Mailing Jewel S. C. WILSON, S. C. WILSON East Mailing Research Station, Maidstone, Kent ME19 6BJ, U.K.Search for more papers by this authorV. H. KNIGHT, V. H. KNIGHT East Mailing Research Station, Maidstone, Kent ME19 6BJ, U.K.Search for more papers by this authorD. J. BARBARA, D. J. BARBARA East Mailing Research Station, Maidstone, Kent ME19 6BJ, U.K.Search for more papers by this author S. C. WILSON, S. C. WILSON East Mailing Research Station, Maidstone, Kent ME19 6BJ, U.K.Search for more papers by this authorV. H. KNIGHT, V. H. KNIGHT East Mailing Research Station, Maidstone, Kent ME19 6BJ, U.K.Search for more papers by this authorD. J. BARBARA, D. J. BARBARA East Mailing Research Station, Maidstone, Kent ME19 6BJ, U.K.Search for more papers by this author First published: September 1983 https://doi.org/10.1111/j.1365-3059.1983.tb02846.xCitations: 6AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Citing Literature Volume32, Issue3September 1983Pages 357-359 RelatedInformation

The effect of donor species used in breeding on juice quality of black currants (Ribes nigrumL.)

SummarySpecies closely related to Ribes nigrum, R. dikuscha and R. bracteosum, and the less closely related species, R. grossularia, have been used as donors of agronomic characters in the black currant breeding programme at East Mailing. The effects of these species on the flavour, colour and ascorbic acid content of juices made from their seedling derivatives were investigated. Early backcross derivatives on average were inferior to the standard processing cv Baldwin, especially with regard to flavour, but which further backcrossing the proportion of individually acceptable seedlings has in general increased. Progress towards black currant quality has been slower in R. grossularia, lines than in R. dikuscha or R. bracteosum derivatives. By BC3 or BC4, selections with juice of commercial quality were obtained in lines derived from each donor species.

The response of black currant cultivars and selections to spring frost

SummaryRepeated night frosts at East Mailing in March and April 1977 severely damaged Baldwin, Greens Black, Tor Cross, Wellington XXX and other early-and midseason-flowering black currant cultivars. Damage to the late-flowering cvs Amos Black, Black Reward, Consort, ‘Mailing’ Jet, and Seabrook’s Black was graded very slight, moderate, slight, slight and severe, respectively. Selections in several progenies, covering a range in flowering seasons from very early to very late, showed from nil to slight damage. Frost room tests on single node cuttings indicated that some of these selections carried intrinsic frost resistance comparable with that of cv Ben Lomond. In certain selections this was combined with late flowering for frost avoidance. The mean percentage kill of buds plus flowers in the frost room was closely correlated with the rate of cooling. The results obtained suggested that a cooling rate of about —0.025°C min-1 with a minimum temperature of —3.25° B would differentiate satisfactorily between ...

Crown rot (Phytophthora cactorum) in glasshouse‐grown strawberries at East Mailing Research Station

SUMMARYFrom 1973 to 1977 the spread of crown rot (Phytophthora cactorum(Leb. & Cohn) Schroet.) in glasshouse‐grown strawberries at East Malling Research Station (EMRS) threatened to disrupt the production of virus‐tested stocks. An eradication programme involving trickle irrigation of plants, rooting ranners above the level of mother plants, regular inspection for disease and routine tests for latent infection, special precautions at repotting and annual renewal of mother plants eliminated the disease in two years, except in a quarantine house containing new importations.Isolates of P. cactorum from strawberry plants and apple trees were moderately or highly virulent to their original hosts but caused only latent infection or limited necrosis in reciprocal inoculations. This supports the separation of the strains commonly attacking these hosts as distinct pathotypes. The evidence suggests that crown rot entered the strawberry stocks at EMRS with infected introduced plants and not from local field sources.

Disease measurement in a study of apple scab epidemics

SUMMARYAn epidemic of apple scab in an unsprayed planting at East Mailing was monitored during the summer of 1979. Different rates and patterns of scab development on six apple cultivars were observed. Of several disease measures investigated the number of colonies/extension shoot best represented the epidemic.More comprehensive disease measurements on leaves, fruits and shoots were made toward the end of the summer. Cultivar differences were demonstrated for all disease measures investigated. The proportion of leaves with scab (incidence) and the number of colonies on leaves (intensity) were the measures with the lowest coefficients of variation. Consistent relationships between incidence and intensity were obtained.The implications of these findings for studies concerned with fungicide evaluation, cultivar susceptibility, disease—quality loss relationships and monitoring for disease management are discussed.

Growth and development of bush tomatoes in relation to temperature

SUMMARYData are presented relating various stages of growth of field-grown bush tomatoes cv. Sleaford Abundance established from dry and pre-germinated seeds and from transplants to accumulated day-degrees. In general, Ontario units predicted the dates of 50% flowering, of the first harvest and the date when 37·5 t/ha of ripe fruit had been picked, more accurately than day-degrees above 10 °C or calendar days. The number of Ontario units from sowing to 50% flowering for dry and pre-germinated seeds were 956 ± 35 and 871 ± 85, respectively. The corresponding figures from sowing to first harvest were 1958 ± 59 and 1867 ± 85. For transplanted crops the number of Ontario units from planting to 50 % flowering and from planting to first harvest were 322 ± 62 and 1352 ± 133, respectively. For transplanted crops the number of Ontario units required to give a yield of ripe fruit of 37·5 t/ha (the minimum level currently necessary on economic grounds for tomatoes for processing) was 1937 ± 112. Using this figure in conjunction with long-term meteorological records it was estimated that crops established from transplants at East Mailing, Kent (latitude 51° N), would fail to give yields of ripe fruit of 37·5 t/ha by late September on only 1–6 occasions in 100 whereas at Wellesbourne, Warwickshire (52° N) and Warsop, Nottinghamshire (53° N) crops would fail to reach this yield on 13–53 occasions in 100. Crops established directly from seeds would fail to give this yield on more than 50 occasions in 100 at all three sites.

Criteria for Assessing the Accuracy of the Pyrone Fluorimetric Assay for Indole-3-acetic Acid

The effects of scattered light and the presence of contaminating fluorophores on the sensitivity and accuracy of the pyrone fluorimetric assay for indole-3-acetic acid (IAA) were investigated. With extracts from plant tissues sources of ambiguity in the fluorescence measurements were established. Criteria, based on the fluorescence spectra and kinetics of change of fluorescence intensity of the pyrone derivative, are presented for assessing the accuracy of IAA estimations using this technique. INTRODUCTION The reaction of indole-3-acetic acid (IAA) with acetic anhydride to form the fluorescent derivative 2-methylindolo-2,3:3',4'-pyr-6-one (2-MIP) provides, in principle, a straightforward estimation of nanogram levels of IAA in partially purified plant extracts (Stoessl and Venis, 1970; Knegt and Bruinsma, 1973). Recent investigations, however, have shown that the reaction is not specific for IAA, but rather exhibits a selectivity for a range of acidic and neutral indole compounds that possess a C3-methylene side-chain (Boettger, Engvild, and Kaiser, 1978; Mousdale, Butcher, and Powell, 1978). In addition, measurements can be seriously distorted by light-scattering effects caused by uncharacterized compo nents present in IAA-containing fractions purified from plant tissue extracts (Eliasson, Stromquist, and Tillberg, 1976; Kamisaka and Larsen, 1977; Mousdale et al., 1978). In view of these findings, the investigation of the accuracy of the pyrone fluorimetric assay was deemed necessary, and resulting detailed criteria for assessing the accuracy of assay measurements are described. MATERIALS AND METHODS Fruit and vegetative tissue samples from apple (Malus domestica Borkh. rootstock M.9 and cv. 'James Grieve' on rootstock M. 26), plum (Prunus domestica L. cv. 'Victoria'), and broad-leaved lime (Tilia platyphyllos Scop.) were collected from both conventional orchard and hedgerow-grown trees at East Mailing Research Station. Freeze-dried material of apple (cv. 'Miller's Seedling') leaf and tobacco (Nicotiana tabacum L. cv. 'Xanthi-nc') stem were provided by Dr. R. M. Fulford (Physiology Department, East Mailing) and Dr. A. Cassells (Department of Horticulture, Wye College, University of London), respectively. Methods for the extraction and purification of IAA from plant tissues and for the fluorescence measurements were as previously described (Mousdale et This content downloaded from 207.46.13.111 on Tue, 09 Aug 2016 06:29:58 UTC All use subject to http://about.jstor.org/terms 516 Mous dale—Fluorimetric 1AA Assay ai, 1978). Fluore scene; spectra were recorded with a Baird-Atomic (Braintree, U.K.) 'Fluoripoint' spectrofluorimeter fitted with a high-intensity Xenon light source; excitation and emission monochromator band widths were 10 nm. Absorption measurements were made with a Pye Unicam (Cambridge, U.K.) model SP8-100 spectrophotometer. IAA (free-acid form) was purchased from Sigma, London, Chemicals Ltd., Poole, U.K.; acetic anhydride (Analar grade) from Fisons Ltd., Loughborough, U.K.; and trifluoroacetic acid (Special for Spectroscopy grade) from British Drug Houses Ltd., Poole, U.K. RESULTS Precision of fluorescence measurements The effects of sampling and other random errors on the accuracy of the assay were tested using nanogram and sub-nanogram quantities of IAA. The major factor limiting accuracy was found to be a transient light-scattering which occurred when reaction mixtures containing trifluoroacetic acid as catalyst were diluted with distilled water to terminate the reaction (Fig. 1). This effect was caused by the formation of fine bubbles in the solution, and could be eliminated by delaying the start of the emission spectrum scanning procedure until 1-5 min after adding water to the reaction mixture. With this precaution, sub-nanogram quantities of IAA could be detected with good reproducibility and with a linear relation between fluorescence intens ity and quantity of IAA reacted (Table 1). Contributions from other fluorophores 2-MIP has characteristic fluorescence excitation and emission spectra (Mousdale et al., 1978). Identical emission spectra and similar excitation spectra were recorded when applying the assay to IAA-containing fractions from plant tissue extracts (Table 2). However, with the exception of the tobacco tissue

The effects of environment and cultural practices on calcium concentration in the apple fruit

Abstract Calcium concentrations in bulked samples of randomly selected apples from field trials are dependent on orchard environment and management in addition to nutrition. Concentrations in individuals within each sample vary widely and adequate numbers of fruit must be analysed to detect the relatively small changes in mean concentrations induced by orchard treatments. Since there is an inverse curvilinear relationship between calcium concentrations and mean mass per apple (average curves may differ according to scion cultivar), concentrations can be altered by factors affecting fruit size. Hence, excessive thinning or irrigation can lower calcium concentration and, at East Mailing, manurial (N, P, K) and soil management treatments have had little effect other than via fruit size. Significant deviations from the average curve can occur as a consequence of weather conditions during the growing period and sometimes because of biennial tendencies. Soil applications of calcium sulphate, of sodium nitrate l...

ScreeningPrunusRootstocks for Resistance to Bacterial Canker, Caused byPseudomonas Morsprunorum

SummaryNew clonal cherry rootstocks selected at East Mailing Research Station were assessed for resistance to bacterial canker. Resistance was not stable at the seedling stage, and trees should be assessed when not less than three years old. Variation in soil conditions markedly affected the response of the rootstock. When a new race of P. morsprunorum was included in the tests many rootstocks were equally resistant to both this and the typical race, but a few hybrid rootstocks had very low resistance to the former. Plum trials under more uniform conditions gave less variable results, but seasonal and other factors induced some variation between inoculations of one year and another, and between inoculations and natural infections.

Integrated pest and disease management: Towards a more rational use of pesticides in orchard management, East Mailing Research Station, UK, April 1978

Integrated pest and disease management: Towards a more rational use of pesticides in orchard management, East Mailing Research Station, UK, April 1978

A bacteriophage specific to race 2 of the cherry strain of Pseudomonas morsprunorum

SUMMARYThe isolation and characterisation of a bacteriophage specific to the recently described race 2 of the cherry strain of Pseudomonas morsprunorum in England is described. The phage was subsequently used in a survey of P. morsprunorum races in commercial orchards and on the cherry cultivars Napoleon and Roundel at East Mailing Research Station.

リンゴわい性台木の根ざし増殖に関する研究

1. Root cutting was evaluated as a commercial propagation technique of the dwarf apple stock cv. East Mailing VII by examining the histological aspects and physiological traits of the cutting material.2. All the cutting material produced adventitious buds and roots regardless of its size (both length and diameter) and sampling location on the root system. However, consistent formation of these organs was achieved only when root pieces more than 10cm in length were used.3. Nursery stocks were produced more efficiently by root cutting than by either traditional mound layering or modified bowed-branch layering.4. Adventitious bud primordia became differentiated in the cortex of root pieces as the regeneration of cutting material progressed. The cells of bud primordia were smaller than those of ordinary parenchyma and distinguishable morphologically from the surrounding tissues. They could be classified arbitrarily into five categories, each corresponding to their developmental stage.5. Adventitious bud formation was stimulated by the pretreatment of cutting material with 50ppm 6-benzylamino purine solution. By paper chromatography, the extract from the cutting pieces showed considerably high cytokinin activity in the same zone as zeatin. The activity gradually increased until adventitious bud primordia manifested themselves, though it was suppressed in the cutting pieces where bud primordium failed to differentiate. Thus, it was suggested that there is a close relationship between bud formation and cytokinin activity of the cutting material.

Weather and fireblight in England

Annals of Applied BiologyVolume 84, Issue 2 p. 275-275 Weather and fireblight in England E. Billing, E. Billing East Mailing Research Station, Maidstone, KentSearch for more papers by this author E. Billing, E. Billing East Mailing Research Station, Maidstone, KentSearch for more papers by this author First published: October 1976 https://doi.org/10.1111/j.1744-7348.1976.tb01760.xAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume84, Issue2October 1976Pages 275-275 RelatedInformation

The effect of resistance to Amphorophora rubi in raspberry (Rubus idaeus) on the spread of aphid‐borne viruses

SUMMARYThe effectiveness of resistance to the aphid Amphorophora rubi in restricting the spread of aphid‐borne viruses was assessed in a field experiment using six genotypes of red raspberry. In one block of the experiment, the genotypes alternated with rows of virus‐infected Mailing Jewel raspberry, and in the other they alternated with virus‐free Mailing Jewel. During 4 years, the numbers of A. rubi and the amount of 52V virus spread in the two blocks were similar, suggesting that this virus was mostly introduced from outside the plots.Lloyd George and Mailing Jewel raspberry became heavily infested with A. rubi and were rapidly infected with raspberry leaf mottle, raspberry leaf spot and 52V viruses. Glen Clova and Norfolk Giant raspberry, which contain minor genes for resistance to A. rubi, were infested with fewer A. rubi and virus spread more slowly in these cultivars. A. rubi were rare on Mailing Orion and an East Mailing raspberry selection (888/49) which have genes A1 and A10 respectively for resistance to A.rubi, and these plants remained largely free of virus. The role of minor and major gene resistance to A. rubi in restricting virus spread is discussed.A few Macrosiphum euphorbiae and Myzus ornatus were recorded on several of the raspberry genotypes.

Performance of ‘Bartlett’ Pear on Standard and Old Home × Farmingdale Clonal Rootstocks1

Abstract Decline- and fire blight-resistant clonal rootstock selections of Old Home × Farmingdale (OH×F), Pyrus communis L. were compared during a 12-year period with Bartlett seedling, P. calleryana Decne. seedling and clonal Old Home as understocks for ‘Bartlett’. Some OH×F clones were found to be more vigorous than Old Home rootstock, while others were much less vigorous. Only OH×F 51 was as dwarfing as East Mailing (EM) Quince A. Trees on some clones of each vigor class were more efficient (yield per unit of tree size) than others of the same class. Yield efficiency was not well correlated with rootstock vigor, but the semi-dwarf clones tended to induce more efficient yield than vigorous ones.

Growth and Yield of Lord Lambourne and Red Delicious Trees on Eight Apple Rootstocks in Cyprus

SummarySixteen rootstock-scion combinations of Lord Lambourne and Red Delicious on East Mailing and Mailing-Merton and Alnarp 2 rootstocks were planted in 1966 on a sandy clay loam soil. After nine years of growth the largest trees of Lord Lambourne were those on M. 12, followed in descending order by MM. 109 and Alnarp 2, then by a group comprising MM. 104, M. 2, Merton 793, M. 4, with the smallest trees on MM. 106. The largest trees of Red Delicious were on M. 12 and Alnarp 2, followed by MM. 109 and then by a group of M. 4, MM. 104, Merton 793, M. 2, with the smallest on MM. 106.The average accumulated yield per tree varied according to rootstock-scion combination, with highest yields for both varieties on MM. 109 and lowest on MM. 106. The smallest trees on MM. 106 will also give high yields per ha at close spacings. Leaf analysis indicated that the rootstock did not influence the uptake of nutrients.

Effects of Scion and Rootstock on Mineral Nutrient Content of Leaves of both Scions and Rootstocks of Sweet Cherry1

Abstract The nutrient content of rootstock and scion leaves from trees of ‘Napoleon’ and ‘Corum’ sweet cherry (Prunus avium L.) growing on Stockton Morello (Prunus cerasus L.) and East Mailing Mazzard F12-1 (Prunus avium L.) was analyzed. The concentration of Ca was greater in ‘Corum’ on F12-1 than on Stockton Morello. Rootstocks interacted with scions for K, P, Mg, Fe, Cu, B, and Zn.

Rootstock Influence on 2,4-D Damage to ‘Bartlett’ and ‘d’Anjou Pear Trees1

Abstract A 2,4-dichlorophenoxy acetic acid (2,4-D) application in September, 1972, to a grass cover crop and most of a weed free 1.2 m wide strip under the tree row followed by sprinkler irrigation within 24 hours injured 8 year-old pear trees. Fall leaf abscission was inhibited and foliage development was abnormal the following spring. ‘Bartlett’/imported French seedling had no apparent damage while ‘Bartlett/Pyrus calleryana Decne., ‘East Mailing Quince A’ and ‘Provence’ quince was seriously damaged. ‘d’Anjou’/imported French seedling was damaged the least of the 9 combinations and was most seriously damaged on the same 3 rootstocks as ‘Bartlett’. Fruit yields were correlated with damage ratings.

The Apple in Java1

Abstract The tropical archipelago of Indonesia is dominated culturally by the relatively small island of Java3, the population center (80 of the 125 million people) of the sprawling island nation. Pomologically, Java is best known for the tropical fruits that abound–particularly the fragrant mangosteen (Garcinia mangostana L.), the red “hairy” rumbutan (Nephelium lappaceum L.), the duku (Lansium domesticum Jack.), the lizard-skinned salak (Salacca edulis Reinw.), the rich and strongly-flavored durian4 (Durio zibethinus Murr.), and other more familiar ones including the banana and coconut. In the highlands which occupy practically 50% of Java’s land area, temperatures drop to bracing levels and above 1300 m even frost is a hazard. In spite of the plethora of tropical fruits, apples are highly prized and there is a sizable import, particularly from Australia. The culture of apples has long been a fond wish and the Dutch imported many types during their long association with Indonesia. Often grafted trees were brought in and as a result one of the rootstocks has produced a local “wild” apple, with small, bitter fruit. This strain is presently used as the local rootstock and is now being exported to the Phillipines because of its suitability in the tropics. The rootstock has been sent recently to East Mailing, Kent, England for identification.