Glen Prosen Research Articles

The Main Morphological Characteristics and Chemical Components of Fruits and the Possibilities of Their Improvement in Raspberry Breeding

Raspberry is a delicious fruit with important nutritional and health properties for consumers. The efficiency of achieving raspberry breeding aims such as productivity, fruit quality, and adequate response to stressors, etc., depends directly on knowledge of the inheritance of traits and genetic factors of influence and their pragmatic use. In this study, the main morphological characteristics and chemical components of fruits of 24 raspberry genotypes were studied in a comparative field trial; 14 were promising selections and the other 10 included their parental forms (Autumn Bliss, Glen Moy, Glen Prosen, Opal, Pathfinder, Titan, Tulameen, Veten, Willamette) and Glen Ample cultivar, which was used as control. The results highlighted significant differences and a large variation among the genotypes (between 2.40 and 4.90 g for fruit weight, 0.19–0.47 kg/cane for yield, 50–106 for drupelets/fruit, 10.0–12.7% for dry matter, 0.23–2.00% pectin, 1.61–2.72% glucose, etc.). The inheritance of the analyzed traits, considered quantitative, was different, but a low heritability was recorded for non-marketable fruits and the number of drupelets in fruit. In several hybrid selections, negative heterosis prevailed, highlighting the breeding difficulties of the important desired traits of the species. The values of heterosis and the broad-sense and narrow-sense heritability of some traits demonstrate that, through judiciously choosing parents, raspberry breeding in the desired direction can be successful.

RASPBERRY BREEDING IN MONTENEGRO

In order to improve the characteristics of fruit and increase resistance to various biotic and abiotic factors, Ekoplant Company (Podgorica, Montenegro) started a raspberry breeding project in 2008. Cross-breeding was performed with planned hybridizations between the most economically important primocane and summer fruiting cultivars and wild raspberries from the northern area of Montenegro. Eleven cultivars ('Tulameen', 'Glen Ample', 'Autumn Bliss', 'Glen Moy', 'Glen Prosen', 'Himbo Top', '‘Polana', ‘Rossana’, 'Porana Rosa', 'Polka', 'Malahat' ) and three genotypes of wild raspberry (Rubus idaeus L.) from 1200 m elevation, which were selected based on taste and quality of fruit from their natural habitats were used as parents in the project. The seed was extracted from the fruit, dried, scarified with sulfuric acid, and then stratified for 30 d to increase germination. Sowing was carried out in March into small trays. After germination, young plants were transplanted into larger containers for the purpose of growing and preparing them for field planting. Planting was performed in the field in Podgorica in spring of 2008 with plants spaced at 5×0.5 m in 20 cm diameter holes in Ekoplant nursery in Podgorica. After the first year, selections were transplanted into two climate zones - Podgorica and Bijelo Polje - Village Potrk. Standard cultivars for comparison were: ‘Tulameen;, 'Malahat', 'Willamette', 'Autumn Bliss' and 'Himbo Top'. Twenty-nine selections were made that had some superior properties compared to the parents or the standard cultivars.

Athyrium distentifolium Tausch ex Opiz (A. alpestre (Hoppe) Rylands ex T. Moore‐non‐Clairv.) including A. distentifolium var. flexile (Newman) Jermy

Woodsiaceae. Athyrium distentifolium, Alpine lady-fern. Fronds bi-pinnate, ovate-lanceolate, yellow-green 20 cm to over 100 cm, arising in a 'shuttlecock' from a central crown. Stipe straight, one fifth to one quarter the length of the blade with pale brown scales, usually broad, but occasionally narrow. Pinnae widely spaced near base of the frond, and sometimes deflexed, crowded near the tip, meeting the rachis at an angle of 900 at the midpoint of the blade, or slightly ascending. Pinnules broadest at the base, tapering to a point. Sori circular, with irregular filaments making up a rudimentary indusium when young, soon obscured as the sori grow. Sori concentrated in the upper part of the frond, becoming sparse towards the base. Number of sori varies with size of frond. Plants frequently infertile (McHaffie et al. 2002). Athyrium distentifolium var.flexile Newman's lady-fern. Fronds bi-pinnate, narrow, blue-green, 10-40 cm, arising from a central crown, erect or sharply angled near the base of the rachis to lie nearly flat against the substrate. Stipe short, one sixth to one eighth the length of the blade, often densely covered with broad, pale scales that may continue beyond the midpoint of the blade. Blade broadest near the base, or nearer the mid-point. Pinnae close together near base of frond, often strongly deflexed to at least half way up the frond. Uppermost pinnae widely spaced. Pinnules taper towards the base. Sori circular, sometimes with only a few sporangia; rudimentary indusium visible while the sorus is still immature. Sori concentrated at base of the frond, becoming less frequent towards the tip. Plants usually fertile (McHaffie et al. 2002). Athyrium distentifolium is a chionophilous fern that grows at altitudes or latitudes which ensure long-lying winter snow cover. Deep snow provides insulation from severe winters, and prevents early growth in a mild spring. Only a limited number of species can tolerate these conditions and this reduces competition. Although previously known as a Scandinavian and continental European species, A. distentifolium was not recognized in Britain until 1844 (Newman 1851). Within Britain it is found only in Scotland where it is confined to the remote Highlands. Soon after it was identified, another similar taxon of uncertain taxonomic status was described (Backhouse 1852). Subsequent research has determined that this is a recessive variety which is now known as A. distentifolium var.flexile. Both taxa are covered in this account.

DIFFERENT RATES OF SPREAD OF RASPBERRY BUSHY DWARF VIRUS AND SOME APHID-BORNE VIRUSES INTO RED RASPBERRY CULTIVARS CONTAINING DIFFERENT RESISTANCE GENES

The incidence of infection with the pollen-borne Raspberry bushy dwarf virus (RBDV) and some aphid-borne viruses was assessed in 6 red raspberry cultivars in a field experiment at Invergowrie, Dundee. The cultivars differed in their resistance to RBDV, and to strains of the main aphid virus vector, Amphorophora idaei. Six years after planting as healthy plants, cv. Glen Clova, that contains the RBDV-resistance gene Bu, was not infected with RBDV, whereas all 5 RBDV-infectible cultivars became infected with RBDV but the virus incidence varied greatly from 2 - 78%. Seemingly, factors other than the presence of gene Bu influence the level of resistance to natural infection with RBDV under field conditions. All cultivars contained genes for resistance to strains of Am. idaei present in the UK and, in PCR assays for Rubus yellow net virus (RYNV) transmitted by this aphid species, the incidence of infection varied greatly. The percent infection with RYNV in cvs Glen Rosa and Leo, that contain the strongest resistance gene A10, was 0 and 9 respectively, in cvs Glen Ample, Glen Prosen and Malling Landmark, that contain gene A1, it was 9, 53 and 19 respectively, and in cv. Glen Clova, that has only minor gene resistance, it was 22. In the four cultivars sensitive to the viruses inducing Raspberry leaf spot mosaic disease, the lowest incidence of disease was 0.6% in the gene A10-containing cv. Glen Rosa and the highest was 80% in the gene A1-containing cv. Malling Landmark. Clearly, there are factors other than the major aphid resistance genes that influence resistance to virus inoculation by Am. idaei under field conditions. None of the raspberry cultivars studied were resistant to Raspberry vein chlorosis virus (RVCV) or to its aphid vector, Aphis idaei. Based on symptomatology, all cultivars became infected with RVCV but the incidence of infection varied from 1 - 100%.

Partial rootzone drying does not affect fruit yield of raspberries

SummaryPot experiments with split-root plants and two years of ®eld experiments with manipulation of soil water content have shown that partial rootzone drying (PRD) does not affect yield in raspberries, Rubus idaeus L. `Glen Ample' and `Glen Prosen'. In some cases PRD can reduce stomatal conductance, thus reducing water loss. This results in a higher water use ef®ciency. Partial rootzone drying may be an ef®cient irrigation strategy where raspberries are produced under shelter.

Occurrence and distribution of Raspberry bushy dwarf virus in commercial Rubus plantations in England and Wales

Serological surveys for Raspberry bushy dwarf virus (RBDV) made between 1995 and 1997 and covering ≈ 10% of the commercial farms growing Rubus (red raspberry and hybrid berries) in England and Wales showed that this virus was present on approximately one‐quarter of all farms and in approximately one‐sixth of all plots tested. RBDV was found in all of the four main raspberry cultivars being grown at that time (Autumn Bliss, Glen Moy, Glen Prosen and Leo), in Loganberry and in Tayberry. Fifteen RBDV genotypes (including two that appeared to be mixed) were identified using RT‐PCR/RFLPs, but the majority of genotypes were found only rarely. Of the RBDV isolates tested, two genotypes each comprised 12·5% and another 46·4%. None of the three most common genotypes was associated solely with single Rubus cultivars and vice versa. It is suggested that two separate outbreaks of RBDV are occurring in England and Wales. One outbreak comprises the most frequent genotype combined with one of the moderately frequent genotypes; this outbreak is largely confined to the main growing areas and is either spreading between farms or coming from multiple local sources. Circumstantial evidence suggests that these isolates (and hence this first outbreak) are of the RB pathotype. The second outbreak consists of the other moderately frequent genotype and those genotypes which are less common. These genotypes appear to be more scattered across England and Wales and seem more likely to be coming from local sources and not to be spreading naturally between commercial farms.

Ripening-related changes in raspberry cell wall composition and structure

Cell walls were prepared from the fruit of two cultivars of raspberry at three stages of ripening; green, white and red (ripe). The cultivars, Glen Clova and Glen Prosen, are subjectively classified, at harvest by growers, as soft and firm fruit, respectively. The cell walls were analysed for neutral sugar composition, uronic acid content, degree of methyl esterification, lignin and ferulic acid-derived dehydrodimers. Solid-state 13C NMR and diffuse reflectance infrared (DRIFT) spectra were acquired for the cell wall residues. For both cultivars the progression from green to white produced minimal changes, save for a reduction in pectin. NMR analyses indicated that the solubilized pectin was acetylated. Progression to the red (ripe) stage, in both cultivars, was accompanied by a reduction in the ordered cellulose and a dramatic reduction in pectin content and the degree of methyl-esterification. Significantly, the softer fruit (Glen Clova) exhibited greater reductions in both parameters, implicating increased pectin hydrolysis, as one of the main factors contributing to the difference in firmness between the cultivars. A relative increase in cell wall-associated protein was seen at the red stage. The nature and function of the protein(s) are, as yet unknown.

Effectiveness of resistance genes to the large raspberry aphid, Amphorophora idaei Börner, in different raspberry (Rubus idaeus L.) genotypes and under different environmental conditions

SummaryThe introduction into commerce of raspberry cultivars with major gene resistance to the large raspberry aphid, Amphorophora idaei, an important pest and virus vector on red raspberry in Europe, has been very effective both in decreasing pest numbers and greatly restricting infection with the viruses it transmits. However, biotypes of the aphid able to overcome these genes have developed in the field in recent years. Additionally, in field and laboratory tests, the response to aphid biotypes and recognised aphid strains of certain raspberry cultivars, such as Glen Prosen and Delight, differ markedly despite the fact that they are reputed to contain the same A. idaei‐resistance gene, A1. In attempts to understand the reasons for this difference in response, analysis was made of the segregation of progeny seedlings from crosses between A. idaei‐resistant and ‐susceptible cultivars to two recognised strains of the aphid. These studies showed that, as expected, cv. Autumn Bliss contained the A. idaei‐resistance gene, A10, and cvs Delight and Glen Prosen each contained the A. idaei‐resistance gene, A1. When progeny seedlings were assayed in a heated glasshouse as young plants and in an unheated Tygan house as 1 m tall plants, the segregation ratios for resistance and susceptibility to A. idaei were largely unchanged. However, when the resistance of individual progeny plants was assessed, c. 37% of the putative gene A1‐containing progeny and 9–23% of the putative gene A10‐containing progeny, behaved differently in these two environments. Experiments involving an A. idaei‐resistant and ‐susceptible parent cultivar showed that shading plants increased their susceptibility to A. idaei colonisation. Whilst this shading effect has implications for experimentally detecting A. idaei‐resistant progeny in segregating raspberry seedlings, it does not explain the difference in field resistance to A. idaei of cvs Delight and Glen Prosen. Such differences in the field seem best explained by the presence in these cultivars of ‘minor’ genes for A. idaei resistance and/or susceptibility that influences the effectiveness of gene A1.

A comparison of nine species of arbuscular mycorrhizal fungi on the development and nutrition of micropropagated Rubus idaeus L. cv. Glen Prosen (Red Raspberry)

Growth, development and nutrient status of micropropagated Rubus idaeus cv. Glen Prosen in response to inoculation with nine species of arbuscular mycorrhizal (AM) fungi from three different genera was investigated. The nine species of AM fungi included, Glomus clarum, G. etunicatum, G. intraradices, Gigaspora rosea, Gi. gigantea, Gi. margarita, Scutellospora calospora, S. heterogama and S. persica. Plant responses to AM fungi varied from growth enhancement to growth depression. Depressive growth effects were specific to Gigaspora species. Furthermore, particular species of AM fungi had unique effects on the mineral status of the raspberry plants. Importance of isolate selection for inoculation of micropropagated raspberry plants is discussed.

The role of ethylene and cell wall modifying enzymes in raspberry (Rubus idaeus) fruit ripening

This study focuses on four raspberry (Rubus idaeus) genotypes from two different genetic backgrounds: cvs Glen Prosen and Glen Clova, bred at the Scottish Crop Research Institute (SCRI) and genotypes bred at Horticulture Research International (HRI), East Malling (EM), EM 4997 and EM 5007. The ripe fruit of each genotype pair were characterised subjectively by raspberry breeders as relatively firm or soft, respectively. Different stages of fruit development from each genotype were used to quantify fruit firmness, rates of ethylene evolution and ripening rate. Penetrometry data confirmed suspected firmness differences. Firmness correlated with rates of ethylene evolution. Rates of ethylene production also correlated with receptacle size. Storage of green fruits in 20 μl l−1 ethylene reduced fruit firmness, enhanced respiration rate and colour (anthocyanin) development and stimulated the development of cell wall hydrolase activities. However, during natural ripening in the field, fruit respiration rate declined, which indicates a non‐climacteric ripening pattern. In drupelets, the activities of polygalacturonase (PG), pectin methylesterase (PME), Cx‐cellulase (Cx) and β‐galactosidase (β‐gal.) increased substantially as ripening progressed. More detailed studies with ripe fruit of cv. Glen Clova indicated major isoforms of PG at pIs 3.3, 8.6 and 10.1; of PME at pIs 7.2, 8.5, 8.7, 8.8; of Cx at pI 2.4; and of β‐gal. at pIs 6.3 and 6.7.

Flower choices by raspberry beetles: cues for feeding and oviposition

Raspberry beetles,Byturus tomentosus, use raspberry as the host plant for feeding, mating and oviposition; the larvae are a major pest on the fruit. This study seeks reasons for their choices between flowers of different cultivars. Beetles showed consistent diurnal movements between different cultivars of raspberry, which were linked to differential behavioural patterns; they fed predominantly on Glen Clova canes in the morning and moved to Glen Prosen later in the day where oviposition behaviour was commoner and substantially more effective. Hence two closely similar cultivars of the same plant species received very different levels of flower damage (from adult feeding) and of fruit damage (from larval infestation). These patterns were linked to subtle differences in cues from the host plant; Glen Clova produces unusually copious nectar which may limit oviposition opportunities because of osmotic threats to eggs and larvae, whereas Glen Prosen has drier flowers for egg laying and apparently emits a short-lived volatile cue that principally attracts female beetles. Selective breeding of the host plant has therefore had unexpected side-effects on interactions with a major pest species, mediated by the behaviour of the insect, and perhaps accentuating natural behavioural preferences that serve to reduce competition between adult and larval stadia.

Infectibility and sensitivity of UK raspberry, blackberry and hybrid berry cultivars to Rubus viruses

SummarySix blackberry or hybrid berry cultivars and 19 raspberry cultivars were assessed for their infectibility with, and sensitivity to, graft inoculation with 10 distinct viruses found infecting Rubus in the UK. Cultivars were grafted with each of, two isolates of the pollen borne raspberry bushy dwarf virus (RBDV), five aphid borne viruses: black raspberry necrosis, raspberry leaf mottle (RLMV), raspberry leaf spot (RLSV), rubus yellow net and raspberry vein chlorosis (RVCV); and isolates of the nematode transmitted nepoviruses, arabis mosaic, raspberry ringspot, strawberry latent ringspot and tomato black ring. All tested cultivars were infectible with a resistance breaking isolate of RBDV but only about half of that number with the Scottish type isolate of the virus. The raspberry cvs Autumn Bliss, and occasionally Glen Garry and Glen Prosen, developed leaf yellowing symptoms following infection with RBDV, but none of the other infected cultivars showed obvious leaf symptoms when kept in a heated glasshouse during the growing season. All tested cultivars were infectible with each of the four viruses transmitted in nature by the aphid, Amphorophora idaei. Most were infected symptomlessly, but seven cultivars developed severe leaf spotting symptoms due to infection with RLMV or RLSV. All but one of the raspberry cultivars were infectible with RVCV, which is transmitted in nature by the aphid Aphis idaei, and almost all infected plants developed leaf symptoms; only one of the hybrid berry or blackberry cultivars tested was infected with RVCV. In tests with the four nepoviruses, all tested cultivars, except Tummelberry, were infectible with at least one or more of these viruses. However, cultivars responded differently to challenge inoculation with different isolates of individual nepoviruses. Several cultivars developed chlorotic leaf mottling following infection with some nepovirus isolates. The implications of these results for virus control are discussed in the light of the changing pattern of virus and virus vector incidence in the UK.

Development of two spotted spider mite (Acari: Tetranychidae) populations on strawberry and raspberry cultivars

Summary.Five strawberry (Fragaria sp.) and five raspberry (Rubus ideaus L.) cultivars were evaluated for resistance to two spotted spider mite (Tetranychus urticae Koch.). Two methods of assessing the development of two spotted mite populations using detached leaves were compared. The number of eggs laid and mites which developed were compared. The strawberry cvs Hapil and Pegasus had significantly greater development of two spotted mite populations than the cvs Rhapsody, Symphony and Elsanta. The raspberry cv. Joan Squires had higher populations of two spotted mite whilst the raspberry cv. Leo the least, when compared with cvs Glen Clova, Glen Moy and Glen Prosen. Differences were observed in oviposition sites and mite distribution when comparing raspberries with strawberries. The method of assessing the populations development of two spotted mite which involved maintaining the cut leaf stem in water may be of potential use for studying population dynamics of both two spotted mite and possible predators over extended periods of time.

Changes in the chemical composition of volatiles released by the flowers and fruits of the red raspberry ( Rubus idaeus) cultivar glen prosen

Volatiles at various stages of inflorescence development, bud formation, flowering, fruit formation and ripening of a red raspberry, were entrained on the porous polymer Tenax TA and analysed by thermal desorption-gas chromatography-mass spectrometry. Major classes of compound identified included aliphatic and aromatic hydrocarbons, aldehydes, ketones, alcohols and esters, monoterpenes and sesquiterpenes. As the inflorescences matured, levels of green leaf volatiles such as trans- β-ocimene and cis-3-hexenyl acetate declined and the monoterpenes, α-pinene, camphene, β-myrcene and limonene increased. During fruit ripening several additional compounds appeared including α- and β-ionone, α- and β-phellandrene and hexanoic acid ethylester. Ethyl acetate at 12–18% was the major detectable volatile product of the ripe fruit.

Cantharid beetle feeding damage toRubusplants in eastern Scotland

SUMMARYIn May 1991 the stems of expanding fruiting laterals of red raspberry (Rubus idaeus) in plantations inTayside, easternScotland were extensively chewed by adults of Cantharis obscura L. (Coleoptera: Cantharidae). This appears to be the firstrecord of damage to plants by this group of insects in the UK. In choice tests, the adultbeetles damaged excised fruitinglaterals of both cultivated black raspberry (R. occidentalis) cv. Cumberland, and red raspberry cv. Glen Prosen, but did little damage to other closely related Rubus species and hybrids, including wild bramble (R. fruticosus agg.) and wild red raspberry (R. idaeus var. vulgatus).

Screening Red Raspberry (Rubus idaeusL.) Germplasm for Freeze Tolerance in Norway

Abstract Freeze tolerance of red raspberry cultivars and selections, including one specimen each from eight indigenous Norwegian Rubus idaeus L. populations, showed that there were significant differences in bud survival and tissue browning in a two-year test at Stj⊘rdal, Norway. Selections from the Norwegian breeding program and the Norwegian cultivar Balder had the most freeze-tolerant buds at the May screening in both years, while the Norwegian cultivar Vene was tolerant in one year. The cultivars Malling Admiral, Nootka, Chilcotin, Glen Isla and Gradina were tolerant in one of the years but not in the other. Meeker, Glen Moy, Skeena, Glen Prosen, Malling Joy, Malling Leo and Malling Orion were not tolerant in either year. The selections from indigenous Norwegian Rubus idaeus were all freeze-tolerant in one year, but less tolerant than the best the other year. Tissue browning was preferred as a screening test for freeze injury in midwinter, while bud growth is preferable in spring.

Infectibility of some new raspberry cultivars with arabismosaic and raspberry ringspot viruses and further evidence for variation in British isolates of these two nepoviruses

SummaryIn field trials at sites of an outbreak of arabis mosaic nepovirus (AMV) in England and of raspberry ringspot nepovirus (RRV) in Scotland, the results of exposure of some new raspberry cultivars to natural infection with these viruses showed discrepancies from those obtained in graft inoculation tests using AMV‐Lib and RRV‐S, the Scottish type isolates. In particular, cv. Glen Prosen, which is immune to AMV‐Lib and RRV‐S, was infected with AMV and RRV in the field trials. Studies on these and other field isolates of AMV and RRV showed that they differed from the type isolates in Rubus host range and in symptomatology in herbaceous hosts. However, whereas four isolates of RRV found infecting Rubus were distinguishable by spur formation in gel double‐diffusion serological tests, six AMV isolates were indistinguishable by this method. Immunoelectrophoresis of virus particles did not distinguish the six AMV isolates, but isolates RRV‐MX and RRV‐T were distinguishable from RRV‐S and the English type isolate, RRV‐E. Like the two RRV type isolates, RRV‐MX contained a single electrophoretic component, but it migrated must faster whereas RRV‐T contained two components, one with a migration rate similar to that of RRV‐MX and the other similar to that of the type isolates. Polyacrylamide gel electrophoresis of protein preparations from highly purified virus particles of RRV isolates E, S and MX detected a single polypeptide of estimated mol. wt 54 × 103, 54 × 103 and 50 × 103 respectively but that of isolate T contained two polypeptides of estimated mol. wt 54 × 103 and 50 × 103. These data suggest that RRV‐T is a mixture of two isolates. In laboratory tests the nematode Xiphinema diversicaudatum transmitted four isolates of AMV efficiently whereas two populations of the nematode Longidorus elongatus were less efficient vectors of four RRV isolates. Neither vector species transmitted virus to any of nine raspberry cultivars. The results are discussed in relation to the control of nepoviruses in raspberry and to the biology of these viruses.

Common resistance in red raspberry to Botrytis cinerea and Didymella applanata, two pathogens occupying the same ecological niche

SUMMARYComparisons were made between Botrytis cinerea and Didymella applanata, which occupy the same ecological niche on canes of red raspberry. Isolates of B. cinerea from diverse localities within the British Isles were pathogenic to the SCRI selection M30 when internodal wounds on young canes were inoculated. A single inoculation frequently caused the buds at several nodes to fail the following spring. Differences in the lengths of the stem lesions that formed indicated differences in isolate pathogenicity, but these were not related to isolate origin. Bud suppression and lateral shoot failure also occurred when petioles of cvs Mailing Orion, Mailing Jewel and Glen Clova were wound inoculated with B. cinerea up to late August.The relative resistance of seven cultivars to three isolates of each pathogen was determined. Principal components analysis of data from five estimates of resistance to each pathogen showed that 40% of the variation described a common resistance to the two diseases.Further analysis showed that cvs Chilcotin and Meeker had the strongest common resistance and that cvs Glen Prosen and Mailing Jewel had the weakest. The remaining variation described cultivar differences in relative bud length after petiole inoculation with either pathogen, and differences in the relative importance of spring and autumn symptoms. Only 7% of the variation indicated independent resistance to the two pathogens and this was not influenced by cultivar differences.

Inheritance of resistance to yellow rust (Phragmidium rubi‐idaei) in red raspberry

SUMMARYThe inheritance of resistance in red raspberry (Rubus idaeus) to yellow rust (Phragmidium rubi‐idaei) was studied in a diallel cross among the cultivars Boyne, Meeker, Mailing Jewel, Glen Prosen and Glen Clova. The progenies and clonally propagated parents were exposed initially in a rust‐infected plantation where the incidence and severity of infection was assessed at the telial stage. The following spring leaves on new canes of the same plants were inoculated with urediniospores in a glasshouse at 18 ± 2 °C. The latent period and number of uredinia per cm2 of abaxial leaf surface were determined 13 and 18 days after inoculation. Cv. Boyne developed only chlorotic flecking on inoculated leaves in the glasshouse and no sporulation was observed. It is postulated that this reaction was determined by a major gene which is designated Yr. Some of the other parents showed incomplete resistance of the slow rusting type, and segregants of Boyne selfed that were susceptible also showed low levels of rust, which suggests that Boyne carries both major‐ and minor‐gene resistance. Diallel analyses of both the field and glasshouse data from the susceptible segregates indicated that the degree of incomplete resistance present was determined predominantly by additive gene action, though small but significant non‐additive effects also occurred: cv. Meeker was the most resistant parent and contributed the most resistance to the progenies.The Meeker progenies also segregated for gene H, which determines cane hairiness and is known to be associated with resistance to other diseases. Segregants without hairs (genotypes hh) were found to be the more resistant to rust.

Responses of Black Vine Weevil Adults Fed Foliage from Genotypes of Strawberry, Red Raspberry, and Red Raspberry-Blackberry Hybrids1

Abstract Adults of the black vine weevil, Otiorhynchus sulcatus (F.), consistently responded with less weight gains, shorter preoviposition periods, and more eggs when fed foliage from genotypes of strawberry than of Rubus species. Among 8 strawberry genotypes tested, the lowest number of fertile eggs were produced from feeding on the cultivar ‘Totem’ and the most from the British Columbia selection 70-20R-15. Among 8 red raspberry cultivars, significant differences were observed in preoviposition periods periods and in both total and fertile eggs laid. Longest preoviposition periods were from feeding on ‘Leo’ and ‘Glen Prosen’; intermediate from ‘Glen Clova’, ‘Mailing Jewel’, and ‘Willamette’; and shortest from ‘Haida’, ‘Chilcotin’, and ‘Meeker’. In other Rubus species, loganberry was similar to ‘Leo’ and ‘Glen Prosen’, while the R. idaeus strigosus selection, Kinburne, gave a preoviposition period as long as loganberry. Since both ‘Leo’ and ‘Glen Prosen’ are Rubus occidentalis derivatives, this parentage might be of value for future breeding for black vine weevil resistance in red raspberry.