Raspberry Plants Research Articles

Pruning Date and Cane Density Affect Primocane Development and Yield of `Autumn Bliss' Red Raspberry

The aim of this study was to determine the effects of date of summer pruning and cane densities on growth and fruiting characteristics of the raspberry (Rubus idaeus) plant. Three summer-pruning dates (early, middle, and late July) and four cane densities (8, 16, 24, and 32 canes/m row) were imposed to the greenhouse-grown primocane-fruiting raspberry `Autumn Bliss' in 2 consecutive years (1994 and 1995). A higher light microclimate and CO2 assimilation rate were measured within the canopy at the lowest density. Some compensation in CO2 assimilation rates were observed in the upper leaves of the high-density treatments, probably in response to low light. Delayed pruning decreased yield per cane and per row. The highest yields per cane were always observed at the lowest cane density. Densities of 16 and 24 canes/m produced the highest fruit yield. Light conditions appeared to be the most important environmental factor affecting plant productivity. Fruit were a weaker sink than roots; therefore, the role of carbohydrate reserves should be investigated.

Uptake, Partitioning, and Storage of Fertilizer Nitrogen in Red Raspberry as Affected by Rate and Timing of Application

The effects of 15N-labeled fertilizer applied to mature summer-bearing red raspberry (Rubus idaeus L. `Meeker') plants were measured over 2 years. Four nitrogen (N) treatments were applied: singularly at 0, 40, or 80 kg·ha-1 of N in early spring (budbreak), or split with 40 kg·ha-1 of N (unlabeled) applied at budbreak and 40 kg·ha-1 of N (15N-depleted) applied eight weeks later. Plants were sampled six times per year to determine N and 15N content in the plant components throughout the growing season. Soil also was sampled seven times per year to determine inorganic N concentrations within the four treatments as well as in a bare soil plot. There was a tendency for the unfertilized treatment to have the lowest and for the split-N treatment to have the highest yield in both years. N application had no significant effect on plant dry weight or total N content in either year. Dry weight accumulation was 5.5 t·ha-1 and total N accumulation was 88 to 96 kg·ha-1 for aboveground biomass in the fertilized plots in 2001. Of the total N present, averaged over 2 years, 17% was removed in prunings, 12% was lost through primocane leaf senescence, 13% was removed through fruit harvest, 30% remained in the over-wintering plant, and 28% was considered lost or transported to the roots. Peak fertilizer N-uptake occurred by July for the single N applications and by September for the last application in the split-N treatment. This uptake accounted for 36% to 37% (single applications) and 24% (last half of split application) of the 15N applied. Plants receiving the highest single rate of fertilizer took up more fertilizer N while plants receiving the lower rate took up more N from the soil and from storage tissues. By midharvest, fertilizer N was found primarily in the fruit, fruiting laterals, and primocanes (94%) for all fertilized treatments; however, the majority of the fertilizer N applied in the last half of the split application was located in the primocanes (60%). Stored fertilizer N distribution was similar in all fertilized treatments. By the end of the second year, 5% to 12% of the fertilizer acquired in 2001 remained in the fertilized plants. Soil nitrate concentrations increased after fertilization to 78.5 g·m-3, and declined to an average of 35.6 g·m-3 by fruit harvest. Seasonal soil N decline was partially attributed to plant uptake; however, leaching and immobilization into the organic fraction may also have contributed to the decline.

Effects of hypoxia on ion accumulation in wild raspberry ( Rubus idaeus) exposed to water released from saline oil sands mine tailings

Composite tailings (CT) technology allows Alberta’s oil sands industry to reduce its volume of extraction tailings and accelerate the process of reclamation and revegetation of affected sites. Wild raspberry ( Rubus idaeus) is desired on reclaimed sites; however, its sensitivity to ions in CT complicates its successful establishment. Hypoxia is another challenge for plants in CT, and is known to affect plant salt resistance. This study examined responses of raspberry exposed to CT release water under well-aerated and hypoxic conditions. Unlike many long-lived woody perennials that have been studied, raspberry did not accumulate Na and Cl in roots and therefore, the ability of roots to store these ions was not affected by the hypoxic conditions. This response suggests that the strategy of raspberry plants to cope with moderate salinity may be to protect roots, rather than shoots, against salt accumulation and possible salt injury. Contrary to Na, Cl, and S, well-aerated raspberry exhibited exclusion as a means of regulating B uptake by the roots. We suggest that the ability of roots to store salt should be used as an indicator of salt resistance in woody perennials designated for reclamation on saline sites.

The defH9-iaaM auxin-synthesizing gene increases plant fecundity and fruit production in strawberry and raspberry

BackgroundThe DefH9-iaaM gene fusion which is expressed specifically in placenta/ovules and promotes auxin-synthesis confers parthenocarpic fruit development to eggplant, tomato and tobacco. Transgenic DefH9-iaaM eggplants and tomatoes show increased fruit production due mainly to an improved fruit set. However, the weight of the fruits is also frequently increased.ResultsDefH9-iaaM strawberry and raspberry plants grown under standard cultivation conditions show a significant increase in fruit number and size and fruit yield. In all three Rosaceae species tested, Fragaria vesca, Fragaria x ananassa and Rubus idaeus, DefH9-iaaM plants have an increased number of flowers per inflorescence and an increased number of inflorescences per plant. This results in an increased number of fruits per plant. Moreover, the weight and size of transgenic fruits was also increased. The increase in fruit yield was approximately 180% in cultivated strawberry, 140% in wild strawberry, and 100% in raspberry. The DefH9-iaaM gene is expressed in the flower buds of all three species. The total IAA (auxin) content of young flower buds of strawberry and raspberry expressing the DefH9-iaaM gene is increased in comparison to untransformed flower buds. The DefH9-iaaM gene promotes parthenocarpy in emasculated flowers of both strawberry and raspberry.ConclusionsThe DefH9-iaaM gene is expressed and biologically active in Rosaceae. The DefH9-iaaM gene can be used, under cultivation conditions that allow pollination and fertilization, to increase fruit productivity significantly in Rosaceae species. The finding that the DefH9-iaaM auxin-synthesizing gene increases the number of inflorescences per plant and the number of flowers per inflorescence indicates that auxin plays a role in plant fecundity in these three perennial Rosaceae species.

First Report of Raspberry bushy dwarf virus on Red Raspberry and Grapevine in Slovenia.

In 2002, severe vein yellowing and partial or complete yellowing of leaves was observed on some shoots of red raspberry (Rubus idaeus) cvs. Golden Bliss and Autumn Bliss. Sap of infected plants of cv. Golden Bliss was inoculated onto Chenopodium quinoa and Nicotiana benthamiana. Faint chlorotic spots were observed on inoculated leaves of C. quinoa approximately 14 days after inoculation but no systemic symptoms appeared. No symptoms were observed on N. benthamiana. Raspberry bushy dwarf virus (RBDV) was detected in the original raspberry plant using double-antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA) with polyclonal antiserum (Loewe Biochemica, Sauerlach, Germany). Systemic infections of inoculated C. quinoa and N. benthaminana were confirmed using DAS-ELISA. In 2001 and 2002, unusual virus symptoms were observed on grapevine grafts (Vitis vinifera) of cv. Laški Rizling. Symptoms appeared as curved line patterns and yellowing of the leaves. No nepoviruses were found in symptomatic plants, but RBDV was confirmed using DAS-ELISA. RBDV infection was later confirmed in grapevine cv. Štajerska Belina with similar symptoms. RBDV was transmitted mechanically from grapevine to C. quinoa where it was detected by immunocapture-reverse transcription-polymerase chain reaction (IC-RT-PCR). IC-RT-PCR was used to amplify a part of the coat protein gene of the virus from raspberry and grapevine, and the amplification products were sequenced (1). The obtained sequence shared at least 93% nucleotide sequence identity with other known RBDV sequences, which confirmed the serological results. To our knowledge, this is the first report of the natural occurrence of RBDV in grapevine and also of RBDV infection of red raspberry in Slovenia. Reference: (1) H. I. Kokko et al. Biotechniques 20:842, 1996.

Identities and Geographic Distributions of Phytophthora spp. Causing Root Rot of Red Raspberry in Chile.

Five identified and two unidentified Phytophthora spp. were isolated from diseased roots of dead or declining red raspberry (Rubus idaeus L.) plants sampled from 18 plantations along a >1,000-km north-south axis in Chile. The array of Phytophthora spp. isolated was strongly associated with geographical location. P. fragariae var. rubi was recovered from 75 and 60% of the plantations in the southern (40°16' to 40°53' S latitude) and central (34°35' to 37°23' S latitude) production sectors, respectively, but was not recovered from any plantation in the northern sector (32°43' to 33°45' S latitude). Similarly, P. megasperma and P. gonopodyides were recovered from multiple plantations in the southern and central sectors but were not recovered in the northern sector. In contrast, P. cryptogea was recovered from 80% of the plantations in both the northern and central sectors but not from any plantation in the south, whereas P. citricolawas isolated from diseased plants in all sectors. In subsequent pathogenicity trials, P. citricola, P. cryptogea, and an unidentified Phytophthora sp. were equally and highly virulent on 'Heritage' red raspberry in each of three greenhouse experiments. The other species were less virulent in the experiment when soil temperatures were highest (mean weekly maximum = 27.5°C) relative to the other two experiments when temperatures were more moderate (mean weekly maxima of 19.9 and 23.7°C). Isolates identified as P. cryptogea were very similar to P. cryptogea isolates recovered previously from kiwi fruit in Chile and from deciduous fruit trees in California with respect to morphological characters and electrophoretic banding patterns of soluble mycelial proteins. Using the same criteria, isolates identified as P. gonopodyides were very similar to isolates recovered earlier from deciduous fruit crops in New York, which previously were identified as P. cryptogea sensu lato but are hereby reclassified as P. gonopodyides.

Identification of Rubus yellow net virus as a distinct badnavirus and its detection by PCR in Rubus species and in aphids

SummaryRubus yellow net virus (RYNV) infects Rubus species and cultivars worldwide and is an essential component of raspberry veinbanding mosaic (RVBMD), a virus disease complex that causes serious decline in plant vigour and productivity. The virus is transmitted, probably in a semi‐persistent manner, by the large raspberry aphid, Amphorophora idaei in Europe, and A. agathonica in North America. The particles of RYNV are bacilliform in shape and measure 80–150 × 25–30 nm, similar to those of badnaviruses. A1.7 kb fragment of the viral DNA was amplified by PCR and then directly sequenced. Analysis of this sequence suggests that RYNV is possibly a distinct species in the genus Badnavirus and is most closely related to Gooseberry vein banding associated virus (GVBAV) and Spiraea yellow leaf spot virus, two other badnaviruses described recently. Using the sequence derived from the PCR‐amplified viral DNA fragment, RYNV‐specific primers were designed and used in PCR to assay for RYNV in a range of Rubus germplasm infected with RYNV, with other unrelated viruses and virus‐like diseases found in Rubus, and in healthy plants. RYNV was detected in all glasshouse cultures of RYNV‐infected plants, whether alone or in complex infections with other viruses, but not from healthy Rubus plants, nor from plants infected with other viruses. It was also detected in field‐grown raspberry plants with and without symptoms of RVBMD and in raspberry plants infected with RYNV by viruliferous A. idaei. RYNV was also detected by PCR in A. idaei following access feeds on RYNV‐infected plants of 1 h or more. PCR failed to amplify DNA from gooseberry infected with GVBAV confirming the specificity of the RYNV analysis. PCR detection of RYNV in dormant raspberry buds allows assays to be made outside the natural growing season, providing a useful application for plant introduction and quarantine programmes.

The Use of Soil Solarization for the Management of Soilborne Plant Pathogens in Strawberry and Red Raspberry Production.

Root rot caused by Phytophthora fragariae var. fragariae and P. fragariae var. rubi are major concerns in strawberry and raspberry production in the Pacific Northwest. Of lesser importance is black root rot of strawberry, caused by a complex of fungi and nematodes. Soil solarization was evaluated in 1997 in a strawberry planting and in 1998 in a raspberry planting for: (i) enhancing plant health and growth, and (ii) reducing population densities of root-destroying pathogens. Plots were solarized from mid-July to mid-September. Maximum and mean soil temperatures in solarized plots recorded at 10 cm depth were 48 and 33°C in the strawberry plots and 46 and 29°C in the raspberry plots. These temperatures were 7 to 17°C higher than temperatures recorded in nonsolarized plots. Soil collected after solarization was assayed by growing bait plants, cv. Totem strawberry or cv. Qualicum raspberry, at 15°C for 6 weeks in saturated soil to promote infections. Root health and plant growth were evaluated after 6 weeks. Solarization significantly reduced (P < 0.05) root necrosis and increased root weight of bait plants compared to plants grown in soil from nonsolarized plots. Infection of strawberry roots by P. fragariae, Pythium, Rhizoctonia, and Cylindrocarpon spp. was reduced (P < 0.05) by solarization in sampled soil. Disease was reduced in cv. Hood strawberries and Qualicum and Skeena red raspberries planted in solarized field plots. In the second growing season, total number and number of healthy primocanes of Qualicum plants were greater (P < 0.05) in solarized plots compared to nonsolarized plots. Solarization combined with applications of mefenoxam was no more effective in controlling diseases than solarization alone, but better than mefenoxam alone. Skeena plants responded similarly, but the differences were not significant. Red raspberry plants growing in solarized soil yielded more fruit than plants growing in nonsolarized soil in the third year after solarization. Solarization has potential as a component in an integrated pest management program of root diseases in raspberry and strawberry production, particularly within the first 2 years following planting.

Beneficial Spectral Characteristics of Red and Black Raspberry Plants (Rubus idaeus and Rubus occidentalis)

ABSTRACT Raspberry naturally occurs in association with trees as a forest border species, thus is ideally adapted for species-diverse agroforestry systems. In spite of thriving in relatively low solar radiation environments, some red (European) and black (North American) raspberry (Rubus idaeus L. and Rubus occidentalis L.) plant surfaces are highly reflective, both species on leaf abaxial surfaces and black raspberry on cane surfaces. Cane surface color varies from green to red. The objective of this study was to quantify plant spectral characteristics in order to assess their potential ecological significance. Leaf reflectance and transmittance were determined using a spectroradiometer with integrating sphere and regulated light source. Reflected irradiance from leaves and canes was measured under natural sunlight with a microscopic lense attachment. Reflectance of abaxial leaf surfaces was 4.3 and 5.3 times greater than abaxial leaf surfaces for red and black raspberry, respectively. This amounted to 27 and 29% of possible reflectance for red and black raspberry compared to a white standard. The glaucus coating on black raspberry canes reflected nearly 50% as much as a white standard. The red color of cane surfaces was due to higher absorption of green and yellow wavelengths rather than increased red reflection. The variety of spectral strategies employed suggest a sophisticated system of protection from pests, disease, herbivores, ultraviolet radiation, oxygen free radicals, and extreme moisture conditions.

Molecular Identification of a Phytoplasma Associated with Witches'-Broom Disease of Black Raspberry in Oregon and Its Classification in Group 16SrIII, New Subgroup Q.

Plants of Rubus occidentalis (black raspberry) 'Munger' exhibiting symptoms of black raspberry witches'-broom (BRWB) disease were observed in commercial fields in Oregon (1). Symptoms were often severe, leading to death of infected plants, and a phytoplasma (mycoplasmalike bodies) was observed in ultrathin sections of diseased plants (1). In the current work, the association of phytoplasma with BRWB was assessed using the polymerase chain reaction (PCR) for specific amplification of phytoplasmal rDNA. DNA template for use in the PCR was extracted from plants as described elsewhere (2). Phytoplasmal 16S rDNA was amplified from diseased black raspberry plants in PCR primed by primer pair P1/P7 and reamplified in nested PCR primed by primer pair R16F2n/R2 (F2n/R2) by a method described previously (2). These results indicated the presence of a phytoplasma, designated BRWB phytoplasma, in the diseased plants. Identification of BRWB phytoplasma was accomplished by restriction fragment length polymorphism (RFLP) analysis of DNA amplified in PCR primed by F2n/R2. Phytoplasma classification was done according to the system of Lee et al. (3). On the basis of collective RFLP patterns of the amplified 16S rDNA, the BRWB phytoplasma was classified as a member of group 16SrIII (group III, X-disease phytoplasma group). The HhaI RFLP pattern of BRWB 16S rDNA differed from that of its close relative, clover yellow edge (CYE) phytoplasma. The RsaI RFLP pattern of BRWB rDNA differed from that of rDNA from all phytoplasmas previously described in group III. Based on these results, BRWB phytoplasma was classified in a new subgroup, designated subgroup Q (III-Q) within group III. The 1.8 kbp DNA product of PCR primed by primer pair P1/P7 was cloned and its nucleotide sequence determined. The sequence was deposited in GenBank under Accession no. AF302841. Results from putative restriction site analysis of the cloned and sequenced rDNA were in excellent agreement with the results from enzymatic RFLP analysis of uncloned rDNA amplified from BRWB diseased black raspberry. Sequence similarity between the 1.8 kbp rDNA of BRWB phytoplasma and that of CYE phytoplasma was 99.4%. The nucleotide sequence data support the conclusion that the BRWB phytoplasma is related to, but is distinct from, other strains that are classified in group III. These findings contribute knowledge about the diversity of phytoplasmas affiliated with group III and provide information to aid the diagnosis of BRWB disease.

Wind reduces growth and yield but not net leaf photosynthesis of primocane-fruiting red raspberries (Rubus idaues L.) in the establishment years

Four primocane-fruiting (PF) red raspberry cultivars, Bogong, Autumn Cascade, Heritage and Dinkum, were grown in exposed or sheltered (50% permeable artificial windbreak) sites fully exposed to prevailing winds in Bouctouche, NB. Shelters were erected at the beginning and removed at the end of each growing season. In the establishment year, all cultivars were evaluated to determine the effects of wind stress on their vegetative and reproductive development and leaf gas exchange. since all cultivars responded similarly to the effect of wind in year one, only Dinkum was monitored in years two and three. In all years, the artificial windbreak resulted in an overall 35% reduction in wind velocity, increased the number of calm days (&lt;5.4 km h−1) and decreased the incidence of strong breezes (&gt;36 km h−1). Interestingly in this maritime climate, the artificial windbreak did not have much of an effect on altering relative humidity, vapour pressure deficits, or air or soil temperature. Plants from sheltered sites consistently had greater above-ground biomass (especially cane dry weight) and longer cane internodes. For two of the three years, leaf area and yield were also greater in the sheltered sites. Leaf gas exchange parameters (Pn, gs and Ci), expressed per unit of leaf area, did not differ between treatments for most of the season, but the sheltered plants retained more leaf area and thus had the potential to fix a greater amount of carbon than the exposed plants. The larger, sheltered plants produced a more extensive fruiting framework, which resulted in increased yields in both the establishment and subsequent year. It is recommended to shelter raspberry plants from wind in the initial establishment years. Key words: Rubus idaeus L., fall-bearing, autumn fruiting, windbreak

Antioxidant activity in fruits and leaves of blackberry, raspberry, and strawberry varies with cultivar and developmental stage.

Fruits and leaves from different cultivars of thornless blackberry (Rubus sp.), red raspberry (Rubus idaeus L.), black raspberry (Rubus occidentalis L.), and strawberry (Fragaria x ananassa D.) plants were analyzed for total antioxidant capacity (oxygen radical absorbance capacity, ORAC) and total phenolic content. In addition, fruits were analyzed for total anthocyanin content. Blackberries and strawberries had the highest ORAC values during the green stages, whereas red raspberries had the highest ORAC activity at the ripe stage. Total anthocyanin content increased with maturity for all three species of fruits. Compared with fruits, leaves were found to have higher ORAC values. In fruits, ORAC values ranged from 7.8 to 33.7 micromol of Trolox equivalents (TE)/g of fresh berries (35. 0-162.1 micromol of TE/g of dry matter), whereas in leaves, ORAC values ranged from 69.7 to 182.2 micromol of TE/g of fresh leaves (205.0-728.8 micromol of TE/g of dry matter). As the leaves become older, the ORAC values and total phenolic contents decreased. The results showed a linear correlation between total phenolic content and ORAC activity for fruits and leaves. For ripe berries, a linear relationship existed between ORAC values and anthocyanin content. Of the ripe fruits tested, on the basis of wet weight of fruit, cv. Jewel black raspberry and blackberries may be the richest source for antioxidants. On the basis of the dry weight of fruit, strawberries had the highest ORAC activity followed by black raspberries (cv. Jewel), blackberries, and red raspberries.

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.

Effects of vermicomposts and composts on plant growth in horticultural container media and soil

Summary Vermicomposts, which are produced by the fragmentation of organic wastes by earthworms, have a fine particulate structure and contain nutrients in forms that are readily available for plant uptake. In greenhouse trials, the growth of marigold and tomato seedlings, in a commercial horticultural potting medium (Metro-Mix 360), was enhanced significantly upon substitution of Metro-Mix 360 with 10% or 20% vermicomposted pig solids or vermicomposted food wastes, when all required nutrients were supplied. Same enhancement in marigold and tomato seedlings' growth occurred also upon substitution of Metro-Mix 360 with composted biosolids, but not with leaf compost. The shoot dry weights of raspberry plants, grown in a mineral soil mixed with vermicomposted pig wastes weighed more than those grown in unfertilized control soil, and were as great as those in soil receiving a complete fertilizer treatment. By comparison, raspberry shoot growth in soils amended with yard, leaf or bark composts, was poorer than that in the unfertilized control soil. Amending the soil with 4% chicken manure compost killed most of the raspberry plants. However, plant mortality was reduced and growth restored when the chicken manure compost was mixed with vermicomposted pig solids, but not with bark or yard composts. Plant growth in soils containing a mixture of chicken manure compost with 20% vermicomposted pig wastes was similar to that of plants grown in the unfertilized control. Our results showed that vermicomposts have the potential for improving plant growth when added to greenhouse container media or soil. However, there seem to be distinct differences between specific vermicomposts and composts in terms of their nutrient contents, the nature of their microbial communities, and their effects on plant growth.

Cold hardening of raspberry plants in vitro is enhanced by increasing sucrose in the culture medium

The influence of exogenously applied sucrose on cold hardening of raspberry (Rubus idaeus L.) in vitro was examined. Raspberry plants (cv. Preussen) were cultured on Murashige‐Skoog (MS) media with different levels (1, 3, 5 and 7%) of sucrose and subjected to low‐temperature acclimation (3/−3°C day/night temperature, 8‐h photoperiod) for 14 days. Cold hardiness (LT50 in controlled freezing), shoot moisture content, osmolality and the amounts of sucrose, glucose and fructose were determined. Exogenously applied sucrose was taken up by plants, but the uptake corresponded to less than 10% of total sugar reserves in the culture. Cold hardiness was primarily affected by acclimation treatment, but sucrose increased cold hardiness of nonacclimated plants and significantly enhanced the effect of acclimation treatment, 5% sucrose in the culture medium being optimal for cold hardening. LT50 values ranged between −4.1 and −7.1°C for nonacclimated, and between −14.2 and −20.7°C for cold‐acclimated shoots. Shoot moisture content was inversely related to medium sucrose level and declined only slightly during cold acclimation. After cold acclimation, plant osmolality predicted hardiness better than shoot moisture content. Plant osmolality and sugar content were increased by increasing the medium sucrose level and, to a greater extent, by cold acclimation. Sucrose, glucose and fructose accumulated during hardening. Sucrose was the predominant sugar, and the rate of sucrose accumulation during cold acclimation was independent of the medium sucrose level or the initial plant sucrose content. A close correlation between cold hardiness and total sugars, sucrose, glucose and fructose was established. These results suggest that sugars have more than a purely osmotic effect in protecting acclimated raspberry plants from cold.

FEEDING STIMULANT ADDED TO BACILLUS THURINGIENSIS BASED INSECTICIDES ENHANCES ACTIVITY AGAINST CHORISTONEURA ROSACEANA (LEPIDOPTERA: TORTRICIDAE)

Additions of feeding stimulants have been reported to increase the efficacy of Bacillus thuringiensis based insecticides (Bartelt et al. 1990). pheast™ (Miller Chemical and Fertilizer Corp., Hanover, Pennsylvania), which derives its trade name from yeast constituents, is one of the most effective feeding stimulants (Farrar and Ridgway 1994). Li and Fitzpatrick (1997) found that the addition of 5% Pheast to B. thuringiensis based insecticides increased the mortality of Choristoneura rosaceana (Harris) larvae fed leaves of raspberry plants, Rubus idaeus L. (Rosaceae), treated with these insecticides in the laboratory. We report results from a test of the effectiveness of Pheast when exposed to field conditions and fed to larvae in the laboratory.

308 Antioxidant Activity in Leaves and Fruit of Blackberry, Raspberry, and Strawberry

Fruit and leaves from different cultivars of thornless blackberry (Rubus sp.), red raspberry (Rubus idaeus L.), black raspberry (Rubus occidentalis L.), and strawberry (Fragaria × ananassa D.) plants were analyzed for total antioxidant capacity (oxygen radical absorbance capacity, ORAC) and total phenolic content. In addition, fruit were analyzed for total anthocyanin content. Compared to fruit, leaves were found to have higher ORAC values. In fruit, ORAC values ranged from 7.8 to 33.7 μmol Trolox equivalents (TE)/g of fresh berries, while in leaves, ORAC values ranged from 20.8 to 45.6 μmol TE/g of fresh leaves. Fruit harvested at different stages of maturity were analyzed in blackberries, raspberries, and strawberries. Blackberries and strawberries had their highest ORAC values during the green stages, while raspberries generally had the highest ORAC activity at the ripe stage (with exception of cv. Jewel, a black raspberry). Total anthocyanin content increased with maturity for all three fruit. There was a linear correlation existed between total phenolic content and ORAC activity for fruit and leaves. For ripe berries, there was also a linear relationship between ORAC values and anthocyanin content. Of the ripe fruit and leaves tested, raspberry plants appeared to be the richest source for antioxidants.

Effect of ammonium or nitrate nutrition on net photosynthesis, growth, and activity of the enzymes nitrate reductase and glutamine synthetase in blueberry, raspberry and strawberry

Blueberry, raspberry and strawberry may have evolved strategies for survival due to the different soil conditions available in their natural environment. Since this might be reflected in their response to rhizosphere pH and N form supplied, investigations were carried out in order to compare effects of nitrate and ammonium nutrition (the latter at two different pH regimes) on growth, CO2 gas exchange, and on the activity of key enzymes of the nitrogen metabolism of these plant species. Highbush blueberry (Vaccinium corymbosum L. cv. 13–16–A), raspberry (Rubus idaeus L. cv. Zeva II) and strawberry (Fragaria × ananassa Duch. cv. Senga Sengana) were grown in 10 L black polyethylene pots in quartz sand with and without 1% CaCO3 (w: v), respectively. Nutrient solutions supplied contained nitrate (6 mM) or ammonium (6 mM) as the sole nitrogen source. Compared with strawberries fed with nitrate nitrogen, supply of ammonium nitrogen caused a decrease in net photosynthesis and dry matter production when plants were grown in quartz sand without added CaCO3. In contrast, net photosynthesis and dry matter production increased in blueberries fed with ammonium nitrogen, while dry matter production of raspberries was not affected by the N form supplied. In quartz sand with CaCO3, ammonium nutrition caused less deleterious effects on strawberries, and net photosynthesis in raspberries increased as compared to plants grown in quartz sand without CaCO3 addition. Activity of nitrate reductase (NR) was low in blueberries and could only be detected in the roots of plants supplied with nitrate nitrogen. In contrast, NR activity was high in leaves, but low in roots of raspberry and strawberry plants. Ammonium nutrition caused a decrease in NR level in leaves. Activity of glutamine synthetase (GS) was high in leaves but lower in roots of blueberry, raspberry and strawberry plants. The GS level was not significantly affected by the nitrogen source supplied. The effects of nitrate or ammonium nitrogen on net photosynthesis, growth, and activity of enzymes in blueberry, raspberry and strawberry cultivars appear to reflect their different adaptability to soil pH and N form due to the conditions of their natural environment.

Effects of Trichoderma harzianum Strain T-22 Sprays on Incidence of Sooty Blotch and Fly Speck of Apple and Botrytis Fruit Rot of Raspberry

Tests were made to determine the effectiveness of Trichoderma harzianum T-22 sprays in controlling sooty blotch (Zygophiala jamaicensis) and fly speck (Gloeodes pomigena) in five experimental scab-resistant apple varieties and botrytis fruit rot in five fall-bearing red raspberry cultivars. T-22 and S-12 surfactant used in these studies were supplied by BioWorks, Inc., Geneva, N.Y. Treatments applied to runoff on foliage and fruit were: unsprayed; T22 (1.2 g·L–1), T22 + S-12 (1.2 g·L–1 + 0.5 g·L–1), Captan 50W +T22 (1.2 g·L–1 + 1.2 g·L–1), and Captan 50W (1.1 g·L–1). Raspberry treatments substituted Rovral for Captaon 50W. Cultivars in the apple and raspberry trials were planted in a randomized complete block design with three blocks in the apple and four blocks in the raspberry planting. All spray treatments were applied to each cultivar in a block. Apples were treated on 5 Aug., 19 Aug, 2 Sept., and 16 Sept. and fruit were evaluated as cultivars ripened from 29 Sept. to 17 Oct. Raspberries were treated on 30 July (34% to 86% bloom), 14 Aug., 28, Aug., and 9 Sept. Evaluation for Botrytis was made throughout this period and data are presented for 12 Sept. Incidence of sooty blotch and flyspeck were ≈50% lower in T22 treatments than in unsprayed controls, but the difference was not significant. Captan treatments had significantly lower incidence of sooty blotch. Captan and T22 treatments had less flyspeck than the unsprayed controls, but the differences were not significant. Significant cultivar × treatment interactions may have resulted from the prolonged evaluation period and obscured differences in treatment effects In the fall raspberries 10% of untreated, 5% of T22 and T22 + S-12-treated, and 2% of Rovral and Rovral + T22 fruit were infected with Botrytis. These differences were highly significant.

Cloning of three genes up-regulated in ripening raspberry fruit ( Rubus idaeus cv. Glen Clova)

Summary cDNA clones of three genes, up-regulated as raspberry ( R. idaeus cv. Glen Clova) fruit ripen, were isolated by differential screening of a cDNA library constructed from RNA extracted from ripe fruit. The expression patterns of these genes were determined in ripening fruit and in other tissues of the raspberry plant. When compared with sequences in databases, the genes were identified on the basis of sequence similarity. The predicted polypeptides coded for by the three clones show similarity to major latex proteins, a class of fruit-specific metallothionein-like proteins, and fruit-ripening associated endo-polygalactu-ronases, respectively. The potential roles of these gene products in fruit-ripening is discussed.