Preferred Cultivars Research Articles

Consumer preference for apples: the role of attributes influencing the choice and consumption

Consumers consider good quality fruits to be those that look good, are firm and offer good flavour and nutritive value. Nowadays. consumers are. however, increasingly interested in food qualities which cannot be discovered by looking. tasting or smelling the products but their roles are not yet really cleared up. Therefore. the objective of this sllldy was to explore the importance of selected kinds of attributes (taste. size, colour, cu ltivar, origin and price) in fluencing the choice of apples of customers. In accordance with several authors, fruit qualities (taste, size and colour) seemed to be the major attributics influencing the choice of apple independently of people's age and gender. However, the size of fruit had lower importance w ith increased age. Generally, females gave higher importance rating for most attributes than did male . The price was getting more important for consumer's choice with age which can be connected with their socioeconomic situation. The origin of fruit and the cultivar did not have important influence on consumer's choice. Authors a lso investigated the preference of consumers for six selected apple varieties ('Jonagold ', 'ldared', 'Royal Gala'. 'Golden Reinders'. 'Braeburn '. and 'Granny Smith '). ancl pointed out the role of the origin in fruit quality and in choice of apple in the case of 'Granny Smith · cultivar. Apple fruit samples from Austria, Argentina, Chile, Hungary and South Africa were involved in this study. Authors evaluated fruit quality parameters of above cu l t ivars and compared them to consumer preference. Consumer preference usually represented the quality att ributes of the fruit well. It is also concluded t hat degree of liking of apple cult ivars varies through gender and age. Children and young consumers preferred 'Royal Gala', 'Granny Smith ·and 'Braeburn '. mostly. In spite of 'Idared' is one of the cultivars grown on the largest area in Hungary, the lowest preference ra t ings were given for it in bot h gender categories. Middle-aged consumers (between 25 and 50 years or age) preferred crispy apples with red or blemished skin color ('Royal Gala·, and 'Jonagold'). 'Jonagold' and 'Idared ' were the most preferred cultivars for the consumers above the age of 50 likely because of their relatively low price, as pr ice plays a significant influencing role in the purchase of these consumers. The relat ively expensive and soury 'Granny Smith ' appeared not rea lly preferred by this age group. I n spite of the significant differences in instrumentally measured fru it quality parameters among 'Granny Smith' fruit samples from different countries, consumers did not give significantly different preference rat ing scores for those.

The effect of grape vine cultivars on Lobesia botrana (Lepidoptera: Tortricidae) population levels

The European vine moth Lobesia botrana Denis & Schiff. (Lepidoptera: Tortricidae) is a key pest in the vineyards of Israel and Europe. Traps baited with the female sex pheromone are commonly used to monitor the pest population. However, the role of the vine cultivars on monitoring the moth population using pheromone-baited traps was not yet studied. The present study aimed to identify the effect of grape cultivars on L. botrana adult distribution patterns in the field, in order to achieve a better understanding of the monitored data in respect to male and female’s host preference. The 3-year study in commercial vineyards used four cultivars: Carignan, Emerald Riesling, French Colombard, and Cabernet Sauvignon. The moth population of each generation was estimated from male counts in pheromone traps; three generations were observed in all experimental orchards, each year. Female host choice was studied by monitoring freshly deposited eggs and newly hatched larvae on vines. The study showed a significant effect of cultivar on numbers of trapped males in most years, and a cultivar effect on female host choice. For both males and females and for all phenological stages of the grapes, Carignan and French Colombard attracted the most and Cabernet Sauvignon the fewest specimens. The results show that cultivar blend within the vineyard can affect the distribution pattern of the pest. Knowledge of the expected choice of the female moth, and of the timing of its decision could lead to an improved monitoring system, with the preferred cultivar as an indicator.

Consumer evaluation of scab-resistant apple cultivars in Sweden

The feasibility of using untrained consumers for sensory evaluation was investigated on Swedish-grown scab-resistant apple cultivars in 2002 (11 cultivars) and 2003 (15 cultivars). The consumers evaluated five cultivars each, including the control cultivar ‘Aroma’. Each cultivar was scored for appearance, texture, juiciness, taste and overall impression by a minimum of 100 consumers in 2002 and by 200 in 2003. All quality attributes were positively correlated when calculations were performed across all consumer scores, with overall impression and taste having the strongest association. ‘Rubinola’ and K:1160 emerged as the best liked cultivars overall. Cultivar means were analysed for relationships with some previously scored or measured variables and with consumer profile data. Positive correlations with overall impression were obtained for amount of red colour in 2002, and for sugar levels in 2003. Among consumer profile variables, age had the largest influence on consumer scores, with some indications that older consumers preferred (or at least tolerated) soft-fleshed cultivars better than did younger consumers. Minimum number of consumers needed to obtain reliable results was determined by computer simulations indicating that the error rate became stabilized already with 50 consumers.;

Studies on the Aroma of Five Fresh Tomato Cultivars and the Precursors of cis- and trans-4,5-Epoxy-(E)-2-Decenals and Methional

Three tasty (BR-139, FA-624, and FA-612) and two less tasty (R-144 and R-175) fresh greenhouse tomato cultivars, which significantly differ in their flavor profiles, were screened for potent odorants using aroma extract dilution analysis (AEDA). On the basis of AEDA results, 19 volatiles were selected for quantification in those 5 cultivars using gas chromatography-mass spectrometry (GC-MS). Compounds such as 1-penten-3-one, ( E, E)- and ( E, Z)-2,4-decadienal, and 4-hydroxy-2,5-dimethyl-3(2 H)-furanone (Furaneol) had higher odor units in the more preferred cultivars, whereas methional, phenylacetaldehyde, 2-phenylethanol, or 2-isobutylthiazole had higher odor units in the less preferred cultivars. Simulation of the odor of the selected tomato cultivars by preparation of aroma models and comparison with the corresponding real samples confirmed that all important fresh tomato odorants were identified, that their concentrations were determined correctly in all five cultivars, and that differences in concentration, especially of the compounds mentioned above, make it possible to distinguish between them and are responsible for the differential preference. To help elucidate formation pathways of key odorants, labeled precursors were added to tomatoes. Biogenesis of cis- and trans-4,5-epoxy-( E)-2-decenals from linoleic acid and methional from methionine was confirmed.

A preference assay for quantifying symbiont choice in fungus-growing ants (Attini, Formicidae)

We describe a bioassay for the quantification of cultivar preference (symbiont choice) of fungus-growing ants. The bioassay simultaneously presents mycelium of multiple pure cultivar genotypes to worker ants in a cafeteria-style test arena, and preferred versus non- preferred cultivar genotypes can then be identified based on the ants- quantifiable behavioral tendencies to convert any of the offered mycelium into a fungus garden. Under natural conditions, fungus-growing ants are likely toexpress such cultivar preferences when mutant culti- vars arise in a garden, or when colonies acquire a novel cultivar from a neighboring colony to replace their resident cultivar. We show that workers from different nests of the fungus-growing ant Cyphomyrmex costatus exhibit repeatable preferences vis-0-vis specific cultivar genotypes. The identified preferred and rejected cultivars can then be used in a performance assay to test whether the ants prefer cultivar genotypes that are superior in enhancing colony fitness (measured, for example, as garden productivity or colony growth), as predicted by symbiont-choice theory.

In the Ant's Garden, Fungal Parasites Are Closely Matched to Their Fungal Hosts

Like all gardeners, fungus-growing ants risk losing their crop to pests. In particular, the cultivated fungi are parasitized by other fungi—of the species Escovopsis—which invade the fungal garden and consume the crop within. In virtually all cases, a single species of ant grows only a narrow range of genetically similar fungal cultivars, and these, in most cases, are parasitized by a few or only one type of Escovopsis. While the ants do their best to protect their crop, it is important for the fungus itself to ward off the depredations of Escovopsis. Exactly how they do this is unknown. In a new study, Nicole Gerardo and colleagues demonstrate that different fungal cultivars have different abilities to ward off potential parasites; that successful parasites can best overcome the defenses of that cultivar they typically infect; and that host-switching by Escovopsis is likely inhibited by the genetically based specificity of these relationships. The authors first showed that growth of the various Escovopsis types toward their preferred fungal cultivars is driven by a signal from the target. Yellow-spored Escovopsis grew faster toward its preferred host (cultivar A) than toward no target, or toward cultivar B, which it does not feed on. Brown-spored Escovopsis, which feeds on both A and B, grew faster toward either than toward no target. Neither the yellow nor the brown types did well against cultivar C, which is only distantly related to their normal hosts. In many cases, cultivar C kept these predators at bay for up to several months. In some trials, however, C did not repel the yellow type and, in fact, in some trials, the yellow fungus grew faster toward C. This suggests genetic variability in the two fungal groups, which the authors confirmed. They showed that genetically similar Escovopsis strains were likely to be inhibited by the same C cultivar, and vice versa—genetically similar C cultivars were likely to inhibit a specific Escovopsis strain. Over time, such close relationships, and the difficulty of overcoming non-host defenses, may inhibit host switching on the part of Escovopsis, and lead to synchronous speciation of the fungal hosts and parasites. On the other hand, the genetic variation that allowed some yellow Escovopsis to attack the C cultivars suggests that host switching remains a possibility among these fungi. These results suggest that the ability of a specific Escovopsis type to parasitize a specific fungal cultivar is aided both by the chemical cues that attract the parasite and the close match between the host's defensive weaknesses and the parasite's strengths. The rapid growth this allows may help the parasite to stay ahead of the ant's anti-fungal defensive mechanisms (like any good gardener, the ant farmers weed out the species they don't want in their garden). More broadly, these results help clarify the variety of mechanisms involved in host–parasite relationships, which exist across all the domains of life.

(96) Sensory Evaluation of Alternative Pear Varieties for the U.S. West Coast

Assessing consumer acceptance is an important aspect of cultivar evaluation. Since 2002, about 2700 consumers have participated in pear preference surveys. Surveys were conducted on multiple dates and at multiple venues from 2002 to 2005 in Oregon and northern California. Survey participants were asked to indicate their preference for pears based on size, appearance, taste, and overall preference. They were also asked to indicate what attributes they liked or disliked about their favorite and least favorite varieties and to indicate their level of purchase intent. Each survey consisted of four to six cultivars, including at least one standard commercial comparison; i.e., Bartlett, Bosc, or Anjou. Data was analyzed (RCBD; Friedman Analysis of Rank or ANOVA/Tukey's HSD) at the OSU Food Innovation Center Experiment Station using Compusense® five v.4.6 software (Guelph, Ont., Canada). Results indicated several alternative possibilities for both summer and winter sales. Among the most preferred cultivars (variable between states) were Anjou (commercial standard winter pear), Bartlett (commercial standard summer pear and most-consumed cultivar), Blake's Pride, Cinnamon, Concorde, and 71655-014. Other major findings were preference for large pears for adults and small for children, overall liking based on sweetness and flavor rather than skin color, and general lack of knowledge of many commercial pear cultivars. Sensory evaluation surveys will be continued in 2006 in California, with focus on differential harvest times for selected preferred cultivars. Consumer preference data is being combined with production and postharvest quality data in order to provide the pear industry a comprehensive data set on potential alternative cultivars.

Consumer Survey of Selected Garden Chrysanthemum Cultivars in Mississippi

The objective of this survey was to determine the levels of liking and willingness to pay for selected garden chrysanthemum (Dendranthema ×grandiflorum) cultivars, and to measure relative infl uence of socioeconomic characteristics on consumer preferences and valuations. The survey was conducted during the 2003 Fall Flower and Garden Fest at the Truck Crops Experiment Station in Crystal Springs, Miss. Nine garden chrysanthemum cultivars were presented to 579 survey participants in three pot sizes. Respondents preferred `Mithra Maroon', `Venus Purple', `Amory Yellow White', `Adonis Purple', and `Road Runner Bronze' more than `Night Hawk Lemon', `Freya Salmon', `Amata Purple', and `Starlet Ivory'. Of the five preferred cultivars, however, respondents were willing to pay more for `Mithra Maroon', `Road Runner Bronze', and `Amory Yellow White'. Consumers of White or Caucasian origin liked the cultivars less and were willing to pay less for them as compared to other respondents who reported other racial origins, primarily Native Americans and African Americans. The levels of liking for the cultivars were similar for participants of different gender classification, but female respondents were willing to pay more for the cultivars. Respondents who previously bought chrysanthemums reported higher level of liking for the cultivars but were not willing to pay more for them. Participants who were interviewed on Saturday liked the cultivars more but were willing to pay less than those who were interviewed on Friday. Larger-sized households tended to like the cultivars less and were not willing to pay more for the cultivars. Respondents did not like the cultivars in larger-sized pots and were not willing to pay more for plants in larger-sized pots included in the survey.

Interaction between natural and synthetic fruit odor influences response of apple maggot flies to visual traps

AbstractIn order to improve perimeter trapping for apple maggot fly behavioral control, we designed a set of experiments which aimed to reach a better understanding of the nature of the interaction between the natural host odor released by susceptible and low‐susceptibility apple cultivars, and an artificial host odor currently employed as a lure along with visual traps for apple maggot fly, Rhagoletis pomonella (Walsh) (Diptera: Tephritidae), perimeter trapping programs. The response of apple maggot flies to lured and unlured visual traps deployed in different rectangular arrays of susceptible and low‐susceptibility apple cultivars (two central trees of a particular cultivar surrounded by four perimeter trees of the same or a different cultivar) was evaluated over 2 years under field conditions. In uniform blocks of susceptible (Tidemann Red, Jersey Mac) or low‐susceptibility (Marshall McIntosh) cultivars, lured traps recovered a significantly greater proportion of the total capture than unlured traps, irrespective of lure position (center or perimeter trees). Unlured traps on central susceptible apple cultivars (Red Astrachan, Gala, Fuji) recovered a significantly greater proportion of the total capture than unlured traps on surrounding low‐susceptibility cultivars (Marshall McIntosh, Paula Red, Red Delicious, and Golden Delicious). Placing the lures near traps on low‐susceptibility cultivar trees surrounding unlured traps on central susceptible cultivar trees reduced apple maggot fly visits to traps on central trees, but the latter still recovered a similar proportion of the total capture as lured traps on perimeter trees. By contrast, placing the lures near traps on central susceptible cultivar trees surrounded by unlured traps on low‐susceptibility cultivar trees allowed lured central traps to receive a significantly greater proportion of the total capture than unlured perimeter traps. We conclude that the synthetic and natural host odor of susceptible cultivars interact additively in attracting apple maggot flies to visual traps, and that, when given the choice, traps and lures should be deployed on preferred rather than on less preferred cultivar trees. Implications for trap deployment strategies for tephritid monitoring and control are discussed in the light of our findings.

Susceptibility of strawberry cultivars to the vine weevil Otiorhynchus sulcatus (Coleoptera: Curculionidae)

Abstract 1 The feeding preference of vine weevil, Otiorhynchus sulcatus (Fabricius), adults for foliage from 21 commercial cultivars of strawberries is investigated using binary choice tests with leaf disks, using ‘Honeoye’ as a standard against which all other cultivars are compared. ‘Delmarvel’, ‘Idea’, ‘Lester’, ‘Primetime’ and ‘Seneca’ are not preferred.2 Variation in leaf nitrogen content is correlated with feeding preference, but does not explain all the variation, because outliers exist for both preferred and nonpreferred cultivars.3 Removal of leaf hairs with adhesive tape permits their role in deterrence to be evaluated. Eight of the 21 cultivars have deterrent leaf hairs. Paradoxically, some highly preferred cultivars (e.g. ‘Latestar’ and ‘Tristar’) have deterrent leaf hairs, and four of the five nonpreferred cultivars lack significantly deterrent leaf hairs.4 The 21 tested cultivars do not differ in their suitability for vine weevil larval development.5 Differences in cultivar susceptibility to vine weevil in the field may involve interactions between the palatability and nutritional value of foliage, which influence fecundity and egg placement, and the tolerance of strawberry plants to larval feeding, determined by root biomass. The nonpreference traits found in the foliage of commercial cultivars of strawberry are present by chance. Accordingly, further selective breeding to enhance strawberry varietal tolerance to vine weevils may be possible.

The use of sensory evaluation and consumer preference for the selection of sweetpotato cultivars in East Africa

AbstractSweetpotato is an important staple crop in East Africa with great potential for introducing improved cultivars, but little is known about which sensory characteristics are desirable. Over a 2 year period, 600 consumers were interviewed at three locations (urban and rural) in the Lake Zone of Tanzania and their preference of 14 locally available sweetpotato cultivars in cooked form was evaluated. A simple questionnaire based on consumers first‐choice preference was used followed by socio‐economic questions. A trained sensory panel profiled the cooked sweetpotato samples, enabling comparisons with preference, location and season. Cluster analysis based on the sensory attributes was used to classify the cultivars into three groups; one cluster comprised the most preferred cultivars and another contained the least. Some cultivars were consistently preferred over the 2 year period while others were not. The location where the cultivars were grown also influenced preference. Stepwise regression indicated that the most discriminating sensory attributes were starch and stickiness. Target levels based on the mean intensity scores of these attributes are suggested as a means of screening new cultivars. The implications of these findings are discussed. Copyright © 2004 Society of Chemical Industry

In Search of the “Ideal” Pear (pyrus spp.): Results of a Multidisciplinary Exploration

ABSTRACT:Preference mapping with 10 pears identified 3 segments among New Zealand consumers. While 1 segment preferred ripe European cultivars, another rejected only the seedling with strong off‐flavors. A 3rd segment combined the 2 former segments, but also rejected 2 hybrid samples. Survey responses to the question “To me, the ideal pear is ⃛” from a 2nd consumer sample confirmed the general preference for juicy and sweet pears, the key characteristics of ripeness. A separate appearance evaluation revealed 4 segments based on color and shape. Combining information from several sources resulted in suggestions for new breeding directions for pears, while highlighting the importance of appearance and the need for more extensive measurements.

Genetic mapping of QTLs conditioning soybean sprout yield and quality

Soybean sprouts have been used as a food in the Orient since ancient times. In this study, 92 restriction fragment length polymorphism (RFLP) loci and two morphological markers (W1 and T) were used to identify quantitative trait loci (QTLs) associated with soybean sprout-related traits in 100 F2-derived lines from the cross of ’Pureunkong’×’Jinpumkong 2’. The genetic map consisted of 76 loci which covered about 756 cM and converged into 20 linkage groups. Eighteen markers remained unlinked. Phenotypic data were collected in 1996 and 1997 for hypocotyl length, percentage of abnormal seedlings, and sprout yield 6 days after germination at 20°C. Hypocotyl length was determined as the average length from the point of initiation of the first secondary root to the point of attachment of the cotyledons. The number of decayed seeds and seedlings, plus the number of stunted seedlings (less than 2-cm growth), was recorded a s abnormal seedlings. Seed weight was determined based on the 50-seed sample. Sprout yield was recorded as the total fresh weight of soybean sprouts produced from the 50-seed sample divided by the dry weight of the 50-seed sample. Four QTLs were associated with sprout yield in the combined analysis across 2 years. For the QTL linked to L154 on the Linkage Group (LG) G the positive allele was derived from Pureunkong (R 2 = 0.19), whereas at the other three QTLs (A089 on LG B1, A668n on LG K and B046 on LG L) the positive alleles were from Jinpumkong 2. QTLs conditioning seed weight were linked to markers A802n (LG B1), A069 (LG E), Cr321 (LG F) and A235 (LG G). At these four markers, the Jinpumkong allele increased seed weight. Markers K011n on LG B1, W1 on LG F and A757 on LG L were linked to QTLs conditioning hypocotyl length; and Bng119, K455n and K418n to QTLs conditioning the abnormal seedlings. The QTLs conditioning sprout yield were in the same genomic locations as the QTLs for seed weight identified in this population or from previously published research, indicating that QTLs for sprout yield are genetically linked to seed-weight QTLs or else that seed-weight QTLs pleiotropically condition sprout yield. These data demonstrate that effective marker-assisted selection may be feasible for enhancing sprout yield in a soybean. The transgressive segregation of sprout yield, as well as the existence of two QTLs conditioning greater than 10% of the phenotypic variation in sprout yields provides an opportunity to select for progeny lines with a greater sprout yield than currently preferred cultivars such as Pureunkong.

469 Some Citrus Flower Characteristics Limit Bee Preference of Hybrids and Their Pollination

Except for `Orlando' and `Minneola' tangelos, most citrus hybrids grown in Florida are small-flowered and produced less than half the nectar of large-flowered cultivars. Sugar contents in large- and small-flowered cultivars were not different in 1997, but the concentration of sugars doubled in 1998 over 1997 for small-flowered hybrids, while nectar volume was about one-half of that in the previous year. Nectar volume of large-flowered cultivars increased slightly in 1998 compared to 1997. Of four aromatic volatiles measured from headspace over flowers, `Robinson' and `Ambersweet' were lowest in total while other cultivars had only some specific differences. Grapefruit flowers produced high limonene levels, while `Sunburst', `Fallglo', and `Valencia' gave off the most myrcene. Bees were tested for flower preference in a round, white screenhouse using a mini-hive and duplicated fresh-cut flower bouquets each day. Bees preferred large-flowered cultivars with more nectar. Some other preferences also were observed. In the field, hedge-rows limited cross movement of bees in mature blocks of hybrids, which limits the number of contiguous rows of the preferred cultivar for good pollinization. Timing of bee hive placement was also critical to get bee movement into the intended block because flowering times differ for some cultivars and bees develop inital preferences.

The importance of being bitter—a qualitative study on cassava cultivar preference in Malawi

We conducted qualitative interviews in Nkhata‐Bay district in Malawi to elucidate why farmers preferentially grow cassava cultivars providing bitter roots. Cassava was mainly grown to produce flour for making the staple food, kondowole. Plants were identified as belonging to one of the 54 mentioned cultivars with local names. All the farmers stated that bitter taste of roots predicted toxicity and necessity for processing. Cultivars were grouped into “cool” or “bitter” based on whether the roots could be eaten fresh, or required processing before consumption as kondowole. Farmers strongly preferred cultivars grown for flour production to have bitter roots since this protected against theft, destruction by animals and deterred household members from unplanned harvest. Since processing is done by women bitterness empowers women to control the families staple crop. Bitter cultivars reportedly yielded more and roots produced an easier to mould kondowole. Bitterness and toxicity were not perceived as a problem.

Performance of Western Flower Thrips (Thysanoptera: Thripidae) on Cultivars of Miniature Rose

The performance of western flower thrips, Frankliniella occidentalis (Pergande), on cultivars of miniature rose, Rosa chinensis ‘minima’ , was measured via larval development and adult oviposition experiments using leaf and petal disks. The time for larvae to complete development on both leaf and petal disks differed significantly among cultivars, although the differences were much more pronounced on petal tissue. Developmental time was prolonged on petal tissue from cultivars with red and orange flowers and generally shortest on white- and yellow-flowered cultivars. Larvae failed to complete development on petal tissue from one red- and one orange-Howe red cultivar. In a no-choice test during 10 d, female thrips deposited significantly different numbers of eggs in flower petal tissue among cultivars, with red- and orange-flowered cultivars being among the least preferred. In choice tests comparing oviposition during 48 h in petal disks from cultivars with the same flower color, a preferred cultivar was revealed in each flower color group. In choice tests under constant light and constant dark conditions, using pair combinations of petal disks from the preferred cultivars, flower color had no effect on choice of oviposition substrate. When leaf and flower petal disks from the same cultivar were compared in choice tests, leaf tissue was consistently the preferred substrate for oviposition,

Symptom Development and Susceptibility of Dwarf Cherry Tomato to Tomato Irregular Ripening, A Fruit Disorder Induced by Silverleaf Whitefly

Silverleaf whitefly (SLW) (Bemisia argentifolii Bellows and Perring) feeding has been associated with development of tomato irregular ripening (TIR) symptoms. Four dwarf cultivars of cherry tomato (Lycopersicon esculentum L.) were infested with adult SLW to observe oviposition preference, tolerance and TIR symptom development. Oviposition preference was observed at low SLW population. Florida Petite was the most preferred and Micro-Tom the least preferred cultivar, with Florida Lanai and Florida Basket intermediate. Each cultivar exhibited TIR symptoms associated with feeding by the SLW. TIR fruit symptoms were expressed as longitudinal red streaks with yellow, green, pink or red blotches externally, and white, yellow or green tissue internally. External TIR symptoms ranged from 32% (Micro-Tom) to 82% (Florida Basket). However, external symptoms disappeared from 34% (Florida Lanai) to 56% (Micro-Tom) of the fruits during ripening. SLW infested plants had 82% (Florida Lanai) to 99% (Florida Basket) of fruits with internal white tissue regardless of external symptoms. Tomatoes with TIR symptoms rarely ripened to a mature red, and sometimes had empty locules, were smaller in size and were seedless.

Antibiosis and antixenosis of chrysanthemum cultivars to the aphid Aphis gossypii

AbstractAn assessment was made of the antibiotic and antixenotic resistance of three cultivars of autumn flowering chrysanthemum (derived from Dendranthema morifolium (Ramat) Tzvelev and D. indicum (L.) Desmoulins) to the aphid Aphis gossypii Glover. Antibiosis was also assessed at the top, middle and lower leaves of the plant. The three cultivars showed a range of resistance with Hero being the most susceptible, Surfine the most resistant and Purple Anne intermediate. There was a trend for antibiosis to improve with position down the plant, however there were cultivar by position interactions. Antixenosis was assessed at two levels, the first being under conditions where the aphid had complete access to the plant in caged choice assays and the second being under conditions where the aphid only had host odour to assess under olfactometer choice conditions. Preferences under the caged choice conditions found Hero to be the most preferred cultivar while there was no preference shown between Purple Anne and Surfine. However, olfactometer assessments showed Hero to be the least preferred of the three cultivars and, again, no preferences could be found between Purple Anne and Surfine.

Resistance of Flowering Crabapple Cultivars to Defoliation by the Japanese Beetle (Coleoptera: Scarabaeidae)

Flowering crabapples, Malus spp., are important small landscape trees in much of the United States and southern Canada. We evaluated 42 cultivars of Malus spp. for resistance to defoliation by Japanese beetles, Popillia japonica Newman, for 2 growing seasons and found marked and consistent variation in resistance. Defoliation caused by beetles ranged from 100 to <10% among cultivars at the same site. ‘Radiant’, ‘Red Splendor’, ‘Royalty’, ‘Liset’, ‘Ruby Luster’, and others were severely damaged, whereas M. baccata ‘Jackii’, ‘Harvest Gold’, and ‘Jewel berry’ were highly resistant in both years. Red - and purple-leaved cultivars, and those with reddish young leaves that mature to green, were generally fed upon more heavily than were cultivars with wholly green leaves. The rank order of cultivars in no-choice leaf disk assays was correlated with damage levels in the field. Longevity and fecundity of females were highest for beetles fed foliage from preferred cultivars. Possible mechanisms of resistance to P. japonica, and the relationship of our results to earlier studies of resistance of Malus spp. to diseases and other insect pests are discussed.

The effect of hydrogen cyanide potential (HCNp) and sward morphology on the relative acceptability to sheep of white clover and Caucasian clover herbage

AbstractThe effect of cyanide concentration and plant morphology on the relative acceptability to sheep of fifteen cultivars of Trifolium repens and one cultivar one cultivar of Trifolium ambiguum were assessed in a field trial at Armidale, Australia (30°S). Preference was shown for the taller, larger leaved cultivars of white clover such as Lucky. Regal, Haifa, Aran, Olwen, and for Monaro Caucasian clover, when differences in leaf size and height were most accentuated. Dry matter consumption was a poor indicator of preference. Acceptability measures were not well‐correlated with HCNp. Cyanide contents increased from January to April, but were considerably lower in July and November. Aran and Olwen had consistently the highest HCNp while Lucky, Regal and Monaro had the lowest HCNp. Sulphur contents were always high (&gt; 2%) and varied only slightly between cultivars. Sheep preferred clover cultivars that were easiest lo harvest; these were large leaved, tall types. However, once the obvious differences in ease of harvesting were removed, sheep grazed opportunistically. Since HCNp had no effect on acceptability, breeders should aim for cultivars with moderate to low HCNp to retain pest protection but minimize goitrogenic potential. Caucasian clover exhibited a different growth pattern to white clover but its acceptability was similar.