Branches Of Apple Trees Research Articles

Effects of Coatings and Pollenicides on Pollen Tube Growth Through the Stigma and Style of ‘McIntosh’ Apple Blossoms

Abstract The use of blossom thinners to prevent fertilization was studied in the laboratory over a three year period. Mature ‘McIntosh’ apple tree branches were cut and blossoms allowed to develop under greenhouse conditions where treatments of several coatings, potential pollenicides and hand pollination were applied. Pollen tube growth through the stigma and style was measured microscopically. Generally, there was more pollen tube growth through the styles of the treated flowers in one of the three years. The most effective coatings for restricting pollen tube growth were Safer-Soap at 40 g·L−1 and PEG-1000 at 20 g·L−1 and 10 g·L−1. Anti-Stress at 50 mL·L−1 and Safer-Soap at 20 mL·L−1 were moderately effective, and Masbrane at 20 mL·L−1 and Nutri-Save at 10 g·L−1 were the least effective. The most effective pollenicides were monobasic ammonium phosphate (MAP) at 15 g·L−1, NaCl at 12 g·L−1, and ammonium thiosulphate (ATS) at 17 mL·L−1. Pollen tube penetration to the base of the style was inhibited by ATS...

Movement of plum curculio adults toward host trees and traps: flight versus walking

AbstractAdult plum curculios, Conotrachelus nenuphar (Herbst), were dislodged from branches of apple trees by tapping on 14 days between blossom petal fall and 3 weeks thereafter. They fell onto a small square of framed white cloth that was quickly but carefully moved to a position beneath or adjacent to the canopy of another apple tree.There, adults were observed for 50‐min periods from 0800–1950 h for propensity to fly from or walk off the cloth or move to hide beneath foliage on the cloth. At each position, the mean time from observation initiation until flight, walking off or hiding did not differ significantly among these behaviors (averaging 21–30 min), but significantly more flew (31–40%) than crawled off (16–19%) or hid (18–20%). Substantial walking off but no flights occurred at air temperatures below 20 °C, whereas at temperatures of 20 °C or greater, propensity for flight was usually significantly greater than that for walking off.Flights were predominantly toward the tree canopy or inter‐tree space, with only a small proportion (17% or less) toward the tree trunk or (in a parallel study) toward an unbaited black pyramid trap (mimicking a tree trunk). Walking was overwhelmingly toward the tree trunk or a black pyramid trap adjacent to the trunk. Our observations lead us to conclude that unbaited black pyramid traps next to trunks of host trees (the most attractive position) can be effective at air temperatures below 20 °C by attracting plum curculio adults that would have entered host trees by walking toward and up tree trunks.Such traps appear to be less effective at 20 °C or greater because under such conditions, adults tend to enter host trees by flight into the canopy.

Effects of augmentative releases of eggs and larvae of the ladybird beetle, Adalia bipunctata, on the abundance of the rosy apple aphid, Dysaphis plantaginea, in organic apple orchards

AbstractThe impact of augmentative releases of larvae and eggs of the indigenous ladybird beetle Adalia bipunctata (L.) (Coleoptera: Coccinellidae) against the rosy apple aphid Dysaphis plantaginea Pass. (Homoptera: Aphididae), a major pest insect on apple trees, was assessed in field experiments in Switzerland, during 1997. In a first experiment, eggs and larvae were released on 3‐year old apple trees infested with five aphids at four different predator‐prey ratios (0:5, 1:5, 1:1, 5:1). In a second experiment, eggs and larvae were released at a predator‐prey ratio of 5:1 on branches of apple trees naturally infested with aphids. In both experiments, the interaction with ants was taken into account and the releases were done at two different times in spring. The results showed that an augmentative release of larvae significantly prevented the build‐up of colonies of D. plantaginea. Significant reductions in aphid numbers were recorded at the two highest predator‐prey ratios, 1:1 and 5:1. Larvae were efficient just before flowering of apple trees at a time when growers normally have to spray their trees. On trees where ants were present the larvae of A. bipunctata were significantly less efficient. Effects of eggs of A. bipunctata, however, were less reliable. At the first date of release (5 April), they did not hatch, probably as a consequence of bad weather conditions.

The potential of three native insect predators to control the rosy apple aphid, Dysaphis plantaginea

The potential of three aphidophagous predators, Adalia bipunctata, Aphidoletes aphidimyza, and Episyrphus balteatus to control the rosy apple aphid, Dysaphis plantaginea Pass., a major pest on apple in Europe, was assessed by means of laboratory and field cage experiments in Northern Switzerland. Under laboratory conditions, all three predators efficiently preyed upon D. plantaginea on apple seedlings. The searching success of larvae of A. bipunctata for individual aphids was not dependent on the size of branches of apple trees varying in leaf surface area from 150 cm2 to 960 cm2. Fifty and 70% of individual aphids were found and killed 6 hours and 48 hours, respectively, after release of single second instar larva of A. bipunctata. In a first field cage experiment in 1996, A. bipunctata, and to a lesser extent E. balteatus, proved to be effective and consistent predators of D. plantaginea during spring conditions, being little affected by cool temperatures and wet weather. In a subsequent field cage experiment in 1997, larvae of A. bipunctata and E. balteatus were released singly and in combination on aphid infested apple seedlings to study interactions between these two promising control agents. Both species had a significant negative effect on aphid population increase. The two species did not significantly interact and thus, their joint effect is best explained by an additive model. Combined releases of the two predator species reduced aphid densities to 5% of the control. This indicates the potential for augmentative releases of these native aphid predators to control D. plantaginea.

Relationship between the early development of apple fruiting branches and the regularity of bearing—An approach to the strategies of various cultivars

SummaryThe growth and fruiting pattern of fruiting branches of apple trees (Malus × domestica Borkh.) was investigated in several cultivars belonging to different ideotypes. The development of the laterals was described over several years, investigating the yearly changes in the bud type (latent, vegetative, non-bearing and bearing inflorescence, scar) since they first developed on one year old wood. The sequences were analysed by calculating the transition probabilities between the bud type of a given year and that of the following year, according to the age of the sequence. In general, the ability to produce a fruit bud after a fruit bud, i.e. the bourse-over-bourse phenomenon (β), and the ability to produce a fruit bud after a non-fruit bud (either vegetative or non-bearing inflorescence) (ϕ) tended to increase with time. The transition between latent buds and growing buds (vegetative or generative) was observed in all cultivars, but at a higher rate for ‘Fuji’, and did not vary according to the age of the sequence. The pattern of transition between growing buds and scar (extinction, i.e. physiological cessation of growth of the lateral) was different. First, 68% to 98% of all extinction phenomena appeared before the third year of the lateral. Second, cultivars such as Granny Smith and Red Winter, showed stronger extinction than spur-type cultivars. The balance between extinction and awakening of latent buds, called extinction assessment (ξ), was positively related to the bourse-over-bourse, over the first two couples of years of lateral life-span. The proportions of bud types on one year old wood was probably important in orientating the development of the laterals branched on the same parent shoot. Our results showed first that the first 2–3 years had a major effect on the development of the laterals over the following years, and secondly, that cultivar growth and fruiting pattern depended on a number of rather strictly defined rules (e.g. β, ϕ, ξ) the combinations of which determine the proper strategy of each cultivar. A better knowledge of these intrinsic rules should lead to an improvement in the training programme of young trees.

Residual Effects of Chemical Induction of Branching of Apple Trees in the Nursery on Their Performance after Transplanting

One-year-old trees of three apple selections [NY73334-35 (A), NY75414-1 (B), and NY75413-30 (C)] from the Geneva Breeding Program were transplanted into an orchard. While at the nursery, the trees were treated with Promalin and Accel, by themselves or in combination, to promote lateral branch formation (feathering). After trees were transplanted, no growth regulators were applied to the trees. One year after transplanting, treated trees of B and C had produced more feathers than the controls. This was particularly pronounced with the very difficult-to-branch selection C. No differences between chemical treatments were found. Regardless of selection, each chemical treatment significantly influenced increase in total extension growth compared to the control and contributed to rapid build up of tree structure. There were no differences between the treatments in tree height, tree caliper, or the number of spurs.

Leader Management and Soil Fumigation Affect Branching and Precocity of Young Apple Trees

Apple (Malus domestica Borkh.) cultivars Spur Galagored (#42) (`Gala'), Jonagored (`Morren's'), and Red Fuji (B.C. #2) (`Fuji') on Mark rootstock and `Gala' on Malling 26 EMLA (M.26) and Malling 9 EMLA (M.9) were planted in the four major apple-production regions of western North Carolina. Three leader management techniques, weak leader renewal, snaked leader, and heading with partial terminal leaf removal (H + PTLR), were applied to five-tree plots beginning the spring after planting. Leader management techniques, weak leader renewal or H + PTLR, which involved dormant pruning or vegetation removal and an interruption in vegetative vigor, reduced total branching and yield during the third year. Fumigation with methyl bromide increased lateral branching and yield in the third year. No significant yield differences were detected for `Gala' grown on M.9, M.26, or Mark rootstocks. Trees grown in the most western region of the state, Haywood County, had smaller trees and reduced yields compared to the other three regions due to a shorter growing season.

Enhancing Branching of Apple Trees in the Nursery with Plant Growth Regulators

Nursery trees of new, promising apple selections [NY-75334-35 (A), NY-75414-1 (B), and NY-75413-30 (C)] from the Geneva breeding program exhibit a distinct apical dominant growth pattern characterized by poor lateral-shoot formation (feathering). To induce feathering, the trees were foliar-treated singly or sequentially with various concentrations of Promalin (1.8%w/w GA4+7 + 1.8%w/w 6BAP) and Accel (0.18% w/w GA4+7 + 1.8% w/w 6BAP), by themselves and in combination. Regardless of branching agent, concentration, and type of application, treated trees, as compared to the control, on average, induced 11.3 vs. 2.2, 6.6 vs. 0.4, and 6.6 vs. 2.0 feathers/tree for selections A, B, and C, respectively. In most instances, higher concentrations of both chemicals induced more feathers than lower concentrations. Tree height and caliper were less affected than lateral-shoot production.

Population Development and Insecticide Susceptibility of Apple Aphid and Spirea Aphid (Homoptera: Aphididae) on Apple2

Colonies of apple aphid, Aphis pomi DeGeer, and spirea aphid, A. spiraecola Patch, were confined separately in bottle cages on apple tree branches to compare population development and susceptibility to insecticides under field conditions. Spirea aphid populations were significantly larger than apple aphid populations eight days after introduction into bottle cages. After two and a half weeks there was a 24-fold and 40-fold increase in the population of apple aphid and spirea aphid, respectively. Apple aphid was more susceptible than spirea aphid to a low concentration of esfenvalerate and to normal field and 2X field concentrations of azinphosmethyl. There was no significant difference between the two aphid species in susceptibility to methomyl, chlorpyrifos and endosulfan. Mortality of apple aphid to the two phosphate insecticides, azinphosmethyl and chlorpyrifos, was similar; however, spirea aphid was more susceptible to chlorpyrifos than to azinphosmethyl. An increased rate of population development and a greater tolerance of azinphosmethyl, the most widely used insecticide for apple insect control, could be contributing factors in the virtually complete domination of spirea aphid over apple aphid in West Virginia apple orchards.

Evaluation ofMicrothrix inconspicuella, [Lepidoptera: Pyralidae], a potential biological control agent forEmex australis in Australia, carried out in apple orchards in South Africa

Host specificity tests carried out in the laboratory in Australia during 1977, showed thatMicrothrix inconspicuella Ragonot could develop on young apple leaves (Harleyet al., 1979). Field studies in unsprayed apple orchards in South Africa showed that some feeding occurred, but fewer than 40% of late instar larvae developed to adults when confined in sleeves on apple tree branches. No feeding or survival occurred in large field cages or in the open. Adults which developed from apple fed larvae were smaller, deformed, occasionally mated and laid fertile eggs but their progeny did not feed or develop on apple fruit or leaves. In conclusion,M. inconspicuella larvae did not develop on apple fruit or leaves in the field, damage was mainly limited to apples already injured and feeding on leaves was minimal. Under normal pest control practicesM. inconspicuella populations did not survive on any part of the apple tree or onE. australis growing under the trees.

NOTCHING TECHNIQUES TO INCREASE BRANCHING OF YOUNG APPLE TREES

A series of experiments were initiated to evaluate the influence of notching on improving lateral branching of young apple trees. Buds on 2-year-old wood of `Redspur' Delicious/MM.111 were notched at 2-week intervals from 6 weeks before bloom to 2 weeks after. Notching increased lateral branching cubically with the greatest response occurring when notching was done 2 to 4 weeks before bloom. Bud break occurred equally well and shoots grew comparably when `Redcort'/M.7 were notched at the tip, middle, or base. Bud break and shoot growth from unnotched buds was greatest at the tip, intermediate in the middle and least at the base. Limbs of `Spygold'/M.7 were spread to a 45 degree angle then one bud from each l-year-old shoot was notched at either the top, side or on the bottom of the shoot. Notching increased lateral branching from all bud positions, but the greatest response was from buds notched at the top and least from those located at the bottom of a branch. Buds of `Marshall McIntosh' were notched on either 1 or 2-year-old wood. Notching increased lateral branching more on 2-year than on 1-year old wood.

NOTCHING TECHNIQUES TO INCREASE BRANCHING OF YOUNG APPLE TREES

A series of experiments were initiated to evaluate the influence of notching on improving lateral branching of young apple trees. Buds on 2-year-old wood of `Redspur' Delicious/MM.111 were notched at 2-week intervals from 6 weeks before bloom to 2 weeks after. Notching increased lateral branching cubically with the greatest response occurring when notching was done 2 to 4 weeks before bloom. Bud break occurred equally well and shoots grew comparably when `Redcort'/M.7 were notched at the tip, middle, or base. Bud break and shoot growth from unnotched buds was greatest at the tip, intermediate in the middle and least at the base. Limbs of `Spygold'/M.7 were spread to a 45 degree angle then one bud from each l-year-old shoot was notched at either the top, side or on the bottom of the shoot. Notching increased lateral branching from all bud positions, but the greatest response was from buds notched at the top and least from those located at the bottom of a branch. Buds of `Marshall McIntosh' were notched on either 1 or 2-year-old wood. Notching increased lateral branching more on 2-year than on 1-year old wood.

NOTCHING TECHNIQUES TO INCREASE BRANCHING OF YOUNG APPLE TREES

A series of experiments were initiated to evaluate the influence of notching on improving lateral branching of young apple trees. Buds on 2-year-old wood of `Redspur' Delicious/MM.111 were notched at 2-week intervals from 6 weeks before bloom to 2 weeks after. Notching increased lateral branching cubically with the greatest response occurring when notching was done 2 to 4 weeks before bloom. Bud break occurred equally well and shoots grew comparably when `Redcort'/M.7 were notched at the tip, middle, or base. Bud break and shoot growth from unnotched buds was greatest at the tip, intermediate in the middle and least at the base. Limbs of `Spygold'/M.7 were spread to a 45 degree angle then one bud from each 1-year-old shoot was notched at either the top, side or on the bottom of the shoot. Notching increased lateral branching from all bud positions, but the greatest response was from buds notched at the top and least from those located at the bottom of a branch. Buds of `Marshall McIntosh' were notched on either 1 or 2-year-old wood. Notching increased lateral branching more on 2-year than on 1-year old wood.

Uptake and movement of the fungicide imazalil following trunk injection into apple and plum trees by a novel, rapid technique

SUMMARYA hand‐held apparatus, produced by modifying a veterinary multiple dosing gun, was used to pressure‐inject aqueous solutions of imazalil into the trunks of plum or apple trees after harvest, before bud burst or during flowering. Bioassay showed that post harvest injection led to movement of imazalil up and down the trunk and into branches of both apple and plum trees. Movement in the trunk after injection before bud burst also occurred in plums but was limited in apples and fungicide was detected in branches only in apples and only at the end of the season. Injection at flowering time resulted in movement of imazalil into branches of apple, but not plum, trees. Imazalil was detected in twigs of apple, but not plum, trees but only after flowering time injections.The technique could be useful for control of tree diseases provided due attention is paid to dose, to the number and siting of injection holes and to the linking of injection time with the epidemiology of the target disease.

Physiological Changes Associated with Increased Lateral Branching of Apple Trees Treated with Aminoethoxyvinylglycine

Abstract In late September of 1981 and 1982, eight-year-old ‘Oregon-spur Delicious’ apple (Malus domestica) trees on M7 rootstock were sprayed immediately after harvest with 500 ppm AVG. The following spring of both years the number of spur leaves and lateral shoots on one-year-old wood was increased on treated trees. Total N was reduced and sucrose and fructose were increased in dormant one-year-old shoots of AVG-treated trees. Cold hardiness was not affected. Throughout the dormant period both apical and one-year-old lateral buds excised from treated trees and incubated in the dark at 24°C produced less ethylene over a period of 24 hr than buds from untreated trees. In situ ethylene production from apical buds of treated trees was also reduced as growth resumed in the spring. Chemical name used: N-(phenylmethyl)-lH-purin-6-amine (AVG).

Visual Monitoring Trap for Tarnished Plant Bug Adults on Apple1

Sticky-coated, non-ultraviolet-reflecting white rectangle traps (15 by 20 cm) hung from apple tree branches at ca. 70 cm above ground proved significantly more effective 10 detecting adult tarnished plant bugs(TPB), Lygus lineolaris (Palisot de Beauvois), than three other sampling methods: visual counts of adults on trees, limb jarring of adults onto a drop cloth, and net sweeps of ground cover vegetation. For 12 orchard situations in which no prebloom. insecticide treatments were applied, there were significant positive linear relationships between levels of TPB-injured fruit at harvest and cumulative trap capture levels through the tight-cluster (r2 = 0.736) and late-pink (r2 = 0.526) stages of flower bud development. If the economic injury level for TPB is considered to be 2.0% fruit damage, then our findings suggest a tentative action threshold of cumulative capture of 3.0 adults per trap through tight cluster or 4.4 adults per trap through late pink.

Dry matter production and nutrient exportation by pruned leaves and branches of apple trees

A trial was conducted on Latossol Vermelho Escuro Orto (Orthox) at Buri, State of São Paulo, Brazil. The material was collected from 'Ohio Beauty¹ and 'Brasil¹ apples trees grafted on 'Doucin'; the trees were 3-4, 4-5 and 6-7 years old. The authors concluded that at the dormant period differen ces were observed on the dry matter production as well on the nutrients exported by the leaves and branches of the two varieties. Branches exported higher amounts of P, Ca, B, Cu and Zn. Larger quantities of N, P and Mn were exported by the 1 eaves.

Effects of Simulated Deer Browsing on Branches of Apple Trees

Effects of Simulated Deer Browsing on Branches of Apple Trees

Influence of Early-Season Temperature on the Growth and Branching of Newly-Grafted Apple Trees

SummaryNewly-grafted trees of apple cv Discovery on MM.106 were grown in pots at 25°C before transfer to growth rooms at 20°C; some were then subjected to 5 or 10 d at 10°C. The continuous 5-d cool period stimulated branching without reducing main shoot growth but the 10-d cool period reduced main shoot growth and did not stimulate branching. Subjecting similar plants to a night temperature of 0°C for various periods also stimulated branching but the number of cold nights and the stage of scion shoot growth influenced the magnitude of the response.

Some Effects of Ringing and Deblossoming Branches of Young Apple Trees on Leaf Composition

Bark rings and blossoms were removed from selected branches of Y-shaped Sunset/M.7 apple trees at full bloom to give the 10 possible combinations of ringed and unringed, deblossomed and cropping branches. Comparisons of leaf areas and dry weight per unit leaf area (specific leaf weight) showed that leaves from ringed branches were smaller and that extension shoot leaves from ringed branches had higher specific leaf weight. Fruiting had little influence on area per leaf but gave lower specific leaf weight than deblossoming. Mineral analyses of leaves from extension shoots in late summer were expressed in terms of unit leaf area and showed significant treatment effects. Ringing both branches reduced the content of mineral elements but ringing only one branch showed smaller effects on nitrogen, phosphorus, and potassium. This suggests that these elements are taken up through the xylem whenever the roots are adequately supplied with nutrients from the branches. Calcium content, on the other hand, was appreciably reduced by any ringing, suggesting that at least some of this element is normally transported in the phloem. There was no evidence in this experiment that low mineral nutrient levels in leaves on ringed branches had been limiting to dry matter production.