Orchard Conditions Research Articles

Promotion of apple tree growth and fruit production by the EBW-4 strain of Bacillus subtilis in apple replant disease soil.

A field trial was conducted near Kelowna, British Columbia, to determine the effect of biological treatments alone and in combination with formalin fumigation in apple replant disease soil. The response was measured by the increase in cross-sectional trunk area, total shoot growth, and fruit yield of McIntosh apple trees on M.26 rootstock. The postplanting drench application of strain EBW-4 of Bacillus subtilis alone was consistently effective in increasing cross-sectional trunk area for 5 years, total shoot growth for 4 years, and fruit yield for 3 years. The biological agent EBW-4 of B. subtilis in combination with formalin fumigation was also effective in promoting total shoot growth and cross-sectional trunk area. The application of formalin fumigation alone was effective in increasing shoot growth for 2 years and cross-sectional trunk area for 1 year only. This treatment did not increase fruit yield for 3 years. The consistent performance of strain EBW-4 of B. subtilis during 1986-1991 indicates that this bacterium has the potential for biological control of replant disease under orchard conditions in the Okanagan Valley of British Columbia.

Field Evaluation of Benomyl to Control Cylindrocladium Fruit Spot of Custard Apple.

Cylindrocladium leaf and fruit spot caused by Cylindrocladium colhounli is a recently reported disease of custard apple (Annona cherimola x A, squamosa). The fungus defoliates leaves and renders fruit unsaleable. A field spray trial showed that seven fortnightly applications of benomyl at 0.25 g, 0.5 g and 1.0 g a.i./L significantly reduced the incidence of disease compared to unsprayed trees. There were no significant differences in control achieved by different rates of benomyl. The levels of benomyl residue in fruit sprayed with the two higher rates were below 2 ppm, 7 days after the last application. The lower rate (benomyl 0.25 g a.i./L) should be recommended to control disease under orchard conditions.

Effects of flooding and alluvium deposition on kiwifruit (Actinidia deliciosa): 1. Early vine decline

Abstract Kiwifruit vines are reported to be very sensitive to anaerobic conditions in the root zone, but this has been little studied under orchard conditions. Opportunity to study this extensively arose when, in March 1988, Cyclone Bola caused flooding in kiwifruit orchards near Gisbome, New Zealand. We sought to identify factors responsible for early decline of flooded vines, and strategies to increase vine survival after flooding. Early decline was defined as premature defoliation in the first 11 weeks following the flood. Vine health and soil conditions were monitored at 10 sites. Vines first showed waterlogging damage 3–7 days after the flood, but the proportion of vines affected varied greatly between sites. Over all sites, one third of the vines experienced early decline. One half of these affected vines were still stressed or dead the following spring (October 1988). Early decline was closely associated with feeder root death. Infections by Phytophthora spp. and site-to-site differences in flood c...

Spread and Persistence of Benomyl-ResistantMonilinia fructicolain South Carolina Peach Orchards

The spread and persistence of benomyl-resistant Monilinia fructicola were studied in an experimental peach orchard, and results were compared with conditions in several commercial peach orchards in which resistance to benomyl had occurred. One fungus strain that was resistant to iprodione was also examined in the experimental orchard. Benomyl-resistant strains became established and spread in the experimental orchard, but the frequency of isolation of these strains relative to sensitive strains declined as the progressed unless the trees were sprayed with benomyl (...)

Seasonal Soil Waterlogging Influences Water Relations and Leaf Nutrient Content of Bearing Apple Trees

Abstract Bearing ‘Macspur’/M.26 apple trees (Malus domestica Borkh.) were grown in plastic-lined basins under orchard conditions. Four treatments were imposed in each of 3 years consisting of controls and 6-week periods of soil waterlogging in the spring, summer, or fall. Stomatal conductance (gs), transpiration rate (E), leaf water content (LWC), and stem water potential (ψstem) were measured at the end of each waterlogging period. Stomatal conductance was significantly reduced by spring and summer waterlogging, but not by fall waterlogging. Reduction in g, and E generally increased over years. Stem water potential after spring and fall waterlogging averaged 8% less negative than controls in all 3 years, with no trend over the 3 years. In contrast, of summer-waterlogged trees was unaffected, 45% was more negative, and 31% less negative than controls in the first, second, and third year of treatment, respectively. Annual reductions in growth and yield due to the waterlogging treatments were related to decreased gs and to both negative and postive changes in ψstem. Leaf levels of N, P, K, and Cu measured in July were reduced only by summer waterlogging, with no trend in reponse over years.

Ethephon and NAA Facilitate Early Harvesting of Pecans

Abstract In an attempt to solve the problems of nonuniform and delayed shuck dehiscense of pecan [Carya illinoensis (Wangenh.) C. Koch], ethephon and NAA were evaluated for their efficacy as harvest-aid treatments. A 3-year study under commercial-like orchard conditions using 75-year-old ‘Stuart’ trees resulted in a spray mixture of 9 mm ethephon and 1.5 or 3.0 mm NAA, or just 9 mm ethephon alone, accelerating shuck dehiscence by 1 to 2 weeks relative to that of the nontreated control. While all three treatments induced some degree of leaflet abscission, the two treatments employing the NAA and ethephon combination induced only about one-fourth (21% vs. 75%) as much leaflet abscission as when ethephon was used alone. However, this level of leaflet abscission (21%), plus an associated 50% drop in net photosynthesis for several days post-treatment, was sufficient to reduce in-shell nut yields in subsequent years. This appears to preclude commercial acceptability of such treatments for pecan. Chemical names used: (2-chloroethyl)phosphonic acid (ethephon), 1-napthaleneacetic acid (NAA).

ALMOPOL: A Cross-pollination and Nut Set Simulation Model for Almond

Abstract ALMOPOL is an interactive computer-based model that simulates the interactions of weather, bloom phenology, blossom quality, and honey bee foraging behavior that culminate in almond [Prunus dulcis (Mill) D. A. Webb] nut set. ALMOPOL enables users to enter orchard conditions, colonies per hectare, and foragers per colony. Information concerning honey bee foraging behaviors and blossom quality (i.e., a blossom's probability of setting a nut if cross-pollinated) can also be entered interactively into the program. Hence, nut set estimates are specific for a given set of weather, orchard, bee behavior, and blossom quality conditions. A description of the logic and data used in ALMOPOL's construction is included.

リンゴ園における葉面積の推定法

The relationship between leaf area and branch diameter was examined to establish a method for estimating orchard leaf area. Measurements were obtained from 15-25-year-old “Fuji” apple trees on a domestic clonal rootstock (Malus prunifolia) trained to an open-center or modified center-leader shape in 22 commercial orchards of various soil conditions located in Aomori prefecture.The relationship between leaf area (Y) and branch diameter (X) was represented by a single regression equation:log Y=-0.710+2.145log X The correlation was fairly high (r=0.931), considering that the sample branches were taken under a wide range of orchard conditions. This was considered to be attributable to the facts that samples were selected from branches of at most 5cm in diameter measured at the point just below the lowest leafy branchlets.The following method was proposed for estimating the total leaf area of an apple tree. The leaf area on all individual branches of less than 5cm in diameter is estimated from their diameter, using the regression equation presented above. The values of the leaf area of individual branches are then summed up for the whole tree.The leaf area of scaffold branches which was estimated using this method gave a close approximation to the actual leaf area (r=0.920).It is concluded that the above estimation method provides a rapid and reasonably accurate measurement of the total orchard leaf area and can be used for a satisfactorily wide range of orchards.

A simple, robust lightmeter for measuring light in orchards

SummaryThe lightmeter is based upon a selenium cell. The sensor has a good cosine response and a maximum output of c. 20mV in full sunlight. Although the wavelength sensitivity of the sensor only approximates that of a quantum sensor the calculated errors under orchard conditions are shown to be negligible.

Effect of rootstock on apple (Malus domestica) tree water relations

The effects of rootstock on mid‐season water relations, under orchard conditions of non‐limiting soil moisture, were determined for bearing ‘Empire’ apple trees (Malus domestica Borkh.) on the clonal rootstocks M9, M26, M7, MM106, and MM104 (most to least dwarfing) in their sixth and seventh growing seasons. Stem water potentials (ψstem) of trees on M9 and M26 were more negative at midday, under warm, sunny conditions, than were the trees on the other three rootstocks. However, change in ψstem per change in stem distance through the canopy (water potential gradient) did not vary among rootstocks at midday. There was no rootstock effect on diurnal variation in transpiration or stomatal conductance. Differences in water storage capacitance, relative to tree size, were determined in a separate study but did not account for the differences observed in ψstem. Calculated hydraulic conductivities of xylem water transport suggest that rootstocks differ in their ability to conduct water to the scion, but hydraulic conductivity of the scion was not affected by rootstock. Root‐stock differences in hydraulic conductivity were not accounted for by differences in tree size.

Effects of fungicides on apple crown rot caused by Phytophthora cactorum

AbstractThe mycelial growth of Phytophthora cactorum on corn meal agar was completely inhibited by metalaxyl or mancozeb at 50 or 100 μg ml−1, but not by fosetyl‐aluminium at the same concentrations. Soil drenches with metalaxyl, followed by metalaxyl+mancozeb, around the base of naturally infected trees under orchard conditions, prevented the growth of P. cactorum in the infected bark of the tree. Soil drenchs with metalaxyl, followed by metalaxyl+mancozeb, also prevented the infection of apple trees with P. cactorum under orchard conditions. The trunk circumference and spur length were not significantly affected by any of the fungicide treatments in all the trials over 2 years, except in one of the four orchards used in the study. Soil drench with metalaxyl alone, or followed by metalaxyl+mancozeb, may provide an effective control method for crown rot of apple trees.

Effects of Fungicide Sprays During Apple Bloom on Pollen Viability and Honey Bee Foraging

Fungicide applications were made during apple, Malus domestica Borkch., bloom to determine the duration of fungicide effects on pollen viability in the field and whether spray applications affect the foraging behavior of honey bees. Apis mellifera L. Fungicide sprays did not affect the numbers of honey bees foraging on trees or their foraging behavior. Mean percent pollen germination was depressed to levels between 12.2 and 31.1% by captan and to 29.5% by Dikar 2 h after spray application. Recovery of pollen viability required 24 to 48 h, depending upon orchard conditions. Benlate, Polyram, Baycor, and Topsin-M had no significant effect on pollen viability. The rapid recovery of pollen viability after initial spray applications and the lack of effect on flower visitation by bees indicate minimal effects on pollination or fruit set under most conditions.

Development of a Mechanical Pecan Harvester

ABSTRACT MECHANICAL harvesting of pecans in Israel has be-come mandatory in recent years as a result of labor scarcity in agriculture. Although the technology for mechanical pecan harvesting is already in common use in many countries, the specific conditions which character-ize the local conditions necessitated new solutions. The newly developed pecan harvester utilizes a new chain-to-soil relationship method that enables the machine to per-form well under wet, heavy soil conditions. Field capacity of 1.2 metric tonne(t) of pecans per h and separation effi-ciency of 98 percent were recorded under different or-chard conditions.

Orchard studies utilizing fluidized bed material

Abstract Fluidized bed material (FBM, a coal/limestone combustion byproduct) was used as a Ca source and lime substitute in established apple (Malus domestica Borkh) and peach (Prunus persia L.) orchards. FBM or limestone had little effect on apple tree Ca status over three growing seasons. Peach leaf Ca concentrations were significantly greater from FBM applied at three times the soil lime requirement (on a weight basis) than limestone applied at the lime requiremnt or a non‐amended control. Peach peel and flesh Ca, however, were not significantly altered. Tissue trace element concentrations (Mn, Fe, Cu, Zn, B ,Al, Sr, Pb) were not affected by treatments. FBM applied at twice the lime requirement, on a weight basis, maintained soil pH at levels equivalent to agricultural limestone applied at the lime requirement during the three growing seasons in both studies. FBM was found to be a satisfactory substitute for agricultural limestone under orchard conditions and when applied at mutiples up to three times ...

PREOVIPOSITION AND OVIPOSITION PERIODS OF THE APPLE MAGGOT, RHAGOLETIS POMONELLA (DIPTERA: TEPHRITIDAE)

AbstractThe preoviposition period of R. pomonella (Walsh) varied from 5 to 11 days at constant and 6 to 15 days at variable rearing conditions. Its duration was influenced by the source of the adults, cultivars for oviposition, and rearing conditions: ca. 3 days longer for adults from infested Wealthy apples than for adults from infested Gravensteins, ca. 2 days longer when the apples for oviposition were late season cultivars, and ca. 1 day longer at variable than at constant rearing conditions. Estimates of the preoviposition period of adults in two unsprayed orchards were 14 and 21 days in 1979 and 16 days in both orchards in 1980, and were 7–14 days longer than that for adults at constant rearing conditions.The oviposition periods of adults were 40–74 days at constant and 25–55 days at variable rearing conditions in 1979, and were influenced by the source of the adults, cultivars for oviposition, and the rearing conditions. Females from infested Gravensteins laid 339.2 and 180.7 eggs/female at constant and variable conditions and those from infested Wealthy 178.4 and 68.8 eggs/female at constant and variable conditions. Females also laid fewer eggs in Red Delicious apples than in Gravenstein, McIntosh, or Cortland apples.The first spray for control of apple maggot in Nova Scotia can be applied at least 14 days after first emergence or first capture as the preoviposition period in natural (orchard) conditions exceeded the recommended time of 7–10 days.

Pesticide deposition on citrus orchard soil resulting from spray drift and runoff.

A substantial loss of pesticide spray mixture is evident during application to citrus trees. Some losses occur as a result of the spray passing between and through target trees. Additional losses occur as the result of runoff and drip from the target trees. The total amount of spray not retained on the tree has been variously estimated to range from 25-40% of the spray gallonage used, depending upon orchard conditions and operational parameters. The waxy composition of the citrus leaf surface is not conducive to the retention of large quantities of aqueous spray mixture. In principle, the amount of runoff could be limited by maintaining the gallons of spray/tree low. The amount applied, however, is dictated by the requirements of the pestcontrol situation (CARMAN 1975). Gallonage can be minimized if pests reside on the exterior foliage (lepidopteran larvae, aphids, katydids) or the pest is active (mites, thrips) and would be likely to contact treated foliage even if not directly exposed to the spray. If the pest is sessile or may frequently reside in the interior of the tree (scales), increased gallonage is required to penetrate the exterior barrier of foliage to wet the foliage, fruit, twigs, and branches inside the tree. Runoff losses of pesticides are then countenanced in order to achieve a thorough wetting of the tree. The most frequently encountered gallonages used for scale control in mature California citrus groves range from 1500 to 3500 gal of spray/A. Aside from the economic disadvantage associated with the non-useful deposition of pesticides, the pesticide reaching the soil surface has been suggested (GUNTHER et al. 1975, SPENCER e__~t al. 1975) as a source of toxicants to workers entering organophosphorus pesticide-treated fields. Tests were therefore conducted to characterize with reasonable accuracy the magnitude and distribution of spray mixture reaching the orchard floor when dilute spray gallonages in the range generally used are applied with oscillating boom spray equipment of the type currently in use.

Oviposition and Development of the Navel Orangeworm in Relation to Almond Maturation1

Under orchard conditions, oviposition by Paramyelois transitella (Walker) begins on maturing almond fruit just prior to initiation of hull-split. After hull-split is complete, half the eggs are laid within the opened area on the inside of the hull or on the exposed shell, the rest on the outside of the hull. Moths preferentially oviposit on previously infested fruit, as compared with uninfested fruit. Infestation develops explosively after dehiscence begins. Most of the larvae hatching during the early stages of hull-split infest the nutmeat directly rather than feeding on the hull. Preventive treatments during this period should be applied before significant hull-split has taken place. Development of the navel orangeworm in new crop fruit in situ was followed by sampling 3 cohorts of dehiscing fruit artificially infested with eggs of a known age. By applying data developed on width of the larval head capsule to these populations, sampled in sequence, development was charted providing estimates of stadial length. First emergence from the new crop occurred in 29 days, in time to cause reinfestation. Fifty % emergence occurred in 42–45 days.

Radiant Output from Orchard Heaters1

Abstract The radiant fractions of four currently available orchard heaters (spot, large cone, return stack and auto clean stack) were determined under orchard conditions using observed surface temperatures, emissivity and the Stefan-Boltzmann Law. The contribution of the flame extending above the spot heater stack to its total radiant output was determined. Stack surface temperatures increased with burning rate on the large cone, return stack and auto clean stack heaters but decreased on the spot heater. The position of the highest temperature was near the bottom of the large cone, return stack and auto clean stack heaters and near the top of the spot heater. Surface temperatures were lower in general on the spot heater than on the other three heaters. The radiant fractions of the large cone, return stack and auto clean stack heaters were greater than 20% and relatively constant with burning rate. Even though the flame contribution is purposely overestimated the radiant fraction of the spot heater was less than 16%. For low wind speeds under which most orchard heating occurs the effect of wind speed on the radiant fraction was negligible.

FACTORS AFFECTING INDUCTION AND TERMINATION OF DIAPAUSE IN PEAR PSYLLA (HOMOPTERA: PSYLLIDAE)

AbstractIn the laboratory, diapause in adult Psylla pyricola Förster was induced by rearing nymphs with exposures to daily photoperiods of 13.5 h or less. The critical photoperiod that induced diapause was not influenced by temperature. Diapause was terminated in laboratory-reared adults and winter form adults collected from orchards in mid-October by exposure to photoperiods greater than 13.5 h. With adults collected from orchards during November, December, and January, diapause was terminated in the laboratory under both short and long photoperiods. With the earlier collections, long photoperiods markedly reduced preoviposition periods but with later collections the effect was not as pronounced because the preoviposition period under short photoperiods decreased markedly with the later collection dates. These results are discussed with relation to observations under natural orchard conditions.

SPARTAN APPLE BREAKDOWN AS AFFECTED BY ORCHARD FACTORS, NUTRIENT CONTENT AND FRUIT QUALITY

Tree age, rootstock, soil type, thinning practices and soil fertilizer application were examined as possible cultural factors affecting Spartan apple (Malus pumila Mill.) breakdown. Postharvest fruit analysis of calcium, potassium, phosphorous, magnesium, boron, acid, fruit diameter, soluble solids and internal chlorophyll content of fruit were also examined as potential correlative factors. A significant negative correlation existed between the incidence of breakdown and flesh calcium content. Boron, potassium, fruit size soluble solids and tree vigor were positively correlated to breakdown. A statistical profile of orchard conditions and fruit mineral levels associated with minimum breakdown is presented.