Kiwifruit Orchards Research Articles

Host preferences ofTrichogrammatoidea bactrae fumata (Hym.: Trichogrammatidae) an egg parasitoid of leafrollers (Lep.: Tortricidae)

Trichogrammatoidea bactrae fumata Nagaraja is a naturally occurring egg parasitoid of some leafrollers in New Zealand kiwifruit orchards. The parasitoid showed a distinct preference for younger host-eggs ofEpiphyas postvittana, in which it achieved a higher rate of successful development. Such a preference is not as apparent withCtenopseustis obliquana. Host-species preference experiments found that the parasitoid rarely attackedPlanotortrix octo, and successful wasp emergence from parasitised eggs of this host was low.Epiphyas postvittana was the preferred host whenT. bactrae fumata was reared on this species. When reared onC. obliquana, the parasitoid showed no preference forE. postvittana orC. obliquana.

Exploration and exploitation of soil by apple, kiwifruit, peach, Asian pear and grape roots

Measurements of root-length density (RLD) in a range of 31 apple, kiwifruit, peach, Asian pear and grape orchards were used to derive indices to describe the exploration and exploitation of rooting volumes. Orchards were of various ages and located on a range of soil types, geographic regions, management systems etc. Data were obtained from core samples of volume 1.66×10-4 m3 randomly taken within a “standard volume”, determined by average planting grids, of 2 m radius centred on tree stems, and 1 m depth. Root systems were described using an exploitation index, E(ϕ), and an exploration index, E(0). E(ϕ) is defined as the proportion of the soil volume which contains roots at RLD greater than or equal to some specified value, ϕ. E(0) is defined as the proportion of the soil volume which contains roots at any RLD greater than zero. These indices are dependent on sample size, as are all volumetric or soil-coring data. Estimates of E(0) for each orchard were obtained as the proportions of cores containing any RLD>O and assessed for dependence on species. Peach trees had a significantly higher value of E(0), equal to almost 1.0, compared to the other four species where E(0) was approximately 0.8 (p≤0.01) or less. There was also some variation with age. E(0) was lower for very young plants which had not fully occupied the sampled soil volume. Exploration indices for woody roots increased with rootstock age but otherwise did not explain large differences in E(ϕ) between species for given ϕ values. For example at ϕ=0.05×104 m.m-3, E(ϕ) was approximately 0.45 for peach and kiwifruit, and 0.05 for apple, Asian pear and grape, whereas at ϕ=0.5×104 m.m-3 the corresponding values were 0.1 and almost zero. Negative exponential curves relating E(ϕ), scaled by dividing by E(0), to ϕ were fitted for each of the 31 orchards. Exponents for these curves, k, were significantly smaller for kiwifruit and peaches than apples, grapes and Asian pears (p≤0.05), and smaller for apples than grapes and Asian pears (p≤0.05). A larger k implies a rapid fall-off in E(ϕ) as ϕ increases. Although all five species contained zero and low RLD samples, only kiwifruit and peaches contained higher RLD values and consequently have higher mean RLD. This trend was consistent across all soils, regions, sampling dates, and plant ages. The analyses demonstrate that core sampling can give useful insights into macro-scale root-system distribution, such as the proportion of a soil volume explored and how it is exploited. If positions of core samples are noted during sampling using angular direction, depth and radial distance as spatial coordinates the method can be used to describe root-system structures.

Thrips obscuratus as a potential vector of Botrytis cinerea in kiwifruit

Evidence is presented that Thrips obscuratus , the New Zealand flower thrips, is capable of carrying conidia of Botrytis cinerea on its body. The distribution of spores on the insect cuticle was studied using scanning electron microscopy (SEM). Adult thrips artificially contaminated with B. cinerea had most conidia on the head, thorax, legs and the abdominal distal segments; few were found on the wings. The conidia were observed most frequently in sculptured areas, inter-segmental regions, or trapped under setae, but very few on the smooth areas. This distribution pattern suggests that adhesion is mechanical. T. obscuratus adults collected from both pistillate and staminate flowers in New Zealand kiwifruit orchards near Motueka in 1991 were vectors of viable B. cinerea inoculum. Between full bloom and complete petal fall, up to 17% of adult thrips sampled were naturally contaminated by the fungus, and up to 12 propagules per contaminated thrips were found. Field infestation of kiwifruit by T. obscuratus , with 10–20 adults per flower, was shown to increase the susceptibility of kiwifruit petals to B. cinerea .

Releases and recoveries ofChilocorusspp. (Coleoptera: Coccinellidae) andHemisarcoptesspp. (Acari: Hemisarcoptidae) in kiwifruit orchards: 1987–93

Abstract Three species of Chilocorus and two species of Hemisarcoptes were introduced into New Zealand kiwifruit (Actinidia deliciosa) orchards between 1987 and 1992 for armoured scale insect (Homoptera: Diaspididae) control. Species and numbers released were: C. bipustulatus (12 836), C. cacti (575), C. infernalis (5990), H. coccophagus (c. 500 000), and H. cooremani (c. 3000). A survey in 1993 of all North Island release sites (n = 20) failed to detect establishment of any Chilocorus species. H. coccophagus was found at sites in Northland, Auckland, Bay of Plenty, Gisborne, and Nelson, and is considered to be established. Post‐release destruction of habitat may have limited establishment of both Chilocorus and Hemisarcoptes.

First report of bacterial canker of kiwifruit in Iran

Symptoms of bacterial canker of kiwifruit consisting of darkening and shrivelling along the bark were observed in kiwifruit orchards in Tonkabon, Iran. Longidutinal sections showed darkening of cortical and woody tissues. A fluorescent pseudomonad was consistently isolated from canker tissues. According to biochemical, physiological and pathogenicity tests the causal agent was identified as Pseudomonas syringae pv. syringae. This is the first report of the disease in Iran.

Effect of feeding pollen substitutes to honey bee colonies used for kiwifruit pollination and honey production

Abstract Feeding pollen substitutes to honey bee (Apis mellifera) colonies in kiwifruit (Actinidia deliciosa) orchards had no significant effect on the amount of kiwifruit pollen collected, but caused a decline in the amount of pollen collected from other sources. Pollen substitutes had no significant effect on honey production from colonies used for kiwifruit pollination or colonies managed solely for honey production.

Deterioration in soil biological and physical properties associated with kiwifruit ( Actinidia deliciosa)

Earthworm populations were measured over a 7 year period in areas of a kiwifruit orchard with two different managements, (1) completely undisturbed and (2) organically managed, i.e. commercially, with only organic fertilisers and no synthetic biocides. Earthworms present were Aporrectodea caliginosa, Aporrectodea longa, and Lumbricus rubellus with an initial population of 400–500 m −2. After 7 years, the earthworm population in the undisturbed plot was zero; there was no significant reduction on the managed plot. After 7 years, water infiltration and air permeability were greater within the vine rows in the managed than the undisturbed plot, and smaller where the soil had been compacted by traffic, soil respiration was least in the undisturbed orchard. After 7 years, surface venting soil macropores were absent in the undisturbed plot. On the managed plot macropores tended to be vertically aligned in the sward between the vine rows and horizontally aligned within the vine rows. Soil chemical properties, measured four times during the 7 years, were similar in both managed and undisturbed plots. The importance of using measurements of biological, physical and chemical soil properties when describing a soil is discussed. Dependence only on assessment of chemical fertility in decision making may result in early stages of soil degradation being unnoticed.

Control of willow‐tree shelter root systems in kiwifruit orchards by root pruning

Abstract The root systems of willow‐tree shelter root systems and adjacent kiwifruit root systems, and measurements of gravimetric soil water content, were mapped in three orchards on deep Te Puke soils, in the North Island of New Zealand. Fruit yields were also obtained from the first (5–6 m from the shelter) and middle (4th or 5th row, 19–24 m from the shelter) rows of the sampled blocks. The three orchards were aged between 11 and 14 years, and each used a different shelter root‐pruning method, i.e., (1) regular annual root pruning where shelter roots were cut on both sides of trees every spring with a 0.8 m deep slit c. 2.5 m from the shelter; (2) occasional root pruning where shelter roots had been cut once 2 years before the experiment; and (3) no root pruning. Root‐length density data were obtained from cores sampled randomly in the 5–6 m headland region between the shelter row and the first row of kiwifruit vines to 2 m depth, and from the first two rows of kiwifruit (up to 10.2 m from the shelter) to 1 m depth. More dead roots were found in the two root‐pruned treatments between the pruning slits and the first row of kiwifruit (P<0.02). However, root pruning had no significant effect on live willow roots in the adjacent two rows of kiwifruit (P < 0.05). Mean live willow root‐length densities over all orchards in the 0–1 m layer were: 0.06 104m/m3 between the shelter and the 1 st row of kiwifruit; and 0.04 104m/m3 between the 1st and 2nd rows. Cumulative distributions of ranked data were used to compare treatments. Root pruning treatments had no significant effects on soil water contents (P < 0.05), but soil water contents were significantly lower within 5 m from the shelter (P < 0.001) compared to more than 5 m distant. The data indicate that shelter roots quickly grow under root‐pruning slits and subsequent pruning is probably ineffective for decreasing water competition in deep soils. Fruit yields and average fruit weights did not differ between root pruning treatments, but the c. 50% lower yields in the kiwifruit row adjacent to the shelter were in agreement with other results which showed that shading from cloth substantially reduced fruit yields.

A Wide and Heavy Infestation with Leptotrombidium scutellare Larvae in the Western Part of Kanagawa Prefecture, Japan(Trombidiformes, Trombiculidae).

Based on the previous data (Uchikawa et al., 1994), we presumed that Leptotrombidium scutellare larvae were distributed widely in man-made environments around densely populated areas inwestern Kanagawa Prefecture, Japan. Employing modified Suzuki's visual sampling method (Uchikawa et al., 1993), this assumption was examined during the period between November 4 and 6, 1993, in Yamakita Town and Minamiashigara City, Kanagawa Prefecture. The above assumption was verified, indicating at the same time that the method was appropriate for our purpose. Many L. scutellare larvae were frequently found on shaded and humid places but not on dry soil surface. Very heavily infested places were encountered in mandarin orange groves and, unexpectedly, in a young kiwi fruit orchard surrounding the center of Yamakita Town with crowded dwellings, and in mandarin orange groves on gently rolling hills of Minamiashigara City. As many as 9, 658 unfed larvae to use in other analyses were taken on sampling and collecting pieces of black cloth during the survey. These larvae were observed to have stayed still in clusters on the cloths sealed in plastic bags that had been kept in a container since the previous day.

Shade cast by shelterbelts around kiwifruit orchards; validation of a computer model

Kiwifruit orchards in New Zealand are usually bounded on all four sides by shelterbelts which protect the vines from wind damage. Unfortunately these shelterbelts also shade the vines and reduce their productivity. A computer model originally developed to calculate light interception by hedgerow apple orchards in the UK was modified to calculate the irradiance over blocks of kiwifruit vines in New Zealand. The model predictions compared well with measured irradiance under both diffuse and sunny conditions for a range of shelterbelt species and dimensions.

Assessment of pesticide contamination of groundwater in New Zealand

Abstract Seventeen areas throughout New Zealand were ranked according to an index of potential pollution, and a selection of wells in six of the higher‐ranked areas were sampled and analysed for a range of pesticides. Land use in these areas includes market gardening, cropping, pipfruit, and kiwifruit orchards. The groundwater systems include shallow alluvial gravel, sand, basalt, and pumice aquifers. A total of 82 wells were sampled. Six wells had detectable levels of pesticides and an additional three wells had trace concentrations of an unidentified pesticide. Seven different pesticides were detected, mostly at concentrations < 1 mg m−3. One well had 37 mg m−3 atrazine and another had 1.7 mg m−3 procymidone. These pesticides were detected in the same wells on subsequent sampling occasions at lower concentrations. The level of 37 mg m−3 exceeded the health advisory limit for drinking water (3 mg m−3 ) of atrazine which has been established by the United States Environmental Protection Agency. The regions sampled in this survey were expected to have the greatest potential for pesticide contamination because of a combination of high pesticide use and vulnerable groundwaters; therefore the level of contamination in groundwater elsewhere in New Zealand should be lower than the levels found in this survey. Although the levels of pesticides were generally very low, unconfined groundwater in New Zealand can be contaminated by pesticides and in some situations there can be significant contamination.

Behaviour of honey bees visiting kiwifruit flowers

Abstract Honey bees (Apis mellifera L.) were shown to be able to discriminate between staminate (male) and pistillate (female) kiwifruit (Actinidia deliciosa) flowers. They exhibited floral sex constancy and showed an overall preference for pistillate flowers when visiting flowers on a tray. This indicates that honey bee pollination of kiwifruit is not a case of “mistake pollination”. Foragers also exhibited flower sex constancy between trips when foraging freely in a kiwifruit orchard. A number of foragers also had foraging areas that they returned to during consecutive foraging trips. Honey bees visited staminate flowers between 1 and 3 days old, and pistillate flowers between 1 and 5 days old in a season when pistillate anther dehiscence took 5 days. When pistillate anther dehiscence took only 3 days, foragers only visited flowers between 1 and 3 days old. This suggests that foragers are able to determine whether a kiwifruit flower contains pollen without having to land on it.

Parasitism of Meloidogyne Spp. On Grape and Kiwifruit By the Fungal Egg Parasites Paecilomyces Lilacinus and Verticillium Chlamydosporium

At various times during the growing season, Meloidogyne egg masses were collected from the roots of either grape or kiwifruit, or from tomato plants grown in association with these two crops. Between 23% and 87% of the eggs were found to be parasitized by fungi. Paecilomyces lilacinus and Verticillium chlamydosporium were the only species consistently isolated from these parasitized eggs. The fungicides mancozeb and iprodione, when used in combination at 150 mg/l, markedly suppressed radial growth of both P. lilacinus and V. chlamydosporium on agar but had no effect on hatch of Meloidogyne eggs or motility of second-stage juveniles. They were therefore used to estimate the degree of natural suppression of root-knot nematodes occurring in grape vineyards and kiwifruit orchards. When applied to field soil in pots, the fungicides reduced population densities of both P. lilacinus and V. chlamydosporium and significantly reduced the percentage of eggs parasitized. However, this did not result in a significant increase in the number of root-knot nematode juveniles in the soil. This suggested that the egg-parasitic fungi had little impact on root-knot nematode populations and that the fungi were mainly eliminating nematodes in excess of the carrying capacity of the root system.

Effects of flooding and alluvium deposition on kiwifruit (Actinidia deliciosa)

Abstract In March 1988, Cyclone Bola caused much flooding in kiwifruit orchards near Gisbome, New Zealand. In Paper 1 (Reid et aI. 1991) we described a survey of flood affected orchards, and considered factors influencing early vine decline(i.e., premature autumn defoliation in the first 11 weeks following the flood). Here we report the effects of the flooding upon performance of the same vines in the following season (October 1988-May 1989). Foliage vigour and trunk growth were closely related to foliage stress in the preceding autumn. One third of the vines suffered early decline. Four teen percent of the vines died; most of these bad shown early decline. Those which survived symptoms of early decline showed poor foliage vigour and trunk growth the following season. Foliage vigour was positively related to feeder root health. Vines surviving symptoms of early decline yielded 26% less mass and 24% fewer fruit than those which showed no early decline. Compared to vines showing adequate vigour, vines with ...

KIWIFRUIT POLLINATION: BEES AND WIND CONTRIBUTION

The aim of the experiment was to define the wind and the bees effect on kiwifrut pollination. Experiment was carried out for two years in an adult kiwifruit orchard, with a ratio between staminate (cv Matua) and pistillate (cv Hayward) vines of 1:7. Four different pollination treatments were tested on kiwifruit. Bees effectiveness was evaluated on both open pollination (OP-Bees) or net-isolated vines conditions (IV-Bees). The results obtained were compared with those achieved on net-isolated vines without bees in (IV-Wind) and on hand-pollinated vines (HP). Four rows (80 vines) were net-isolated and 14 uniform vines per treatment were choosen to collect productive data. In the IV-Wind treatment traps were used to capture insects present inside the nets. Wind speed was detected inside and outside the nets. Data showed that the net isolation system did not consistently modify wind speed and no insects were founds in the traps. As far as productive data best results were obtained on HP vines. Bee-pollinated vines always reached higher yield and average fruit weight than wind-pollinated vines. However no statistical differences were detected between fruit weight of OP-Bees and IV-Wind vines treatments. The results showed that in general bees represent a more efficient pollination agent than wind, even if the health of the bees and the position of the hives in the orchard have to be carefully considered to achieve best results.

Survival and viability of sclerotia of &lt;i&gt;Sclerotinia selerotiorum&lt;/i&gt; in two kiwifruit orchards in the Bay of Plenty

Survival and viability of sclerotia of &lt;i&gt;Sclerotinia selerotiorum&lt;/i&gt; in two kiwifruit orchards in the Bay of Plenty

Sclerotinia infection in two kiwifruit orchards in the Bay of Plenty

Sclerotinia infection in two kiwifruit orchards in the Bay of Plenty

Observations of equilibrium evaporation from a windbreak-sheltered kiwifruit orchard

Eddy correlation measurements of sensible heat and evaporation fluxes from a kiwifruit orchard confirm earlier, less comprehensive measurements that the spatially-averaged evaporation rate from well-watered and well-sheltered orchard blocks in the northern part of New Zealand occurs at the equilibrium rate ( E q . In this humid coastal climate the rapid onset of dewfall after sunset prevents night-time water use, which contrasts with other work showing that nocturnal transpiration may represent 25% of the daily water economy of a kiwifruit vine. Sensible heat fluxes measured at both shelter height ( h) and 2.25 h agreed within 5%, implying the existence of a constant flux region above shelter height. Under the low windspeed conditions common in mid-summer, the aerodynamic resistance to scalar transport between the canopy and the height of the windbreaks is shown to be of comparable magnitude (about 65 s m −1) to both the canopy ‘stomatal’ and boundary-layer resistances. One consequence of this is that transpiration will be less sensitive to stomatal regulation. Independent of imposed wind and radiative conditions, the effect of the close-spaced windbreaks and crop geometry is to create an orchard environment that is an efficient absorber of radiation but which is relatively poorly coupled with overhead conditions through turbulent exchange.

Use of pollen traps to investigate the foraging behaviour of honey bee colonies in kiwifruit orchards

Abstract The efficiency of a pollen trap in trapping kiwifruit (Actinidia deliciosa) pollen pellets was investigated. The trap had an average daily efficiency of 16.5 and 16.7% on 2 consecutive days. Hourly efficiencies varied between 0 and 25% with the highest efficiency in the middle of the day which coincided with periods of maximum honey bee (Apis melifera) foraging activity. The amount of staminate pollen in foragers' corbiculae was closely related to the proportion of staminate pollen on their body indicating that pellets can be used as a measure of pollination efficiency.

Male density and arrangement in kiwifruit orchards

In 1988 and 1989, flowers were removed before opening from all pollenizers (male vines) except that closest to the middle of an orchard block 76 m long and 24 m wide, containing 140 vines at 4m × 4m spacing. Fruit set decreased from 100% in vines nearest the central male to 17% in 1988 and to only 7% in 1989 in the most distant vines. Mean fruit weight for each vine decreased from 110 to 34g in 1988 and from 113 to 37g in 1989, fruit weight decreasing the further the vine was from the pollen source. As a consequence, yield progressively decreased from vines adjacent to the pollenizer (54.9 and 58.9 kg per vine in 1988 and 1989, respectively) to those most distant (3.7 and 1.9 kg per vine in 1988 and 1989, respectively). The area covered by a pollenizer, i.e. the area within which plants produce at least half the number of seeds of those closest to the pollenizer, was 229 m 2 in 1988 and 103 m 2 in 1989. Since pollen transfer, rather than its availability, is the main factor limiting pollination, to achieve full pollination about 118 pollen sources ha −1 must be provided in kiwifruit orchards, without regard to planting distances and canopy sizes. Male vines occupy too much canopy space and it is suggested that they be eliminated; instead, sectors of female vines at appropriate positions in the orchard should be grafted with male scionwood.