Hort 16A Research Articles

The impact of Hayward green kiwifruit on dietary protein digestion and protein metabolism

PurposeThe purpose of the study was to determine if an actinidin protease aids gastric digestion and the protein anabolic response to dietary protein.MethodsHayward green kiwifruit (containing an actinidin protease) and Hort 16A gold kiwifruit (devoid of actinidin protease) were given in conjunction with a beef meal to healthy older subjects. Twelve healthy older males (N = 6) and females (N = 6) were studied with a randomized, double-blinded, crossover design to assess muscle and whole-body protein metabolism before and after ingestion of kiwifruit and 100 g of ground beef. Subjects consumed 2 of each variety of kiwifruit daily for 14 d prior to each metabolic study, and again during each study with beef intake.ResultsHayward green kiwifruit consumption with beef resulted in a more rapid increase in peripheral plasma essential amino acid concentrations. There were significant time by kiwifruit intake interactions for plasma concentrations of EAAs, branched chain amino acids (BCAAs), and leucine (P < 0.01). However, there was no difference in the total amount of EAAs absorbed. As a result, there were no differences between kiwifruit in any of the measured parameters of protein kinetics.ConclusionConsumption of Hayward green kiwifruit, with a beef meal facilitates protein digestion and absorption of the constituent amino acids as compared to Hort 16A gold kiwifruit.Clinical trialNCT04356573, April 21, 2020 “retrospectively registered”.

Effect of Temperature Treatment in Trees at Flowering and Maturation Season on Quality of Gold Kiwifruit (Actinidia chinensis ‘Hort 16A’) after Low Temperature Storage

Effect of Temperature Treatment in Trees at Flowering and Maturation Season on Quality of Gold Kiwifruit (Actinidia chinensis ‘Hort 16A’) after Low Temperature Storage

Green kiwifruit extracts protect motor neurons from death in a spinal muscular atrophy model in Caenorhabditis elegans.

Kiwifruit is considered a functional food and a good source of nutraceuticals. Among the possible beneficial effects of kiwifruit species, a neuroprotective activity exerted in rats with learning and memory impairment induced by exposure to different chemicals was reported. We sought to investigate the neuroprotective activities of kiwifruit toward spinal muscular atrophy (SMA). To this purpose, we have used a recently developed Caenorhabditis elegans SMA model, displaying an age‐dependent degeneration of motor neurons detected as locomotory defects, disappearance of fluorescent markers, and apoptotic death of targeted neurons. Although an anti‐nematode activity is reported for kiwifruit, it has been verified that neither green (Actinidia deliciosa, cultivar Hayward) nor gold (Actinidia chinensis, cultivar Hort 16A) kiwifruit extracts cause detectable effects on wild‐type C. elegans growth and life cycle. Conversely, green kiwifruit extracts have a clear effect on the C. elegans SMA model by partially rescuing the degeneration and death of motor neurons and the locomotion impairment. The gold species does not show the same effect. The components responsible for the neuroprotection are macromolecules with a molecular weight higher than 3 kDa, present in the green and not in the yellow kiwifruit. In conclusion, this is the first study reporting a protective activity of green kiwifruit toward motor neurons. In addition, we demonstrate that C. elegans is an animal model suitable to study the biological activities contained in kiwifruit. Therefore, this model can be exploited for future investigations aimed at identifying kiwifruit molecules with potential applications in the field of human health.

Flavonoid-Rich Extract of Actinidia macrosperma (A Wild Kiwifruit) Inhibits Angiotensin-Converting Enzyme In Vitro.

Increasing interest in flavonoids in kiwifruit is due to the health-promoting properties of these bioactives. Inhibition of the angiotensin-converting enzyme (ACE) is one of the main therapeutic targets in controlling hypertension. The present study investigated the ACE inhibitory activity of flavonoid-rich extracts obtained from different kiwifruit genotypes. The flavonoid-rich extracts were prepared from fruits of Actinidia macrosperma, Actinidia deliciosa cv Hayward (Green kiwifruit), and Actinidia chinensis cv Hort 16A (Gold kiwifruit) by steeping the lyophilized fruit samples in 70% aqueous acetone, followed by partitioning the crude extracts with hexane. The composition of each extract was analyzed using ultrahigh-performance liquid chromatography-mass spectrometry (UPLC-MS/MS). The ACE inhibitory activity of the fruit extracts was performed using a fluorescence-based biochemical assay. The subclass flavonol was the most abundant group of flavonoids detected in all the extracts tested from three different kiwifruit cultivars. Quercetin-3-O-galactoside, quercetin-3-O-glucoside, quercetin-3-O-rhamnoside, quercetin-3-O-rutinoside, quercetin-3-O-arabinoglucoside, catechin, epigallocatechin gallate, epigallocatechin, chlorogenic, ferulic, isoferulic, and caffeic acid were prominent phenolics found in A. macrosperma kiwifruit. Overall, the flavonoid-rich extract from A. macrosperma showed a significantly (p < 0.05) high percentage of inhibition (IC50 = 0.49 mg/mL), and enzyme kinetic studies suggested that it inhibits ACE activity in vitro. The kiwifruit extracts tested were found to be moderately effective as ACE inhibitors in vitro when compared to the other plant extracts reported in the literature. Further studies should be carried out to identify the active compounds from A. macrosperma and to validate the findings using experimental animal models of hypertension.

Effect of long-term cold storage on physicochemical attributes and bioactive components of kiwi fruit cultivars

Various kiwi fruit cultivars, bred in Korea, were kept in cold storage for 8–24 weeks for possible increase of their quality. Firmness significantly decreased at initial time in all cultivars. The rate of softening was the slowest in “Hayward”, followed by “Hort 16A”, “Haenam”, “Daheung”, “Bidan”, “Hwamei”, and “SKK 12”. Sensory value increased with decreasing of firmness. Soluble solids content increased with storage time while acidity gradually decreased. Reducing sugar content significantly increased at early stage of storage with decreasing of starch content. There was no difference of these indices among cultivars. Respiration rate increased with time and then decreased during cold storage. Peaks time was different between cultivars, therefore we represented trend of respiration changes in all cultivars. All kiwi fruit cultivars showed climacteric patterns in respiration. The rate of softening was closely related to the degree and peak time of ethylene production. The highest shelf life was in “Hayward” and “Hort 16 A” (24 weeks) and the lowest in “SKK-12” (8 weeks). All investigated cultivars bred in Korea showed much lower shelf life than “Hayward” and “Hort 16 A”. Radical scavenging assays and chemometrical processing were used for the determination of bioactive kiwi fruits’ compounds. Polyphenols in water extracts were the highest in “SKK-12” and the lowest in “Hayward” [16.34 ± 1.11 and 5.30 ± 0.45 mg gallic acid equivalents (GAE)/g dry weight (DW)]. The values of β-carotene activities (27.61 ± 2.44% and 8.33 ± 0.74%) and Ferric-reducing/antioxidant power [(FRAP, Trolox equivalent (TE)/g DW) 24.55 ± 2.01 and 7.12 ± 0.41] were the highest in “SKK-12”. The lowest results were estimated in “Hayward”. All kiwi fruit cultivars showed a high level of correlation between the contents of phenolic compounds (polyphenols, tannins, and flavonoids) and their antioxidant values. We presented for the first time the results of shelf life of new cultivars bred in Korea and their comparison with the widely studied ones, such as “Hayward” and “Hort 16A”. Cold storage extended shelf life in kiwi fruit without any chilling injury or color change. According to the antioxidant properties of different cultivars, the highest was in “SKK-12” with the lowest shelf life and the lowest was in “Hayward” with the highest shelf life.

Bioactive compounds and the antioxidant capacity in new kiwi fruit cultivars

The aim of this investigation was to find the best among seven different kiwi fruit cultivars (‘Hayward’, ‘Daheung’, ‘Haenam’, ‘Bidan’, ‘Hort16A’, ‘Hwamei’ and ‘SKK12’) for human consumption and to classify them as groups. Therefore, the contents of bioactive compounds and the level of antioxidant capacities of these cultivars were determined in four different extracts and compared. It was found that the contents of the bioactive compounds and the level of antioxidant capacities in different extracts differ significantly (P<0.05). Bioactive compounds and the antioxidant capacities were significantly higher in ‘Bidan’ and ‘SKK12’ cultivars than in other studied samples. The ethanol and water extracts of these cultivars exhibited high binding properties with human serum albumin (HSA) in comparison with catechin. In conclusion, based on fluorescence profiles the seven new kiwi fruit cultivars can be classified for three groups: ‘Hayward’ (including ‘Daheung’, ‘Haenam’, Hwamei’ and ‘SKK12’), ‘Bidan’ and ‘Hort 16A’. In MS – profiles some differences in the peaks were found between the cultivar groups. All studied fruits could be a valuable addition to known disease preventing diets.

Physiological components of kiwifruits with in vitro antioxidant and acetylcholinesterase inhibitory activities

Five domestic kiwifruit varieties, Bidan (BD), Chiak (CA), Haegeum (HG), Haehyang (HH), and Mansoo (MS), in Korea and two imported varieties, Hayward (HW) and Hort16A (HT), from New Zealand were evaluated main active component groups in the fruit extracts involved in antioxidant and anti-dementia activities. HW, HT, and HH exhibited higher soluble solid content. BD, HG, and HH contained high total phenolics (TP), whereas two imported kiwifruits and green kiwifruits (MS and CA) had low TP content. BD showed the highest antioxidant and antidementia activities among kiwifruits studied. Vitamin C (Vc) in kiwifruit extracts had the highest correlation with antioxidant activities. TP in kiwifruits had the highest correlation with acetylcholinesterase inhibitory activity. Butyrylcholinesterase activity was not significantly correlated with TP or Vc content, but the butyrylcholinesterase activity was significantly correlated with total flavonoids. The results above suggest that domestic varieties have a potential source of Vc and phenolic bioactivities.

A Randomized Steady-State Bioavailability Study of Synthetic versus Natural (Kiwifruit-Derived) Vitamin C

Whether vitamin C from wholefoods has equivalent bioavailability to a purified supplement remains unclear. We have previously showed that kiwifruit provided significantly higher serum and tissue ascorbate levels than synthetic vitamin C in a genetically vitamin C-deficient mouse model, suggesting a synergistic activity of the whole fruit. To determine if these results are translatable to humans, we carried out a randomized human study comparing the bioavailability of vitamin C from kiwifruit with that of a vitamin C tablet of equivalent dosage. Thirty-six young non-smoking adult males were randomized to receive either half a gold kiwifruit (Actinidia Chinensis var. Hort 16A) per day or a comparable vitamin C dose (50 mg) in a chewable tablet for six weeks. Ascorbate was monitored weekly in fasting venous blood and in urine, semen, leukocytes, and skeletal muscle (vastus lateralis) pre- and post-intervention. Dietary intake of vitamin C was monitored using seven day food and beverage records. Participant ascorbate levels increased in plasma (P < 0.001), urine (P < 0.05), mononuclear cells (P < 0.01), neutrophils (P < 0.01) and muscle tissue (P < 0.001) post intervention. There were no significant differences in vitamin C bioavailability between the two intervention groups in any of the fluid, cell or tissue samples tested. Overall, our study showed comparable bioavailability of synthetic and kiwifruit-derived vitamin C.

Kiwifruit: our daily prescription for health

Kiwifruit are unequalled, compared with other commonly consumed fruit, for their nutrient density, health benefits, and consumer appeal. Research into their health benefits has focussed on the cultivars Actinidia deliciosa 'Hayward' (green kiwifruit) and Actinidia chinensis 'Hort 16A', ZESPRI(®) (gold kiwifruit). Compared with other commonly consumed fruit, both green and gold kiwifruit are exceptionally high in vitamins C, E, K, folate, carotenoids, potassium, fibre, and phytochemicals acting in synergy to achieve multiple health benefits. Kiwifruit, as part of a healthy diet, may increase high-density lipoprotein cholesterol, and decrease triglycerides, platelet aggregation, and elevated blood pressure. Consuming gold kiwifruit with iron-rich meals improves poor iron status, and green kiwifruit aids digestion and laxation. As a rich source of antioxidants, they may protect the body from endogenous oxidative damage. Kiwifruit may support immune function and reduce the incidence and severity of cold or flu-like illness in at-risk groups such as older adults and children. However, kiwifruit are allergenic, and although symptoms in most susceptible individuals are mild, severe reactions have been reported. While many research gaps remain, kiwifruit with their multiple health benefits have the potential to become part of our "daily prescription for health."

The effects of temperature and pH on the extraction of oxalate and pectin from green kiwifruit (Actinidia deliciosa L.), golden kiwifruit (Actinidia chinensis L.), kiwiberry (Actinidia arguta) and persimmon (Diospyros kaki)

SummaryOxalates and pectin were extracted from four locally grown fruits at three different pH levels, 6.9, 0.6 and −0.3, at two different temperatures, 21 and 80 °C. Green kiwifruit (Actinidia deliciosa L. Hayward), golden kiwifruit (Actinidia chinensis L. Hort 16A Zespri), kiwiberry (Actinidia arguta, CV. Takaka Green) and persimmon (Diospyros kaki) contained moderate levels of oxalates. Total and soluble oxalates were more efficiently extracted at 21 °C using 2 m HCL, while the highest amounts of pectin were extracted from the fruits at 80 °C using 0.2 m HCL. Extraction using 0.2 and 2 m HCL gave the highest yields of total oxalates, which ranged from 47.1 to 220.4 mg total oxalates per 100 g dry matter (DM) for persimmon and kiwiberry, respectively. Extraction using water at 21 °C gave soluble oxalate contents ranging from 21.2 mg 100 g−1 DM, for persimmon, to 105.0 mg 100−1 DM, for kiwiberry fruits. Extraction of pectin was not achieved efficiently using water at either temperature, while extraction using 2 m HCL gave lower values; optimal extractions of pectin were achieved at 80 °C using 0.2 m HCL.

First Report of Bacterial Canker of Kiwifruit Caused by Pseudomonas syringae pv. actinidiae in Spain.

Bacterial canker of kiwifruit caused by Pseudomonas syringae pv. actinidiae was first described in Japan and Korea and is currently an emerging disease that causes major losses in China, Italy, New Zealand, France, Portugal, and Chile. Gold kiwifruit (Actinidia chinensis), especially cvs. Jin Tao and Hort 16A, seem to be more susceptible than green kiwifruit (Actinidia deliciosa) cvs. Hayward and Summer. The bacterium affects male and female woody vines equally, with young vines being more susceptible. The most characteristic symptoms that appear in early spring are reddish orange or white exudates associated with cankers and wounds in branches and/or trunk, as well as brown leaf spots. Buds and fruits were also affected (1). In Spain, 1,132 ha of kiwifruit orchards yielded 25,285 t of fruit in 2009 (2). Most Spanish kiwifruit is cultivated in Galicia (northwest Spain), where the main cultivar is Hayward. In 2010, the first plantation of cv. Jin Tao and one plantation of cv. Summer were established in this area close to Hayward woody vine. In early spring 2011, 80% of the vines in one orchard had twigs with reddish exudates and branches and trunks as well as leaves with angular spots surrounded by yellow haloes. Isolations from both Actinidia spp. were conducted on nutrient agar with sucrose. One hundred and twelve isolates were obtained and seventy-seven were aerobic, gram negative and nonfluorescent on King's B medium. Biochemical tests performed were levan, oxidase, potato rot, arginine didhydrolase, hypersensitivity in tobacco, and utilization of 49 carbohydrates by the API 50 CH system (BioMérieux, Marcy l'Etoile, France). Three PCR protocols were used: two with pathovar-specific primers (PSAF1/PSAR2 and PSAF3/PSAR4) and one with nonspecific primers (PsITSF1/PsITSR2) (3). The results of all biochemical and molecular tests were in agreement with those expected for P. syringae pv. actinidiae. The 16S-23S region of strain EFA 37 isolated from A. deliciosa cv. Summer was sequenced (GenBank Accession No. JF815537) and had 100% sequence identity with P. syringae pv. actinidiae (GenBank Accession Nos. AY342165 and D86357). Pathogenicity tests were performed on 15 plants of A. deliciosa cv. Hayward (five plants per isolate) with the Spanish representative strain EFA 37 and compared with two reference strains isolated from both Actinidia species in Italy and five plants of an untreated control. Three buds per healthy vine were wounded with a sterile needle, inoculated with 30 to 50 μl of each bacterial suspension (108 CFU/ml), sealed, and then covered with plastic. Five leaves per healthy vine were also pierced with a sterile needle and then atomized with the same suspension. Symptoms began to appear after 5 days on inoculated vines, but not on untreated control vines. The bacterium, P. syringae pv. actinidiae, was reisolated from symptomatic plants. The kiwifruit orchard with affected plants was eradicated (25 ha). To our knowledge, this is the first report of P. syringae pv. actinidiae in Spain.

(Methylsulfanyl)alkanoate ester biosynthesis in Actinidia chinensis kiwifruit and changes during cold storage

Four 3-(methylsulfanyl)propionate esters, ethyl 3-(methylsulfanyl)prop-2-enoate, two 2-(methylsulfanyl)acetate esters and their possible precursors 2-(methylsulfanyl)ethanol, 3-(methylsulfanyl)propanol and 3-(methylsulfanyl)propanal were quantified from the headspace of Actinidia chinensis ‘Hort 16A’ kiwifruit pulp by GC–MS–TOF analysis. The majority of these compounds were specific for eating-ripe fruit and their levels increased in parallel with the climacteric rise in ethylene, accumulating towards the very soft end of the eating firmness. No ethylene production could be observed after long-term storage (4–6 months) at 1.5 °C and the levels of all methylsulfanyl-volatiles, except methional, declined by 98–100% during that period. This depletion of (methylsulfanyl)alkanoate-esters after prolonged cold storage points towards little flavour impact of these compounds on commercial ‘Hort 16A’ kiwifruits. However, ethyl 3-(methylsulfanyl)propionate is suggested to be odour active in ripe ‘Hort 16A’ fruit that has not been stored. Gene expression measured by q-RT PCR of six ripening-specific alcohol acyltransferase (AAT) expressed sequence tags and (methylsulfanyl)alkanoate-ester production of cell-free extracts were also significantly decreased after prolonged cold storage. However, (methylsulfanyl)alkanoate-ester synthesis of cell-free extracts and AAT gene transcript levels could be recovered by ethylene treatment after five months at 1.5 °C indicating that the biosynthesis of (methylsulfanyl)alkanoate-esters in ‘Hort 16A’ kiwifruit is likely to depend on ethylene-regulated AAT-gene expression. That the composition but not the concentration of (methylsulfanyl)alkanoate-esters in fresh fruit could be restored after ethylene treatment suggests that substrate availability might also have an impact on the final levels of these volatiles.

Identification of Pseudomonas syringae pv. actinidiae as Causal Agent of Bacterial Canker of Yellow Kiwifruit (Actinidia chinensis Planchon) in Central Italy

AbstractAngular, necrotic leaf spot, longitudinal cracks along the petiole, oozing and wilting of branches were observed during summer 2008 on Actinidia chinensis (yellow kiwifruit) cultivar Hort16A, cultivated in different orchards located the province of Latina (central Italy). Symptoms closely resembled those incited by Pseudomonas syringae pv. actinidiae on kiwifruit A. deliciosa. Isolates obtained from typical lesions were assessed by means of biochemical, pathogenicity and host range tests and compared with some Pseudomonas syringae pathovars by enterobacterial repetitive intergenic consensus (ERIC‐PCR) analysis. The isolates belong to Pseudomonas LOPAT group Ia, incited the death of pot‐cultivated A. chinensis cv. Hort 16A and A. deliciosa cv. Hayward plants in few days, but did not cause any symptoms to the other inoculated plant species. Upon ERIC‐PCR analysis, all the isolates showed similarity with P. syringae pv. actinidiae NCPPB 3739, type‐strain of the pathovar. This is the first report of this pathogen on A. chinensis in Italy and, as far as we currently know, in the world.

First Report of Verticillium Wilt of Gold Kiwifruit, Actinidia chinensis Cv. Hort 16A, Caused by Verticillium albo-atrum in Chile.

Gold kiwifruit, Actinidia chinensis Planch cv. Hort 16A, was first planted in Chile in 2003 and vines started dying within 2 years. By the end of the 2007-2008 growing season, as much as 80% of the plants in several orchards had died. The disease was characterized by a conspicuous reddish brown discoloration of the xylem and the sudden wilting and dieback of plants any time during the growing season. In the spring, entire plants or parts of plants failed to break buds. In others, the buds broke, but juvenile leaf clusters then wilted and died. On severely affected plants, scion watershoots wilted and died. The disease was often accompanied by shallow cracking of the bark and slight sponginess of the underlying cortex. The disease was apparently most severe in sites that had been planted to Gold kiwifruit immediately after removal of apple, pear, citrus, or grape. Orchards planted following long-term maize, wheat, or grass culture were almost disease free. A fungus was consistently isolated from symptomatic vascular tissue disinfected in 1% sodium hypochlorite and plated on potato dextrose agar. Conidiogenous cells were arranged in verticels; conidia were hyaline, elliptical, single celled, and measured 3.5 to 8.5 × 1.8 to 4.3 μm (average 5.5 × 2.5 μm). Dark, resting mycelium developed after 1 to 2 weeks of incubation. On the basis of these morphological characteristics, the fungus was identified as Verticillium albo-atrum Reinke & Berthier. Identification was confirmed by sequencing part of the internal transcribed spacer (ITS) region with primers ITS1 and ITS4. The sequence of a representative isolate showed high homology (98% identity over a length of 494 bp) with a DNA fragment (NCBI Accession No. 108476) of V. albo-atrum from alfalfa. To complete pathogenicity tests, 20 healthy, 1-year-old Hort 16A kiwi vines grafted on Hayward kiwifruit (A. deliciosa Chevalier) seedlings were inoculated by injection of 20 μl of 106 conidia/ml into stems of the scion. Twenty control plants were injected with an equal volume of sterile distilled water. Plants were held in a controlled environment facility at 24°C with 16 h of light per day. Eight weeks after inoculation, typical wilting and dieback symptoms developed on 90% of the plants. Control plants injected with water remained healthy. Verticillium wilt has never been reported on kiwifruit (A. deliciosa) in Chile. V. albo-atrum has a rather narrow host range and is mainly reported as a pathogen on alfalfa, hop, soybean, tomato, and potato (1). To our knowledge, this is the first report of V. albo-atrum causing wilt and dieback on Gold kiwifruit (A. chinensis) cv. Hort 16A. The fungal isolates have been deposited in the Plant Pathology Laboratory of the Sanidad Vegetal Department of Agricultural Sciences Faculty of University of Chile under the name Actinidia chinensis/V. albo-atrum No. 1 to 8. Reference: (1) E. K. Ligoxigakis et al. Phytoparasitica 30:511, 2002.

Comparison of soil quality and nutrient budgets between organic and conventional kiwifruit orchards

Three long-term (>10 years) systems of kiwifruit production were compared at 36 sites with respect to simple input/output nutrient budgets, extractable soil nutrient levels, soil organic matter status, the size and activity of the soil microbial biomass, earthworm numbers and key soil physical properties. These systems were (i) conventional production of the green-fleshed variety ‘Hayward’ (Green), (ii) organic production of ‘Hayward’ (Organic) and (iii) conventional production of the yellow/gold-fleshed variety ‘Hort 16A’ (Gold). Crop yields and nutrient removals were least for Organic and greatest for Gold, with Green being intermediate. The major nutrients removed in the harvested crop were K and N. Simple input/output nutrient budgets showed that inputs greatly exceeded removals in the harvested crop for all nutrients considered (i.e. N, P, S, K, Mg, Ca) in all three systems, suggesting nutrient inputs could be reduced. Soil organic C and total N content were greater under Organic and Gold than Green whilst extractable P was least under Organic. Soluble C, basal respiration and metabolic quotient were unaffected by production system whilst microbial biomass C and N were greatest under Organic. Within systems, organic C, total N, microbial biomass C and N and mineralisable N were greater between plant rows than below the vine canopies whilst the reverse was the case for metabolic quotient and extractable P. Soil bulk density was least and water content at field capacity and earthworm numbers were greatest under the organic systems. It was concluded that long-term soil fertility can be maintained adequately under organic management and added benefits are increased organic matter content, a larger microbial biomass and improved soil physical condition. Although Organic orchards generally produce less fruit than their Green counterparts, mainly because of fertiliser differences and the absence of synthetic growth regulators, comparatively good returns and surpluses can still be achieved.

Vine death of Hort 16A in Chile caused by &lt;i&gt;Verticillium alboatrum&lt;/i&gt;

GOLD kiwifruit Actinidia chinensis Hort 16A is being grown under licence in Chile as part of the ZESPRI global supply strategy for the cultivar The first plantings were made in 2003 Vines started dying within 2 years and by May 2007 up to 50 of vines had died in the older orchards The problem is continuing The disease is caused by Verticillium alboatrum a soilborne pathogen that infects the roots subsequently invading the whole plant Apparently healthy plants suddenly develop necrotic patches on leaves and the whole plant wilts and dies Other symptoms include cracking of the bark brown discoloration of vascular tissues and profuse growth of watershoots from the rootstock and lower scion This is the first record of this fungus causing a serious disease in kiwifruit A number of remedies including soil and trunk injections with fungicide and soil fumigation for replant sites are being evaluated

Prediction of final weight for Actinidia chinensis ‘Hort1 6A’ fruit

Growth of the fruit of Actinidia chinensis ‘Hort16A’, a new yellow‐fleshed cultivar commercially produced in New Zealand, was monitored non‐destructively over five seasons at two sites. Fruit were destructively harvested at various times during the season to obtain measurements of individual fruit fresh weight and three linear measurements of fruit size, from which a regression relation was derived to enable estimation of fruit fresh weight from the fruit measurements (R2 > 0.99). This enabled growth of cohorts of tagged fruit to be followed by nondestructive measurements of the fruit dimensions, and growth curves of each cohort average obtained. A mathematical function was fitted to each growth curve, to estimate the maximum mean fruit weight and to interpolate between observations at various times during fruit growth. These interpolated data were used to obtain a simple relationship between mean fruit weights at different times during fruit growth. From c. 80 days after mid bloom (DAMB), prediction of fruit weights was found to be independent of season and site. Earlier than this, there was a marked increase in prediction uncertainty, which was independent of site. Average fresh weight at 200 DAMB could be predicted from an estimate of average fresh weight 50 DAMB with a standard deviation of 10.2 g, whereas at 100 DAMB this reduced to 5.5 g. The prediction method was validated using data collected over two seasons and the same two sites used to create the prediction method, as well as data over the same two seasons collected at two more southern sites.