Zealand Vineyards Research Articles

Integration and holistic analysis of multiple multidimensional soil data sets

Complex matrices such as soil have a range of measurable characteristics, and thus data to describe them can be considered multidimensional. These characteristics can be strongly influenced by factors that introduce confounding effects that hinder analyses. Traditional statistical approaches lack the flexibility and granularity required to adequately evaluate such matrices, particularly those with large dataset of varying data types (i.e. quantitative non-compositional, quantitative compositional). We present a statistical workflow designed to effectively analyse complex, multidimensional systems, even in the presence of confounding variables. The developed methodology involves exploratory analysis to identify the presence of confounding variables, followed by data decomposition (including strategies for both compositional and non-compositional quantitative data) to minimise the influence of these confounding factors such as sampling site/location. These data processing methods then allow for common patterns to be highlighted in the data, including the identification of biomarkers and determination of non-trivial associations between variables. We demonstrate the utility of this statistical workflow by jointly analysing the chemical composition and fungal biodiversity of New Zealand vineyard soils that have been managed with either organic low-input or conventional input approaches. By applying this pipeline, we were able to identify biomarkers that distinguish viticultural soil from both approaches and also unearth links and associations between the chemical and metagenomic profiles. While soil is an example of a system that can require this type of statistical methodology, there are a range of biological and ecological systems that are challenging to analyse due to the complex interplay of global and local effects. Utilising our developed pipeline will greatly enhance the way that these systems can be studied and the quality and impact of insight gained from their analysis.

A closed-loop circularity in wood sugar as a renewable carbon source for fungal pigment production and application of pigments in wood colouration

The main objective is to demonstrate closed-loop circularity in the production of fungal pigment from renewable wood sugar hydrolysate (WSH) and impregnation of colour pigment into wood. Talaromyces sp 43 M, isolated from a New Zealand vineyard, was identified as Talaromyces ruber (TR) using multi-gene phylogenetic analysis. A mild pretreatment followed by ball milling was used to prepare Pinus radiata pulp which was enzymatically hydrolysed to generate WSH. Malt 30 g/L or WSH 40 g/L were optimum carbon sources when supplemented with peptone 10 g/L and meat extract 1 g/L as optimum nitrogen sources giving maximum production of extracellular pigment. TR completely metabolizes multiple carbon sources as well as fermentation inhibitors to elicit pigment production. The CIELAB colour characteristics of the pigment vary as a response to carbon sources (malt vs WSH) and fermentation time. The fluorescent pigment produced in malt and WSH medium were efficiently impregnated into wooden blocks.

Grapevines escaping trunk diseases in New Zealand vineyards have a distinct microbiome structure.

Grapevine trunk diseases (GTDs) are a substantial challenge to viticulture, especially with a lack of available control measures. The lack of approved fungicides necessitates the exploration of alternative controls. One promising approach is the investigation of disease escape plants, which remain healthy under high disease pressure, likely due to their microbiome function. This study explored the microbiome of grapevines with the disease escape phenotype. DNA metabarcoding of the ribosomal internal transcribed spacer 1 (ITS1) and 16S ribosomal RNA gene was applied to trunk tissues of GTD escape and adjacent diseased vines. Our findings showed that the GTD escape vines had a significantly different microbiome compared with diseased vines. The GTD escape vines consistently harbored a higher relative abundance of the bacterial taxa Pseudomonas and Hymenobacter. Among fungi, Aureobasidium and Rhodotorula were differentially associated with GTD escape vines, while the GTD pathogen, Eutypa, was associated with the diseased vines. This is the first report of the link between the GTD escape phenotype and the grapevine microbiome.

A Review of Cultural Practices for Botrytis Bunch Rot Management in New Zealand Vineyards.

Botrytis bunch rot of grapes (BBR) causes substantial crop and wine quality issues globally. Past and present foundations for BBR control are based upon synthetic fungicides and varying forms of canopy management. Many authors regard the continued dependence on fungicides as unsustainable and have urged greater deployment of cultural, biological and nutritional strategies. However, in contrast to organic wine production, the uptake of alternative strategies in conventional vineyards has been slow based on cost and perceived reliability issues. This review summarises research from many different wine growing regions in New Zealand with the aim of demonstrating how traditional and newly developed cultural control practices have cost-effectively reduced BBR. In addition to reviewing traditional cultural practices (e.g., leaf removal), mechanical tools are described that remove floral trash and mechanically shake the vines. Multi-omics has improved our knowledge of the underlying changes to grape berries after mechanical shaking. Exogenous applications of calcium may correct calcium deficiencies in the berry skin and reduce BBR but the outcome varies between cultivar and regions. Nitrogen aids in grapevine defence against BBR but remains a complex and difficult nutrient to manage. The sustainable growth of organics and The European Green Deal will stimulate researchers to evaluate new combinations of non-chemical BBR strategies in the next decade.

Diversity and Bioactivity of Endophytic Actinobacteria Associated with Grapevines

Grapevine trunk diseases (GTDs) are a significant problem for New Zealand viticulture. Endophytic actinobacteria are of interest as potential biocontrol agents due to their ability to inhibit plant pathogens and improve plant growth. However, no studies have investigated the diversity of actinobacteria associated with grapevines in New Zealand vineyards and their bioactivity. Actinobacteria diversity in different ‘Sauvignon blanc’ vine tissues from three vineyards (conventional and organic management, and different vine ages) was assessed using different methods and media. Forty-six endophytic actinobacteria were isolated, with more isolates recovered from roots (n = 45) than leaves (n = 1) and shoot internodes (n = 0). More isolates were recovered from the organic (n = 21) than conventional (n = 8) vineyard, mature (25-year old; n = 21) than young (2-year old; n = 2) vines and using a tissue maceration technique (n = 40). Actinomycete Isolation Agar, International Streptomyces Project 2, and Starch Casein media were effective for actinobacteria isolation. Most of the isolates recovered belonged to Streptomyces, with one isolate identified as Mycolicibacterium. Forty isolates were assessed for antifungal activity and plant growth-promoting (PGP) characteristics. Of these, 13 isolates had antifungal activity against test GTD pathogens (Dactylonectria macrodidyma, Eutypa lata, Ilyonectria liriodendri, Neofusicoccum parvum, and N. luteum). Eighteen isolates exhibited more than one PGP trait; 25siderophore production (n = 25), phosphate solubilization (n = 6), and indole acetic acid production (n = 16). Two strains, Streptomyces sp. LUVPK-22 and Streptomyces sp. LUVPK-30, exhibited the best antifungal and PGP properties. This study revealed the diversity of culturable endophytic actinobacteria from grapevines in New Zealand vineyards and their biocontrol potential against GTD pathogens.

Ryegrass resistance to glyphosate and amitrole is becoming common in New Zealand vineyards

The prevalence of herbicide resistance in ryegrass (Lolium spp.) in the wine-growing regions in New Zealand is poorly understood. Cases of glyphosate, glufosinate and amitrole-resistant ryegrass were documented in a few vineyards in New Zealand in 2013, but there have been no regional surveys for resistance. To address this knowledge gap, 106 vineyards were visited across the important New Zealand wine-growing regions of Marlborough and Waipara in late February 2021, and Hawke’s Bay and Gisborne in late February 2022, and seed samples from individual plants at each site surviving weed-control measures were collected. Ryegrass was found in more South Island (68%) than North Island (20%) vineyards. These seeds, and those from a susceptible ryegrass population were sown in marked rows into trays (10-20 seeds per herbicide) and grown in a glasshouse. When seedlings reached the 3-4 leaf stage, trays were sprayed at the highest recommended label rate of glyphosate. Samples with enough seed were also screened against additional herbicides, amitrole, glufosinate or clethodim. The results indicated 39% of the surveyed vineyards contained glyphosate-resistant ryegrass, with cases detected across all regions, including 58% of vineyards in Marlborough. Eleven of the 27 Marlborough vineyards screened contained amitrole-resistant ryegrass; six samples were also resistant to glyphosate. However, glufosinate and clethodim were still effective against ryegrass at the sites tested. Considering the levels of herbicide resistance to ryegrass observed in this study, growers should explore alternative weed-suppression measures, including tilling, cover-crops, grazing, mowing and the use of herbicides with different modes of action.

Grapevine Leafroll-Associated Virus 3 Genotype Influences Foliar Symptom Development in New Zealand Vineyards.

Grapevine leafroll disease (GLD) constrains wine production worldwide. In New Zealand, the main causal agent of GLD is grapevine leafroll-associated virus 3 (GLRaV-3). To control GLD, an integrated management program is used and includes removing (roguing) GLRaV-3-infected vines from the vineyard. The classical foliar symptoms from virus-infected red-berry cultivars are leaves with dark red intervein, green veins, and downward rolling of margins. Growers use these phenotypic cues to undertake visual symptom identification (VSI) for GLD. However, the influence of the known large genetic variation among GLRaV-3 isolates on the foliar symptoms from different grapevine cultivars remains undescribed, especially in cool-climate growing environments, such as New Zealand. Over three vintages (2015, 2016, and 2017), VSI for GLD was undertaken at three field sites in New Zealand (Auckland, Hawke’s Bay, and Marlborough), each including four cultivars (Merlot, Pinot noir, Sauvignon blanc, and Pinot gris) infected with three GLRaV-3 genotypes (Groups I, VI, and X) or GLRaV-3-uninfected control plants. Throughout this study, no visual symptoms were observed on white-berry cultivars infected with GLRaV-3. For red-berry cultivars, the greatest variability in observed foliar symptoms among regional study sites, cultivars, and GLRaV-3 genotypes was observed early in the growing season. In particular, Group X had significantly delayed symptom expression across all three sites compared with Groups I and VI. As the newly infected, young vines matured in years 2 and 3, the GLRaV-3 genotype, cultivar, region, and environmental conditions had minimal influence on the accuracy of VSI, with consistently high (>95%) within-vintage identification by the end of each vintage. The results from this study strongly support the use of VSI for the GLD management of red-berry cultivar grapevines, Merlot and Pinot noir, as a reliable and cost-effective tool against GLD.

Developing a mealybug pheromone monitoring tool to enhance IPM practices in New Zealand vineyards

Mealybugs are phloem-feeding insects found on many crops worldwide. In New Zealand vineyards, they transmit the economically important Grapevine leafroll-associated virus 3 (GLRaV-3). For some mealybug species, synthetic sex pheromones have been commercialised, and are used as monitoring tools. The mealybugs Pseudococcus longispinus and Pseudococcus calceolariae are major pests in many New Zealand vineyards. We present work on the development of a combined P. longispinus and P. calceolariae pheromone lure. The optimal dose for monitoring P. longispinus was found to be 10 µg of the (S)-(+)-enantiomer, either alone or in the racemic mixture. Addition of the corresponding alcohol did not improve trap catch of P. longispinus. Both the P. longispinus and the P. calceolariae pheromone lures remained active in the field for 90 days. Combining the 2 species’ pheromones had no negative effects on male mealybug trap catch for either species. We conclude that the pheromone ester alone is the best lure for the male P. longispinus. Combining the two mealybug species’ pheromones into a single lure provides the New Zealand viticultural industry with an efficient monitoring tool. Late-vintage deployment of baited lures will provide information on mealybug abundance and local distribution that will inform the scope of future insecticide programmes, to target areas based on need rather than an area-wide application by default.

AMF Community Diversity Promotes Grapevine Growth Parameters under High Black Foot Disease Pressure.

Black foot disease is one of the main grapevine root diseases observed worldwide and is especially problematic in New Zealand. Arbuscular mycorrhizal fungi (AMF) have been shown to reduce infection and mitigate the effect of black foot disease on grapevine rootstocks. In contrast to prior studies, which have limited their focus to the effect of one, two or a combination of only a small number of AMF species, this study used whole AMF communities identified from 101-14, 5C and Schwarzmann rootstocks sampled from New Zealand vineyards. The effect of AMF on black foot disease was investigated in a ‘home’ and ‘away’ experiment using three commercial grapevine rootstocks. The study produced some evidence that AMF treatments lowered disease incidence at 5 cm and disease severity in vines by 40% to 50% compared to the vines inoculated with the pathogen only. This work also showed that the presence of high disease incidence may have limited the potential disease protective effect of AMF community. However, despite the high disease incidence and severity, AMF inoculation increased vine growth parameters by 60% to 80% compared to the vines inoculated with the pathogen only. This study is the first to provide an understanding on how young grapevine rootstocks inoculated with their ‘home’ and ‘away’ AMF communities would respond to challenge with a black foot pathogen species mixture. Further research is required to understand the mechanistic effect of AMF colonization on the increase of grapevine growth parameters under high black foot disease pressure.

Grapevine rootstocks drive the community structure of arbuscular mycorrhizal fungi in New Zealand vineyards.

Arbuscular mycorrhizal fungi (AMF) are often regarded as non-specific symbionts, but some AMF communities show host preference in various ecosystems including vineyards. Grapevine plants are very responsive to AMF colonization. Although these fungi have potentially significant applications for sustainable agricultural ecosystems, there is a gap in knowledge regarding AMF-grapevine interactions worldwide and especially in New Zealand. This study focused on identifying AMF taxa colonizing grapevines in New Zealand vineyards and investigated the effect of grapevine rootstocks on AMF community diversity and composition. Denaturing gradient gel electrophoresis (DGGE) and trap cultures were used to characterize the AMF communities. Grapevine roots from three vineyards and nine rootstocks were analysed by DGGE and used in trap cultures for AMF recovery. Trap cultures allowed the recovery of six AMF spore morphotypes that belonged to Ambispora sp., Claroideoglomus sp., Funneliformis sp. and Glomus sp. Bands excised, reamplified and sequenced from the DGGE were assigned to Glomus sp., Rhizophagus sp. and Claroideoglomus sp. The AMF community analyses demonstrated that rootstock significantly (P < 0·05) influenced the AMF community composition in all sites. The study showed that for a comprehensive identification of AMF, both results from trap culture and molecular work were needed and that the rootstock cultivar was the main driver of the arbuscular mycorrhizal community colonizing the roots. This study provides a firm foundation for future research exploring the beneficial use of AMF in enhancing grapevine production and sustainability.

Retention and Transmission of Grapevine Leafroll-Associated Virus 3 by Pseudococcus calceolariae

Grapevine leafroll-associated virus 3 (GLRaV-3), an economically significant pathogen of grapevines, is transmitted by Pseudococcus calceolariae, a mealybug commonly found in New Zealand vineyards. To help inform alternative GLRaV-3 control strategies, this study evaluated the three-way interaction between the mealybug, its plant host and the virus. The retention and transmission of GLRaV-3 by P. calceolariae after access to non-Vitis host plants (and a non-GLRaV-3 host) White clover (Trifolium repens L. cv. “Grasslands Huia white clover”), Crimson clover (T. incarnatum), and Nicotiana benthamiana (an alternative GLRaV-3 host) was investigated. For all experiments, P. calceolariae first instars with a 4 or 6 days acquisition access period on GLRaV-3-positive grapevine leaves were used. GLRaV-3 was detected in mealybugs up to 16 days on non-Vitis plant hosts but not after 20 days. GLRaV-3 was retained by second instars (n = 8/45) and exuviae (molted skin, n = 6/6) following a 4 days acquisition period on infected grapevines leaves and an 11 days feeding on non-Vitis plant hosts. Furthermore, GLRaV-3 was transmitted to grapevine (40−60%) by P. calceolariae second instars after access to white clover for up to 11 days; 90% transmission to grapevine was achieved when no alternative host feeding was provided. The 16 days retention period is the longest observed in mealybug vectoring of GLRaV-3. The results suggest that an alternative strategy of using ground-cover plants as a disrupter of virus transmission may be effective if mealybugs settle and continue to feed on them for 20 or more days.

A small effect of conservation agriculture on soil biodiversity that differs between biological kingdoms and geographic locations

SummaryLarger easily visible animals and plants are negatively affected by agrochemicals used for intensive food production, but we do not understand the general spatial and temporal effects of agrochemicals on the multitudes of bacteria, fungi, and small invertebrate animals that underpin ecosystem productivity. We sequenced the 16S, ITS2, and COI DNA barcode regions from 648 New Zealand vineyard soil samples managed under either conventional or low-agrochemical-input conservation approaches across two regions and three seasons in 1 year and discovered at least 170,000 phylotypes (taxa) with >97% genetic identity. Management approach correlated with a significant 2%–10% difference in the abundances of phylotypes that differed over regions and seasons. Although the data show that agrochemicals do not have a large effect on soil biodiversity on average, the important finding is that the magnitude of impact differs between taxa types and locations, and some taxa most affected also influence the quality of agricultural produce.

Pathogenic fungi isolated in association with grapevine trunk diseases in New Zealand

ABSTRACTGrapevine trunk diseases (GTDs), caused by a complex of fungi, are a global threat to vineyard longevity. Identifying the fungi in each growing region is crucial for interpreting symptoms and understanding disease progression. Despite considerable research, the spectrum of fungi involved in GTDs in New Zealand remains uncertain and species identities within key taxonomic groups require validation with molecular sequences. We provide a synopsis of fungi from known pathogenic GTD taxa that have been identified in culture-dependent studies in New Zealand, especially those accessible through culture collections such as the International Collection of Microorganisms from Plants (ICMP). Results from a 2007–2010 countrywide vineyard survey for GTD fungi are presented, plus new isolates and associated DNA sequences from a 2017 survey of Marlborough and Hawke’s Bay vineyards and from institutional microbial collections. These new records clarify that authentic Eutypa lata and Phaeomoniella chlamydospora fungi, which are widely studied GTD pathogens, are present and probably common in New Zealand. First records of Inonotus, Diatrype, Sporocadus and Phaeoacremonium species are presented from New Zealand vineyards. The DNA sequences presented from GTD pathogens will facilitate the use of molecular detection technologies for measuring pathogen distributions in New Zealand vineyards and for biosecurity detections.

Identifying plant DNA in the faeces of a generalist insect pest to inform trap cropping strategy

Monocropping elevates many insects to the status of economic pests. In these agroecosystems, non-crop habitats are sometimes deployed as trap crops to reduce pest damage. This environmentally friendly alternative to pesticides can be particularly fitting when dealing with native invaders that may be afforded legal protection or enjoy public sympathy as is the case for the ground wētā Hemiandrus sp. ‘promontorius’ (Orthoptera) in New Zealand. However, this approach requires knowledge of the insects’ diet to select the most appropriate plant species for trap cropping. Here, ingested plant DNA in the faeces of wētā was analysed to help develop strategies for mitigating its damage in New Zealand vineyards. DNA was extracted from faeces of wētā collected from six different vineyards over four seasons. Using a DNA metabarcoding approach, we amplified the rbcL gene region and sequenced the amplicons on an Illumina MiSeq platform. The identity of plants in the diet of this insect was determined by comparing the sequences generated with those available in the GenBank database and cross-checking the results with a database of plants known to be present in New Zealand. A total of 47 plant families and 79 genera were detected. Of the genera identified, Vitis, Poa, Festuca, Anthoxanthum, Anagallis, Camelina, Epilobium, Menyanthes, Pedicularis, Urtica, Garrya, Pinus and Tilia were the major ones (i.e. they were present in more than 50% of the faecal samples). The composition of the above plant taxa in faecal materials was significantly different between collection sites or dates, except for Menyanthes. The occurrence of the latter was significantly different between collection sites. These results indicate that effectively mitigating wētā damage to vines requires the use of a diverse mix of plant species for trap cropping as wētā seem to be highly generalist in their feeding behaviour even when plant diversity is relatively low.

Pruning Wound Protection Strategies for Simultaneous Control of Eutypa and Botryosphaeria Dieback in New Zealand.

The grapevine trunk diseases Eutypa and Botryosphaeria dieback threaten the sustainability of vineyards worldwide. This study aimed to develop practical and efficient wound protection strategies, which will lead to widespread adoption of preventative control for these diseases and increased longevity of vineyards. Five fungicides (tebuconazole, carbendazim, fluazinam, mancozeb, and flusilazole) were evaluated for efficacy against Eutypa lata and Neofusicoccum luteum infection on pruning wounds of 'Sauvignon blanc' in a New Zealand vineyard. All five fungicides controlled infection by both pathogens to varying degrees, with mean percent disease control of 70 to 90% for E. lata and 33 to 93% for N. luteum. This has led to the first known registration of a fungicide, fluazinam (Gem), for simultaneous control of both Eutypa and Botryosphaeria dieback. Furthermore, application of carbendazim with tractor-driven sprayers provided similar control of E. lata and N. luteum to that when applied by hand with a paintbrush. This constitutes the first report of Botryosphaeria dieback control with fungicides applied with tractor-driven sprayers.

Factors influencing virulence and conidial production of Neofusicoccum species on grapevine shoots

Botryosphaeriaceae species are acknowledged as important wound pathogens of grapevines worldwide but reports as to the relative pathogenicity of species have varied. This study showed that the multiple vineyard isolates of Neofusicoccum luteum and N. parvum tested all caused disease of different grapevine stem tissues, but with great variation in symptoms and conidial release between isolates of each species. Overall, N. luteum caused longer lesions and produced more conidia than N. parvum on detached soft and semi-hard green shoots and on soft shoots of potted grapevines as well as on hard shoots of mature vines. With Sauvignon blanc, longer lesions and more conidia were produced on semi-hard green shoots and trunks of potted vines and on semi-hard green shoots of mature vines, than with Pinot noir. All isolates of N. luteum and N. parvum released conidia from stem lesions at all temperatures (10–25 °C) and RH (80–100%) tested, with most isolates releasing greatest numbers in high RH (~100%) and temperature (25 °C). This study showed that the two most commonly found species in New Zealand, N. luteum and N. parvum, were able to infect grapevine tissues and produce conidial inoculum under the temperatures and humidities commonly found in New Zealand vineyards.

Mealybug preference among clover cultivars: testing potential groundcover plants to dissociate mealybugs from grapevines

The choice of groundcover plants used under grapevines may reduce the quantity of mealybugs found on grapevines in New Zealand vineyards. Preferences of Pseudococcus calceolariae and P. longispinus mealybugs on five clover cultivars were tested under ‘no-choice’ and ‘choice’ conditions. Two plants of each cultivar: ‘Karridale’(KS) (Trifolium subterraneum, L.), ‘Tripoli’ (TW), ‘Nomad’ (N) (T. repens), ‘Crimson cv’ (C) (T. incarnatum) and ‘Strawberry cv’ (S) (T. fragiferum) grown in pots, were arranged in randomised designs for the no-choice and choice tests and inoculated with newly emerged mealybugs. In the no-choice test, significantly more mealybugs (either species) were observed on KS and C than on TW, N, or S plants after 21 days. In the choice test, significantly more P. calceolariae were observed on KS than on TW, N, or S, while mealybug numbers on C were intermediate. Numbers of P. longispinus were significantly higher on KS and C than on TW, N or S. Mealybugs demonstrated preferences for KS and C over TW, N or S. These findings could aid development of recommendations for groundcover management in vineyards.

Restricted glyphosate translocation in Lolium multiflorum is controlled by a single incomplete dominant nuclear gene

ABSTRACTThe mode of inheritance for herbicide resistance was investigated in a population of Lolium multiflorum (Italian ryegrass) with restricted glyphosate translocation mechanism of resistance. The degree of dominance for glyphosate resistance in Italian ryegrass was evaluated in the progenies of F1 families which were created by reciprocal-crossing between resistant (R) and susceptible (S) parental individuals. The results showed an intermediate level of glyphosate resistance for F1 families compared to that of the parental types. The phenotypic resistance segregation was also investigated using backcross families which were created by pair-crossing the F1 individuals to the susceptible population, and the observed segregation values fitted a one-gene model very well. Thus it appears that glyphosate resistance in the Italian ryegrass obtained from a New Zealand vineyard with restricted herbicide translocation is controlled by a single incompletely dominant nuclear gene.

Do spittlebugs feed on grape? Assessing transmission potential for &lt;i&gt;Xylella fastidiosa&lt;/i&gt;

The bacterium Xylella fastidiosa is a causal agent of Pierce’s disease in grapevines and is considered to be vectored by several xylem-feeding insects. Xylella fastidiosa and its primary insect vector Homalodisca vitripennis are not currently present in New Zealand, but considered a biosecurity threat to the wine industry. Should it be introduced, infection and dispersal of X. fastidiosa within New Zealand vineyards could occur through extant vectors, especially spittlebugs. Electrical Penetration Graph technology was used to compare the feeding behaviour of three spittlebug species (Philaenus spumarius, Carystoterpa fingens and Carystoterpa minor) on grape (Vitis vinifera Sauvignon blanc) and their original host plants. Results suggest that Philaenus spumarius feeds on grape more than the other two spittlebug species. As Philaenus spumarius has been reported as a vector of X. fastidiosa, their potential to transmit the bacterium into grapevines is discussed based on the real feeding times recorded by EPG.

Sensitivity of &lt;i&gt;Botrytis cinerea&lt;/i&gt; to fungicides used in New Zealand wine grape spray programmes

Fungicide resistance development in Botrytis cinerea threatens the efficacy of anilinopyrimidine (AP) fungicides, which have been used for botrytis bunch rot control in New Zealand vineyards for about 20 years. A 2016 survey of 33 vineyards in Gisborne, Hawke's Bay and Marlborough showed that the majority of 670 isolates tested in agar-based assays were sensitive to the AP cyprodinil (EC50 &lt; 1 mg/litre), although 18% showed low-resistance (EC50 1-10 mg/litre) and 10% showed medium-resistance (EC50 &gt;10 mg/litre). There was high cross-resistance to the APs cyprodinil and pyrimethanil. The survey also established baseline sensitivity to the succinate dehydrogenase inhibitor (SDHI) fungicide boscalid and &gt;90% of isolates were sensitive (EC50 &lt; 5 mg/litre). There was a low degree of cross-resistance between the SDHIs boscalid and fluopyram. There was also high sensitivity to fludioxonil (0.009 to 0.018 mg/litre) and to fenhexamid (0.49 to 0.76 mg/litre).