The genotype of nodule occupants in four annual clovers Á balansa (Trifolium michelianum), Persian (Trifolium resupinatum), gland (Trifolium glanduliferum) and arrowleaf (Trifolium vesiculosum) Á was investigated. The clovers were inoculated with the ALOSCA † group C granule preparation of strain WSM1325. A total of 224 strains were recovered from root nodules with between 55 and 58 strains for each clover species. Genotyping showed that no strains had fingerprints identical to strain WSM1325. The nodule occupants were diverse with 26, 35, 31 and 32 genotypes identified on arrowleaf, balansa, gland and Persian clovers, respectively. Arrowleaf clover had some specificity for genotype A with 43% of nodules occupied by this strain. The most dominant strain for the other three clovers ranged between 13%Á18% occupancy. This work demonstrates a high diversity of naturalized rhizobia strains in New Zealand soils that had the ability to nodulate these top flowering annual clover species.
Ethyl formate (EF) is a Generally Recognised As Safe (GRAS) alternative to methyl bromide, with potential to control surface pests on New Zealand avocados before export. 'Hass' avocados, two-spotted spider mites (TSM) and oleander scale (OS) insects were fumigated with 1.2% EF (240 g VAPORMATE™/m 3 ) at 6°C for 1, 2 or 4 h. Fruit were then stored at 5°C for 3 weeks before external and internal fruit quality assessment. Survival of pest species was assessed 1 or 7 days later. Fumigation with 1.2% EF + 10% CO 2 for 2 or 4 h controlled all life stages of non-diapausing TSM and all life stages of OS, apart from crawlers (0.3-0.7% survivorship). Diapausing TSM were harder to control (17% ± 4.8% mortality; 4-h treatment). Ethyl formate treatment resulted in damage to avocado skins (41% ± 5.3%-91% ± 2.0%), and an increase in vascular browning and rots. The EF fumigations of avocado fruit at doses used here have potential to control non-diapausing mites and scale insects, but treated fruit were of unacceptable quality. Future studies could examine whether prior cool storage could reduce fruit damage.
The controlled atmosphere temperature treatment system (CATTS) was assessed as a disinfestation tool to control codling moth (CM; Cydia pomonella) larvae inside apples. Codling moth mortality and apple quality were assessed after exposure to one of 10 treatments, which were combinations of five variables, namely, O 2 concentration (air 20.9%, 1, 2 or 3%); CO 2 concentrations (air 0.04% or 15%); 12 or 24°C/h ramp rate up to 46°C; air speed 1.3 m/s; and either 2.5-or 3-h treatment time. CATTS treatments resulted in higher CM mortality than equivalent hot air treatments. The treatments involving 1 or 2% O 2 combined with 15% CO 2 and a ramp of 12°C/h or 24°C/h to 46°C, with a total treatment time of 3 h or 2.5 h and a 1.3 m/s air speed resulted in 100% mortality of CM. However, all CATTS and hot air treatments compromised apple quality. High CM mortality can be achieved using CATTS, but refinement of the protocol is needed to improve fruit quality outcomes.
Insect removal from kiwifruit is important for improving access to overseas markets. Insect removal from kiwifruit by physical treatments such as high pressure washing is hugely successful but kiwifruit packing is carried out "dry". Therefore, one potential option is the use of 'air-knife' blowers to remove insects. A system with air-knives from the sides and top that was mounted over a single-lane Compac grader was able to remove over 90% of artificially inoculated diapausing two-spotted mites (≈ 85/fruit). The difference in pest levels between untreated 'Hayward' kiwifruit fruit naturally infested with a wide range of insects (n=2194) and fruit exposed to air-knives (n=2204) was: mealybug 100%, beetle/weevils 91-100%, oribatid mites 93%, tuckerellid mites 98%, unidentified mites 88% , booklice 86%, thrips 74-100%, Collembola 63%, cockroaches 100%, spiders 43%, scale insects 40%. Air-knives had no noticeable effect on 'Hayward' or 'Zesy002' (Gold3) fruit quality. These results indicate that air-knives using a high air-flow/low-pressure system can effectively remove high rates of "mobile" insects and first-instar scale insects, and can probably be implemented logistically and economically from a commercial perspective.Pre-treatment dips to enhance the removal of apple leafcurling midge from apples using high pressure washing The presence of apple leafcurling midge (ALCM) on apples is of concern for many of New Zealand's export apple markets. High pressure washing (HPW) systems have been implemented in export packhouses to reduce the risks associated with various pests; however, higher removal rates of ALCM are required to improve access to challenging markets. A range of pre-treatment dips to improve ALCM removal efficacy when applied before HPW were tested, and the impact of these pre-treatment dips on pest viability determined. Removal of ALCM cocoons by HPW alone was 41%, compared with pretreatments of hot water at 51°C (66%), Saturate® (58%), Prospect oil® (57%), malic acid (53%), citric acid (48%), lactic acid (46%), acetic acid (39%), HarvestCide® (37%) or sodium bicarbonate (37%). However, only the hot-water treatment significantly enhanced removal compared with HPW alone. In a second trial, removal of ALCM cocoons with HPW was 69% and hot water + UV-C increased removal to 76%, although this difference was not statistically significant. Overall, none of the pre-treatment dips was found to reduce ALCM viability significantly compared with HPW alone.
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