Three different types of roller, single or tandem (twin) with rigid rollers, and pneumatic (rubber-tyred), were used with one pass on pasture infested with grass grub (Costelytra zealandica (White)) to examine their effect on grass grub and earthworm mortality, and subsequent pasture yield. The rigid tandem rollers had three types of surface—smooth, grooved, and knobbled. The first two of these were tested with three different diameters and under five different loads. A spiked roller was also used. All rollers were towed at 2.8 km/h. The heaviest tandem rollers with grooved or knobbled surfaces caused 77–88% mortality of immature third instars which was 18% of the population present. Second instars and mature third instars were not significantly affected. Depression of the soil surface increased linearly with roller weight and the amount of depression could be used to predict the mortality of immature third instar larvae. There was no significant difference in grass grub mortality or pasture response between rollers of different diameter when operated at their maximum loaded weights. Some tandem rollers gave increases in pasture yield in the following spring and summer, but there were no significant differences attributable to different types, weights, or diameters. The spiked roller had no significant effect on grass grubs or pasture. Earthworm density was reduced by some rollers but the effect did not seem to persist into the second year.
Latania scale, (Hemiberlesia lataniae (Signoret)), is now established in the North Island of New Zealand. The significance of this pest and methods of distinguishing latania scale from greedy scale (Hemiberlesia rapax (Comstock)) and oleander scale (Aspidiotus nerii Bouché) are discussed. Keywords: latania scale Hemiberlesia lataniae greedy scaleinsect pests Hemiberlesia rapax oleander scale Aspidiotus nerii New Zealand
Two sampling methods for estimating fruit number per tree were assessed on 'Gala' apple after the imposition of different crop levels by hand thinning. A multiple linear regression equation was developed for one of the sampling techniques relating the sample estimate and trunk cross-sectional area to the total fruit number per tree. Strong positive relationships were found between fruit numbers per tree and total yield, and the total weight of small fruit. These two relationships were similar over two seasons and two orchard sites. Weak relationships were found between fruit number per tree and average fruit weight and the total weight of medium or large fruit. These relationships varied between seasons and orchards. Keywords: apples Malus domestica crop loadinghand thinningcrop estimationyieldfruit size
Abstract The occurrence of the root-knot nematode (Meloidogyne spp.) on subterranean clover in the lower south-west of Western Australia, and its association with root rot of this pasture species were investigated. Meloidogyne arenaria was associated with roots of subterranean clover sampled from all 12 field sites. This is the first record of M. arenaria on subterranean clover in Australia or elsewhere. There was a negative relationship between gall and root rot indices of the tap roots but not of the laterals. Although pathogenicity tests with M. arenaria at five inoculum levels (0, 8, 16, 40, and 80 × 102 eggs per 250 cm3 pot) showed that it is pathogenic at higher inoculum levels (> 16 × 102 eggs per pot), none of these levels resulted in root necrosis.
Measurements were made of herbage dry matter production and composition of pastures in the second year after drilling of ‘Grasslands Pawera’ red clover (Trifolium pratense L.) with or without ‘Grasslands Nui’ perennial ryegrass (Lolium perenne L.) into grass-white clover dominant swards in autumn and spring. Tillage treatments included cultivated seedbed, overdrilling into paraquat-sprayed bands, and blanket spraying with paraquat or glyphosate. Unmodified resident pasture produced more total yield than the autumn-sown cultivated treatments, but yields from spring-sown treatments were not significantly lower than the resident pasture yield. Contribution of red clover to yield was 13–26% with full cultivation and 4–7% with band spraying of paraquat, but did not significantly modify the distribution of herbage production. Red clover density varied from 6 to 8 plants/m2 in band-sprayed treatments, about a third of the density obtained with full cultivation. This study indicates that interruption of pasture supply and lower productivity occurred for 2 years after overdrilling of a high yielding resident pasture with cultivation, or spraying with glyphosate or paraquat. Although red clover seedlings were established and grew to provide more herbage in the second than in the first year, continuing loss of plants reduced the influence of red clover on pasture yield and its seasonal distribution.
Botrytis cinerea was frequently isolated from rapidly senescing or moribund tissues (stamens, calyptrae, immature berries and flowers or partly developed berries, miscellaneous leaf, stem and tendril pieces) of grapevine; the calyptrae being more heavily contaminated than the stamens in the flower bunches. There was a significant difference in the extent to which intact and injured berries were infected by the pathogen 3 weeks before harvest. Bunches infested with light-brown apple moth (Epiphas postvittana (Walker)) were more rapidly infected by B. cinerea. Of thecultivars tested, 'Mataro' was the least susceptible to predisposition wounding because the berries had a high critical turgor; however, once the berries were split, they appeared to be as susceptible to infection as the other cultivars tested. The longer the berries were exposed to surface wetness, the higher the degree of infection. A minimum temperature difference of 9°C caused a significant difference of 6-12 h in the length of the infection period. Infection of berries occurred over a wide range of temperatures (15-25°C).
A survey of ripened onion (Allium cepa L.) bulbs, collated from field-grown crops in the commercial areas of New Zealand, was undertaken to investigate how the characteristics of flavour precursors, phenolics, sugars, dry matter, and hardness varied. The majority of samples were of ‘Pukekohe Long Keeper’ (PLK) and the early selection of this cultivar, ‘Early Long Keeper’ (ELK). A sample of the white onion ‘Dehyso’ and three Japanese onion cultivars was obtained for comparison. Percentage dry matter (DM %) for PLK and ELK for the 1983 harvest was similar for all sites and averaged 13.4%; total sugars averaged 0.45 mmole/g fresh weight. The white ‘Dehyso’ onions had a higher dry matter percentage (DM%) (15.9%) and a greater proportion of fructose compared with glucose than PLK or ELK onions. PLK and ELK samples collected from one site in 1984 had significantly different DM% and total sugars compared to other sites. There was a significant difference in average fresh weight for bulbs between sites. Total phenolics content (absorbance at 270 nm) was similar for all ELK and PLK onions, but the ‘Dehyso’ and Japanese ‘Sapporo Yellow’ cultivar had phenolic contents respectively ⅓ and ½ the levels found in ELK and PLK. PLK and ELK onions were harder than the Japanese cultivars, although one PLK sample was very soft. There was considerable variation in total flavour precursor content of the ELK and PLK samples. ELK samples in 1983 were significantly higher in total flavour precursors than PLK samples in 1983. ‘Dehyso’ onions were highest in flavour precursor content, whilst ‘Sapporo Yellow’ onions were lowest. ELK and PLK samples from one site in 1984 were much lower in flavour precursor content and indicated a strongly modifying influence of environment on flavour precursor levels.
Abstract Display life of Leucospermum cv. Firefly is restricted by foliage damage. Treatment with sucrose solutions, either continuously during display (1% sucrose) or for a 24 h pulse treatment at 20° C (5% sucrose), failed to reduce leaf desiccation. Continuous 5% sucrose treatment induced more severe leaf damage and reduced leaf display life further, whereas flower head display was increased greatly with continuous sucrose treatments. Preservatives improved the water balance (expressed as nett water loss) of inflorescences during display life, but failed to reduce the rapid decline in water uptake that occurred during the first days of display. During continuous treatment, transpiration was reduced, possibly as a result of greater leaf damage in treated inflorescences. Keywords: postharvest Leucospermum water balancesucrosewater stresspreservativewater uptaketranspirationdisplay lifecutflowersfoliage damage
In two growing seasons, navy beans cv. Sanilac were sown at populations ranging from 44 to 120 plants/m2 with or without irrigation and shelter in Canterbury. In the two seasons, rainfall was 156% and 66% of the long term mean. Irrigation had the largest effect on seed yield. In 1983/84 irrigated plants yielded 319 g/m2 and unirrigated plants only 278 g/m2. In the drier season, irrigated plants yielded 309 g/m2 while the dryland crop yielded only 131 g/m2. Shelter had only a small effect on seed yield, in only one season, despite reducing wind run by about 40%. Generally, higher plant populations resulted in higher seed yields particularly with irrigation. However in 1984/85, unirrigated crop yield with 30 plants/m2 was 135g/m2andat 120plants/m2 only 125 g/m2. The results indicated that navy beans should be grown with irrigation in Canterbury to be a viable farm option. High plant populations may produce higher yields and ease harvesting problems.
Blackcurrant bushes (cv. Magnus) planted on a free-draining Lismore stony silt loam were used to study the yield responses to four irrigation regimes, using one unirrigated and three irrigated treatments. Irrigation treatments were applied each time gravimetric soil samples (0–150 mm deep) taken 300mm from the hedgerow fell to 10,15,or20%soil moisture (s.m.) content. In the first two years, the 15 and 20% s.m. treatments produced yields 150-220% higher than both the unirrigated and infrequently irrigated 10% s.m. treatments. As the unirrigated and 10% s.m. treatment bushes developed with time, the annual yield differences decreased to a level where, by the fifth harvest, the 15 and 20% s.m. treatment yields respectively were only 15% and 37% higher than the unirrigated treatment yield. Average berry weight increased with irrigation frequency during the first three seasons. However, differences in berry weight decreased gradually with timeandby the 1986/87 season showed no significant differences between treatments. No consistent trend was obvious from the sugar levels recorded during the trial period. Generally sugar levels were not significantly different in wet seasons but in drier seasons, irrigation tended to reduce total soluble solid levels by around 1–1.5% compared to the unirrigated treatment. The 15 and 20% s.m. treatments required on average 5 and 14 irrigations per season respectively to maintain their particular soil moisture level. Because of the poor performance of the treatments irrigatedbelow 15% soil moisture and the excessively high number of irrigations required to maintain soil moisture levels above 20% it seems unlikely that the optimum regime will be outside the 15 to 20% soil moisture range.
Abstract The fungicides imazalil and prochloraz suppressed the in vitro growth of four fungal storage pathogens of tamarillos (Colletotrichum gloeosporioides (Penz.) Arx, C. acutatum Simmonds, Phomopsis sp., and Phoma exigua Desm.). Imazalil was as effective as prochloraz against P. exigua but prochloraz was more effective against C. gloeosporioides, C. acutatum, and Phomopsis sp. The proportion of fruit affected by four storage disorders (body lesions, stem-end lesions, calyx mycelium, and calyx necrosis) was reduced after dipping with prochloraz (250–1000 mg/litre) compared with fruit dipped in cold water (CW). A combined imazalil and prochloraz dip (CF) resulted in the greatest reduction in these disorders. Fruit from one orchard were dipped and stored for4,6,and8 weeks at3.5± l° Cfollowedby 1 week at 20 ± 2° C. The number of sound fruit after storage was increased by 36% and 35% respectively for the CF strategy and the hot water dip (HW) when compared with the cold water dip (CW). In fruit that were c...
The effects of three inter-row spacings (3 m, 1.5 m, and 0.75 m), and two support systems (training vertically or on a V-shaped trellis) on total yield, yield components, and ease of hand picking of autumn rasperries (Rubus idaeus L. ‘Heritage’) was investigated in a 3-year field trial in Canterbury. In the first year, number of fruiting canes/m2 and yields/ha were both increased as row spacings were reduced from 3 to 0.75 m. However, in the second and third seasons, although these parameters were increased as spacings were reduced from 3 to 1.5 m, a further reduction in spacing to 0.75 m had no effect. Neither the number of berries per fruiting cane nor yield per fruiting cane were significantly affected by row spacings, although there was a tendency for mean berry weight to increase as row spacing was reduced. Reducing row spacing from 1.5 to 0.75 m made access to rows difficult and reduced picking rate. Training canes on a V trellis had no significant effect on any of the measured parameters at either the 3 m or 1.5 m spacings. It was concluded that if straddle sprayer equipment was used, yields of autumn raspberries could be maximized by planting them as close as 1.5 m apart.
A paddock-scale experiment was conducted over two seasons to determine whether winter barley will fit adequately into a fanning system that requires both feed and grain, and to investigate how grazing affects the grain yield components. The 6-row ‘Illia’ and 2-row ‘Priver’ cultivars produced 1.3–2 t/ha of DM by mid August when sown in April. Grazing to ground level in August reduced grain yields by about 10%, by reducing the ear population, despite the fact that mainstem apices were below soil level at thetime of grazing. Combine harvested grain yields ranged from 2.3 to 3.6 t/ha in seasons with below average rainfall. Keywords: winter barleygrain yieldcereal greenfeedgrain yield componentsapex development
Abstract Root-length densities (RLD; root length per unit volume of soil) were measured in core samples taken from nine North Island kiwifruit orchards. Despite differences in vine spacings, root-stock ages and types, soils, climates, and management, there was a consistent pattern to root systems. In orchards younger than 10 years, roots explored bowl-shaped soil volumes and mean RLD fell with both depth and radial distance from vines. In older orchards, root systems of adjacent plants met so that soil volumes available to plants were completely explored and mean RLD fell with depth. Roots were found at depths greater than 1 m in most orchards. In both young and old orchards, RLD ranged from 0 to 8 cm/cm3 but proportions of zero values increased towards the peripheries of root systems. These proportions were used to subdivide rooting volumes into volumes of total occupancy in which all RLD were greater than zero, and volumes of partial occupancy in which volumes containing roots were interspersed with 'void' volumes without roots. These results are discussed in relation to water and nutrient uptake. Keywords: Actinidia deliciosa root explorationrooting volumevoid volumetotal occupancypartial occupancykiwifruitroot distributionroot length
‘Red Delicious’, ‘Golden Delicious’, ‘Braeburn’ and ‘Granny Smith’ apples stored in polyethylene bags (polybags) 25 (μm thick containing microperforations made with a 1 mm diam. cold needle, had less bitter pit after 7 weeks storage at 1°C and 7 days shelf-life simulation at ambient temperature than unbagged apples from the same storage environment. Carbon dioxide concentrations increased and oxygen decreased as the number of microperforations in polybags was decreased. Commercially acceptable levels of bitter pit (less than 5%) could be obtained with ‘Red Delicious’ apples when CO2 and O2 concentrations inside polybags exceeded 5% and fell to 15–16% respectively. ‘Red Delicious’ and ‘Golden Delicious’ apples stored in microperforated polybags lost less weight, were firmer and had better eating quality than fruit not stored in polybags. It is suggested that polybags containing 50–70 microperforations could be adopted commercially for the apple cultivars tested, to reduce bitter pit and maintain fruit quality.
Achillea millefolium L. (yarrow), a perennial competitive ruderal, has become an increasing problem on arable land in New Zealand as a result of reduced cultivation, horticultural development, and the ineffectiveness of herbicides. Research conducted mainly in Canterbury, on aspects of the seed and rhizome biology of A. millefolium, is considered in relation to its control. It is concluded that major difficulties still exist in the selective control of this weed in crops. Strategic cultivations during pre-sowing fallows and the use of glyphosate and clopyralid as broadcast or directed treatments are the best control options.
Light-brown apple moth (Epiphyas postvittana) has developed a low level of resistance to azinphos-methyl in two small areas of a major horticultural district in New Zealand. It is not known whether resistant individuals form isolated populations or are a part of a much larger population. Hence, it is uncertain whether this resistance has the potential to develop and spread. Models representing the range of possible situations are described and management options assessed by deducing the consequence they would have in each of the possible situations. It is concluded that the continued use of organophosphate insecticides incurs the risk of a development and spread of resistance. The best alternative is to use pyrethroids in the affected areas but such an option is not without its own costs. Keywords: decision analysislight-brown apple mothmodelsazinphos-methylresistanceorganophosphatespyrethroids
Kiwifruit (Actinidia deliciosa ‘Matua’) vines were grown under five maximum/ minimum temperature regimes (21/17,21/13,21/7, 17/7 and 13/7°C) from budbreak to post-flowering. Assessments were made of the germinability and viability of pollen extracted from flowers off these vines. Percentage germination was evaluated, after 3.5 h incubation, under different incubation temperatures ranging from 7 to 35°C. Highest germination (90%) was obtained under the warmest (21/17°C) development temperature regime. Percentage germination declined as the development temperature decreased and was only 25% at 13/7°C. Maximum percentage germination under all development treatments occurred at incubation temperatures between 22 and 28°C; very little germination occurred at and below 13°C or at 35°C. Pollen tube distortions were common atc 35°C. Percentage germination was similar to percentage viability for pollen from warm development temperatures but only half of the viable pollen from the coolest temperature germinated.
Abstract Luxury uptake of potassium (K) from potassium chloride (KC1) by pasture plants is a major disadvantage in its use as a fertiliser for pastures. Luxury uptake shortens the fertiliser's effective life and causes excessively high concentrations of potassium relative to calcium, magnesium, and sodium. This can result in health problems for grazing stock. A further disadvantage is that KC1 is readily leached from the soil if there is heavy rain. Coating KC1 has been tried as a way of slowing the release of K and its uptake by ryegrass, and of reducing loss by leaching. Coating KC1 with sulphur reduced its rate of dissolution greatly and avoided luxury uptake by the grass. On an extremely K deficient soil there was some loss of growth relative to uncoated KC1 for 2 months, but over the next 4 months, the sulphur-coated KC1 gave higher yields. Wax-coated KC1 gave practically the same results as uncoated KC1. A leaching test was used to measure rate of solution of KC1 and its results related well to the reduction of luxury uptake. Keywords: potassium fertiliserslow release fertiliserspastureluxury uptakecation ratiosleachingryegrass
