摘要:

Otago apricots (Prunus armeniacaL.) are damaged by the endemic leafroliers,Planotortrix octoDugdale andCtenopseustis obliquana(Walker), and an Australian species,Epiphyas postvittana(Walker), all of which are quarantine pests on export fruit. Mating disruption, using sex pheromones, represents one promising option for pest management with reduced insecticidal inputs for apricots. Two pheromone blends were used: one, designed to disrupt the two endemic species, was (Z)‐5‐tetra‐decenyl acetate and (Z)‐8‐tetradecenyl acetate, (25:75) and the other, forE. postvittana, was (E)‐1 1‐tetradecenyl acetate and (E)‐9,(E)‐11‐tetradecenyl‐1 acetate (95:5). No moths of three leafroller species were caught in pheromone traps at the centre of 0.1 ha plots of apricot trees treated with polyethylene tubing dispensers, at 1000/ha, whereas those outside the treated area (70 m distant) continued to catch. In commercial orchards, dispenser blends prevented trap catch and reduced damage in apricots on 1–3 orchards per year over 5 years. Dispensers, insecticides, and combinations of the two were equally effective in preventing damage to the fruit and gave better results than the untreated. Dispensers were not as effective as an insecticide programme at one large site over 4 years, except in the centre of the block. Dispensers were less effective where the tree canopy cover was incomplete and this effect was more important than the size of the area treated. Apricots were successfully exported from a 4.8 ha planting that was protected from leafroller damage by the endemic leafroller pheromone dispensers alone in 1996, and those forE. postvittanaand the endemic leafroliers (two different dispenser blends) in 1997. Differences between prospects for the use of mating disruption in summerfruit (stonefruit) and pipfruit (pome fruit) are discussed.

ISSN:0114-0671    

DOI:10.1080/01140671.1998.9514063

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Bioassays are described for measuring the ovipositional and larval preferences of three leafroller species,Planotortrix octo, Epiphyas postvittana, andCtenopseustis obliquana, for different apple (Malus domestica) cultivars. In four‐cultivar choice tests, mated female moths were offered terminal shoots in a large screen cage; first instar larvae selected terminal leaves in a smaller test arena. There were high levels of oviposition and settlement on all cultivars which agreed with field evidence of their susceptibility. However, there was overall higher oviposition of the three leafroller species (combined) on ‘Royal Gala’ compared to ‘Jonafree’, and forE. postvittana, higher oviposition on ‘Liberty’ than ‘Jonafree’. These cultivar preferenceswerealso expressed in the responses of the first instar larvae of the respective species. The preference ofE. postvittanalarvae for ‘Liberty’ and ‘Royal Gala’ rather than ‘Fiesta’, and the preference of P.octolarvae for ‘Liberty’ rather than ‘Jonafree’, were not matched by adult oviposition behaviour of the species.C. obliquanashowed no significant cultivar preferences but the acceptance ranking of the cultivars was the same in both the oviposition and larval tests. The bioassays are considered suitable for testing of leafroller oviposition and larval preferences using a wider genetic pool of apple cultivars in parallel with measurements of leafroller colonisation in the field.

ISSN:0114-0671    

DOI:10.1080/01140671.1998.9514064

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

A late frost occurred in the Southland region of New Zealand in November 1995 when many winter wheat (Triticum aestivumL.) crops were at early grain fill, and resulted in a large number of insurance claims for frost damage. In this study, frost damage was characterised. Spikes in affected crops were sharply tapered from a point half to two‐thirds from their bases. Grains were as much as 80% lighter in upper parts of affected spikes. Overall yield losses as a result of frost of between 13 and 33% were calculated in affected crops. Grains were sectioned and examined with a scanning electron microscope. Whereas in healthy grains, the layers making up the pericarp and testa were compressed, in frosted grains these layers comprised loosely compressed and unstructured networks of cells. The aleurone layer was less ordered in frosted than in normal grains, and was not always readily distinguished from the starchy endosperm. Rehydration of frosted grains was accompanied by expansion of pericarp and testa cells, whereas little cell expansion occurred in normal grains. Blisters were common in frosted grains, where the outer layers were detached from the remainder of the pericarp.

ISSN:0114-0671    

DOI:10.1080/01140671.1998.9514065

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Five‐year‐old ‘Braeburn’, ‘Royal Gala’, ‘Oregon Red Delicious’, ‘Splendour’, ‘Granny Smith’, and ‘Fuji'/MM. 106 apple (Malus domesticaBorkh.) trees growing under an ultra‐high density planting system (20 000 trees/ha) were root pruned in September 1994. Trees were pruned to a depth of 30 cm with a sharp spade along both sides of the row and between trees, 20 and 30 cm from the trunk. Root pruning resulted in decreased tree height, shoot length, branch number, trunk and shoot diameter compared to the control. Root pruning increased floriferousness e.g., the number of flowering spurs in subsequent season. Total carbohydrates (TCHO) and TCHO concentration in tissues of the trees were altered by root pruning treatments. Elevated shoot TCHO concentration was associated with higher flower initiation (flowering spurs per tree in the following season) whereas higher root TCHO was associated with higher total yield. The mean value for root reserves in August 1995 for the control trees was 111 g/plant and 84 g/plant for the 20 cm root‐pruned trees. Fruit yields were 4.1 and 2.6 t/ha respectively. Total yield and average fruit size were reduced by root pruning. The data suggest that root pruning created a lack of balance between reproductive characters and potential yield. This may be explained by reduced shoot leaf area (fewer bourse and shoot leaves) limiting carbohydrate supply and the effects of root pruning on TCHO, yield, and flowering are consistent with the predictions of an earlier model.

ISSN:0114-0671    

DOI:10.1080/01140671.1998.9514066

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Gas exchange attributes of fruits affect their responses to modified atmosphere and surface coating treatments. In this study, variations in respiration rate, internal partial pressures of O2and CO2, and skin permeance to O2and CO2associated with storage at 0, 5, 10, 15, 20, 25, and 30°C were characterised in ‘Braeburn’ apples (Malus domesticaBorkh.) There was an 11‐fold difference in respiration rate between fruit kept at 0 and 30°C, although permeance to each of the two respiratory gases differed only by a factor of two. The differing effects of temperature upon these two variables was responsible for the depression of internal O2and elevation of internal CO2associated with increase in temperature from 0 to 30°C. The magnitude of decline in internal O2was slightly greater than the increase in internal CO2over the temperature range in the experiment. For apples that were respiring aerobically, and with a respiratory quotient of unity, this would indicate that the fruit skin had a somewhat higher permeance to CO2than to O2, Permeance values for the two respiratory gases were strongly related but permeance to CO2exceeded that to O2for fruit with a low permeance to O2. This is attributable to the greater ease of diffusion of CO2through the cuticle, an effect which became more pronounced as transcuticular diffusion was facilitated at high temperatures. Given the importance of internal atmosphere composition in affecting respiration rate and disorder development in apples, the gas exchange characteristics of ‘Braeburn’ appear likely to be influential in the outcome of different storage regimes.

ISSN:0114-0671    

DOI:10.1080/01140671.1998.9514067

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Variable effects on tomato (Lycopersicon esculentum(L.)) yield were found in irrigation trials carried out in five seasons from 1973–74 to 1980–81. Only in one season was there a consistent positive response to irrigation; this was the season when soil moisture deficit was highest. The causes of the general lack of an irrigation response were not identified in this study; but observations suggested that the crop's water requirements were being supplied by subsurface water as well as rainfall, irrigation, and soil moisture storage in the 0–430 mm depth (A and B horizon). The subsurface water could have been supplied either by upward flux or by deep rooting. Further investigations are needed to clarify the character of tomato rooting systems and the contribution of upward flux from a water table to the root zone water economics.

ISSN:0114-0671    

DOI:10.1080/01140671.1998.9514068

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Growth of taro (Colocasia esculentaL. Schott) ‘Alafua Sunrise’ and ‘Niue’ was recorded in a high (16 mm water/day) and in a low (5.8 mm water/day) watering‐level treatment. Recording took place at intervals for a period of 21 weeks, when corms had just passed optimum maturity. Leaf, root, and corm growth measurements were all higher in the high watering‐level treatment; with corm fresh and dry weights reaching up to 80% higher than in the low watering treatment. The harvest index and water use efficiency are both generally higher in the high watering‐level treatment. The harvest index tended to be higher in ‘Niue’ and water use efficiency tended to be higher in ‘Alafua Sunrise’. The increased corm weight in the high watering‐level treatment may have been attributed to the earlier increased leaf and root growth. The expected better corm growth of the drought tolerant ‘Alafiia Sunrise’ in the low watering‐level treatment did not occur in this experiment; possibly because it was conducted in low light conditions.

ISSN:0114-0671    

DOI:10.1080/01140671.1998.9514069

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

A single postharvest application of 1‐methylcyclopropene (MCP) was effective in prolonging vaselife ofCymbidiumorchids by 6 or 7 days, to c. 19 days. It also prevented repeated applications of ethylene shortening the vaselife ofCymbidiumorchids. The anti‐ethylene effect of one MCP treatment persisted throughout three successive challenges with ethylene at 5‐day intervals. A supra‐optimal concentration of MCP (500 ppb) showed no adverse effects. MCP was also effective in protectingCymbidiumorchids against accelerated senescence caused by damage to the pollinia. Individual flowers with damaged pollinia senesced even more rapidly than ethylene‐treated intact flowers. In the presence of MCP, flowers with damaged pollinia had a vaselife almost equal to that of undamaged flowers. This is a significant finding for the orchid export industry.

ISSN:0114-0671    

DOI:10.1080/01140671.1998.9514070

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

A range of bacteria were screened to identify potential antagonists againstBotrytis cinereaon grape tissue (Vitis viniferaL.). From dual culture tests, 13 isolates were selected which exhibited antagonism towardsB. cinereamycelial growth. Inhibition zones ranged between 3 and 12 mm. These isolates were screened in a grape leaf bioassay. Irradiated leaf discs were inoculated with5. cinerea(1 × 104spores/ml) then challenged with bacteria applied at 1 × 108colony forming units (cfu)/ml in tryptic soya broth (TSB). Sporulation ofB. cinereawas significantly (P =0.05) reduced on leaf discs treated withSerratia liquefaciensisolates B47 and 171B by 62 and 57% respectively, 7 days after application. In a second leaf bioassay, B47 applied in TSB significantly (P =0.05) reducedB. cinereasporulation by 65% after 21 days compared to a 39% suppression achieved with isolate 171B (applied in TSB) and the fungicide, iprodione. However, when applied in Ringers solution, both isolates failed to reduceB. cinereasporulation. This research has identified two isolates ofS. liquefaciensable to suppress sporulation ofB. cinereaon grape tissue and has shown that bacterial application solution can strongly influence the degree of suppression achieved.

ISSN:0114-0671    

DOI:10.1080/01140671.1998.9514071

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

A bacterium, isolated from infected tubers of calla (Zantedeschiaspp.), was confirmed as a soft rot pathogen by completion of Koch's postulates and was identified asErwinia carotovorasubsp.carotovora(Jones 1901) Bergey et al. 1923. This paper confirms the identity ofE. carotovorasubsp.carotovoraas the cause of bacterial soft rot of this important ornamental plant in New Zealand.

ISSN:0114-0671    

DOI:10.1080/01140671.1998.9514072

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor