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Rotorua, New Zealand

Gaskin R.E.,Plant Protection ChemistryNZ | Pak H.A.,121D Plummers Point Road
New Zealand Plant Protection

Best practice guidelines have been developed in recent years for application of low volume, concentrated pesticide sprays to avocado orchards. Oil sprays, an important component of spray programmes on avocado orchards, have been excluded from the concentrate programme because of the risk of damage to the crop. Two unreplicated trials were undertaken on commercial orchards, one each in Northland and Bay of Plenty, from December 2012-December 2013. Each plot consisted of a single orchard block (ca 1 ha) per treatment. Dilute (0.5% oil) high volume sprays (up to 3000 litres/ha) were compared with concentrated (1.5% oil) low-volume sprays (up to 1000 litres/ha) containing a horticultural superspreader adjuvant. Monitored pest populations were comparable in both treatments throughout the year with no detrimental impacts of concentrate oil sprays on either export packout rates or storage quality of fruit after harvest. Safe use of concentrate oil sprays on avocados is practical using a horticultural superspreader adjuvant. © 2014 New Zealand Plant Protection Society (Inc.). Source

Gaskin R.E.,Plant Protection ChemistryNZ | Manktelow D.W.L.,Manktelow and Associates Ltd. | Northcott G.L.,Northcott Research Consultants Ltd
New Zealand Plant Protection

Autumn leaf scars are an important pathogen infection site for European canker on apples. Trials were undertaken to evaluate the effects of adjuvants on spray coverage of new leaf scars, and determine if adjuvants could (1) impart any significant rainfastness to protectant captan sprays and (2) provide any redistribution of captan during a rain event post-leaf drop. Retention on fresh leaf scars was increased with the use of organosilicone-latex sticker adjuvants only. Rain had little effect on spray residues but these adjuvants could improve rainfastness of captan due to their effects on spray retention. Retention on stem wood and around leaf nodes was increased by up to seven-fold with the use of superspreader-type adjuvants, due to redistribution of spray runoff from leaves. High initial deposits resulted in post-rain residues on leaf scars three-fold higher than a captan spray alone. Redistribution of captan onto exposed leaf scars in rain appears likely with these adjuvants. © 2014 New Zealand Plant Protection Society (Inc.). Source

Horgan D.B.,Plant Protection ChemistryNZ | Gaskin R.E.,Plant Protection ChemistryNZ
New Zealand Plant Protection

Spirotetramat (Movento®) is a systemic insecticide that is used to control scale insects on kiwifruit. The use of protectant copper sprays on kiwifruit has become increasingly common due to the bacterial disease Pseudomonas syringae pv. Actinidiae. This study investigated the interaction of copper with spirotetramat and how it influenced the uptake and translocation of spirotetramat within the plant. Movento® 100SC sprays should not be tankmixed with copper sprays because the uptake and translocation of spirotetramat is likely to be compromised. These negative effects were minimised when an organosilicone/organic fluid blend adjuvant (Du-Wett®) was included in the tank mix. Pre-and post spray applications of copper, at least 1 week either side of spirotetramat applications, are unlikely to significantly affect the uptake and translocation of spirotetramat, and thus have any effect on its activity. There were no marked differences between two commercial copper formulations, in their effects on spirotetramat uptake but minor differences in translocation were observed. © 2015 New Zealand Plant Protection Society (Inc.). Source

Forster W.A.,Plant Protection ChemistryNZ | Pathan A.K.,Plant Protection ChemistryNZ | Kimberley M.O.,Scion Research | Steele K.D.,Plant Protection ChemistryNZ | Gaskin R.E.,Plant Protection ChemistryNZ
ACS Symposium Series

Extensive experimentation in recent decades has assisted in developing a better understanding of the individual processes (spray adhesion, retention, uptake and translocation) that control the biological efficacy of applied herbicides. Various models are available, each usually limited to predicting the efficacy of an individual process. In this study, spray retention, uptake and translocation of glyphosate (as influenced by an organosilicone surfactant Silwet L-77®) on three plant species was determined. Non-linear regression models were used to describe the relative effects of retention, uptake and translocation processes on bioefficacy. All three variables were highly correlated, making it difficult to distinguish their relative influence on bioefficacy. Uptake and translocation were highly correlated (> than 0.98 for all species studied), with about 40-45% of the glyphosate taken up translocated for all three species. Overall the best model, explaining 85-99% variance, used retention and uptake together. It appeared that the bioefficacy of glyphosate towards barley and broccoli was 30-50% related to retention and 50-70% related to uptake, while glyphosate efficacy towards bean was entirely related to uptake and not directly related to retention. For practical purposes, it is reasonable to expect that experimental results from retention and uptake studies (or predictions of each from available models) considered together will give a good indication of the relative bioefficacy of different formulations for a given AI, across a wide range of systemic active ingredient (AI) and species, minimising the need for translocation measurements. © 2014 American Chemical Society. Source

Nairn J.J.,Plant Protection ChemistryNZ | Forster W.A.,Plant Protection ChemistryNZ | Van Leeuwen R.M.,Plant Protection ChemistryNZ
New Zealand Plant Protection

An empirical spray droplet adhesion model, developed to predict the adhesion of spray formulations to non-hairy leaf surfaces based on their specific wettability, has previously been improved to allow predictions to hairy leaves, since it had been discovered that leaf hairs cause a significant, consistent increase in droplet shatter compared to nonhairy leaves (super-hairy leaves demonstrate distinctly different adhesion behaviour). The current study investigated the effect of spray formulation surface tension on droplet adhesion to hairy leaf surfaces. The amount of shatter on hairy leaves was found to increase with decreasing surface tension. The relationship derived improved the adhesion model. This enables the model to better predict the effect of spray formulation on spray droplet adhesion of hairy leaf species. © 2014 New Zealand Plant Protection Society (Inc.). Source

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