Background: Phosphorous acid is being investigated as a fungicide for the management of a needle disease caused by Phytophthora pluvialis in Pinus radiata in New Zealand. However, little is known about the penetration characteristics of this fungicide into Pinus radiata foliage. This study was undertaken to determine: i) the penetration characteristics of a commercial phosphorous acid formulation, applied at 3 kg ha -1 and 12 kg ha -1 in 100 L water, into Pinus radiata foliage and, ii) the effect of four commercially available adjuvants on phosphorous acid uptake into Pinus radiata foliage. Efficacy of the best treatment was tested in vitro with two Phytophthora species, Phytophthora kernoviae and P. pluvialis.

Spirotetramat (Movento† ) is a phloem-and xylem-mobile insecticide developed and registered for use pre-flowering to control armoured scale insects on kiwifruit vines in New Zealand. In a field study in 2010Á11, the effectiveness of a postharvest application was investigated. A single spray of spirotetramat plus adjuvant(s) reduced the percentage of scale-infested fruit from 49% on control vines to less than 7.5% on spirotetramat-sprayed vines 12 months later. No residues were detected in the fruit. Applying spirotetramat with a penetrating adjuvant (Engulf † ) provided the best result, with only 1.5% of the fruit infested. Despite the high pest pressure, counts of scale insect crawlers on sticky bands remained very low for 18 months after treatment. Uptake of spirotetramat into the mature kiwifruit leaves occurred in less than 24 h and was not affected by leaf age. Translocation out of the leaf was slow and decreased with leaf age, indicating that a postharvest spray should not be applied to canopies exhibiting advanced senescence. These results show that a single postharvest application of spirotetramat plus adjuvant(s) can provide excellent season-long control of armoured scale insects on kiwifruit while minimizing the risk to crop pollinators and the potential for residues in fruit.

Spirotetramat (Movento) is a systemic insecticide that can control scale insects on kiwifruit It must be tankmixed with a spray adjuvant to maximise leaf uptake This study investigated how two adjuvants a penetrating oil and a superspreader affected spray retention and uptake of spirotetramat into kiwifruit leaves from dilute and concentrated spray mixes Spray retention and distribution of airblastapplied high volume dilute sprays containing the oil adjuvant were good but retention was reduced when sprays were concentrated Concentrated sprays containing the superspreader adjuvant were retained and distributed similarly to the dilute sprays containing oil adjuvant Spirotetramat uptake into foliage was generally low but was greater with the oil penetrant than with the superspreader Concentrating sprays and increasing adjuvant concentrations could increase insecticide uptake as could combining the two adjuvants together in a spray The potential of the adjuvants to maximise spirotetramat efficacy in concentrate sprays and to reduce residues at harvest is discussed

Why this research Matters Management of dense infestations of wilding Pinus contorta in New Zealand requires high doses of herbicides; 18 kg active ingredient (a.i.) ha−1 triclopyr and 5 kg a.i. ha−1 dicamba are used in combination with a complex mix of adjuvants (methylated seed oil, non‐ionic surfactant and ammonium sulfate) and other active ingredients. From the perspective of cost and environmental impact there is a need to reduce the complexity of this tank mix and the rates of active ingredients. Using radiolabelled herbicides, this study evaluated the effect of dose and adjuvants (crop oils, non‐ionic surfactants, and organosilicones) on needle injury and uptake of triclopyr and dicamba into P. contorta needles at 24 hr or 7 days after treatment (DAT). The uptake of triclopyr decreased significantly with increasing concentration (0.75%–6%) resulting in the highest uptake dose at the equivalent of 18 kg a.i. ha−1 triclopyr at 7 DAT. When applied at 18 kg a.i. ha−1, none of the adjuvants tested significantly increased the uptake of triclopyr (applied as Grazon®), with ~50% uptake occurring at 7 DAT. The uptake of dicamba (applied as Kamba® at 5 kg a.i. and 10 kg a.i. ha−1) was significantly affected by dose and adjuvants. The uptake of dicamba applied at 5 kg a.i. ha−1 was low at 7 DAT with no adjuvant (31%); however, use of a methylated seed oil doubled the uptake. When triclopyr and dicamba were applied together, there was no evidence that either active ingredient negatively affected uptake of the other, with triclopyr enhancing uptake of dicamba. These results show potential to reduce the amount of herbicide used for conifer control without compromising efficacy.

Plant fluorescence is normally measured using the ratio Fv/Fm (quantum yield) An alternative measurement fluorescence decline ratio (Rfd) can be used instead of Fv/Fm The usefulness of the Rfd ratio in comparison to Fv/Fm was tested with three plant species of differing leaf character Diurnal trends were measured after treatment with two herbicides diuron a lipophilic photosynthesis inhibiting herbicide and dalapon a lesslipophilic nonphotosynthesis inhibiting herbicide In wheat both herbicides were tested with three nonionic surfactants of differing hydrophile lipophile balance (HLB) The Rfd ratio was a more sensitive numerical indicator of plant responses and provides an alternative approach to monitoring and measuring the effect of stress factors in plants