No abstract

AKD-2023, 3-dodecyl-1,4-dihydro-1,4-dioxo-2-naphthyl acetate (proposed common name acequinocyl) is a novel miticide now under commercial development. It has outstanding miticidal activity against economically important spider mites with the new mode of action of inhibition of mitochondrial electron transfer at complex III.

To investigate the factors governing retention of pesticidal spray solutions on plant surfaces, a new retention model for droplets on solid surfaces has been introduced as where ΔΘ = Θa – Θr. The minimum sliding volumes (MiSV) of surfactant aqueous solutions (2 g litre−‐1; surface tensions; 28·5 – 72·5 mN m−‐1) on smooth surfaces of paraffin wax and polymer sheets were measured and the validity of the above retention equation was verified on combinations of these solutions and surfaces. A concept of the specific adhesional force (Fa) of a droplet was defined as which was the maximum adhesional force on a unit length of the width of the contact circle of a droplet, and Fa values of the solutions on the surfaces were compared. The predominant factors for droplet retention are discussed on the basis of this model.

Conidia of Botrytis cinerea caused typical lesions on cucumber leaves in the presence of purine-related compound (ATP, ADP, cyclic AMP, AMP, IMP, adenosine, inosine, adenine and uric acid) or allantoic acid solution containing glucose. In order to investigate the process of infection by B. cinerea stimulated with the purine-related compound or allantoic acid solution containing glucose, we examined each infection process by the fungal conidia in the presence of the solution on cucumber leaf disks under light microscope.In glucose solution, the conidia germinated, formed primary appressoria and elongated superficial hyphae, but invasion into cucumber leaves was not observed.In purine-related compound solution containing glucose, the conidia formed secondary appressoria after elongation of superficial hyphae, and invasion by them was observed. The secondary appressoria seem to belong to the multicellular type of compound appressoria group, according to Emmett's classfication of appressoria. Among purine-related compound solutions, inosine solution showed the most remarkable effects on lesion formation and induction of the secondary appressoria. Next, we examined the role of glucose and inosine in infection process by B. cinerea on cucumber leaves.When glucose solution was removed within 16 hr after inocu lation and inosine solution was added instead, formation of the secondary appressoria and lesions was not observed.Formation of the secondary appressoria and lesions was observed with the removal of glucose solution beyond 18 hr after inoculation and alternative addition of inosine solution, especially when the glucose solution was removed after 18-24 hr of inoculation, the secondary appressoria and lesion formation was the most remarkable.The above results suggest that glucose plays important role in the conidial germination, formation of the primary appressoria and following elongation of the superficial hyphae, and that inosine plays important role in the secondary appressoria formation and their invasion into cucumber leaves.

A leaf immersion method to evaluate leaf surface wettability was investigated.Retention figures of immersion solutions containing a dye (Direct Fast Scarlet 4B5) 1.0% and surfactant(s) 0.2% on leaf surfaces were classified into six types (A-E and O) and the specific retentions (Up-2) on leaf surfaces were obtained at immersion lengths of more than 10cm for Gramineae and 5cm for soybean, cowpea and others with a solution making a continuous thin film (A-1 retention).Up-2 and whole-leaf retentions were measured for 23 crops from eight families. The former fell in a narrow range of ca. 0.6-1.1ul/cm2 for all the leaves but the latter was divided into two groups; almost the same retention (Cucurbitaceae, Brassicaceae and Malvaceae) and fairly varied retention (Gramineae, Legminosae and Solanaceae).It was possible to evaluate wettability on specific retention figures with the leaf immersion method we have developed.