Phytoparasitica

Matthews, G. A.

doi: 10.1007/bf02980327pmid: N/A

Pesticides are applied principally as water-based sprays through hydraulic nozzles, often with large volumes of water. Such treatment is usually effective, but inefficient. Improvements are needed to reduce contamination of users and the environment; achieve better integration with biological factors; and minimize selection of resistant pest populations. Nozzle selection is aimed at improving application with less environmental contamination. Other new developments, including closed transfer systems, air assistance and use of rotary atomization and electrostatics, are discussed.

Grinstein, Avi; Katan, Jaacov

doi: 10.1007/bf02980325pmid: N/A

Grinstein, A.; Matthews, G. A.

doi: 10.1007/bf02980326pmid: N/A

Grinstein, A.; Riven, Y.; Elad, Y.

doi: 10.1007/bf02980335pmid: N/A

Botrytis cinerea causes latent infections of rose flowers, which can develop into aggressive rot (botrytis blight) at pre- and postharvest stages. Botrytis blight is the cause of major rose flower losses. The effect of deposit and cover density of fungicides (pyrimethanil or prochloraz-Zn—folpet) on the development of botrytis blight was tested. For pyrimethanil drop size and cover density (ranging between 80 and 1000μm drops/cm2) had no effect on disease rate, if the pesticide deposit was sufficient for disease control. For prochloraz-Zn— folpet, however, control efficacy (for equal deposit) increased with cover density. Secondary distribution of pyrimethanil was by the vapor phase. Effective control was obtained when rose petals were exposed only to pyrimethanil vapors, while any direct contact with the fungicide was prevented; no control was recorded for prochloraz-Zn—folpet under these conditions. Botrytis blight was delayed in cut flowers when bunches of 20 flowers were wrapped in packing paper strips or cellophane bags which had been sprayed previously with pyrimethanil and packed (20 bunches) in cardboard boxes. No pesticide stains could be seen on the flowers.

Gamliel, A.; Stapleton, J. J.

doi: 10.1007/bf02980329pmid: N/A

Combining organic amendments with soil solarization is a nonchemical approach to improvement of the control of soilborne plant diseases. Pathogen control in solarized— amended soil is attributed to a combination of thermal killing and enhanced generation of biotoxic volatile compounds. Apparently, pathogen sensitivity to biotoxic volatile compounds is enhanced with an increase of soil temperature and acts in combination with antagonistic microbial activity. Enhanced biocontrol also may be involved with some amendments. Toxic volatile compounds including alcohols, aldehydes, sulfides, isothiocyanates, and others were detected in soil amended with cruciferous residues during heating. Field solarization of soil amended with composted chicken manure gave better control of pathogens and higher yield of lettuce and tomato than either treatment alone.

Stanghellini, M.

doi: 10.1007/bf02980334pmid: N/A

Zoosporic plant pathogens are associated with destructive root and foliar diseases of numerous crops. This paper describes events which led to the discovery, specificity, and potential significance of surfactants (which are commonly considered the ‘inert’ components of many fungicides) in the control of zoosporic pathogens. The latter include certain downy mildews and numerous species in the generaPythiwn andPhytophthora. Zoospores are the weak link in the life cycle of these pathogens because they have no cell wall. The absence of a cell wall imparts a high degree of vulnerability to this spore stage and surfactants were demonstrated to rupture selectively the plasma membrane which encases the zoospore, thereby resulting in the rapid death of the zoospore.

Smith, Penelope Ann

doi: 10.1007/bf02980336pmid: N/A

Integrated pest control of the whitefly,Bemisia argentifolii (Bellows & Perring), depends heavily on biological control. The insect pathogenic fungusPaecilomyces fumosoroseus (Wise) Brown & Smith is being developed for control of this pest. Oil and emulsion formulations of fungal conidia are known to enable infection at low field humidities. These formulations also increase the infectivity to a wider range of whitefly instars as compared to aqueous formulations.

Austerweil, Miriam; Grinstein, A.

doi: 10.1007/bf02980333pmid: N/A

Three automatic pesticide application systems are presented: an automatic thermal vaporimeter; a cold fogger (low volume mist applicator or mechanical aerosol generator); and an automatic air-assisted sprayer for controlled droplet application (CDA). The automatic thermal vaporimeter is thermally regulated to prevent spontaneous ignition of the evaporated pesticide, and is equipped with an automatic quantity-control system. One vaporimeter is capable of treating an area of 0.4 ha when an air circulation system is operated. The efficacy of some commercially available cold foggers for pest control was evaluated in various crops (rose, gerbera, gypsophila, tomato) and under different application conditions in plastic houses in Israel. Uniform spray distribution and good penetration into the foliage, with a high ratio of the deposits on upper: lower leaf surfaces and lower: upper parts of the plants, were obtained when assisted by indoor air movement (e.g. by horizontal air blowers). There was a high correlation between the deposition patterns produced by cold foggers and their biological efficacy against pests and disease agents. The third system—the automatic CDA air-assisted sprayer—was designed with the purpose to benefit from the advantages of the knapsack mist blower, at the same time avoiding operator mistakes. It consists of an air-assisted sprayer, self-propelled along a monorail, which revolves on its axis during its forward movement, applying drops in the 100 μm volume median diameter size range and leaving an even deposit within a 14–18-m-wide swath. The advantages of automatic pesticide application systems are: no exposure of the operator to toxic materials; increased efficiency and effectiveness; optimal timing; and reduced error by the operator. Reduced pesticide dosages make them of increasing importance in modern agriculture.

Hall, Franklin R.

doi: 10.1007/bf02980330pmid: N/A

Pesticides are under an increasing array of criticism by the public and policy makers as being excessively hazardous to the environment. This has resulted in a wide variety of pesticide use reduction programs for agriculture worldwide. These include less active ingredient per unit area, safer products, and new delivery systems. As a result of these policies, and regulatory thrusts, there are numerous opportunities for improved efficiency of utilization with a better understanding of droplet placement criteria, including spray droplet quality,e.g. size/density parameters, formulation interactions, and a better educated user. This minireview revisits some recent trends in our efforts to improve the dose-transfer efficiency of the modern crop protection agents.

Hirsch, I.

doi: 10.1007/bf02980331pmid: N/A

Trials were conducted to study spray deposition in the cotton canopy and downwind drift using a conventional boom and nozzle arrangement, in comparison with an experimental boom onto which 15 airfoil-shaped ‘winglets’ were attached. The aircraft used was an Ayres Turbo Thrush. Spray deposition was assessed by analysis of the fluorescent tracer distributed over cotton string placed in a cotton field, inside the canopy and on both sides of cotton leaves collected from the top and inside the canopy. Drift was compared by flying two aircraft simultaneously, each with its respective boom, flying 1 km apart at 90° to the wind direction, spraying water over horizontal and vertical water-sensitive card samplers. Droplet count was recorded from card sampler lines, located downwind at a distance of 50 m up to 200 m. Results have shown that the winglet boom, when operated 1 m above the canopy, produces a better deposit than the conventional boom and nozzle at various levels in the canopy, on the upper sides of the leaves; the deposit on the underside of leaves in the upper part of the cotton plant is also increased. More drift was detected with the conventional boom and nozzle arrangement on both vertical and horizontal targets.