The Evaluation of Aerial Application Systems1

There is no single measurement technique suitable for the evaluation of all aerial application systems, since the type of measurement required, and the technique used to obtain it, are dependent on the application method. In this paper, techniques used by the authors to assess atomiser performance, droplet dispersion, deposition, and aircraft swath width are described. The applicability of each technique to various application methods is described.     

Modern Technology for Aerial Application of Agrochemicals1

Most pesticides and fertilizers are applied by aerial techniques in the agricultural farms of Hungary. The importance of the work done by plane or helicopter is characterized by the following data: in regions having many planes more than 50% of the plant protection activity is carried out by aerial application. Another characteristic feature of Hungarian agricultural aviation is the fact that almost 35% of the total spraying involves the application of herbicides, defoliants and desiccants. Large-scale use of formulations dangerous for the environment has made it necessary to take some important measures, such as directed spraying, regulation of drop sizes etc. With the development of these methods and the transformation of spraying equipment it became possible to carry out spraying under optimal biological conditions. Nowadays aircraft are used in at least one production process for crops such as cereals, rice, maize, sunflower, sugar beet, potato and vegetables and vines (chemical weed control, spraying for the control of fungi or insects, desiccation). Finally it should be mentioned that all equipment is mounted with the membrane-lock nozzles developed by the Aviation Service of the Ministry of Agriculture and Food to meet the requirements of modern technology. A very promising part of this activity is the development of rotating nozzles for helicopters (electrically driven) and for planes (wind driven).     

Economic Evaluation of the Aerial Application of Cereal Herbicides1

A physical evaluation of the spray pattern achieved by a Piper Pawnee when set up to spray a cereal herbicide has been extended to include an estimation of both the biological and economic results for United Kingdom conditions. The result shows the economic importance of choosing the correct flight lane separation and the need to use a correctly set-up aircraft.     

Design and Development of a Disc-Windmill Atomiser for Aerial Applications1

For greater efficiency in aerial applications of pesticides it is essential to get a greater fraction of the emitted formulation to the true biological target To achieve this and at the same time ensure that environmental pollution is a minimum requires the use of a narrow droplet spectrum of the correct mean size. The best atomisers currently made for aircraft use produce at best only about 40 % of the emitted volume in sizes within 25 % of the desired size and in many cases the percentage is far smaller. A simple spinning disc atomiser has been designed at Cranfield which operates in the filament mode of droplet formation at flow rates many times greater than the usual maxima for these devices. This improvement is achieved by using a high velocity radial airflow in the region of atomisation. This same air, arising from the forward speed of the aircraft, is used to rotate the disc by shaping it to be a high solidity windmill. Test results show that a 5 cm diameter disc will atomise up to 11/min into droplet sizes from 80 μm to 300 μm VMD, depending upon the chosen blade setting, and that, for any given blade setting, up to 80 % of the emission will be within ± 25 % of the mean size. It is anticipated that mass production of the atomiser will commence in 1983.     

Electrostatic Application with Rotary Atomisers1

The APE80 charged rotary atomiser, and its larger, JUMBO, counterpart, both developed at Rothamsted, are briefly described. Recent design modifications allow control of the trajectory and subsequent distribution of the spray. Some field results illustrate the increase in deposition obtained with charged sprays and the effect on spray penetration.     

Evaluation of Novel Pesticide Application Techniques1

Most new pesticides are assessed in the laboratory and field assuming commercial application in sprays diluted to around 2001/na or more. Relatively few products are registered for ULV/CDA (ultra-low volume/controlled droplet application) sprays. Methodology for comparative assessment of novel application techniques is considered.     

A Rapid Method of Calculating the Downwind Distributions from Aerial Atomisers1

There are many diverse views about the effects of wind on aircraft sprays. Some operators wish to spray only when the air is still, others will not spray unless the wind speed is at least 3 m/s. The basis of this difference is the fear of, as against the use of, the downwind movement of droplets. This note uses a simple model of droplet behaviour in a wind to try to predict the deposit distributions downwind of a spraying aircraft. The results demonstrate that the level of turbulence caused by the wind blowing over the earth's vegetation reduces the downwind distance most small drops travel before being captured. Trees create more turbulence than cereal crops, which create more turbulence than bare earth or short grass. The deposit density at a given distance downwind reduces with decrease in aircraft flying height, wind speed and smoothness of the canopy. It remains roughly constant with increasing droplet size until a critical diameter is reached when it falls rapidly with increase in droplet size. This critical size depends upon windspeed and turbulence intensity. A downwind buffer zone between the spray area and a sensitive crop is desirable and its minimum size can be determined using the techniques discussed in the paper.     

Mycological Diagnostic Problems1

In diagnostics we are constantly confronted with the gaps that exist in our knowledge of the pathogenic fungal flora. This situation is illustrated by recent information concerning various economically important fungal diseases. Where such problems arise it is only through international cooperation in diagnostic mycology that they can be efficiently tackled and solved. It appears that with increasing frequency the exact identification and differentiation of fungi is only made possible through familiarity with their growth characteristics in culture. Fungus culture collections can here play an important role, since exact comparison and identification is made possible. Such pathogenic fungi should be made available for diagnostic purposes under the auspices of the Plant Protection Services, so that the risk of unwanted spreading of these pathogens can be avoided. The Plant Protection Services would in fact become more effective in their attempts to prevent and limit the distribution of harmful organisms.     

Prospects for Improving Pesticide Application in Hungary1

In Hungarian agriculture, large-scale farming is characteristic. The average size of State Farms exceeds 7000 ha, while that of the agricultural cooperatives approaches 4000 ha. In general, farms are well mechanized and agrochemical usage is also high. Per hectare of arable land in Hungary, the amount of pesticides applied annually is about 5 kg active ingredient. The application is carried out by 7000 large-scale ground equipments, 4000 machines for orchard and vineyard treatments, and 115 brigades for aerial application. The selection of both appropriate equipment and mode of application has an important role in achieving adequate biological efficacy at reasonable cost while ensuring energy saving and protection of the environment Now and in the future, great importance must be given to the following:a) widespread use of up-to-date equipment for pesticide application; b) nozzle selection in accordance with the purpose to be achieved; c) avoiding or impeding the total depreciation of machinery; d) regular control of the correct adjustment and the general state of equipment and establishment of an adequate servicing system; e) selection of equipment adapted to the pesticide formulation concerned; f) increased use of specific pesticide formulations; g) increased use of additives in order to control surface tension, droplet formation, drift etc.; h) establishment of a balance between use of ground and aerial equipment under given farm conditions; i) improvement of economical aerial application in plant protection; j) development of test methods and equipments to control the standards of application; k) examination of combinations of pesticides and other chemical (e.g. fertilizers).     

High Performance Self-Propelled Sprayers1

Self-propelled sprayers, which are the result of recent technological advances in farm machinery for crop protection, combine the advantages of ground equipment and airborne spraying appliances: a work rate of 100 ha per day can be achieved under comfortable working conditions, their ease of handling makes it possible to work at short notice and at almost any time of the year. Labour costs are reduced, and effective treatment can be guaranteed. This is the main economic justification of the use of these machines which, in view of their relatively high purchase cost, are suitable for farms of at least 300-400 ha.     

Wheat Diseases in Turkey1

Cereal crop production is one of the most important projects in the agricultural improvement programme for Turkey. Overall, wheat represents 61 % of the cereal crop. While wheat production was almost 4 million tons in 1950, this reached a limit of 10 million tons in 1970. A number of diseases continue to afflict the crop from time to time, causing heavy losses. The most important of these are: bunt ( Tilletia foetida and T. caries ), loose smut ( Ustilago nuda ), rusts ( Puccinia strilformis, P. graminis f. sp. tritici, P. recondita f. sp. tritici ), leaf blotch ( Septoria tritici ), root and foot rots ( Fusarium spp., Drechslera sorokiniana, Pseudocercosporella herpotrichoides, Alternarla alternate, Sclerotium spp. and Rhizoctonia spp.). The diseases appear all over the country. Average losses due to rusts in epidemics are estimated at about 30–35 % in the whole country. Annual losses from covered smut are about 15–20 %, and from loose smut from 0.1 % to almost 20 % depending on the weather conditions of the year, on variety and on locality. Root rots have gained importance in some places, especially in Thrace in the last few years. In addition to the above diseases, several others occur occasionally but are of minor importance: powdery mildew ( Erysiphe graminis f. sp. tritici ), dwarf smut ( Tilletia contraversa ), flag smut ( Urocystis tritici ), take-all ( Gaeumannomyces graminis ) and a wheat mosaic virus (recently observed in a province of Central Anatolia).     

Droplet Formation and Deposition1

At the EPPO Conference in Belgrade on 1970 the author reported on work showing that small, uniform, and non-volatile droplets appeared to offer the prospect for greatly reduced dosages of pesticides by both providing a more effective deposit and by controlling drift. Three recent studies provide further evidence for this hypothesis, which questions the very principles on which our present spraying practices are based. However, the deposition of droplets by the external forces of wind and gravity imposes lower limits on the droplet sizes capable of being used. These are 30 μm for insecticides and fungicides (except in the case of flying insects) and 150 μm for herbicides, since the droplets require sufficient energy to impact themselves on the target. Electrostatic charging of droplets promises to free us from these size constraints by providing the droplet with a depositional force of its own, allowing it to impact on any surface. Electrostatics, however, is solely a force of deposition and thus must be balanced with the forces required for spray dispersion so that the droplets can penetrate the crop canopy and/or be transported to the target     

Fireblight monitoring in Lithuania1

Lithuania has requested that its whole territory should be recognized by the EU as a protected zone for Erwinia amylovora . Fireblight monitoring was performed in 1998/2002 with the aim of detecting and identifying the bacterium, and of determining its distribution in the country. The study consisted of periodic surveys (at least twice a year) of nurseries, orchards, collective farms and host plants, growing individually or in small groups, as well as the surrounding zone within a radius of 250 m. Tests, under conditions of quality control, were applied to host plants with and without symptoms, using detection methods such as ELISA and immunofluorescence (with polyclonal antibodies), semi-selective plating and pathogenicity.     

Analyzing Cost Effectiveness of EPIPRE1

EPIPRE is an integrated pest and disease management system for wheat, fully computerized, based on on-line calculations of costs and benefits of pesticide treatments; it is field-specific and utilizes disease and pest monitoring in the field. The development of the project took five years (1977/1981). Cost effectiveness has been estimated in retrospect and in prospect using 1980 as a base year, covering the period 1977 through 1985. Future costs were disccrunted at a 10 % rate. The Net Present Worth of the project was estimated at nearly eight million Dutch guilders. The nonmeasurable effects of the project seem to be even more important than the measurable effect.     

Criteria for Choosing Application Techniques for Desert Locust Control1

Insecticides may be applied in several ways to control desert locusts. The traditional method, of feeding poisoned bait to hopper bands, uses insecticide very efficiently and is inexpensive when put into practice on a limited scale. However, it is both expensive and ineffective when a plague arises. Treating individual bands with contact insecticides is similar and suitable for operations on a modest scale in countries where much of the land is developed for agriculture. Two large-scale methods, matching the size of a locust plague occurring in uncultivated deserts, are the treatment of swarms of adults and spraying dieldrin onto the natural vegetation of the breeding sites. Despite the small dose rate of dieldrin needed - tens of grams per hectare - the last method is very expensive when breeding occurs over the large areas which are susceptible - hundreds of thousands of square kilometres. Although all methods are suitable and used for particular circumstances, the last alone is the only one of general value and practical feasibility that can match the dimensions of a locust plague. Despite its high cost and the use of small dose rates of a persistent organochloride insecticide, the analysis of benefits and costs indicates that it will be the method mostly used in deserts, if a plague occurs again. The arguments leading to this conclusion are presented to illustrate an example of the type of study required to decide how to apply pesticides in practice for more familiar pest management tasks.     

New Techniques in Seed Treatments1

The paper deals with the treatment of seeds other than cereals and describes the technique of seed coating with the incorporation of the required pesticides. The formulation of the pesticides has to be modified for this technique. The advantages of seed coating are given and include the increased loading of chemicals onto seeds, thereby increasing the diseases and pests that can be controlled by the coating technique.     

International Cooperation in Plant Protection1

Preventing the introduction of dangerous organisms into new countries and regions requires an international approach. The article reviews the most dangerous organisms for different continents, and describes in particular the procedures developed in Europe for assessing quarantine risks, through international cooperation within the European and Mediterranean Plant Protection Organization. The activities of EPPO are reviewed, and also those of the ISHS Plant Protection Commission, especially in relation to fruit-tree viruses. The implementation of international cooperation within the European Community, and specifically in Denmark, is described.     

Economic Aspects of Pest Control1)

The activities of economists associated with the IBP project entitled « The Principles, Strategies, and Tactics of Pest Population Regulation and Control in Major Crop Ecosystems » and their interaction with entomologists in the design and implementation of integrated control strategies are described. Profit maximization criteria and a method of considering farmers behaviour with respect to risk are developed. The term «economic threshold » is further clarified; and a simpler concept, « the damage threshold », is introduced. Regional institutions such as pest management co-operatives and districts and the factors which affect their introduction and successful operation are considered.     

The Performance of Rotating Metal-Foam Atomisers1

Prototype rotating metal-foam atomisers, designed for aerial application, have been extensively tested both in the laboratory and under field conditions. Laboratory tests were carried out in a wind tunnel and field tests in a large-scale aerial operation. The metal-foam atomisers showed advantages in droplet-spectrum control and vibration levels over currently available equipment, and, when used to spray 150,000 ha of cotton, four units required no maintenance. Rotating metal foam atomisers can operate safely at the high rotational speeds used for medium volume spraying of droplets with a diameter less than 50 μm (as in tse-tse control).     

Possibilities of Microwaves in Soil Disinfestation1

In the search for alternative methods for soil disinfestation, various soil types (sand-loam, loam, clay-loam) with mycelium of Rhizoctonia solani, Fusartum oxysporum f. sp. lycopersici and Trichoderma longibrachiatum and seeds of Lepidium sativum , all present at various depths, were treated with microwaves (2540 MHz, 600 W). High lethality was found to be dependent on the duration of irradiation. The granulometric composition of the soil had a relatively strong effect on killing rate. The reaction to soil moisture content was remarkable, but quite reproducible: two maxima in killing rate could be established, one with extremely dry soil and the other with a relative soil moisture content of 60%. The effect of irradiation on CO₂ production and N-mineralization in the soil was also investigated.