Recent Trends in Weed Control in Freshwater1)

While in many situations, such as irrigation and drainage ditches, the unobstructed movement of water is paramount and complete control of the weeds is needed, most freshwater nowadays has many functions some of which involve biological systems in which weeds play an important part. Trends in the development of new weed control techniques aimed at replacing traditional hand cutting methods while maintaining the required condition of the water are briefly reviewed. These include mechanical, chemical and biological methods all of which contain potentially valuable tools for the management of freshwater ecosystems.     

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).     

Chemical Control of Botrytis cinerea on Grapes in New York (USA)1

Control of gray mold in New York vineyards is difficult to achieve at the present time. Benomyl-resistant strains of Botrytis cinerea have been isolated from vineyards in all grape-growing regions of New York State. Because of this resistance and lack of governmental registration of new fungicides, growers must choose among only moderately effective fungicides such as captan, folpet, dicloran and copper. Current research indicates that either vinclozolin or iprodione at 850 g/ha to 1100 g/ha applied twice, beginning at about 5 % sugar content and two weeks later, will provide excellent control of gray mold on ripening berries, whereas sprays applied at 5 % or 90 % bloom and at berry touch are not effective. An application of gibberellic acid (GA3) (10 or 25 (µg/ml) on Aurore (S.5279) at 10–15 cm shoot growth reduced the severity of gray mold on clusters of ripe fruit, but not the incidence of it. A single application of triadimefon at 30 mg/1 sprayed on Vignoles (Ravat 51), when fruit clusters averaged 17 % surface area infected with Uncinula necator and 2.6 % sugar content, retarded the development of powdery mildew and subsequent berry splitting, and ultimately reduced the severity of gray mold by 50 % at harvest, 6 weeks later.     

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.     

Integrated Control in the Netherlands 1)

In the Netherlands the need for an ecological approach in pest control has led to the establishment in 1958 of the Research Group on harmonious control of arthropod pests later renamed into Research Group on integrated control of arthropod pests which has several sections. This Group is part of the National Council for Agricultural Research of the Organization for Applied Scientific Research (TNO). There is a close co-operation between many Research Institutes towards developing integrated control of which the TNO Research Group is the co-ordinating body. The research priorities have been clearly defined and the ways leading to a practical implementation of integrated control studied.     

Cost/Benefit Analysis as Used in the United Kingdom for Eradication Campaigns against Alien Pests and Diseases1

The reasons for using, and the methods used for cost benefit analysis of eradication campaigns against alien pests and diseases in the UK are discussed. Details of the costanalysis for a current campaign against white rust of chrysanthemums ( Puccinia horiana ) are given.     

Grey Mould Damage and Control in Hungary1

Grey mould is one of the most important fungal diseases of grapevine, and for this reason the successful control of Botrytis cinerea determines the result of grape growing. As far as damage is concerned, the most important infection occurs at the end of flowering and just before ripening. The conidia of the fungus infect the berries through wounds, which may be caused by hail or storms, or by chewing insects, or also, most importantly, by physiological berry splitting. This occurs when a long dry period in summer is followed by a rainy autumn at ripening time. The prevention of wounds is one of the most important aspects of control. For the first half of the year, we propose using the traditional contact fungicides against grey mould. The use of benzimidazole-type systemic fungicides is proposed only for the last two treatments, because they have a low persistence and because in this way we avoid the development of resistance to these systemic fungicides.     

New Atomizer Developments in the Hungarian Aviation Service1

In the practice of aerial application of chemicals in Hungary, the need arose in the mid-70's to solve the spray atomization problem for the ULV range. First experiments were carried out with imported equipment, in view of the lack of Hungarian-manufactured equipment. Unfavourable practical experiences impelled the Air Service in Hungary to develop and manufacture new spraying equipment, specially adapted to local requirements. The Unirot-4 electrically driven rotary drum became the first successful atomizer, which was put into large-scale operation in recent years. This multi-purpose spraying equipment is now essential on helicopters used for ULV and LV applications. The X-2 fan-driven rotary drum is being developed for fixed-wing aircraft.     

Trends and Costs in the Development and Testing of Plant Protection Machinery1

New developments in plant protection technique give rise to new requirements in the development of spray equipment, which must then be tested for its efficiency, uniformity and optimum performance in relation to output and droplet characteristics. The problems in doing this are illustrated by the results of a trial on orchard spraying in Hungary. The need to relate performance to biological requirements is particularly stressed.     

Seed-borne Pathogens on Wheat (Particularly Smuts) in Turkey1

The important seed-borne diseases of wheat in Turkey are common bunt ( Tilletia caries and T. foetida ), loose smut ( Ustilago nuda tritici ), dwarf bunt ( T. contraversa ) and flag smut ( Urocystis tritici ). Seed treatment against common bunt is widely used in Turkey. The damage is about 10–15 %, sometimes 90 % in some fields where seeds are sown without treatment. About 10 % of wheat fields were infected with bunt during 1972–1974. Seed treatment with carboxin (Vitavax) is recommended against loose smut of wheat in Turkey, but has not yet been used. Some wheat varieties, especially Siirak (1593/51) wheat, are highly susceptible to loose smut. The proportion of smut-infected heads reached 30–40 % in this variety and about 32 % of wheat fields were infected with loose smut during 1972–1974. The damage was about 6 % in infected fields. Yield losses were at least 35,000 tons. Dwarf bunt is distributed at high altitude (1300–2000 m) in eastern Turkey; 2500 ha of wheat fields are infected with dwarf bunt. The disease causes 1–80 % losses in some fields. The wheat variety Yayla 305 is recommended for infected areas. Flag smut is present in some areas of Turkey, but yield losses are not important. Seed treatment is effective against seed-borne spores.     

New Experience with Formulations for ULV Application1

For economical and environmental reasons, new application methods and formulations of pesticides are continually being tested. Amongst the application methods, aerial ULV spraying is becoming more and more important. There are two main fields for aerial ULV application: crop and non-crop spraying. Non-crop spraying is widely used for locust, mosquito and tsetse control. ULV formulations used for these purposes must be specially designed due to the extraordinary conditions in which they are applied. The choice of solvent, which should have a certain dissolving power, will determine the viscosity, volatility and phytotoxicity of the formulation. Because the positive and negative physical properties of the available solvents are sometimes inversely related, a suitable formulation is always a compromise. As an example, the physical properties of two endosulfan ULV formulations for crop spraying and non-crop spraying (tsetse control) are discussed.     

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.     

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.     

Electrodynamic Spraying and the Control of Pests of Agricultural Crops1

A new method of agrochemical application, electrodynamic spraying, has recently been developed by ICI. It combines the convenience of ULV application with a very high order of accuracy. Using an electric field effect, the spray droplets are charged so that they deposit onto both exposed and hidden surfaces of the target plant Since the introduction of the first commercial machine, the « Electrodyn >> sprayer, which was primarily designed for use in cotton, further developments have taken place and systems are now being evaluated for the control of insects, diseases and weeds in a variety of crops.     

Prevalence and Control of Septoria Leaf Blotch in the Aegean Region1

While a number of common wheat diseases are well controlled in Turkey, Septoria leaf blotch (due to Septoria tritici ) has been gaining in importance in Turkey since 1967, when the Mexican wheat varieties were first imported. Surveys in six locations in the Aegean Region in April-May 1975–1977 showed that S. tritici was common throughout the region. In 1978, trials with four fungicides (mancozeb, benomyl, carbendazim in two formulations) in eight combinations showed that threefold treatment with benomyl was most effective. However, a better economic return was obtained with two applications of Derosan. The first application can usefully be combined with normal weed control.     

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.     

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.     

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     

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.     

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.