Research on Septoria Leaf Blotch: Recent Advances1

A review of the recent advances in research on Septoria leaf blotch is given with particular emphasis on epidemiology and control strategies. The effect of straw infected with pycnidia of Septoria tritici or perithecia of its perfect stage Mycosphaerella graminicola , infected seeds and alternative hosts on the initiation of epidemics is discussed. Reference is made to the effect of plant stature on the vertical progress of the disease. The role of fungicide protection in the control of the disease is discussed. Resistance and tolerance to Septoria leaf blotch is dealt with in more detail, with reference to the author's own research, and with implications on breeding strategies.     

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.     

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 Trends in the Chemical Control of Wheat Diseases1

Following a list of the economically most important fungal wheat diseases, recent trends in chemical seed treatment are discussed. Different fungicide mixtures are now available for the replacement of mercurial dressings, but are generally more expensive. The control of fungal diseases by spraying has become more and more common over the past ten years in certain countries. Advantage has been taken of the curative action of the modern systemic chemicals. The major diseases are powdery mildew, rusts, eyespot, glume-and leaf-blotch. The general application of a fungicide programme is restricted by regional wheat prices, and should also be limited to reduce environmental contamination. Knowledge about economic thresholds and correct timing of control are indispensable, and in special cases the development of warning systems is advisable. The role of Cycocel (chlormequat) is also discussed. A danger of fungicide resistance in populations of plant pathogenic fungi has arisen with the introduction of the systemic fungicides (one-site-inhibitors). As yet, however, no economically important case of fungicide resistance within cereal pathogens is known. Factors favouring the stepwise selection of resistant strains under field conditions are discussed in detail, and experimental data are presented on this subject. Other positive or negative side-effects of the modern fungicides are described.     

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.     

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.     

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.     

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     

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).     

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.     

Integrated Control Strategy in the United States and its Practical Implementation1)

A major research effort in the United States to develop practical integrated control programs for six major agro-ecosystems utilizing, among a broad array of tactics, systems analysis is described. Problems associated with the implementation of pest management systems are outlined with examples given from tobacco programs in North Carolina and cotton programs in California and Texas.     

Comparison of Programmed and Supervised Control Systems for Field Crops1

The effects of increasing inputs of pesticides, nitrogen and growth regulators were studied in field trials in winter wheat and spring barley in southern Sweden. The trials also included a comparison of different strategies: no control, routine control and supervised control. In 1982 EPIPRE, a computerized pest and disease management system developed in the Netherlands, was included. High inputs of nitrogen only slightly influenced the yields. In winter wheat, routine control, comprising one insecticide and three fungicide sprays, heavily increased the yield and was more profitable than supervised control. On an average only 1.2 pesticide sprays were carried out in supervised plots. However, in spring barley supervised control was slightly more profitable than routine control comprising one fungicide and one insecticide application. The average number of sprays in supervised was 0.6 only. In both winter wheat and barley the yield increase for routine control significantly increased with increasing nitrogen level. In barley a significant relationship between number of aphids per tiller and yield increase could be proved.     

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.     

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.     

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.     

Wheat Leaf Rust Uredospore Production on Adult Plants: Influence of Leaf Nitrogen Content and Septoria tritici Blotch

ABSTRACT Leaf rust uredospore production and lesion size were measured on flag leaves of adult wheat plants in a glasshouse for different lesion densities. We estimated the spore weight produced per square centimeter of infected leaf, per lesion, and per unit of sporulating area. Three levels of fertilization were applied to the plants to obtain different nitrogen content for the inoculated leaves. In a fourth treatment, we evaluated the effect of Septoria tritici blotch on leaf rust uredospore production. The nitrogen and carbon content of the spores was unaffected or marginally affected by lesion density, host leaf nitrogen content, or the presence of Mycosphaerella graminicola on the same leaf. In leaves with a low-nitrogen content, spore production per lesion was reduced, but lesion size was unaffected. A threshold effect of leaf nitrogen content in spore production was however, evident, since production was similar in the medium- and high-fertilizer treatments. In leaves inoculated with M. graminicola and Puccinia triticina, the rust lesions were smaller and produced fewer spores. The relationships among rust lesion density, lesion size, and uredospore production were fitted to a model. We determined that the density effect on spore production resulted mainly from a reduction in lesion size, the spore production per unit of sporulating surface being largely independent of lesion density. These results are consistent with those obtained previously on wheat seedlings. The main difference was that the sporulation period lasted longer in adult leaves.     

Plant Quarantine Facilities in The Netherlands1

In The Netherlands germplasm and plants collected in the wild for breeding and scientific purposes may only be imported with a special licence. For this material specific post-entry import requirements are prescribed. A glasshouse with special quarantine facilities has been built on the premises of the Plant Protection Service at Wageningen. In this paper the special facilities needed to carry out post-entry quarantine are described.     

Maize Pests and their Importance in Turkey1

Maize and related crops suffer from a large number of insect pests in Turkey but all are not of the same importance in different parts of the country. This paper lists about 80 species, of which only a few ( Sesamia nonagrioides, Helicoverpa armigera, Ostrinia nubilalis , cutworms ( Agrotis spp.), Tanymecus dilaticollis, Gryllotalpa gryllotalpa ) are of primary importance. The pest status and distribution of each species is described.