50 Years of Plant Pathology
N. V. Hardwick, Central Science Laboratory, Sand Hutton, York YO41 1LZ, UK
Editorial responsibilities during MAFF’s ownership were shared between entomology and plant pathology colleagues at the Plant Pathology Laboratory, Harpenden. The first 30 years of Plant Pathology is a history of discovery and practical advice, charting and informing on both the specific and the wider issues that affected UK agriculture and horticulture. It was fitting that the first paper in Plant Pathology was on a highly practical subject and of immediate concern to growers and written by Large (1952a). It was on seeking replacements for sulphuric acid as a potato haulm killer, initiated because of a then world shortage of sulphur and a desire to find materials that could be used through ordinary farm equipment. It is interesting to note that half a century later sulphuric acid is still the preferred material and is used on 70% of potato crops (Bradshaw et al., 1999).
There were some key papers published during the 30 years, including those of Large on disease/yield loss relationships and the control of potato late blight (Phytophthora infestans) (Large, 1952b, 1953, 1956). Understanding of the development of plants in relation to the environment and disease progress is important and Large (1954) published an illustrated key of the Feekes scale of development stages in cereals which became the standard reference for pesticide application. It was only replaced as the national standard by the decimal key of Zadoks et al. (1974) 20 years later.
The study of cereal diseases also became important when it was perceived that yields were beginning to suffer as a consequence of disease. National surveys, first of spring barley and then of winter wheat, were established to identify the major diseases (King, 1972; 1977). Large and Doling (1962) measured the effects of cereal mildew (Erysiphe graminis) on yield and Jenkins et al. (1972) examined the use of fungicides for the control of diseases of spring barley in the South-west of Britain. Intermittent surveys of diseases in horticultural crops were also undertaken (Fletcher & Harris, 1976).
Of the many surveys published on pest damage, the most comprehensive were those on yield losses in Brussels sprouts caused by the cabbage aphid (Brevicoryne brassicae) in England and Wales in 1946-55 (Strickland, 1957) and on wireworm (Agriotes lineatus) damage to potato crops in England and Wales in 1954-1960 (Strickland et al., 1962). Crop losses caused by cereal pests were also featured and the impact of the grain aphid (Rhopalosiphum padi) on wheat ears was investigated. Results of this work have had a major impact in identifying both crop development stages and infestation levels as a guide to the justified use of aphicides for the control of this pest (George & Gair, 1979). A 25-year study of the carrot fly (Psila rosae) in eastern England (Coppock, 1974) provided information on the incidence of damage to carrot crops, as well as basic data on the life history and seasonal activity of the pest, with a view to considering non-chemical means of control.
The emerging crisis to wild life in the early 1960’s, as a result of the widespread use of persistent organochlorine compounds, such as aldrin, dieldrin and heptachlor, led to the publication of two supplements, collated by A H Strickland, on possible chemical alternatives (Anonymous, 1965, 1967).
Developing rapid diagnostic tests was an important area of interest, particularly for the plant health services, e.g. Graham (1963) described a serological test for black leg (Erwinia carotovora subsp. atroseptica). Also of interest to plant health were the introduction of alien pests and diseases and their eradication or containment. During the late 1970s the American serpentine leaf miner (Liriomyza trifolii) was accidentally introduced into commercial nurseries in England and Wales but was successfully eradicated after a rigorous campaign (Bartlett & Powell, 1981). Baker (1967) reported on the first outbreaks of chrysanthemum white rust (Puccinia horiana) in 1963 and the attempts made to eradicate the disease. The ability to illustrate symptoms of this disease highlighted the value of the journal’s provision for black and white photographs.
Assistance with pest identification was provided by keys on British aphids of economic importance (Stroyan, 1952), root-lesion nematodes occurring in Britain (Corbett, 1970) and lepidopterous larvae attacking aerial parts of brassica crops in the UK (Emmett, 1980).
Guile (1966) published a paper on cyst chromogenesis in pathotypes of the potato cyst nematode (Heterodera rostochiensis) which stimulated further studies at Rothamsted and elsewhere on morphological differences between the pathotypes and the recognition that there were two species, namely H. rostochiensis and H. pallida. Cooke (1973) showed that ectoparasitic nematodes of the genera Longidorus, Trichodorus and Paratrichodorus were pests of economic importance to the growing of sugar beet.
The development of sex-attractant traps to monitor pea moth populations (Macaulay, 1977) was a major advance in the control of this pest. These traps enabled growers to predict when sprays should be applied and when they were unnecessary.
During this period there were great advances in the biological control of cucumber pests. Early experiments demonstrating successful control of the red spider mite (Tetranychus urticae) by its predator Phytoseiulus riegeli (Legowski, 1966) eventually lead to large-scale commercial trials of an integrated control programme that combined chemical and biological agents (Gould, 1971). Work on the mass-rearing of the two key biological agents was published by Scopes (1968, 1969).
Other key papers included Hirst et al. (1955) on the use of volumetric spore traps for identifying ascospores of Venturia inaequalis as the main source of apple scab and indicating their value in disease forecasting. Smith (1956) published his blight forecasting scheme which was to replace the Beaumont Period and remains the standard scheme for the UK.
An important role for the journal was the publication of a section on ‘New or unusual plant diseases and pests in England and Wales’. The series began with the second issue of Volume 2 in 1953 (e.g. Storey & Wilcox, 1953). This provided a vehicle for the publication of short reports on interesting occurrences of established pests and diseases and on pest and diseases that were new to a region or host. ‘England and Wales’ was dropped and ‘unusual’ changed to ‘uncommon’ in Volume 5, issue Number 2. A further change to ‘New or unusual records of plant diseases and pests’ occurred in the first issue of Volume 27.
Weather has a crucial influence on the incidence of pests and diseases and, for the first 30 years, each volume of Plant Pathology was an important source of meteorological data for the previous year. Twice-yearly the Agricultural Section of the Meteorological Office provided a summary, with histograms, of the weather for the previous six months in six regions of England and Wales.
As well as the science, the pages also contain, to the discerning, a history of the advisory services and their scientists. Any student or research worker setting out on a new project could benefit from scanning the contents of these volumes as they contain many gems of information that may prevent the proverbial re-inventing of the wheel.