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Surveys of sugar beet crops for beet cyst nematode {Heterodera schachtii Schmidt) in seven selected areas of England have provided data on distribution of the pest and on some factors affecting its occurrence, These data were mapped by CAMGRID computer program. Infestations occurred mostly on the East Anglian fenland (14% of fields infested) and in this area were more frequent nearer the sugar beet processing factory. In the remaining areas the few infested fields (5% or less) were generally scattered but a small concentration of infestation occurred in the West Midlands in an area of intensive horticulture with frequent brassica crops. The survey data did not support the view that beet cyst nematode infestations occur more frequently near access points to the crop. In the surveyed areas frequency of host crops appears to be more important than soil type in determining the likelihood of infestation. [ABSTRACT FROM AUTHOR]

Early records of beet cyst nematode (Heterodera schachtii Schmidt) in Britain and the history of regulatory measures to control it are summarized. Data collected between 1928 and 1976 were computer mapped on a 10 km grid scale to illustrate the cumulative distribution of beet cyst nematode in Britain. The distribution of the nematode was compared with that of its principal host, sugar beet. Data collected between 1962 and 1977 in East Anglia were computer mapped on a 1 km grid scale to show the detailed distribution of beet cyst nematode in that area. The advantages of computer-generated distribution maps over manually produced maps are discussed. [ABSTRACT FROM AUTHOR]

Either of two fumigant nematicides, dazomet or dichloropropanedichloropropene, applied prior to planting at 336 kg a.i./ha, gave good control of Longidorus elongatus (de Man) Thorne & Swanger and transmission of raspberry ringspot virus in a raspberry plantation. Either of two oxime-carbamate nematicides, aldicarb or oxamyl, at 7-84 kg a.i./ha gave only moderate control of nematode numbers and only limited control of virus transmission. Quintozene (89-6 kg a.i./ha) decreased L. elongatus numbers slowly and controlled virus transmission in the field. Pratylenchus crenatus Loof numbers were controlled only by dazomet, dichloropropane-dichloropropene or aldicarb. In a supplementary field experiment the acquisition and transmission of tomato black ring virus by L. elongatus in strawberries was inhibited by oxamyl for less than 19 wk. Little difference in the duration of the inhibitory effect was found between the three rates of oxamyl tested (5-56, 11-2 and 22-4 kg a.i./ha). [ABSTRACT FROM AUTHOR]

Field trials in Scotland in 1972 and 1973 tested the effects of three systemic nematicides (aldicarb, fenamiphos and oxamyl) and the fumigant dichloropropane-dichloropropene mixture (D-D) on the incidence of spraing in potato tubers (cv. Pentland Dell) and on total numbers of trichodorid nematodes, the vectors of tobacco rattle virus. Spraing incidence was least in plots treated with aldicarb or oxamyl. D-D and fenamiphos were effective in decreasing spraing incidence in one year but not in the other. Whereas D-D killed the trichodorid vectors, aldicarb and oxamyl did not kill them but apparently affected their behaviour. None of the chemicals was phytotoxic or decreased tuber yield. [ABSTRACT FROM AUTHOR]