A wide range of cultivated brassica accessions including broccoli, Brussels sprouts, Chinese cabbage, cauliflower, collard, kale and swede material was tested against the cabbage aphid, Brevicoryne brassicae, at HRI, Wellesbourne in the field and laboratory in both 1992 and 1993 . In the field, B, brassicae attack was assessed as the proportion of infested plants and the numbers of aphid colonies present . In the laboratory, aphid performance was measured in terms of the pre-reproductive and reproductive period, population increase, and insect mortality . Interpretation of the data was facilitated by plotting sorted accession means against normal order statistics . This statistical approach indicated the spread of variation amongst the accessions and permitted identification of extremes . Partial levels of antixenosis resistance were discovered in red brassicas . Glossy accessions of cabbage and cauliflower possessed antixenosis and antibiosis resistance that lasted throughout the season of crop growth in the field . Other accessions were shown to withstand aphid attack and therefore possessed tolerance . The laboratory studies provided information on mechanisms of antibiosis resistance . The potential value of the different sources of resistance is discussed .

The presence of resistance to potato cyst-eelworm in wild Lycopersicon species was confirmed.The resistance of two plant accessions, L. pimpineIliJolium, B6173, and L. peruvianum, B6001, was compared in screening tests against three eelworm isolates, using the susceptible L. esculentum Ailsa Craig as a control. Both accessions were shown to possess high levels of resistance to the Wren isolate (pathotype A) of H. rostochiensis, and resistance to the Castle Donington (pathotypes A, B, and E) and Hare Lane (pathotype B) isolates. The level of resistance in L. pimpinellifolium was greater than that in L. peruvianum. Because of its greater resistance, and the ease with which it can be hybridised with tomato cultivars, L. pimpinellifolium was chosen as a donor parent for breeding programmes designed to incorporate potato cyst-eelworm resistance into a commercial tomato variety.The resistance ofL. pimpinellifolium, B6173, to the Wren isolate of H. rostochiensis was shown to be controlled by a single dominant gene for which the symbol Hero is proposed.

SUMMARYA laboratory method for testing cruciferous plants for their non‐preference resistance to cabbage root fly is described. Test plants were fully randomized on a turntable inside a large chamber containing cabbage root flies. The apparatus was housed in a controlled environment room. The root‐fly eggs, laid in the sand surrounding test plants, were extracted using a flask flotation method which was quicker and more efficient than the stirring technique which it superseded. Two batches of plants were tested alternately, one being exposed to the flies, while the other was sampled for eggs. Each batch of test plants received three 1‐day exposures to egg‐laying, their positions within the test chamber being changed for each exposure to ensure complete randomization.This test method gave highly consistent results and indicated that there were differences in the flies' preference both between cultivars of radish and cauliflower and for individual plants within cultivars. Plants representing the extremes of preferences discovered in the two crops were saved for further study.It was not possible to correlate seed weight, time of seedling emergence, foliage surface area, or hypocotyl attitude in relation to soil level, with the egg‐laying preference of the cabbage root flies.

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