Some field observations on Lupin virus diseases and a study on its mosaic disease.
AbstractFollowing a review of the literature on lupin viruses in general, the author fully describes and tabulates the results of his studies on a destructive mosaic disease of sweet yellow lupins (Lupinus luteus) [cf. R.A.M., xxiii, p. 301] in Holland.
Seed collected from a diseased crop in North Brabant was sown at Wageningen in 1940 and gave rise to plants characterized by abnormally narrow, erect, mottled pinnate leaves and mostly abortive flowers; they retained their green colour until the late autumn, These observations apply to plants with secondary infection, those to which it was primarily conveyed by aphids, presumably Myzus persicae, suffering less severely. Another disease resembling 'browning' [cucumber mosaic virus: ibid., xv, p. 510] developed somewhat later than the yellow lupin virus. Original v. Sengbusch seed sown in 1941 produced a healthy crop.
Of the plants inoculated with the yellow lupin virus by Rawlins and Tompkins's carborundum abrasion method [ibid., xv, p. 737], Double Stringless and Ceka beans, Alaska Perfection, and small green Dutch peas, Oldambster field and garden broad beans, Limburg Maas red clover, crimson clover, and yellow and white (L. alba, German and Greta) lupins reacted positively, while the response of blue lupins (L. angustifolius) was doubtful. In every case the predominant symptom was a mosaic pattern, only white lupins, especially Creta, developing an intensive necrosis. Of 170 yellow lupin seedlings arising from the seed of nine infected plants, 8 (about 5 per cent.) became diseased, but all 37 Double Stringless beans from the seed of two inoculated plants remained healthy.
The yellow lupin virus withstood a temperature of 60° to 70° C., and was still active after four days in darkness at 20° and in dilutions of 1 in 600. It was transmitted by aphids from yellow lupins to small green Dutch peas. The yellow lupin mosaic virus is regarded as distinct from any other hitherto described, and is named Lupinus virus 1. Control should consist in aphid extermination, early sowing, eradication of diseased plants, and the breeding of resistant varieties.
A preliminary note is given on a virus disease of white lupins resembling the yellow lupin mosaic but shown by inoculation experiments to be different.