EXPERIMENTS AND OBSERVATIONS ON A VIRUS DISEASE OF WINTER SPINACH (SPIN ACIA OLERACEA)

Abstract

SummaryA disease of winter spinach common in the Thames Valley has been shown to be of a virus nature. It is characterized by a mottling and malformation of the leaves, stunting of growth and death of the plants. The causal agent has been shown to be identical with cucumber mosaic I of Ainsworth.The disease is most prevalent in the earlier sown crops, and this appears to be correlated with their liability to be infested with aphides. Field observations on a number of farms indicated a correlation between intensity of aphis infestation and intensity of disease.Seed‐borne infection, though possible, has not been proved.Under field conditions in the Thames Valley it is suggested that a main source of contamination of winter spinach is the outdoor vegetable marrow crop.Postponement of date of sowing until the latter half of September is suggested as a method of reducing the amount of disease.