Problems in the Cultivation of Winter Lettuce

In a four‐year study of winter lettuce cultivation, attention has been given to the effects of variety, dates of sowing and transplanting, method of preparing seed‐beds, nature of field soil, and fungicidal treatments upon percentage survival and date of maturity of the crop The inferiority of the variety Trocadero Improved to such a winter variety as Imperial is due mainly to its susceptibility to Pythium root rot. This disease often causes severe thinning of the stand of Trocadero seedlings and dwarfing of many of the survivors Late autumn plantings of Imperial and other winter varieties survived better overwinter on a medium‐heavy loam than on a light sandy soil. The disparity varied in different seasons and was not associated with severity of winter The dates of maturity of the crop in relation to dates of sowing and transplanting have been determined over the four‐year period. On the basis of these, and on the records of survival and of market prices, an estimate can be obtained of the financial aspects of different cultural methods Fungicidal treatment in the seed‐bed of plants set out in the field in November gave little improvement in survival; but pronounced benefit was obtained by February or March dusting of seedlings which had overwintered in the seed‐bed The onset of disease in overwintering seed‐beds was found to be influenced by the nature of the soil and by the manner of preparation of the seed‐bed The interrelations of overwintering and soil type are briefly discussed, with special reference to the effects of soil type (i) on the root system, and (ii) on microbiological interference with invasion of die stem by Botrytis