Further Experiments on the Control of the Apple Blossom Weevil,Anthonomus Pomorum L.

The age at anthesis of tomato plants grown from weekly sowings varied throughout the year. This was related to the mean day-length from germination to anthesis, the asymptotes being an age of 40 to 50 days and a mean day-length of approximately 10 hours. Age at anthesis was also related to the total radiation received and the seasonal variation in flowering age could be explained by postulating (a) a minimal total radiation requirement for anthesis to occur and (b) a minimal age of 40 to 50 days before which anthesis could not occur. Sowings that began to flower between the autumnal and vernal equinoxes exhibited a considerable delay in attaining anthesis and the age at first flowering increased to values exceeding 110 days from sowing. The factor causing this delay was removed at approximately the vernal equinox, and a spring-like flush of flowering occurred during the month of March, with more than 20% of all the sowings beginning to flower during this one month. The data suggest that the factor responsible for this phenomenon might be light duration or it might be total radiation. It was found that the seasonal pattern of flowering exhibited a rapid increase in the weekly rate of flowering from early March to early May, followed by a progressive decline until July. From July until the following early March a low weekly rate of flowering was maintained.