天狗巣病

The object of this work was to find some explanations on the cause of early death of diseased paulownia tree making direct analysis to compare carbohydrate and nitrogen content of healthy shoots with those of diseased shoots affected by witche's-broom. Both diseased and healthy shoots were divided into three parts as shown with the Fig. 1 : upper parts (A-B, A'-B'), middle parts (B-C, B'-C') and lower parts (C-D, C'-D'), and were used as the samples of analysis. Bertrand's method was used for carbohydrate content, and Kjeldahl's method for nitrogen. The results were as follows. 1. Total carbohydrate, total nitrogen, soluble and proteinic nitrogen contents of three parts of healthy shoots increased in the order of upper, middle and lower part, while in the diseased shoots it was vice versa, except soluble nitrogen. 2. Each of total carbohydrate, total nitrogen, and proteinic nitrogen of diseased shoot was decreased in upper part to 50%, in middle part to 60%-70% and in lower part to 70%-85% against each of the same parts of healthy shoot. C/N ratio of the diseased shoot was not appreciably different from that of the healthy. These results apparently showed the starved condition of the diseased shoot. It was concluded that the starvation was caused by the decrease of photosynthesis, the increase of respiration and the inhibition of carbohydrate translocation of the diseased leaves, and that the cause of early death of diseased paulownia tree was due in part to the starvation.