茭白纹枯病发生规律及产量损失测定

茭白纹枯病发生规律与产量损失的研究结果表明:高温高湿、种植过密、偏施氮肥、缺乏钾素是病害加重的主要原因;田间发病盛期在7月中旬至8月中旬;单茭重减低率与病级之间呈极显著线性相关;始病期越早,危害越重,产量损失也越大;病害危害程度与有效分蘖数(孕茭数)减少率、单茭重减低率、产量损失率之间呈高度正相关。在产量损失构成中,有效分蘖数的减少为主要因素。

The epidemic development of water bamboo sheath blight and its yield loss assessment

The epidemic development of water bamboo sheath blight (Rhizoctonia sonani Kuhn) and its yield loss were investigated in 1991. The results showed that high temperature and humidity, over-density of plants, over-nitrogen and lack of potassium were favorable to disease epidemic. The explosive phase of epidemic in the fields was from about the middle of July to the middle of August. The loss of available tillers, single stem weight and yield was significantly related to the disease index. The earlier and more severely the disease occurred, the greater yield loss was. The decrease of number of available tillers was the main factor in the components of yield loss.