Root rot of vanilla

This disease often occurs on vanilla and does little or no harm to other species of orchids. In the early stage of the disease, the underground pole browned and died, and then the aerial root was also the same. Because it is very damaged, it often dies before or after contact with the soil, the stems and leaves are weak and turn light green and yellow, and the stems curl due to the depletion of water and nutrients. Finally, the plant wilted and became light brown until it completely dried up. In general, the disease has no symptoms before orchid seed-bearing, which indicates that seed-bearing may weaken the plant and aggravate the disease.

The disease was identified as Fusarium batatatis var.vanilliae, and the pathogen was not transmitted by water. There are several factors that may aggravate the disease: (1) excessive pollination and excessive seed setting per plant; (2) dry environment; (3) lack of some important nutrients (such as phosphorus); (4) low PH value of growth matrix; (5) excessive light. The best way to control the disease is to select disease-resistant varieties. In different vanilla, some of them have been found to be resistant or resistant. In order to reduce the incidence, it should be done: (1) to place the plant in an environment conducive to its healthy growth, such as moderate shading and enhanced root protection, especially at the beginning of and during the dry season; (2) moderate or mild pollination; and (3) irrigation of orchids where possible. (Liu Zhongjian)