Orchid spot disease

1. Harm: distributed in Japan and Germany. It can harm many kinds of orchids under natural conditions and can be artificially inoculated on many kinds of plants such as Orchidaceae and Solanaceae. There are spots on the leaves of orchids, affecting its ornamental value.

2. Symptoms: first, the formation of rectangular yellowish green spots between the veins, and then necrotic mottled symptoms.

3. The pathogen: orchid mottle virus (Orchid fleck virus,OrFV) is baculovirus. The particle size in the extract of orchid diseased leaves is 150nmX4Onm, and after purification, the particle size is 100~140nmX32~35nm. The dilution end point of the crude extract of orchid diseased leaves is 1O-2. The in vitro antiviral period after purification is more than 1 day under the condition of 6 ℃.

4. The characteristics of the disease: the virus transmission medium is still unknown and the aphid inoculation is not successful. It can be inoculated artificially on orchids and some dicotyledons, but it is difficult. Inoculation is easy to succeed under the condition of high temperature (more than 30 ℃).

5. Prevention and control methods:

(1) for some valuable virus-free orchids, they must be isolated from the orchid production base.

(2) in gardening operations such as ramets and turning pots, fingers and tools have to be re-sterilized every time they are planted.

(3) washing roots cannot be washed in the same container, and running water should be used to wash roots.

(4) the media such as peat, moss and gravel used for orchid culture should be disinfected.

Liu Zhongjian