Methods and Technical Key Points for Pest and Disease Control in Phalaenopsis (Moth Orchid)
Doing a good job of pest and disease control is an important part of successfully cultivating Phalaenopsis. Disease prevention is routine work: the growing environment must be well ventilated, the potting medium and air humidity suitable, and Bordeaux mixture, chlorothalonil, thiophanate-methyl and similar chemicals sprayed regularly to prevent disease. Once pests or diseases occur, apply chemicals promptly for control.
I. Main diseases and their control:
1. Petal gray mold: black mold spots form on the petals, and mycelium can be seen on the mold spots.
2. Anthracnose: large dark brown or light brown oval or irregular lesions grow on the leaves, and on the lesions there are small dark brown or pink concentric-ring dots.
3. Southern blight: the pathogen invades the roots and leaves, causing root rot or soft rot of the leaves. White mycelium grows on the affected parts and the potting medium, later turning into brown sclerotial granules.
4. Bacterial soft rot: water-soaked spots appear on the leaves, and the spots appear transparent when held toward a light source.
For fungal diseases such as gray mold, anthracnose and southern blight, apply chemicals such as thiophanate-methyl, carbendazim, zineb-maneb and anthracnose-specific fungicides. For bacterial soft rot, apply chemicals such as agricultural streptomycin.
II. Main insect pests and their control:
1. Thrips: they damage the flowers and young new leaves; flower buds shrivel, turn yellow and drop off; after mature buds are damaged, the tepals shrink and twist; after petals are damaged, white spots or streaks form and the petals fade in color.
2. Scale insects: the affected leaves become dull in color, and in severe cases the leaves turn yellow, wither and drop off.
3. Mites: the damaged leaves show dense silvery-gray small spots, which gradually change into dark brown patches, and finally turn yellow, wither and drop off.
4. Butterfly and moth larvae: they chew on young leaves, leaving transparent feeding marks or holes on the leaves, and when they damage flowers they chew on the petals.
For thrips, scale insects, mites and the like, spray chemicals such as omethoate. For butterfly and moth larvae, spray chemicals such as methomyl and dichlorvos.