How to control Osmunda japonica pests and diseases?

Pest control of Lagerstroemia speciosa: Lagerstroemia speciosa occurs every year, which makes axillary buds, leaves and branches of Lagerstroemia speciosa covered with white spots. Make the whole branch black, causing leaves and flowers to fall off. The control method is to smear branches with omethoate stock solution once every 10 ~ 15 days during the incubation period of nymphs from late March to early April every year, for two consecutive times. When scale insects occur in the growth period, it should be sprayed with 1000 ~ 1500 times omethoate solution. Or spray with 20% triadimefon 5000 times solution.