Key Points of Pest and Disease Control Techniques for the Chinese Medicinal Herb Platycodon grandiflorus

I. The main diseases of Platycodon grandiflorus are ring rot and spot blight, both of which are related to excessive planting density and high temperature with high humidity. During the summer season of high temperature and high humidity when the disease easily occurs, field drainage should be strengthened to reduce field humidity and thereby alleviate the disease. In the early stage of the disease, spray with 1:1:100 Bordeaux mixture, 65% zineb 600-fold dilution, 50% carbendazim, 1000-fold dilution of tuijunte, or 50% thiophanate-methyl 1000-fold dilution, once every 10——15 days, for 2——3 consecutive applications.

II. The main insect pests of Platycodon grandiflorus are aphids and black cutworms.

1. For aphids, spray 50% dichlorvos 1000——1500-fold dilution, or 40% dimethoate 1500——2000-fold dilution, or 5% fenitrothion 1000——2000-fold dilution for control, once every 7——10 days, for 2——3 consecutive sprays.

2. When black cutworms cause damage, use 50% phoxim 250——300 milliliters per mu, mixed with 15 kilograms of moist fine soil to make poisoned soil; or use 90% trichlorfon crystals 250 grams plus an appropriate amount of water mixed with 5 kilograms of roasted cottonseed cake to make poisoned bait, and scatter it along the rows near the root zone in the evening for control.