It's necessary to assess the disease status for tea to identify common types of harmful diseases to production thereby having estimates, forecasts and preventive measures. Through the 2013 survey results on 6 tea varieties which producing in Phu Tho, some main diseases have been identified such as gray blight and brown blight diseases
some riskily harmful diseases such as tea root rot disease, Twig dieback, bud blight and horse hair blight Grey blight mainly appears in July and October, PH1 and PH8 are mainly harmed varieties with from 41.08 to 55.96 percent of the leaf. The brown blight mainly appears in June and August on PH1, PVT varieties with 44.28 to 54.92 percent of the tea leaves.