(1) Anthrax: This disease mainly endangers leaves. Old leaves are easily affected with this disease, and most of scabs are observed in the margin of leaves. In the initial stage of disease onset, there appear hazel spots on the surface of leaves that are enlarged later and progressed to russet to brown disease spots and eventually large grey-white spots with small black granules. Plants are especially affected with this disease in high temperature, damp and rainy seasons. In case of improper ventilation or weak plant growth, this disease mostly is expanded.
(2) Grey speck disease: This disease mainly affects leaves and new treetops. In the initial period of disease onset, spots on the surface of leaves are approximately round in brown and then enlarged in grey white, and apophysis in the margin becomes black brown. Generally several disease spots are combined with each other to form large irregular spots. In the later period of disease onset, disease spots send forth small black dots. Initially, new treetops send forth long disease spots in light brown and water light form that are gradually sunken and shrunk, and then discontinuous small longitudinal divisions occur to form ulcer plaques. As the base falls after new treetops are affected, this is also called "disconnection disease". In order to prevent and treat anthrax and grey speck disease, 1% bordeaux mixture or 65% multiplied zineb liquid (600 times) shall be sprayed after new treetops grow out; Affected leaves shall be immediately removed after disease onset, and 50% multiplied topsin liquid (500~800 times) or 75% multiplied chlorothalonil liquid (600~1000 times) shall be sprayed.
Common pests of camellia: Euproctis pseudoconspersa, parametrites theae, scale insects, ectropis obliqua, tea ambiguous aphid, caloptilia theivora, clania minuscula butler, homona coffearia.
(1) Euproctis pseudoconspersa: It is a major defoliator of theaceae plants. The larvae eat leaves, which severely affects the growth and flowering of camellia. The length of adult pests is 8~13mm. The color of the body is fawn or dark brown. Fore wings are covered with dark brown scales, and there are two yellowish white rippled horizontal belts from the front margin to the posterior margin with 2 black dots in the apex angle. The length of old and mature larvae is 20mm, the head is tawny and the body is yellow in the cylinder form. Three sections of the chest are fine, and there are two brown strip lines in both sides of the back of the body. This pest produces two generations in Jiangsu and Zhejiang area every year, especially in 5~6 months and 7~9 months. Prevention and treatment methods: Remove the egg mass in winter; Damaged leaves are removed at the beginning of incubation when they endanger leaves. In the period of young larvae, fenitrothion and dichlorvos and other pesticides at 1000 times are applied.
(2) Parametrites theae: Affected treetops are hollow and dead. The length of adults is 5~7mm in dark grey with the metal luster. Fore wings are long and narrow and many small black dots are spread. There are two large black round spots in the middle part of wings near the posterior margin. The length of mature larvae is 7~9mm, and the head is small and dark brown, and all sections of the chest and abdomen are honey yellow, and the body is covered by sparse short hairs. This pest produces one generation every year in Anhui province, Jiangsu province, Zhejiang province, Jiangxi province and Sichuan province, etc., and larvae live through the winter within treetops. At the beginning of July to the last period of September in the next year, newly hatched larvae invade into leaves and eat leaf pulp, and then eat young treetops after 3 years old to apical buds. Affected buds are dead and then the pests eat other treetops, thus directly affecting the formation of leaf buds and flower buds. Prevention and treatment methods: Immediately remove pest treetops and destroy them; Spray 40% omethoate liquid (1000 times) before larvae endanger leaves and do not invade young treetops.
(3) Icerya purchasi: There are many kinds of pests that endanger camellia, mainly including icerya purchasi maskell, ceroplastes japonicus, coccus hesperidum, ceroplastes rubens, sugar pill pest, coconut scale, pseudaonidia, aonidiella aurantii, etc. Prevention and treatment methods: Spray 40％ multiplied omethoate liquid (1000~1500 times) to kill them.
