Control Methods and Key Technical Points for Black Fruit Disease of Goji (Lycium barbarum)
Goji root rot is widespread and causes serious damage. Plants killed by the disease account for 3%-5% each year, causing great losses to goji production. According to research by Lu Zhankui and others at the Ningxia Academy of Agriculture and Forestry Sciences, root rot symptoms fall into the following two types: (1) Root decay type. Roots or the root crown show varying degrees of decay and peeling, and the stem...
Black fruit disease is one of the main diseases of goji. The pathogen damages green fruits, flowers and buds of goji, and also damages young shoots and leaves.After green goji fruits are infected, small black spots or black patches or black net-like patterns begin to appear. On cloudy and rainy days, the lesions expand rapidly, turning the fruit black and producing orange-red conidial masses, making it unfit for medicinal use. On sunny days the lesions develop slowly, the lesions turn black, and the unaffected parts can still turn red. After flowers are infected, black spots first appear on the petals; in mild cases the corolla falls off but the plant can still bear fruit, while in severe cases the flowers become black, the ovary shrivels, and no fruit is set. After buds are infected, small black spots or black patches appear in the early stage, and in severe cases they become black buds that cannot open. After branches and leaves are infected, small black spots or black patches appear.
The pathogen overwinters in diseased fruits, and conidia can also overwinter on the surface of black fruits. It is mainly transmitted by wind and rain to nearby healthy flowers, fruits, buds and other parts, infecting the host and causing damage; temperature promotes the onset of the disease. Goji can be infected by this disease from the early fruiting stage in early May to the late fruiting stage in mid-October. In the early stage (May-June), when the daily average temperature is above 17°C, the relative humidity is around 60%, and there are 2-3 rainy days per ten-day period, the disease can occur in the field. In the peak stage (July-September), when the daily average temperature is about 17.8-28.5°C, there are more than 4 rainy days per ten-day period, and the average humidity for two consecutive ten-day periods is above 80%, the disease incidence increases sharply. In the late stage (October to the first frost), when the ten-day average temperature is 9.2-14.6°C, as long as there is more than one rainy day in the field, the disease can still occur severely.
The control methods are: in winter, clean up the goji orchard and remove and burn diseased fruits, leaves, branches and so on; spray a 600-fold dilution of 50% Tuzet wettable powder; spray a 100-fold dilution of equal-amount Bordeaux mixture.