Ginkgo diseases restrict income growth: control methods for two diseases

    In recent years, ginkgo production has been vigorously developed in various regions as one of the paths to increase farmers' income. However, in production practice, ginkgo often encounters constraints from two diseases: one is "ginkgo seedling stem rot", and the other is "ginkgo brown spot disease". Both diseases spread through rainwater and cause secondary infection. 

Ginkgo seedling stem rot

   "Ginkgo seedling stem rot" is a typical stem disease, with symptoms of "drooping", "upward spread", and "central sclerotia". "Drooping" has two types: one is in the early stage of disease, when the stem base of ginkgo seedlings near the ground turns dirty brown and droops slightly downward. The other is in the middle stage of disease, when leaves droop but do not fall off. "Upward spread" means that in the middle stage of disease, the lesions gradually encircle the stem base of ginkgo seedlings and quickly expand upward. "Central sclerotia" means that in the middle-to-late stage of disease, the cortex on the stem shrinks slightly, the pathogen continues to invade the xylem and pith, and the pith turns dark brown, gradually becoming hollow in the center, and produces small black sclerotia, spreading to the roots, ultimately causing all root cortex in the lower part to rot and the upper plant to wither and die. Usually, in years when the plum rain season arrives early and lasts for a short time, the disease occurs early and severely, causing seedling death, and in severe cases the seedling death rate reaches over 90%. 

Ginkgo brown spot disease

   "Ginkgo brown spot disease" is a typical leaf disease. The symptom is large coalesced lesions, that is, initially small round spots that are reddish-brown with dark edges, expanding along leaf veins, with most small lesions connecting into irregular large lesions, forming coalesced masses, and finally covering most ginkgo leaves, with small black dots (acervuli) scattered on both sides of the lesions. In summer and autumn, high temperature and high humidity favor the disease, causing early defoliation, reduced ginkgo growth, weakened growth vigor, and affecting the emergence of new shoots and fruit bearing, but it does not cause seedling or tree death. 

    To control the "two diseases" of ginkgo, the key lies in management. Specific measures: 

    Strengthen ginkgo orchard management. For ginkgo planting sites, winter orchard cleaning should be done well, promptly destroying residual branches and fallen leaves in the orchard to reduce overwintering inoculum sources; in conjunction with hilling in ginkgo orchards, weeds in the orchard should be removed promptly; in the rainy season, clear ditches and drain water to reducefield humidity and strengthen the disease resistance of ginkgo seedlings. 

    Strengthen fertilizer management. Both base fertilizer and topdressing should mainly use organic fertilizers to promote vigorous growth of seedlings and improve the disease resistance of ginkgo trees. 

    Strengthen temperature and light management. In high-temperature seasons, set up shade frames over seedbeds and add shade nets; in the disease season, seedbeds can be covered with rice straw to reduce light intensity and soil temperature, lower the disease incidence, and promote vigorous growth of ginkgo seedlings. 

    Strengthen chemical control. Chemical agents can be selected from 400 g/L flusilazole emulsifiable concentrate (also known as Guixing) 8000—10000 times dilution, or 62.25% mancozeb·myclobutanil wettable powder (also known as Xingjie) 600 times dilution, or 10% polyoxin B wettable powder (also known as Baokang) 800 times dilution, evenly sprayed on the leaves of ginkgo seedlings or mature ginkgo trees.