What to Do About White Fruit Disease in Mulberries? A Detailed Guide to Prevention and Control Methods
Mulberry white fruit disease is the common name for sclerotinia disease and is the main disease of mulberry fruit. When the disease is severe, it can cause a complete loss of the mulberry fruit harvest. The pathogen is Sclerotinia sclerotiorum. The primary sources of infection for sclerotinia disease are mainly soil mixed with sclerotia, diseased residual branches and fallen leaves, and compost. Under suitable temperature and humidity conditions, the sclerotia germinate and grow apothecia, and the apothecia release ascospores, which spread with airflow and infect female flowers, green fruit, and the new shoots and tender buds of early-bearing mulberries. When spores invade the female flowers, they produce a large amount of mycelium, the fruit flesh swells and turns milky white, and after being crushed, a rotten stench can be smelled.
What to Do About Mulberry White Fruit Disease
(1) Choose disease-resistant varieties for fresh eating; the Da 10 variety may be planted on a small scale. For processing into juice, choose the relatively disease-resistant 46C019 variety and the resistant variety Su Shen No. 72. Note that the 46C019 variety must not be planted mixed with the Da 10 variety.
(2) Choose a suitable site for establishing the orchard. To establish a specialized mulberry orchard for processing, choose a plot with convenient drainage and irrigation, fertile soil, higher terrain, and easy mechanical cultivation. It is required that within a 10-kilometer radius around the orchard, no tall mulberry trees that bear mulberries or mulberry trees used for sericulture may be planted.
(3) Reasonable close planting and scientific fertilization. For the Da 10 variety, it is advisable to plant no more than 300 plants per mu and train them into a medium-trunk tree form. For the 46C019 variety, plant 111 plants per mu, with a row spacing of 3 m and a plant spacing of 2 m, and train them into a medium shrub form. For the Su Shen No. 72 variety, plant 300 plants per mu, with a row spacing of 3 m and a plant spacing of 0.74 m, and train them into a tree form 2.5 m tall with multiple main trunks, which is favorable for ventilation, light penetration, and mechanical cultivation. Fertilization principles: after fruit harvest is finished, apply heavy organic fertilizer, with decomposed chicken manure and soybean cake being optimal. From after the beginning of winter to before budding, mainly use special compound fertilizer, with 0.5 kg urea per plant as the standard, and appropriately increase nitrogen fertilizer.
(4) Cultivation. In the early stage of establishing the mulberry orchard, besides rapeseed and legumes, a small amount of low-growing crops may be intercropped, but in the later stage no crops may be intercropped. After fruit harvest is finished, combine fertilization with mechanical or manual deep plowing of the soil, and deep plow once more during winter or spring fertilization, leaving no blind spots. When white fruit disease is found early, using the removal method has a certain effect. When there are many diseased fruits, deep plowing is more thorough, especially spring deep plowing, which is very important because it can destroy the surface sclerotia and apothecia, prevent spores from dispersing, and achieve disease prevention without sterilization.
(5) Chemical control. Before and after flowering of fruit mulberries and during the green fruit stage, use 40% dimethachlon wettable powder at 800-1200 times dilution, or 70% thiophanate-methyl powder at 1000 times dilution, or 50% carbendazim wettable powder at 500 times dilution to comprehensively spray the branches, trunks, leaves, fruits, and ground surface of fruit mulberries for prevention, once every 6 days for a total of 2-3 sprays. When disease is present, spray once every 4 days until a small amount of mulberry fruit turns from green to red, then stop spraying.