How to prevent and control powdery mildew on goji berry? Latest methods shared
Goji berry powdery mildew, also called goji berry leaf spot, mainly damages leaves and fruits. When leaves are infected, round to nearly round spots appear initially, 2-4 mm in size, with brown edges and grayish-white centers. Black-gray mold-like substances often grow on the underside of the leaves. Infected fruits also develop similar symptoms. Let's take a look at the prevention and control methods for goji berry powdery mildew!
Symptoms
Goji berry powdery mildew mainly harms leaves. The leaf surface becomes covered with white mold spots (initial stage) and powdery spots (later stage). The white mold spots and powdery spots are both the symptoms of this disease and the signs of this disease (fungal conidiophores and conidia). In severe cases, the goji berry plant appears white overall, which is quite striking. Photosynthesis of the diseased plant is blocked, eventually causing the leaves to gradually turn yellow and fall off easily.
Pathogen
The pathogen of goji berry powdery mildew is Oidium sp. of the Deuteromycota. In cold regions, the fungus overwinters in the soil as the sexual fruiting body, cleistothecium, along with diseased residues. In warm regions, the fungus mainly carries out primary infection and reinfection through asexual conidia, completing the annual disease cycle, with no obvious overwintering period. Warm and humid weather or planting site conditions are favorable for disease development, but the fungal spores have drought-tolerant characteristics and can still germinate normally and infect and cause disease under high-temperature and dry weather conditions.
Conditions for Disease Development
The pathogen of goji berry powdery mildew overwinters as mycelium or conidia on dead branches and fallen leaves of goji berry or in the soil along with diseased fruits. The following year, conidia spread through wind and rain to carry out primary infection and reinfection, expanding the damage. Disease is likely to occur in years with high temperature and abundant rain, high soil moisture, humid air, soil nutrient deficiency, and weakened plants.
Prevention and Control Methods
1. Select good goji berry varieties, such as Ningqi No. 1. After leaf fall in autumn, clean the goji berry orchard in time, remove diseased leaves and diseased fruits, and bury them deeply or burn them in a centralized manner to reduce the source of inoculum.
2. Strengthen cultivation management. It is recommended to apply compost fermented with Japanese enzyme bacteria, and increase the application of phosphorus and potassium fertilizers to enhance disease resistance.
3. Starting in June, spray 70% mancozeb wettable powder at 500 times dilution, or 75% chlorothalonil wettable powder at 600 times dilution, 64% sandofan wettable powder at 500 times dilution, or 30% Ludebao suspension concentrate at 400 times dilution, once every about 10 days, for 2-3 consecutive applications. Stop using the chemicals 7 days before harvest.