Effective fungicides for strawberry gray mold include iprodione, dimetachlone, fludioxonil, and polyoxin

AbstractEffective fungicides for strawberry gray mold include iprodione, dimetachlone, fludioxonil, and polyoxin, among others. Gray mold in strawberries is typically triggered when the temperature is between 0-35°C, the humidity is between 80-90%, or there is standing water on the plant surface.

Effective fungicides for gray mold

Iprodione: Iprodione is a broad-spectrum contact fungicide that acts simultaneously on mycelium, sclerotia, and spores. It effectively controls spore germination and mycelial growth of the pathogen, but cannot penetrate within the plant body, making it a protective fungicide. It has good fungicidal efficacy against Botrytis cinerea, Sclerotinia, Sclerotium, Streptomyces, and Cladosporium species, among others.

Dimetachlone: Dimetachlone is a potent fungicide exclusively developed by experts to target bacteria, fungi, and viruses that crops are prone to infection by. It features broad-spectrum activity, sterilization, treatment, systemic absorption, penetration, and a long duration of efficacy. It also has the dual effects of systemic absorption and penetration. When sprayed on leaves, it can rapidly penetrate into the diseased area, thoroughly killing various pathogens from the surface inward.

Fludioxonil: Fludioxonil works by inhibiting a transfer process related to glucose phosphorylation, which controls the growth of fungal mycelium, thereby causing the pathogen to die. Its mechanism of action is unique and has no cross-resistance with existing fungicides.

Polyoxin: Polyoxin is a metabolite produced by Streptomyces aureochromogenes and belongs to the broad-spectrum antibiotic class of fungicides. It has good systemic properties, works by interfering with the biological composition of the fungal cell wall, and can also control pathogen sporulation and the spread of lesions.

Characteristics of gray mold

The strawberry gray mold pathogen consists of mycelium and conidia. It overwinters in the soil as sclerotia and diseased plant debris, and can spread through watering, airflow, and agricultural activities. Disease is typically triggered when the temperature is between 0-25°C and the humidity is above 90%, or when there is standing water on the plant surface. Disease can also be triggered when the temperature is between 0-35°C and the humidity is above 80%.

High air humidity, watering followed by overcast and rainy days, and low-lying areas with standing water all favor the occurrence of strawberry gray mold. Typically, disease is more severe when planting on flat beds and with prostrate cultivation covered by plastic film, while it is milder when planting on high ridges with plastic mulch.

Symptoms of gray mold

Strawberry gray mold generally begins during the flowering stage. The pathogen initially infects the weaker parts of the strawberry plant, causing flowers to turn light brown, die, and rot, with gray mold developing later. It gradually invades around the old yellow leaves at the base, forming V-shaped yellowish-brown spots, or it begins infecting along the areas where petals have fallen, later becoming circular necrotic spots with indistinct concentric rings, on which a small amount of gray mold grows.

Infection of strawberry fruit begins from residual petals and parts touching the ground, and can also invade from areas in contact with early-stage and diseased plant tissue. In the early stage, it appears as water-soaked grayish-brown mold that causes the plant to die. The color gradually darkens, and in the later stage it causes the fruit to rot, with a dense gray mold layer appearing on the fruit surface. When the petiole is affected, light brown lesions appear, causing the petiole to die and shrivel, with a small amount of sparse gray mold appearing on it.

Prevention and control of gray mold

After harvest, thoroughly remove diseased leaves and debris from the strawberry plants. Before transplanting and before preparing the seedbed, spray the surfaces of the soil, greenhouse film, and walls to eliminate the pathogen. This can be combined with spraying New High-Fat Film to increase efficacy.

Drip irrigation for water conservation and high-ridge planting with plastic mulch can be adopted. Use ultraviolet-blocking film to inhibit sclerotia germination. Spray fungicides for prevention and control during early flowering, flowering and fruit-setting stages, and before watering. This can accelerate fruit development, preserve flowers and fruits, balance nutrition, and also prevent deformed strawberries, improving strawberry quality and yield. After watering, appropriately increase ventilation, and use Meizhi liquid at 70-100 times dilution for spray control.

Note: When disease occurs, promptly remove diseased flowers, leaves, and fruits, then place them in plastic bags and take them outside for disposal. When disease occurs, appropriately raise the indoor temperature.