The clear formulation of Lanfeng is a combination of pyraclostrobin and thiophanate-methyl, with a total content of 50%, in the form of a suspension concentrate (SC).
The rationale behind this combination is clear:One is responsible for rapid penetration, and the other for systemic translocation within the plant.
I. Division of roles between the two components
PyraclostrobinIt belongs to the methoxyacrylate class, and its target site is the cytochrome bc1 complex (Complex III) in the mitochondrial respiratory chain of pathogenic fungi, where it interrupts energy synthesis in the pathogen by blocking electron transport.
In the plant body, it manifests asStrong penetrability and certain systemic action.— It can penetrate the leaf surface and enter the leaf tissue, thereby inhibiting the expansion of mycelium on the underside of the leaf. However, note that:This degree of systemic uptake is not equivalent to the whole-plant translocation characteristic of triazoles.It should not be simply described as a "systemic therapeutic agent."
Thiophanate-methylIt belongs to the benzimidazole class; after spraying, it is converted into carbendazim within plant tissues, interfering with the formation of the spindle apparatus during fungal mitosis. It providesTrue systemic translocation and relatively long residual efficacy.请提供需要翻译的中文段落内容。
Value of the combination: pyraclostrobin is responsible for rapid interception at the early stage of infection (penetrating into leaf tissues and inhibiting hyphae that have already begun to expand), while thiophanate-methyl provides sustained suppression within the tissues. Two pathways, one fast and one slow.
II. Why It Is Particularly Suitable for Citrus Anthracnose
Citrus anthracnose has a characteristic that determines the suitability of this compound formulation:Latent infection请提供需要翻译的中文段落。
Pathogen spores invade during the young fruit or tender leaf stage and, after penetration, remain latent within the tissue for an extended period without producing visible symptoms. When the fruit approaches maturity, tree vigor declines, or the plant encounters adverse conditions (drought, insect damage, mechanical injury), the latent mycelium suddenly expands and lesions appear rapidly.
This means:By the time you see the lesions, the pathogen has long been established within the tissue.Pure protective agents are powerless at this stage — they can only intercept on the surface and have no effect on hyphae that have already entered the tissue.
The systemic property of thiophanate-methyl precisely addresses this issue: the agent enters the tissue, converts into carbendazim, and inhibits latent mycelium. The penetrant property of pyraclostrobin then compensates for rapid interception at the leaf surface layer.
This is why "latent infection diseases" require systemic fungicides.
III. Dosage and Water Volume
Registration: Citrus anthracnose, 1250-1800 fold dilution, spray.
The technical requirements provide the key information:
Depending on disease incidence, 2–3 applications may be made per season, with an interval of 7–10 days between applications.Water dilution rate: 60–111 kg/muNote that the spray should be uniform and thorough.
The water dilution rate of 60–111 kg/mu is the key point.Citrus trees have large canopies and abundant leaves. To ensure that the spray solution reaches the inner canopy and the undersides of leaves, an adequate water volume is essential. Many growers spray only the outer periphery of citrus trees, leaving the leaves and fruit in the inner canopy completely untreated, yet it is precisely in the high-humidity environment of the inner canopy that anthracnose is prone to occur.
Adjustment range of 1250–1800-fold dilution.: 1,800-fold dilution is used for preventive application (before disease onset or when tree vigor is good), and 1,250-fold dilution for the early stage of disease development (when disease severity is increasing). This range is not arbitrary; it provides users with flexibility to adjust according to disease severity.
IV. There is also apple ring rot in the registration form.
The product performance section only mentions citrus anthracnose, but the directions for use also include the application for apple tree ring rot:
Apply the product starting at the early stage of apple ring rot infection. Spray twice with an interval of 10 days. The spray volume is approximately 82.5 L per mu. Use a maximum of 2 times per season, with a pre-harvest interval of 28 days.
82.5 liters per muThis figure is quite specific. The water volume for apple tree spraying is directly related to tree age and canopy size. The 82.5 L figure represents the water volume under the conditions of the registration trial, and in practical application it should be adjusted according to the tree — the water volume for large trees will be significantly higher than this figure.
Pre-harvest interval: 28 daysUnlike apples, citrus must be calculated separately.
V. The resistance risk of both components is not low.
This is a point that must be emphasized:Pyraclostrobin and thiophanate-methyl belong to two classes of pesticides with a high risk of resistance development.
Strobilurin fungicides(Pyraclostrobin, azoxystrobin, kresoxim-methyl, trifloxystrobin) are recognized as one of the fungicide classes with the highest resistance risk, andStrong intra-group cross-resistanceChanging varieties is not the same as rotation.
Benzimidazoles(Methyl thiophanate, carbendazim, and benomyl) also carry a high risk of resistance, with cross-resistance among the three.
Mixing formulations does not mean they can be used repeatedly at high frequency.Its positioning should be as the core application during the critical period, rather than the sole program for the entire season.
Rotation directions: triazoles, organic sulfur protective agents (mancozeb), copper-based formulations, and microbial-source formulations.
6. Application Precautions
Do not apply the pesticide on windy days or when rain is expected within 4 hours.请提供需要翻译的中文段落。4 hours, which is stricter than the "1 hour" of other products. The reason may be that the suspension concentrate requires time to dry for adhesion to the leaf surface, and the penetration of pyraclostrobin also requires time.
Shake the suspension concentrate well before use.It will separate upon standing. Shake well before opening and stir after pouring.
Secondary dilution during pesticide preparation.First, dilute into a mother liquor in a small container, then add water to the required volume.
Do not mix with strongly alkaline pesticides or copper-containing formulations.