Lanfeng Jinduo is a compound formulation of sulfur and carbendazim, formulated as a 50% wettable powder, with only one registered target: peanut leaf spot, applied at 160–240 g/mu by spraying.
One target, one bottle of combined formulation—it looks simple. But the occurrence pattern of peanut leaf spot disease has a characteristic that determines why this combination is worth developing separately.
In the field, "leaf spot disease" generally includes two types:
Brown spot diseaseThe lesions are circular and brown, with a distinct yellow halo at the margins. They mostly begin on the older lower leaves.
Black spot diseaseThe lesions are nearly circular and dark brown, with a black mold layer on the underside and an indistinct yellow halo.
The occurrence times of the two diseases differ slightly —Brown spot disease generally occurs earlier than black spot disease.However, in the field, they often occur in an overlapping manner.
This characteristic determines the control strategy:Starting from the lower older leaves, with two peak occurrence periods.请提供需要翻译的中文段落内容。
The pathogen of peanut leaf spot overwinters as mycelium or conidia in infected plant debris, and produces conidia the following year, which are spread by rain, wind, and airflow.
Infection begins on the lower older leaves.There are three reasons for this:
1. High humidity on lower leaves (close to the ground, poor ventilation).
2. Lower leaves age and have weak resistance.
3. Pathogens splash with rainwater and spread upward from the ground.
Two peak occurrence periodsTypically, during the flowering-to-pegging stage to the pod-setting stage, there are two distinct increases, which are related to rainfall events.
This determines the target site and timing of pesticide application.The spray nozzle must be directed at the middle and lower portions of the canopy, not merely sweeping the top; intervention should be implemented after the rainy season and before disease incidence rises.
Sulfur belongs to the class of inorganic sulfur protective agents, and its mode of action isMulti-site, non-specificInterfering with pathogen metabolism — it does not act on a specific enzyme system, thereforeIt hardly develops resistance.请提供需要翻译的中文段落内容。
Sulfur also has two additional characteristics:
Also has acaricidal activity.Spider mites are also a common problem on peanuts, and one component of sulfur can address both issues.
The efficacy of the pesticide is significantly affected by temperature.Within a certain temperature range, activity increases as temperature rises, but once the crop tolerance threshold is exceeded, the risk of phytotoxicity increases. This necessitates the selection of application timing — during hot seasons, avoid midday and choose early morning or late afternoon.
Carbendazim belongs to the benzimidazole class and is a systemic therapeutic fungicide. After penetrating leaf tissues, it interferes with the formation of the spindle apparatus during fungal mitosis.
Its value lies in dealing with mycelium that has already invaded.Leaf spot disease involves a process from spore germination to lesion appearance, during which carbendazim can suppress the pathogen.
However, its resistance risk is relatively high.— This is precisely why sulfur is needed.
Sulfur (multi-site, virtually no resistance) + carbendazim (single-site, high resistance risk) — the core value of this combination isResistance hedging请提供需要翻译的中文段落。
Sulfur forms a barrier on the surface, reducing the opportunity for pathogen invasion.
The multi-site action of sulfur dilutes the selection pressure of carbendazim.
Carbendazim treatment of mycelium that has already penetrated the tissue
At the same time, the acaricidal activity of sulfur provides additional value, while the systemic property of carbendazim compensates for the limitation that sulfur can only remain on the surface.
160-240 g/mu, spray.The dosage range is relatively wide and can be adjusted according to disease severity: use the lower limit at the early stage of disease onset, and the upper limit when disease severity increases.
The optimal timing for pesticide application is the early stage of leaf spot disease onset.— Note that this refers to the "early stage." Leaf spot disease starts from the lower older leaves. Intervention should be initiated when scattered lesions are first observed on the lower leaves, rather than waiting until the upper leaves are also affected.
"Once every 7-10 days"— shorter than the 10–15 days of carbendazim alone. The reason is that the residual efficacy of the sulfur film is greatly affected by rainfall and temperature, and in the mid-to-late growth stages of peanut (pod-setting stage), the leaves are dense and new leaves continue to expand, requiring supplemental protection.
Both the upper and lower surfaces of peanut leaves should be sprayed.The stomata on the leaf underside are numerous and humidity is high there, making it the main portal of entry. Peanut leaves have trichomes that hinder droplet adhesion, so a small amount of adjuvant can be added to improve it.
Temperature is the primary risk factor for sulfur.Applying pesticides when the temperature exceeds 30°C can easily cause phytotoxicity, especially during the mid-to-late growth stages of peanuts under high-temperature conditions. Application should be scheduled in the early morning or late afternoon.
Do not mix with mineral oils or certain organophosphorus pesticides.Mixing sulfur with these agents may cause phytotoxicity.
Do not mix with copper-based formulations or strongly alkaline pesticides.Carbendazim decomposes under alkaline conditions.
Some crops are sensitive to sulfur.(For example, the young and tender tissues of cucurbits and some fruit trees), peanuts are relatively tolerant, but it is still recommended to conduct a small-area trial spray before the first use.
SafetyThe product is of low toxicity, but sulfur dust is irritating to the eyes and respiratory tract. A mask should be worn during preparation of the spray solution.
