Guangzhou Fuerle Health Technology Co., Ltd , https://www.fuerlegroup.com
**Prevention and Control of Peanut Diseases and Pests**
*Source: Seed World*
Authors: Hou Delian, Hou Junhui, Liu Meizhen (Baoqing Agricultural Technology Extension Center, Heilongjiang Province)
**1. Peanut Diseases**
**1.1 Bacterial Wilt**
Also known as "green disease," "dead seedlings," or "peanut pods," bacterial wilt is a soil-borne bacterial disease that affects the vascular system of peanuts. It can rapidly kill a large number of plants within a short time. The disease can occur from the seedling stage to the entire reproductive period, with the flowering stage being the peak time for infection.
The pathogen mainly infects the roots, causing discoloration and softening of the root tissues, while the vascular bundles turn dark brown and spread upward. When the infected area is cut open and pressed, milky white bacterial exudate can be observed. Affected plants show symptoms of dehydration and wilting, starting from the top down, with leaves turning dark green but remaining intact. From the onset of the disease, it typically takes 7 to 15 days for the plant to die.
**1.1.1 Agricultural Prevention and Control**
Planting resistant varieties is one of the most effective methods to prevent bacterial wilt. Crop rotation is also crucial—alternating with crops such as corn, millet, or rice and dry crops helps reduce disease occurrence. A rotation period of 3 to 5 years is recommended.
**1.1.2 Chemical Control**
Apply 25% thiophanate-methyl mixed with soil at the planting stage, or irrigate the roots with a 1000-fold dilution. Alternatively, soak seeds in a solution of streptomycin at concentrations of 200–400 ppm.
**1.2 Stem Rot**
This is an aggressive disease that initially affects the cotyledons, leading to rotting and then invading the stem base. Water-soaked yellow-brown spots appear at the base of the stem, which later turn dark brown. In severe cases, the plant wilts and dies. In adult plants, similar lesions develop at the main stem and branches, eventually causing the stem base to darken and the plant to collapse.
**1.2.1 Agricultural Prevention and Control**
Avoid continuous planting of the same crop. Stem rot is often caused by seed-borne pathogens. Ensure seeds are fully dried and selected before storage, avoiding any moldy or low-quality seeds.
**1.2.2 Chemical Control**
Treat seeds with 50% carbendazim WP at 0.3% of the seed weight. During the seedling stage, spray with 40% carbendazim gel suspension diluted 1000 times, applying once before flowering. Use 1125–1500 kg/ha of liquid. Alternatively, spray 70% thiophanate-methyl at 800 times dilution on the stems.
**1.3 Root Rot**
Root rot can affect peanuts throughout their growth cycle. Infected plants become stunted, with yellowing and drying of leaves from the top down. The main roots turn black and rot, eventually leading to plant death. The disease spreads primarily through rain and field water. Factors such as excessive moisture, low soil temperature, or early and deep sowing can increase the risk.
**1.3.1 Agricultural Prevention and Control**
Implement proper crop rotation, select high-quality seeds, and ensure adequate drying before storage. Prepare the land properly, add organic fertilizers, prevent waterlogging, and maintain good field management.
**1.3.2 Chemical Control**
Use 50% carbendazim WP to coat seeds at 0.3% of the seed weight. At the early stage of the disease, spray 50% carbendazim at a 1000-fold dilution to control its spread.
**1.4 Black Mold**
Black mold primarily occurs during the early growth stages of peanuts. The fungus first infects the cotyledons, causing them to blacken and rot, and then attacks the seedling roots. Under wet conditions, a thick layer of mold covers the base of the stems, leading to dehydration, wilting, and eventual plant death.
**1.4.1 Agricultural Prevention and Control**
Adopt rational crop rotation and choose disease-resistant varieties.
**1.4.2 Chemical Control**
In the early stages of the disease, apply 50% carbendazim at 1000 times dilution or 70% thiophanate-methyl at 1000–1500 times dilution via foliar spray. Apply once every 7–10 days, repeating 2–3 times. This can be combined with foliar fertilization for better results.
By combining these agricultural and chemical practices, farmers can effectively manage peanut diseases and improve yield and quality.