Tianyingjiao, a key economic crop in Xinle City, faces significant challenges during the hot and rainy months of July and August. This period is also marked by an increase in pests and diseases, which often lead to leaf drop, fruit fall, and reduced yield and quality. The main diseases affecting Tianyingjiao include blight, anthracnose, viral infections, and scab. Common pests such as the cotton bollworm, aphids, beet armyworm, and cabbage caterpillar also pose serious threats during this time.
**1. Identification of Major Diseases and Symptoms**
- **Blight (Fungal Disease):** This disease causes dead branches and trees, with symptoms appearing on leaves, stems, and fruits. Infected leaves show green circular lesions that spread quickly under high humidity, leading to soft rot. Stems develop brown streaks, causing upper parts to die off. Fruits often show dark green water-stained spots at the base, spreading rapidly and affecting both flesh and seeds. High humidity and dense planting increase the risk.
- **Anthracnose:** Caused by fungal infection, it leads to defoliation. The city mainly experiences black anthracnose, which affects leaves, fruits, and stems. Leaves show water-soaked spots that turn gray or black, while stems develop irregular brown lesions. Dry conditions cause the affected areas to crack. Overwatering, high humidity, and excessive nitrogen fertilizer promote its spread.
- **Viral Disease:** Spread mainly through aphids, this disease manifests as mosaic, arbuscular, or yellowing symptoms. Mosaic types cause mottled, deformed leaves, while arbuscular types result in stunted growth and narrow leaves. Yellowing leads to leaf and fruit drop. High temperatures and dry weather, along with drought-prone fields, make plants more susceptible.
- **Scab (Bacterial Disease):** Affects leaves, stems, and fruits. Early signs include black-green or yellow-green spots, sometimes with roten patterns. Leaves and stems show raised, scab-like lesions, while fruits develop dark green, round or oval spots.
**2. Main Pests and Their Damage Periods**
The primary pests affecting Tianyingjiao include the cotton bollworm, beet armyworm, and cabbage caterpillar. These pests are most active from late June to early September, with peak damage occurring between July and August.
**3. Pest and Disease Control Measures**
- **Field Management:** Regular fertilization and proper drainage after rain can help improve plant resistance and reduce disease occurrence.
- **Chemical Control:**
- **Viral Disease:** Early control of aphids using 10% imidacloprid diluted 1500 times. For infected plants, use 20% virus A WP (400 times) or 1.5% phytosanitary emulsion (500 times).
- **Blight:** Apply 75% chlorothalonil (600 times), 64% mancozeb (400 times), or 70% mancozeb (400 times).
- **Anthracnose:** Use 75% chlorothalonil (600 times), 70% thiophanate-methyl (400 times), or 80% anthraquinone formamide (600–800 times).
- **Scab:** Spray 72% streptomycin for agriculture or neophytin at 3000–4000 times.
- **Pests (Cotton Bollworm, Beet Armyworm, Cabbage Caterpillar):** Mix 52.25% chlorpyrifos (1000 times) with high-efficiency cypermethrin and phoxim (1:1 ratio) and spray at 1:1000.
**4. Notes on Disease and Pest Control**
Effective control requires timely intervention at the early stages of disease. It is recommended to apply treatments 2–3 times, with intervals of 7–10 days. Monitoring field conditions and adjusting control measures accordingly ensures better results and long-term protection of the crop.