Occurrence Trend and Integrated Control of Diseases,Pests and Weeds in Wheat in the Middle and Late Stages

As the growth of wheat was impacted by the winter drought in 2007 and the low temperatures and frost damage from January to February in 2008, the proportion of high-quality wheat in the first category decreased, while the share of second and third types increased. Following the return of spring wheat, strengthening field management—particularly the prevention and control of diseases and pests in later stages—became critical for ensuring a successful 2008 harvest. **I. Trends in Wheat Diseases, Pests, and Weeds in 2008** Based on current data from wheat and poultry pest monitoring stations, combined with an analysis of regional resistance levels and spring weather conditions, it is predicted that mid- and late-season wheat diseases, weeds, and pests will generally be more severe in 2008. Key issues include wheat sheath blight, stripe rust, leaf rust, leaf blight, powdery mildew, scab, wheat cyst nematode, midge, underground pests, aphids, and wheat spiders. (a) **Wheat Field Weeds**: Moderate occurrence is expected, covering 35–40 million mu. Common species include leeks, wild garlic, sow thistle, valerian, motherwort, wild rape, maimai, and wild oats. (b) **Sheath Blight**: A major concern, especially in areas with high population density, affecting 45–48 million mu. The peak period is expected to last until late April. (c) **Stripe Rust**: Moderate occurrence overall, but serious outbreaks are possible in Nanyang, Xinyang, and Zhumadian, covering 10–15 million mu. The disease typically appears from mid-April to early May. (d) **Leaf Rust**: Moderate occurrence, mainly in central Henan, affecting 18–25 million mu. The most damaging period is late May. (e) **Leaf Blight**: Moderate occurrence, with some regions facing higher risks, covering 20–22 million mu. The threat period runs from late April to late May. (f) **Powdery Mildew**: Moderate to heavy in some areas, especially in irrigated fields, affecting 22–27 million mu. The peak occurs between early April and early May. (g) **Scab**: If rain occurs between late April and early May, scab could affect over 15 million mu. (h) **Wheat Cyst Nematode Disease**: Light occurrence, reported in Xuchang, Zhengzhou, and Jiaozuo, covering 15–18 million mu. (i) **Wheat Midge**: Overestimation expected, with local reoccurrence in Pingdingshan, Zhumadian, Luohe, and other areas, covering 17–20 million mu. Adult emergence peaks in late April. (j) **Underground Pests**: Significant occurrence, affecting 35–42 million mu. (k) **Aphids**: Moderate during the seedling stage, with overpopulation during heading. Some northern and western regions may see 50–60 million mu affected. The risk period ends in mid-May. (l) **Wheat Spiders**: Moderate occurrence, particularly in hilly and dry areas, covering 20–25 million mu. The damage period lasts from late March to mid-April. **II. Comprehensive Control of Wheat Diseases and Pests** (a) **Jointing Period**: During this stage, weeds, sheath blight, wheat spiders, and golden needle beetles are the main concerns. For broadleaf weed control, options include 75% superstar dry suspension (1–1.5 g), 10% tribenuron-methyl (10–15 g), or 20% prolonged emulsifiable concentrate (50–60 ml). For grassy weeds, use 6.9% horse oil emulsion (60–70 ml) or 3% Sema EC (25–30 ml) per acre, mixed with 30–45 kg water. To control sheath blight, apply 20% Jinggangmycin wettable powder (30–40 g) or 12.5% diniconazole (20–30 g) per mu, mixed with 40–50 kg water. For wheat spiders, use 40% omethoate EC (1000 times dilution), 20% carbendazim (2000 times), or 0.9% avermectin EC (3000 times). For ground pests like golden needle beetles, apply 40% chlorpyrifos EC or 50% phoxim EC (800–1000 times dilution) via irrigation. When multiple pests occur simultaneously, mix fungicides and insecticides to improve efficiency. (b) **Boot to Heading Stage**: This period sees powdery mildew, sheath blight, rust, aphids, midge, and red spider. Apply 40% chlorpyrifos emulsifier (50–60 ml) plus 0.9% abamectin EC (10–15 ml), or 10% imidacloprid (10–20 g) plus 12.5% diniconazole (30–40 g), or 20% triadimefon EC (60–70 ml) plus 25% propiconazole EC (30–35 ml) and 200 g monobasic potassium phosphate, all mixed in 40 kg water. During midge infestation, mix 3% methylisothiophos granules (3 kg) with 5% phoxim granules (3–5 kg), add 20 kg fine soil, and spread evenly in the field, followed by watering for better control. (c) **Heading to Filling Stage**: This period is critical for aphids, armyworms, midge, stripe rust, leaf rust, leaf blight, powdery mildew, and head blight. Most pests and diseases multiply rapidly from late April to early May, coinciding with the sensitive phase for wheat. Protect and utilize natural enemies, and combine biological and chemical control. Use 12.5% diniconazole (30–40 g), 20% triadimefon EC (60–80 ml), 25% propiconazole EC (30–35 ml), or 30% tebuconazole suspension (10–15 ml) plus 50% fresh air fog (8–10 g) per mu. Mix with 40 kg water and spray thoroughly. **III. Six Key Points to Improve Control Effectiveness** 1. Use biological or high-efficiency, low-toxicity pesticides to reduce reliance on harmful chemicals, avoiding banned substances like methyl parathion and monocrotophos. 2. Apply pesticides according to established thresholds; ensure all affected fields are treated promptly. 3. Rotate pesticide use and mix them to prevent resistance and maintain effectiveness. 4. Ensure proper spraying techniques—target the base of wheat stems for sheath blight, and spray the upper parts for aphids and midge. 5. Observe safety intervals, stopping pesticide application 15 days before harvest. 6. Apply nitrogen and potassium fertilizers to prevent premature leaf aging, extend photosynthesis, and avoid dry hot winds, thereby increasing yield and quality.

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