The diamond borer, commonly referred to as the rice stem borer, is a significant pest that affects rice cultivation, particularly in regions like Hunan Province in China. In recent years, its presence has been more pronounced in Xiangdongnan compared to northwestern Hunan. While rice is its primary target, these pests also attack other crops such as alfalfa, corn, sugarcane, and even certain grass weeds. Interestingly, after winter, some larvae can migrate to broad beans, rapeseed, and wheat, further exacerbating their impact. They typically cause damage during critical growth stages of rice, leading to issues like dry sheaths, dead hearts, empty panicles, and reduced grain fill.
In Hunan, the Huaihua rice variety experiences three generations annually, though in areas like Xiangnan, there may be incomplete or full four generations observed. Winter larvae often reside in rice roots, straws, and stubble. The first peak of adult activity occurs from May to June, followed by another in July, and a final surge from August to September.
Sanhua rice, another major pest in the region, exclusively targets rice and completes four generations per year. Its larvae overwinter in rice roots, emerging in April. The first generation peaks in May, the second from late June to mid-July, the third in August, and the fourth in mid-to-late September. These pests exhibit phototaxis, preferring to lay eggs in lush, fertile fields.
To manage these pests, several strategies can be employed. Agricultural control includes removing white panicles, which house third and fourth-generation larvae preparing for winter. This task is easier in late September to early October when larvae are visible. Removing affected rice plants or cutting infested fields can help reduce future infestations. Additionally, timely harvesting and processing of rice straw are crucial. Leftover straw can serve as breeding grounds for next season’s pests, so it should be removed or burned post-harvest. Water management also plays a role; flooding during winter can drown larvae, while strategic irrigation can disrupt breeding cycles.
Physical controls involve the use of frequency vibration insect traps. Installing one trap every 150 meters starting in late April can significantly reduce pest populations. Chemical controls require precision timing, targeting young larvae during peak periods. Reducing pesticide usage while maintaining efficacy is key to minimizing environmental impact.
For chemical treatment, options include applying 30 to 40 ml of 5% Ruijin suspension per acre, 120 to 150 ml of 20% triazophos EC, or 100 to 120 ml of 15% state microemulsion per 45 kg of water. Maintaining a shallow water layer during spraying aids in enhancing effectiveness.
These integrated pest management practices ensure sustainable rice cultivation while minimizing ecological disruption.
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