Timing and Methods for Controlling Rice Diseases at the Heading Stage and the Striped Stem Borer
In Changhua, Taichung and Nantou counties and cities, early-planted rice is about to enter the heading stage. Due to continuous rainfall in recent days, conditions are favorable for the occurrence of panicle blast and sheath blight, and monitoring data on the striped stem borer show that a relatively large number of adult moths have appeared since the 22nd, and the larvae that hatch after egg-laying will damage the rice. The Taichung District Agricultural Research and Extension Station urges farmers to carry out preventive spraying 3 to 5 days before rice heading to avoid damage to rice production from pests and diseases such as panicle blast, sheath blight and the striped stem borer.
Before rice heading, rice blast spores are carried by wind, rain or dew and land on the ligule and leaf node of the flag leaf. When the panicle emerges, it is infected as it passes through these parts, and the neck of the infected panicle often bends, commonly known as hanging panicle or hanging dog. Sheath blight initially infects the leaf sheath of the lower leaves of the rice plant, then gradually spreads upward, producing tiger-stripe-like symptoms.
From 7 to 10 days after a large emergence of adult striped stem borer moths, the newly hatched first-instar larvae bore into the leaf sheath of the lower leaves of the rice plant to feed, and this is the critical time for controlling the striped stem borer. If spraying is delayed, the larvae bore into the stem to cause damage, and white ear symptoms will appear.
The Taichung Station urges simultaneous control
Liao Junda, associate researcher at the Taichung Station, said that due to the recent warmer weather and continuous rainfall, farmers are advised to apply pesticides before heading; otherwise, after rice heading there is a risk of panicle blast and sheath blight, and a large outbreak of the striped stem borer has also recently been found, which will cause losses if not controlled. He suggested that farmers can spray pesticides to control all three pests and diseases at the same time: rice blast, sheath blight and the striped stem borer. For pesticides and application methods, farmers may consult the Plant Protection Information System or local improvement stations.
