Occurrence and Control Methods of Rice Pests and Diseases at the Mid-Season

According to field surveys of pests and diseases by each forecasting station, the field moth population of the third generation of the rice leaf roller is currently large, and the egg mass is high. All towns are urged to actively carry out control work.

I. Occurrence situation:

(1) Third generation of the rice leaf roller:

1. Field moth population: According to observations at each forecasting station, the field moth population began to surge starting from 7/28, with 530 moths/mu at the Xiayang station, 800 moths/mu at the Jinze station, 313 moths/mu at the Zhujiajiao station, 1065 moths/mu at the Zhendian station, and 890 moths/mu at the Liantang station. On 7/31, the field moth population rose further, with the highest field reaching 2050 moths. The field moth population is expected to continue rising.

2. Field egg mass: According to a general survey on 7/30, the average egg mass per mu was 10,600 grains, with the highest field reaching 40,000 grains per mu; grade 1 eggs accounted for 72.5%, grade 2 eggs accounted for 22.5%, and grade 3 eggs accounted for 5.0%. A systematic survey on 8/1 showed an average egg mass of 21,700, with the highest field at 87,500. In addition, according to the dissection of some female moth ovaries by the district station on 7/30, grade 1 and grade 2 accounted for 28.6%, while grade 4 and grade 5 accounted for 71.4%, indicating that some of the field population is already from local insect sources, and adults will continue to lay eggs. The egg hatching peak is expected around 8/3.

(2) Rice planthoppers:

According to light trap observations by the district station, an adult immigration peak appeared on 7/20-22, with a cumulative total per light trap of 2558 white-backed planthoppers, 818 brown planthoppers, and 122 small brown planthoppers. In addition, according to a general survey on 7/30, the field egg mass was relatively high: the average egg mass of white-backed planthoppers was 307,700 grains per mu, with the highest field reaching 1,675,000 grains per mu; the average egg mass of brown planthoppers was 73,000 grains per mu, with the highest field reaching 950,000 grains per mu; the average egg mass of small brown planthoppers was 108,700 grains per mu, with the highest field reaching 512,500 grains per mu. The egg grades were mainly grade 1 and grade 2, and the peak hatching period is expected around 8/3.

(3) Sheath blight:

According to surveys, sheath blight is currently fairly common in early-planted and early-sown fields. A general survey on 7/30 showed an average diseased plant rate of 0.61%, with a disease index of 0.18; the highest field had a diseased plant rate of 7.8%, with a disease index of 2.52. In particular, most machine-transplanted rice has already closed its rows, and the field microclimate is dense and poorly ventilated. Combined with continuous high temperatures in early August, this is conducive to the occurrence and spread of sheath blight. All towns are urged to pay attention and do a good job in controlling rice sheath blight.

(4) Rice stripe disease:

At present, the first disease peak of rice stripe disease has appeared in the field, and individual fields are relatively seriously affected. According to a general survey on 7/30, the average diseased plant rate was 1.34%, with a disease index of 0.91; the highest field had a diseased plant rate of 6.4%, with a disease index of 4.75.

II. Control recommendations:

1. Control focus: primarily control the third generation of the rice leaf roller, sheath blight, and rice planthoppers, while also controlling rice stripe disease and the large rice borer.

2. Control targets: all rice.

3. Control time: 8/4-6.

4. Pesticides to use: per mu, use 130 milliliters of 20% monosultap?profenofos + 60 grams of 20% emamectin?chlorfenapyr (or 80 milliliters of 20% pyridaphenthion) + 35 grams of 15% validamycin A.

III. Precautions

1. For fields where rice stripe disease has already occurred, in conjunction with this control, add 45 milliliters per mu (3 packets) of 8% jankeweike (ningnanmycin) aqueous solution, dilute with 50 kilograms of water and spray, then spray a second time after 5 days to passivate the virus and slow the spread of the disease.

2. In machine-transplanted rice fields, within 3 meters along the field ridge, use 75 milliliters of 40% chlorpyrifos?phoxim EC with a small sprayer to control the large rice borer.

3. After application, avoid directly discharging the pesticide liquid and field water into fish ponds, shrimp ponds, and other aquaculture areas.

4. If there is a shower within 4 hours after application, please promptly carry out follow-up treatment.

5. In high-temperature weather, apply the pesticide in the early morning or evening, and be sure to take self-protection measures to prevent poisoning accidents.