方新政 黃杉茋 郭振欽 李對 張賜海 何新奇
黃榮作 林義雄 郭白井 方德利 郭聰明 黃天福
The Occurrence of Rice Diseases and Insect Pests in Tainan District During 1977
H.C. Fang, S. C. Hwang, C. C. Kuo, T. Li, T. H. Chang, H. C. Ho, T. T. Huang, I. H. Lin, P. C. Kuo, T. L. Fang, T. F. Huang, T. M. Kuo
1. The major rice diseases and insect pests that occurred in Tainan District during 1977 were leaf blast, neck blast, sheath blight and brown plant-hopper in the first crop season and bacterial leaf blight, sheath blight, brown plant-hopper grass leaf roller and infertile syndrome of rice in the second crop season.
2. The relationships between the occurrence of diseases and insect pests and climatic factors were:
(1) Leaf blast: The infected acreage and injury percentage in the first crop season were 1953.3 hectare and 2.5% and 431.8 hectare and 0.58% in the second crop, respectively Owing to the less rainfall, longer daylight during February, March and April in 1977 The outbreak of leaf blast was later and less serious than that of the past years This phenomenon may also due to growing the resistant rice variety Tainan No. 6 in some part of this area where rice blast was easily tended to occur.
(2) Neck blast: The infested acreage and injury percentage were 1764.6 hectare and 10.6% in first crop and 574.4 hectare and 4.9% in the second crop, respectively. Because of the more precipitation during May and June that was just in the blooming stage of rice, therefore the injury was more serious in some parts of this district.
(3) Sheath blight: The infected acreage and injury percentage were 5327.7 hectare and 13.1% and 974.6 hectare and 9.4% in the first and the second crop season respectively Owing to the warm climate and continuing rain in the late growth stage in the first crop (May, June), the damage caused by this disease was serious especially in Yin-Lin and Chiayi areas where plating dates were late In the second crop, these were less rain after October and the temperature was declined so the infection of this disease was not serious.
(4) Bacterial leaf blight: This disease did not occurred in the first crop, but was heavily occurred in the second crop in 1977 compared with that of the past years This was due to the tow times of typhoon attack on rice and the increased acreage of cultivating disease susceptible varieties such as Tainung No. 67, Tainan No. 6 and African variety”etc.
(5) Brown plant-hopper: The infested acreage and damage were 1187.7 hectare, 1.1% and 16067 hectare, 9.5% in the first and second crop season respectively. This insect/pest is used to being more serious in the second crop than tin the first crop But it produced high population and so caused much damage in the first crop in 1977 This was due to the fact that there were dry weather, high temperature, short precipitation and the longer daylight during the growing period of the first crop in this year In the second crop of this year, the population of this insect was low and it caused less damage that was due to the two times typhoon attack on rice in July and August.
(6) Grass leaf roller: This was not importantly economic insect pest in rice crop, but its population seems to increase the become important in recent years The infested acreage was 195 hectare and 6684.9 hectare in the first and the second crop, respectively.
3. The results obtained from the light trap indicated that the major insects in 1977 were brown plant-hopper, green leafhopper, grass leaf roller, rice stem borer, and zigzag leafhopper etc The population of these insects were highly influenced by the amount of precipitation; this is the population of insects is reduced sharply following the heavy rain Brown plant-hopper first showed up in the middle April and started to caused damage on rice in the late of April The population of this insect was fluctuated owing to the rainfall during May and June It reached the lowest point at the end of August due to the twice storms cause in July and August and then climbed up again from the early of September and reached the highest point at the early of November Since it was just in the rice growing season during September and October and the climatic condition was favored for the existence of this insect, most of this insects was short-winged type and seriously infected the rice plants and caused widely and much damage Because of the senescence of rice plant in the late growth stage and the conditions were not favored for the survival of this insect, most of the insects were the long-winged type and started to move away It caused the population of this insect collected from the lamp trap increased rapidly. The appearance of grass leaf roller was started from the late of February but it did not caused much damage in first crop The population of this insect was decreased in July and August due to the twice storms attack during this period and it climbed up in September and October and then caused serious injury.
4. The total acreage of rice in the first crop was about 65,000 hectare in Tainan District and the major varieties were Tainan No. 5, Tainan No. 6, Tainung No. 67, Kaohsiung No. 139, Taichung sen No. 1, Africa variety, etc Tainan No. 6 was the widest grown variety and its acreage had 28,266 hectare (44.41%) Tainan No. 5 with 23,513 hectare (36.94%) was the second The acreage of rice in second crop was about 116,000 hectare and the major varieties grown were Tainan No. 5, Tainan No. 6, Tainung No. 67, Nan-Kai-Yi No. 121, Kaohsiung Sel. No.1, Africa variety, etc Tainan No 5 with 56,949 (48.76%) was the leading variety and 28,941 hectare (24.79%), 10,367 hectare (8.88%) and 4,515 hectare (3.87%) for Tainan No. 6, Tainung No. 67 and Africa variety, respectively.