Insects and diseases are a continuing menace to forests. Various insects, such as the gypsy moth, the tussock moth, and the spruce budworm, devastate extensive areas by defoliation. Other insects serve as carriers for the causative agents of diseases that destroy trees. Parasitic tree diseases may be caused by bacteria, fungi, viruses, and nematodes, or by such parasitic plants as the mistletoe or dodder. Noninfectious diseases of trees include sunscald; drought injury; root drowning, or suffocation; nutritional excesses or deficiencies; winter injury; and injury from smoke, gases, and fumes.
- menace [ˈmenəs] n.威胁
- gypsy moth [ˈdʒipsi - mɔθ] n.舞毒蛾
- tussock moth [ˈtʌsək - mɔθ] n.毒蛾
- spruce budworm [spru:s - ˈbʌdwə:m] n.云杉蚜虫
- devastate [ˈdevəsteit] v.糟蹋
- defoliation [ˌdi:fəuliˈeiʃən] n.落叶
- causative agent [ˈkɔ:zətiv - ˈeidʒənt] n.病原体
- bacteria [bækˈtiəriə] n.细菌
- fungi [ˈfʌndʒai] n.真菌
- virus [ˈvaiərəs] n.病毒
- nematode [ˈnemətəud] n.线虫
- mistletoe [ˈmisltəu] n.槲寄生
- dodder [ˈdɔdə] n.菟丝子
- sunscald [ˈsʌnskɔ:ld] n.日灼病
- drought injury [draut - ˈindʒəri] n.旱害
- root drowning [ru:t - ˈdrauniŋ] n. 根部溺死
- suffocation [ˌsʌfəˈkeiʃn] n.窒息
- nutritional [nju:ˈtriʃənəl] adj.营养的
- deficiency [diˈfiʃənsi] n.缺乏
- fume [fju:m] n.浓烟
