Studies On The Pathology & Control Of Fusarium Wilt Of Melonis

Fusarium wilt of melon, caused by Fusarium oxysporum f.sp melonis (f.o.m), is prevailing in Gansu province. This paper first systematically reported the etiology, occurrence regularity and control technique of this disease.We investigated the occurrence of melon wilt in the Xifeng, Gansu and isolated the pathogen in lab. According to the pathogenicity, biological characteristics, culture behavior of these isolates, we confirmed the pathogen which made the melon wilt is the members of Fusarium oxysporum f.sp.menlonis.The studies of biological characteristic of pathogen showed that the temperature for mycelium growth and conidial germination is 10-35℃, and the suitable temperature is 20-30℃. Light is beneficial to mycelium growth, but disadvantage to the formation of spores. The range of pH suitable for spore germ is between 2.0 to 8.0, but the optimum is 6.0 and the spore couldn't germ over 9.0, which indicated that the pathogen tended to grow under slight acid condition. Shaking culture was advantage to mycelium growth and conidial germination.The study on inoculating methods of Fusarium wilt of melon showed that the percentage of disease is high when inoculated with pouring the wound root. Artificial inoculating other plants showed that Fusarium oxysporum f.sp melons has strict host specialization.The results which investigated the occurrence of Fusarium wilt of melon in Gansu province indicated that this disease occurred in all areas. The percentage of disease was about 20% in general years, seriously occurred years it could up to 80-90%. It may be caused serious yield reduction and even more no yields. It lightly occurred in Hexi Corridor such as Dunhuang, Mingqing, and more severely in middle of Gansu such as Lanzhou, and most severely occurred in eastern Gansu such as Qingyang, Pingliang and other regions. This disease occurred in all growth period of melon and first appeared in the stage of seedling. The period of seriously occurred in flowering to fruiting. Usually, the disease developed gradually from the vine-top to the vine -bottom until the whole plant died. There were three kinds of symptom which usually see in the field : damping-off, dwarf and wilt. Different cultivars had different resistance to the disease. Thin-skin melons had higher resistance than thick skin melons. According to the color of the skin,the order of disease resistance was: yellow>green>green white>white. The varieties which ripen lately had better resistance than the ripen early ones. In addition, the unreasonable method of breed seedling and rotation also caused the appearance of the wilt of melon.The study of control technique showed that different cultivars of melon had different resistance, among which Tailong1,Longtian1,Elizatbeth and Yujinxiang had higher resistance. It can effectively reduce the occurrence of this disease by rotation with non-melon crops at least 3-5 years. Using chemicals, such as JiangGenBao, GuaKuQing, Carbendazim and other fungicides which mixed with soil then filled into the hole digging on the surface of the soil or poured the roots directly at the early stage of melon swelling, can also control this disease effectively.