Dang Thi Kim Uyen, Nguyen Van Hoa
Tran Vu Phen
One of the most severe fungal diseases on dragon fruit (Hylocereus undatus)(DF) is anthracnose caused by Colletotrichum gloeosporioides. During a disease survey on DF in March and December 2015, 50 isolates of Colletotrichum were recovered from DF in the main growing areas in the South of Vietnam. Based on the morphological characteristics of colony, color, appearance, shapes of conidia and sequences of ITS regions, C. truncatum was identified as another causal agent of anthracnose on DF. The favorable temperatures for colony growth on PDA medium were of 25 to 37ºC and the pH of4.5 to7.5. On the evaluation effect of seven fungicides, the result shown Difenoconazole, Propiconazole + Difenoconazole, and Azoxystrobin + Definoconazole were the most inhibitory to fungal growth at 50 ppm and 100 ppm, percentages of the inhibition was up to 83.75; 93.75 and 93.75 % respectively. Among three plant extracts of Impatiens balsamina, Pachyrhizus erosus, and Caulis opuntiae, the extract of I. balsamina at 2.0; 3.0 or 4.0% was the most efficacy on inhibition of mycelial growth of the fungus, up to 93.7%.The other PDA medium test using Streptomyces isolate TG12, TG 17, the result shown that TG12could control well C. truncatum up to 60.37% and TG17 to C.gloeosporioides at 71.33%. Under glasshouse and field conditions, the Difenoconazole, Azoxystrobin + Difenoconazole, Propiconazole + Difenoconazole and Impatiens balsaminaextract, Trichoderma and Streptomyces solutions could control well the development of C. truncatum on both lesion diameter and severity.