Rootrot disease of sintunes (Citrus reticulata Blanco): its development, biological control, and socio-economic impact
1996
Carambas, B.D.M.
A single organism was consistently isolated both from the infected root and stem of the szinkom citrus (Citrus reticulata Blanco). The fungus isolate was identified as Botryodiplodia sp. Pathogenicity test manifested that the isolate was pathogenic on szinkom citrus seedlings inoculated through injured stem and uninjured root. The fungal attack was faster when the seedlings were wounded than when unwounded. Results of cultural study showed that the isolate grew well on potato dextrose agar. The second preferred growing medium was corn meal agar, followed by oatmeal agar, while the least preferred was malt extract agar. Its optimum growth was observed at pH 4.5, while its greatest diameter growth was observed under natural light. Improved growth was observed with increasing glucose concentration. Bioassay test revealed that Trichoderma harzianum was the most effective in inhibiting the growth of the isolate followed by T. veride. The least effective was T. koningii. Greenhouse test showed that fewer seedlings were infected by the pathogenic inoculum when treated with the antagonist through injured stem while a lower control resulted when seedlings were treated through uninjured root. The case study conducted showed that root rot disease rank as the number one problem in citrus plantations of the majority of the farmers interviewed. All of them admitted that their gross income was immensely affected with the outbreak of the disease so much so that their future plans has to be adjusted to the present situation
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