Bacterial fungicide from Kamantigue controls Phytophthora disease of durian

Durian (Durio zibethinus Murr.) is an export winner fruit crop in the Philippines. The durian fruit contain high amount of calcium, phosphorus, potassium, and vitamins. It commands high price because of its peculiar taste, flavor and nutritional value. Diseases, however, remains to be the limiting factor in durian production. With the ability to cause 20-25% yield loss, the Phytopthora disease is considered economically important in durian growing countries such as Thailand, Malaysia, Indonesia, and the Philippines. The pathogen, Phytophthora palmivora Butler infects all parts of the durian tree in all stages of its development causing patch or stem canker, root rot, leaf blight, die-back of seedlings, and mature trees, and rotting of mature and immature fruits. Current disease management strategies involve the use of fungicides and proper cultural practices. However, due to high cost of fungicides and the risk to health and environment, there is a need to search for alternative method that is safe, effective and economical. Thus, Dionio et al. (USeP) conducted a 1-year study to determine the effectiveness of Kamantigue or garden balsam (Impatiens balsamina) in controlling the Phytophthora disease of durian. Findings of the study revealed the following: Extracts from mature seeds of red and violet Kamantigue had greater toxic activity than pink and white Kamantigue. Extracts prepared under sterile condition and stored earlier under ambient room condition (28 deg-30 deg C) or in air-conditioned room (26 deg-27 deg C) completely inhibited growth of P. palmivora in vitro up to 13 weeks of storage. The time of extract applicated affected the number of lesions induced by P. palmivora on 6-month-old durian seedlings of the 'Monthong' variety. Spraying of extract 1 hour before and 1 hour after spray inoculation of P. palmivora reduced lesion number by 86% and 78%, respectively. Spraying of extract 24 hours before inoculation of P. palmivora gave comparable result of 60% reduction in lesion number. Compared with seedlings inoculated with P. palmivora alone, seedlings which were also sprayed with the Kamantigue extract had significantly lower percentage defoliation. Seedlings sprayed with the extract 1 hour before inoculation had 13.4% defoliation. Those sprayed 24 hours before inoculation had 12.6% defoliation while those sprayed with extract one hour after inoculation had 12.2% defoliation. Scraped canker lesions sprayed with 1:1 (wt/r) extract and the pure crude extract were generally dry 3 weeks after extract application. All treated lesions were dry up to the 4th week of application while untreated lesions remained wet. Results of the study showed that matured fruit/seed of red and violet Kamantigue or garden balsam can be used as protectant botanical fungicide for the control of Phytophthora leaf blight of durian. However, for patch canker treatment, the affected portion must be well scraped before application of the extract in order to get better results. The researchers recommended validation trials for both leaf blight and patch cankers treatments. Evaluation of the effectiveness of the extract to control major diseases of other crops should also be done. Information generated by the study is important in reducing production cost. Kamantigue is available all year round. Furthermore, the environmental and health hazards caused by synthetic pesticides can be reduced.