Bioecology Pathogens
HDB-causing bacteria, including gram-negative aerobic bacteria, rod-shaped Tungga and rarely in pairs, measuring 0.45 to 0.75 x 0.65 to 2.1 microns, move with flagella (Ou, 1985), while the yellow colonies. Besides seeds and seedlings, is a source of transmitting Xoo straw, ratun, and weed host (Wakimoto and Mizukami, 1969 in Mew et al. 1989). Xoo bacterial cells grow and multiply very quickly. At the beginning of growth (within 2-4 days) in both rice leaves resistant and susceptible varieties, breeding bacteria cells from 103-104 to 107-108 cells / ml. Further, the Xoo breeding resistant varieties leaves more slowly than in the leaves of susceptible varieties. It is the impact on the development of disease resistance varieties in the field (Leach et al., 1989).
Symptom
Bacterium Xanthomonas oryzae pv. oryzae can infect rice plants ranging from seedlings to harvest. There HDB du kinds of symptoms are symptoms that occur in young plants aged less than 30 days after the plant is called crackle, whereas symptoms on seedlings until plants reach stadia concoction called blight (blight). Crackle is the most destructive symptom of the disease HDB, while the most common symptom is a blight symptoms. HDB disease symptoms on plants in the nursery are usually characterized by a yellow color on the edges of the leaves are not easily observed. Symptoms were found in seedling growth phase until the ripening phase is blight symptoms (water soaked) until a yellow stripe on the flag leaf. Symptoms begin to appear at the end of the leaf then widen, causing a wavy leaf edge. Also found bacterial exudate also colored milk or form dew drops on young leaves in the morning. At stadia further development of disease symptoms, injury turns yellow white. Later in the severely infected leaves, the leaves tend to be accompanied by gray mold appears saprofit (IRRI, 2008).
Control
The main component of HDB control include: (1) the use of resistant varieties: (2) health test seed: (3) treatment seed: (4) the use of chemicals (hakterisida), (5) biological control, and (6) control of disease in an integrated manner.
- Use of Resistant Varieties
HUB control through resistance varieties proved to be effective in the tropics, especially the use of major resistance genes (major gene resistance). In addition, partial resistance to the HUB is also common in rice and noodles as noodles resistivity have been combined to obtain rice varieties have polygenic resistance (Kush et al., 1989).
- Seed Healthy
Seed treatments can be done both physically and chemically. Some of the ways that treatment can be applied according to Devadath (1989) are: (1) soaking the seeds in hot water 57 ° C for 10 min (2) soaking the seeds in a mixture of ethyl-HgCl 0.05% + 0.02% 100 12 hours Agrimycin followed by soaking the seeds in hot water 52-54 ° C 30 min, and (3) drying the seeds 5 days followed by hot water treatment of 52 ° C 10 min. Biological control bacteria by seed encapsulation can be done by using antagonistic bacteria (B. subtilis) (Ou, 1985).
- Control of Chemically
A variety of chemicals, including inorganic compounds, organic compounds, and antibiotics have been investigated efficacy of the HDB. Some of them declared effective. Spraying plants with such bactericidal, Kasugamycin, Phenazin, and streptornycin HDB can suppress the intensity on the field. The bactericidal usage constraints at the farm level is the high cost and the results can not be perceived directly (Ou, 1985). It was also reported that spraying with streptomycin suiphat tetraciklin + combination + 300 g copper occichlorid 1250 g / ha effectively eradicate HDB developments (Tamil Nadu Aqricultural University, 1999).
Triny (2008) reported that 56% of copper oxide with a concentration of 3 g / 1 were applied at the time of the first fertilization and spraying when plants are flowering simultaneously providing lower disease severity than the control.
- Biological Control
HDB biological control efforts using microbial antagonists has been done, but its efficacy has not been proven in the real field. Gnamamanickam et al. (2004) reported that Bacillus HDB can hit up to 50% on home screen. Bacillus lentiis produce the same anti-bacterial aminoglycosida with kanosomin. Additionally Bacillus treatment can increase the number of tillers 3-fold, and can produce 2,4-diacetylphloroglucinol (DAPG) is able to suppress the existence of HDB until 64%. One alternative 'control is to apply the leaf extract HDB prosophis julifora 10% 20 kg / ac. 20% solution of cow dung, 40 kg / ac and oil nimbi 3% / 6 l / ac (Tamil Nadu Agricultural University, 1999).
- Crop Management
Integrated Crop Management (ICM) is an attempt to increase the yield and efficiency of rice production inputs with regard to the use of natural resources wisely. Technology component in PTT are: 1) the use of high-yielding rice varieties or high yielding rice varieties and or high economic value, 2) the use of certified seeds of high-quality seed, 3) the use of site-specific balanced fertilizer, 4) the use of compost and organic materials or manure as fertilizer and of soil, 5) management of rice seedlings and plants healthy through: setting legowo cropping systems, the use of high power grow seedlings with sorting through seeds; planting young seedlings by the number of seedlings 1-3 seeds per hole; irrigation and drainage intermittent and weed control, 6) pest control with an integrated approach, and 7) use of thresher (Agency for Agricultural Research and Development, 2008).
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