Eight easy ways to fight bacterial blight

What is a bacterial blight?

Bacterial blight is a water-borne disease. It infects plants when droplets carrying the bacteria (Xanthomonas oryzae pv. oryzae) land on leaf wounds, which are caused by a range of factors including heavy rains and typhoon winds. Rice plants are more susceptible to the disease under high temperatures and humidity, and when nitrogen fertilizers are used.

It was first first reported in the Fukuoka Prefecture, Japan, in 1884. The disease was unknown in the area until farmers began using soybean cake and green manure to fertilize their lowland ricefields. This was the first clue that bacterial blight has a voracious appetite for mixtures of rice and nitrogen. Since then, the disease has traveled the world to settle in places where the two are found in abundance.

Symptoms and effects

Symptoms of bacterail blight in rice includes turning of leaves to pale yellow and wilt during the seedling until the early tillering stage. The process is also called Kresek which may cause in partial or total crop failure.

Bacterial blight only became significant in Southeast Asia forty years ago when the International Rice Research Institute (IRRI) introduced IR8, a nitrogen-responsive variety. The variety was highly susceptible to bacterial blight and it "assisted the disease to spread wider".

The disease had cut yields by 20 to 50 percent in the 1960's and the highest yield loss was reported at 80 percent in some areas during the epidemic.

Ways to Control

IRRI's scientists solutions ranged from hazardous chemicals to genetically modified rice called BB Rice, but for MASIPAG and the farmers, there are at least eight easy and environmental-friendly ways to control bacterial blight in rice:

1. avoid excessive use of fertilizer rich in nitrogen;
2. do not use residues from infected plants as organic fertilizer;
3. provide only adequate irrigation and sufficient drainage;
4. save the seeds from those plants with resistance to plant for the next season;
5. maintain diversity in the farm by planting different crops at the same time or changing crops every season to decrease the pest population;
6. be cautious in transplanting seedlings from the seedbed to the field, since tearing of the roots is a significant cause of infection;
7. plant different varieties of seed, and those developed from multiline breeding, with different levels and means of resistance as a precaution against large crop loses; and
8. remove infected plants and other possible hosts of the pathogen.

Based on MASIPAG's experience, bacterial blight is not a large-scale problem in the Philippines, since farmers can easily deal with it.

Source:
http://www.ias.ac.in/currsci/dec101999/REVIEWARTICLE.PDF
Kuyek, Devlin. BB Rice: IRRI's First Transgenic Field Test. Biothai, GRAIN, KMP, MASIPAG, UBINIG, R. Quijano and O.B. Zamora. Philippines. May 2000