Non-stop rain is a double-edged sword. On one side, you will have a relatively good night sleep because of the cold weather. On the other side, you will be restless at the thought of bacterial diseases invading your rice farm.

Bacterial leaf streak (BLS) is one of these diseases. Less invasive and less popular than bacterial leaf blight (BLB), it is more prevalent when it rains non-stop like nowadays.

According to Dr. Hoai Xuan Truong, plant pathologist from PhilRice, BLS damage ranges from 10 to 20% when most of the leaves are infected.

“Its symptoms are almost similar to BLB,” said Dr. Truong. For BLS, farmers should pay close attention to fine yellow lines on the leaf surface. Almost half of the leaf will eventually turn brownish and the tip will be droopy. In contrast, for BLB, up to 2/3 of the leaf becomes infected, yet the whole leaf remains erect. In the field, a pronounced mass of rustic yellow color above the canopy is a sign of BLS infestation. Scenes such as this are visible in some rice farms in Guimba and other farms in Nueva Ecija.

Dr. Truong said, BLS infestation comes in earlier than BLB. If conditions like continuous rains are favorable, BLS signs become visible 40-50 days after seeding (DAS).

The first and best preventive option, according to Dr. Truong, is to maintain good drainage. This ensures that water will not stagnate in the paddy.

In addition, water stagnation also prevents good aeration, which eventually causes poor root development and lesser number of tillers.

Planting of resistant varieties is another effective strategy, according to Dr. Truong. PSB Rc82 and PSB Rc18 are some of the varieties resistant to BLS. Dr. Truong cautions on planting hybrid rice varieties during wet season, as most of these are highly susceptible to BLS and other diseases. Dry season is the best time to grow hybrid rice.

Dr. Truong further added that a variety resistant to BLB is also likely to be resistant to BLS.

When copper-based fungicide application is the preventive option taken, farmers must make sure to apply before 40-50 DAS. Beyond that, it is useless to spray; chances are the bacteria must have taken their place inside the leaf. One important consideration in applying fungicide is that it must be done when it is not raining. Otherwise, the fungicide will just be washed away before it can even take effect.

Meanwhile, PhilRice plant breeders are developing lines resistant to blast, BLB, and other rice diseases using both conventional and biotechnology approaches.