Bacterial Leaf Blight (BLB) is a very major and devastating disease of rice. How to control it?

By: MeriKheti
Published on: 29-Sep-2023

Bacterial leaf blight disease is a major threat to rice production worldwide, as rice is the staple food of more than half of the global population.


Following are the symptoms, causes, epidemiology, various management measures of Bacterial Leaf Blight (BLB)


Introduction

Bacterial leaf blight in rice produced by Xanthomonas oryzae pv.oryzae .This disease is one of the most damaging ones  to paddy plants. Bacterial leaf blight (BLB) predominantly affects the leaves of rice plants and can cause severe output losses if not carefully handled.


Also  read: Steps towards a vaccine to reduce rice yield losses due to diseases


Symptoms of BLB


BLB symptoms usually start as tiny, water-soaked lesions on the leaves and progress to elongated, yellow to brown stripes. These stripes are generally wavy and run the length of the leaf blade. As the illness advances, tiny spots combine, causing entire leaves to perish. In extreme circumstances, BLB also damages leaf sheaths and panicles, resulting in significant yield losses.


Causes and pathogens

BLB is caused by the Gram-negative bacteria Xanthomonas oryzae pv oryzae, which lives in the intercellular spaces of rice plants. It penetrates the plant via wounds or natural pores and multiplies inside the plant tissues, resulting in disease symptoms. The causative agent of this illness produces a number of virulence factors, including extracellular enzymes and toxins, which contribute to its pathogenicity.


Epidemiology

BLB thrives in warm, humid settings, making it most common in tropical and subtropical locations. Raindrops, wind-blown rain, irrigation water, polluted agricultural equipment, and plant debris all contribute to the disease's spread. The presence of the infection in seeds also causes the spread of BLB to new locations.


Also read: Know about major diseases in paddy crop and how to control them


Disease cycle

Understanding the disease cycle is critical for effectively managing BLB. It starts with the pathogen being introduced into a paddy field and then spreads to host plants. Infected plants discharge bacterial cells into the environment, infecting adjacent plants. Environmental elements including temperature and humidity impact the disease's progression.


Impact of BLB on paddy production

BLB leads to considerable economic losses in paddy production. Yield losses in highly damaged areas might vary between 20% and 50%. These losses have an impact not just on food security, but also on rice farmers' livelihoods, particularly in places where paddy is the predominant staple crop.


How to control BLB?


Let's talk about the solutions


Use of resistant varieties: Breeding programmes have produced rice cultivars with varied levels of resistance to BLB. These resistant types can significantly lower the severity of the illness.


Crop rotation:which includes non-host crops, helps to prevent pathogen buildup in the soil.


Hygiene: Proper sanitation practices, such as eliminating contaminated plant debris and sanitising agricultural implements, help to prevent the infection from spreading.


Chemical control: Copper-based bactericides and antibiotics can be used in conjunction to reduce BLB, although their efficacy may decline over time owing to resistance. To treat this illness, spray 2.5 grammes of copper oxychloride per litre of water and 0.5 grammes of streptomycin per litre. From a distance, the signs of this condition appear to be zinc insufficiency. If zinc (Zn) deficient symptoms are present, spray the paddy with a mixture of 5 grams of zinc sulphate and 2.5 grams of slaked lime per litre of water. Zinc insufficiency is readily handled.


Biological control: Beneficial bacteria and biocides are being investigated as environmentally beneficial alternatives to BLB management.


Also  read: You can reduce your agricultural costs by adopting organic pest control tips.


Challenges and possible future

Despite efforts to manage BLB, issues persist. The introduction of new disease strains with higher virulence has the potential to overcome previously resistant kinds. Furthermore, there is a need to establish sustainable and eco-friendly management approaches to lessen the environmental effect of chemical control techniques.


To summarise, bacterial leaf blight of rice is a devastating disease that has a significant impact on rice production and food security in many regions of the world. Understanding its origins, symptoms, and management measures is critical to mitigating its impact and ensuring a steady supply of rice for the world's rising population. Continued study and collaboration among scientists, farmers, and policymakers is critical in the ongoing fight against BLB.