Devastating Leaf Blight Of Wheat: The Integrated Management Approach

Are you concerned about the health of your valuable wheat crops due to the threat of Wheat Leaf Blight? Don’t worry! This article is your go-to resource to learn crucial information and discover effective strategies to tackle this fungal menace.  

Alternaria triticina, a fungal plant pathogen, is responsible for inducing leaf blight in wheat plants. As wheat plants age, their susceptibility to this disease increases, as the fungal pathogen is unable to affect young wheat seedlings that are less than four weeks old. The symptoms caused by them are usually not evident until the plants are about seven weeks, but severe infection can cause up to 80% yield loss. Temperature of about 20-25 °C and high relative humidity favors the development of this disease.  

Type of infestation

Leaf blight of wheat has a complex disease cycle that involves primary and secondary infections. 

• The primary mode of spread occurs by both external and internal seed borne conidia.
• The secondary infection mainly happens through the wind-borne conidia.

Scientific Name: Alternaria triticina 

Symptoms of Wheat Leaf Blight

The following points will help you to easily identify the symptoms caused by leaf blight of wheat.  

• Generally, the disease first appears in the field when the wheat plants are 7 to 8 weeks old.
• The lowermost leaves always show the first sign of infection, which gradually spreads to upper leaves.
• Reddish brown colored oval shaped spots develop on the young seedlings with bright yellow margin.
• When the infection becomes severe, multiple spots merge leading to leaf dryness.
• Heavily infected fields exhibit a scorched appearance that is noticeable even from a distance.
• Certain varieties experience a significant reduction in grain yield, up to 90%, if the infection occurs during or prior to boot leaf stage.

Control Measures

An integrated Pest Management measures includes cultural, mechanical, biological and chemical method which is often required to control leaf blight of wheat effectively. 

Cultural Measures

• Grow resistant wheat varieties like Co 25, Sonalika, Arnautka, E6160 and K7340.
• Use only clean and disease-free seeds for planting.
• Avoid sowing wheat in infected fields for at least two years.
• Early planting can help avoid the peak period of wheat leaf blight infection.
• Proper nutrition management, including balanced fertilization and irrigation can also help to reduce the incidence of leaf blight disease in wheat.

Mechanical Measures

• Collect and burn the infected plants to reduce the spread the leaf blight disease.

Biological Measures

• Anshul Tricomax Bio fungicide contains Trichoderma viridae which suppresses the growth of pathogens by producing antibiotics. The recommended dosage is 3 gm per liter of water.
• Mildown Bio fungicide contains Bacillus subtilis which competes with the disease-causing organisms and induces systemic acquired resistance against bacterial pathogens. For treating 1 kg of seed, mix 7.5 to 10 ml of mildown in 50 ml of water and apply them on seed for proper coating. Before sowing, shade dry the treated seeds for about 20-30 minutes.
• Amruth Almonas Bio Fungicide is a biological fungicide containing the cells of rhizobacteria and Pseudomonas fluorescence which exhibit antibiosis effects on disease causing pathogens. The recommended dosage for seed treatment is 3-5 ml per liter of water.

Chemical Measures

Chemical control is an important aspect of managing wheat leaf blight disease. Some of the commercial chemicals used for controlling leaf blight are mentioned in the table below, 

Product Name	Technical Content	Dosage
Kavach Fungicide	Chlorothalonil 75% WP	1-2 gm/lit of water
Ergon Fungicide	Kresoxim-methyl 44.3% SC	1-1.5 ml/lit of water
Indofil Z 78 Fungicide	Zineb 75% WP	2-2.5 gm/lit of water
Vespa Fungicide	Propiconazole 13.9% + Difenconazole 13.9% EC	0.75-1 ml/lit of water
Bayer Buonos Fungicide	Tebuconazole 38.39% SC	1.25 ml/lit of water
Dhanuka M45 Fungicide	Mancozeb 75% WP	3-4 gm/lit of water
Blue Copper Fungicide	Copper Oxychloride 50% WP	1-2 gm/lit of water