Turcicum leaf blight of maize

In this PPT you will come to know about TURCICUM LEAF BLIGHT OF MAIZE, its causal agent, epidemiology, favorable conditions of occurrence of TLB and its management practices.

1. PAT-301 DISEASE OF FIELD AND HORTICULTURAL CROPS AND THEIR MANAGEMENT -I (1+1)

2. TURCICUM LEAF BLIGHT OF MAIZE BY: B.SUBHASH (2018042069)

3. DISEASE NAME: Turcicum leaf blight PATHOGEN NAME: COMMON NAME: Helminthosporium   turcicum HOSTS: corn, Johnson grass (or) Sudan grass, sorghum, maize, Exserohilum turcicum

4. TAXONOMY Kingdom: Fungi Phylum: Ascomycota Class: Dothideomycetes Order: Pleosporales Family: Pleosporaceae Genus: Exserohilum Species: Exserohilum turcicum

5. INTRODUCTION Turcicum leaf blight (TLB) or Northern Corn Leaf Blight (NCLB) is a ubiquitous foliar disease of corn (maize) caused by Exserohilum turcicum , the anamorph of the ascomycete Setosphaeria. The TLB fungus survives through the winter on infected maize residue at the soil surface. Infection occurs during periods of moderate (64° to 81°F), wet and humid weather. The disease begins as long, slender, grayish or tan leaf lesions that run parallel to the mid vein. Lesions can eventually expand to a more oblong or “cigar” shape. Lesions may also form on husks. Loss of photosynthetic tissue can result in decreased yield, and silage quality can be affected.

6. PATHOGEN CHARACTER Mycelium is branched, septate, inter and intra cellular. Conidiophores arises in groups, long, unbranched, slightly curved,geniculate and yellowish brown Conidia borne singly, distinctly curved, fusiform, long, 3-7 septate.

7. SYMPTOMS Early symptoms are oval, water-soaked spots on leaves. Mature symptoms are characteristic cigar shaped lesions that are 3 to 15cm long.  Lesions are elliptical and tan in color, developing distinct dark areas as they mature that are associated with fungal sporulation.

8. Disease cycle

9. EPIDAMOLOGY T he fungus causing TLB overwinters as mycelia and conidia on maize residues left on the soil surface. Conidia may also be transformed into thick-walled resting spores called chlamydospores. During warm, moist weather in early summer, new conidia are produced on the old maize residue and carried by the wind or rain to lower leaves of young maize plants. Infection and disease development are favored by heavy dew, frequent rainfall, high humidity, and moderate temperatures. Infection by germinating conidia occurs when free water is present on the leaf surface for 6-18 hours and the temperature is between 66 and 80°F (18-27°C).

10. MODE OF SPREAD AND SURVIVAL Dormant mycelia in plant debris. Secondary spread through wind-borne conidia FAVOURABLE CONDITION Cool and humid climate.

11. MANAGEMENT Spray with MANCOZEB @ 2.0 g/lit. Resistant varieties - sartaj , Deccan 105 , trishulata , Deccan 109, EH-40146, JH-1267