Finger Millet Downy Mildew: Sclerophthora Macrospora
- The infected plants are dwarf in appearance with shortened internodes.
- The leaves are formed closely and thus give a bushy and bunchy appearance.The leaves become pale green.
- The symptom is well expressed on the earhead which bears abnormal spikelets exhibiting various degrees of proliferation instead of normal spikelet.
- The whole earhead gives a brush-like appearance.
Identification of pathogen:
- Infected plant reveals the systemic mycelium of the fungus Sclerophthora macrospora within the crowns, stems, and leaves.
- A few axillary buds may escape the colonising hyphae emanating from the crown tissue and may produce an occasional healthy tiller free of mycelium. Mycelium has not been observed to progress far in roots.
- Mycelium is coenocytic, multinucleate, intercellular. Narrow “extension” hyphae, closely associated with vascular bundles, carry the fungus up the leaf sheaths.
- Localised branching and proliferation of these hyphae into the tissue between the bundles occurs, increasingly so in the upper sheath.
- Massive development of multi-diameter mycelium occurs in the lamina, again associated initially with the bundles.
- sporangiophores which protrude through the stomata and produce six or more lemon-shaped, apically poroid sporangia.
- Sporangia mature rapidly, each releasing 50 or more motile zoospores.
- Zoospores are ovoid to pyriform in shape.
- Affected plants should be destroyed by burning.
- Keep the field clean.
- In the case of severe attack spray Mancozeb on the standing crop at the rate of 2 g/litre of water.
- TamilNadu Agritech Portal