Brown Spot of maize:
Symptoms:
- Water soaked lesions, which are oval, later turn into light green and finally brown. The symptoms can develop on the leaf blade, stalk, sheath, and husks. On the leaf blade, these lesions consist of small chlorotic round to oblong, yellowish to brown in color, spots, arranged as alternate bands of diseased and healthy tissue. On the leaf midrib, these lesions are circular and dark chocolate brown, distinctly different in appearance from those present on leaf blade.
Management:
- Cultural Control- Use disease free seeds. Field sanitation-removal of collateral hosts and infected debris in the field. Use of soil amendments.
- Chemical Control– Treat the seeds with Captan 50 % WP or Thiram 75 % WP @ 2g/kg. Spray the crop in the main field twice with Mancozeb 75 WP @ 600- 800g dissolve 250-300 lit. of water/acre once after flowering and second spray at milky stage.
Stem Borer:
Symptoms:
- The larva yellowish brown with reddish brown head and prothoracic shield and measures 25 mm long with series of black dots Adult is a medium sized straw coloured moth.
Management:
- Cultural Control: Destruction of stubbles, stalks, weeds and alternate host of stem borer helps in minimizing the pest build-up in the area. Removal of dead hearts and infected plants showing early pin holes damage also help in controlling this pest.
- Mechanical Control: Clipping of lower leaves of Maize (up to 4th).
- Biological Control: Release eggs of Trichogramma chilonis @ 20,000/acre at weekly interval 4-5 times starting with complete germination of the crop checks this pest effectively.
- Chemical Control: Spary of Fenvalerate 20% EC @ 120-160 ml or Cypermethrin 10% EC @ 220-300ml and Deltamethrin 2.8% EC @ 50-60 ml dissolve in 250-300 lit.of water/ acre after notice this pest.
Common Rust:
Symptoms:
- Circular to oval, elongated cinnamon-brown powdery pustules are scattered over both surface of the leaves. As the plant matures, the pustules become brown to black owing to the replacement of red uredospores by black teliospores.
Management:
- Cultural Control- Plant hybrids like Deccan, ganga-5, Deccan maize-103 and DHM-1 which are resistant to this disease.
- Biological Control- Soil application of Pseudomonas fluorescens or Trichoderma viride @ 1 kg / acre + 25 kg of well decomposed FYM (mix 10 days before application) or sand at 30 days after sowing.
- Chemical Control– Spray Mancozeb 75% WP @ 2.5g/lit. of water spray can be taken as soon as first symptoms are observed it can be repeated at 10 days interval till flowering.
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