Plant Propogation and Nursery Management

Exercise 15

Part-II Application of plant protection chemicals in the nursery.

Materials required: Specific pesticide, spraying equipment, sensitive balance and water.
Procedures:

• The nursery plants being tender in nature are more prone to be infested by insect-pests and disease and may cause considerable loss. Some of major insect-pests include scales, thrips, white flies, beetles, mealy bugs, mites, leaf eating caterpillars, leaf miners, cutworms, snails and slings.
• The common diseases are damping off, powdery mildew, leaf spots, blights and dieback etc.
• Damping off is caused by many fungi but Pythium, Phytophthora, Rhozoctonia and Botrytis are major casual fungi. It usually appears shortly after the emergence of seedlings. The main symptoms of this disease are the girdling of the seedling stem near the soil surface.
• The prevention of these diseases, insect-pests and environmental factors can be made in following ways.
Disinfestations:

• It is the process of removing organisms from the seed surface. The chemicals used to disinfect the seeds are ethyl alcohol, calcium hypo chloride and mercuric chloride.
• In general, 50 percent ethyl alcohol, 2 percent calcium chloride and 0.01 percent mercuric chloride concentration are used.
• The duration of treatment varies from 5 to 30 minutes, depending on size and type of the seed. Prolonged soaking should be avoided as it affects germination. After treatment the seeds are washed with tap water and immediately sown in the nursery.
Disinfection:

• It is the process to eliminate seed borne diseases. Hot water treatment is most effective disinfection treatment. In this treatment dry seeds are kept in hot water (50 to 55oC) for 10-30 minutes, depending upon the kind of seeds and type of pathogen.
• Seeds should be stirred continuously and temperature and duration of treatment should be monitored precisely.
• The seeds are spread in thin layers after the treatment and sun or air drying is followed and sown afterwards. Seeds can also be treated with mercuric chloride and formaldehyde. Nowadays, aerated steam is used commercially.
• This involves precise control on temperature and vapour flow rate, where injury to seeds is minimum.
Precautions:

• Precise control of time and duration of treatment is necessary.
• Seed viability may be lost if not done properly.
• Injury to seed coat or embryos should be avoided.
• Proper drying is required before storage or sowing.
• Protection: Treatment of seed with different chemicals to protect from pathogens is protection. It includes dry seed treatment and wet seed treatment.
• Dry seed treatment: In this method, seeds are thoroughly shaken with chemical in a rotating seed duster for some time, so that chemicals stick properly to the surface. Commonly used chemicals are Brassicol, Captan, Agrosan-G, Ceresan, Thiram and Dithane M-45.
• Wet treatment method: In this method seeds are immersed in the liquid suspension of t chemical for specific time. Continuous stirring is required so that chemicals do not accumulate at base. After treatment, seeds are dried in sun or shade.For the control of common insect-pest and disease of nursery and their management is listed in the following table:
Common insect-pests and diseases of nursery and their management:

A. Insect pests	Management
Scales	Single spray of Rogor or Metasystox (0.05 percent) is quite effective. Repeat it after 15 days interval. Crude oil spray is also useful for controlling the scales.
Thrips	Two sprays of Metasystox or Rogor (0.05 per cent) at fortnightly interval on new growth reduces the population of thrips considerably)
Mealy bugs	Collect and destroy the adults. Soil raking in December-January to kill the pupae. Spray Dimethoate (0.05 per cent) on the crawling insects during February-March Use Ostico sticky bands on the trunks of the mother plants.
White flies	Spray Phosphomidon (0.02 percent) or other systemic insecticide in the early stages of infestation.
Mites	Give two sprays of Acaricides like Dicofol(0.05 per cent) and Wettable Sulphur (0.2 per cent) at fortnightly intervals.
Leaf eating caterpillars	Spray Sevin/Carbaryl (0.1 per cent) at the first appearance of the caterpillars. Neem oil (1 per cent) is also effective.
Cut worms	Use light traps for catching the adults. Use poison baits consisting of Malathion (0.1 per cent) , wheat bran and jaggery. Spray Malathion or Quinalphos (0.05 per cent) before the expected attack of the worms)
Leaf miners	Two sprays of Metasystox or Rogor (0.05 per cent) at fortnightly interval on newly emerged growth flushes are sufficient for controlling the population of leaf in the nursery.
Snails and slugs	Hand picking and destruction is the most effective method. Spray of common salt (2 percent) is very useful in controlling snails and slugs. Use Metalaldehyde pallets.
B. Diseases
Damping off	Treat seeds before sowing with ceresin, Thiram or Agrosan @ 2 g per kg seeds. Spray Captan or Bavistin (0.2 per cent) in the nursery.
Powdery mildew	Give one prophylactic spray of Karathane or Calixin or Wettable Sulphur (0.2per cent). Repeat it again if cloudy weather persists for a longer period.
Blights	A single spray of Dithane Z-78 or Bavistin (0.2 per cent) is very effective to check blight disease in the nursery plants
Leaf spot	Give a single spray of Dithane Z-78 or Bavistin (0.2 per cent)
Dieback	Prune the dead portion of plant. Apply Blitox or Bordeaux paste to the cut portion. Spray Benlate (0.2 per cent ) as soon as the symptoms become visible.