The orchard management is a delicate and labor intensive job. The person incharge needs to have deal with the everyday problems. There are several chemicals and mixtures which are used to solve everyday problems.
Wound disinfectant solution
- Mercuric chloride : 1 g
- Methylated spirit : 250 ml
- Water : 750 ml
Glass vessels or porcelain jars should be used for preparation and storage of the solution. Apply the disinfectant solution on the cut-ends and the wounded surface with a large swap of cotton. Allow the disinfectant to evaporate and cover the treated surface with a brush.
- Copper sulphate : 2 Kg
- Quick lime : 3 Kg
- Water : 30 litres
Dissolve 2 Kg of copper sulphate in 15 litres of water. Take another 15 litres of water. With a small quantity of the second lot of water slake slowly 3 Kg of quick lime. Add the remaining quantity of water to it. Mix both the concentrated solutions and stir. Apply the paste to cut surfaces and wounds with a brush.
- Ridomil MZ : 2 g
- Linseed oil : 100 ml
Mix both the constituents thoroughly and apply the paint with a brush. A special painting kit (fungicide, linseed oil, sharp knife, brush, pruning sccateur and container) has been designed for the mass treatment.
- Lime (slaked) : 25 Kg
- Copper sulphate : 500 g
- Gum/Suresh : 500 g
- Water : 100 litres
Dissolve the suresh/gum in hot water. Add all the constituents thoroughly. Whitewash the main trunk up to a height of 30 cm from the ground level in February-March and again, before the onset of monsoon (July-August).
- Monohydrated copper sulphate : 1 Kg
- Hydrated lime dust : 2 Kg
- Boiled linseed oil : 3 litres
For the preparation of Monohydrated copper sulphate, spread the copper sulphate crystals on a sheet of iron (Tawi) or a frying pan over fire till they crumble into a white amorphous powder. Lime dust and copper sulphate powder are mixed thoroughly and then boiled and cooled linseed oil is added to the mixture. All the three ingredients are thoroughly homogenized. Bordeaux paint is now ready for application. It should either be stored in a closed vessel or made fresh, when required. Bordeaux paint makes the covered surface impervious to water. It is quite helpful in protecting the wounds from the wood rotting fungi.
Bordeaux mixture (2:2:250)
- Copper sulphate : 2 Kg
- Quick lime(unslaked lime) : 2 Kg
- Water : 250 litres
Copper, wooden or earthen containers should be used for the preparation of Bordeaux mixture. The raw material should be of good quality. Use copper sulphate of 98 percent purity. Quick lime should be free from earth and sand. Solution of copper sulphate and lime should be made separately. For preparing the copper sulphate solution, dissolve 2 kg of copper sulphate in 125 litres of water. Copper sulphate dissolves slowly in cold water. Thus use hot water or suspend copper sulphate in gunny sac into a wooden barrel or an earthen pitcher during winter season, so that the material remains immersed. Slake 2 kg of quick lime in another vessel and add water slowly, when the lime is completely slaked, add enough water to bring the volume to 125 litres. Then mix the two solutions either by pouring the copper sulphate solution into the lime solution slowly or the two solutions together into a third vessel. Strain the lime solution before mixing it with copper sulphate solution. Also, stir the mixture all the time while pouring. Stir and strain the mixture again when pouring into the sprayer pumps.
How to test Bordeaux mixture
a) If the Bordeaux mixture contains excess of lime, it turns the red litmus paper blue and if it contains excess copper, it turns the blue litmus paper red. An excess of copper compound in the mixture is toxic to foliage.
b) Dip a knife or iron blade or nail in the Bordeaux mixture and observe if copper deposits on it. A deposit of copper on the metal indicates that the mixture is unsafe. Add more lime solution to make the mixture safe.
c) A more accurate test can be made with ferrocyanide of potassium. Add a few drops of the Bordeaux mixture to small quantity of ferrocyanide. If no change occurs, the mixture is safe but if it turns into reddish brown colour, it indicates that copper compound is present in excess. So, add more lime solution to make the mixture safe.
Bordeaux mixture should not be applied, when it is raining or on exceptional hot day when the plants are showing sign of temporary wilting. Fresh Bordeaux mixture should be sprayed as it loses its fungicidal activity on storage.
Courtacy Agriculture Extension Wing Punjab Pakistan