WHEN TO SPRAY (against potato blight)
The right time for the first dusting or spraying is just before the leaves of the potatoes meet in the rows ; this usually happens at the end of June or early in July. Don’t wait until you see blight spots on the leaves— if you do find any, spray at once.
If dusts are used, further applications are needed every fortnight; with the spray, a second application after three weeks should be sufficient. But if the blight attack is severe, a third spraying may be needed in August.
Note on Copper Based Fungicidal Sprays
Bordeaux and Burgundy mixtures, copper based fungicides, are fairly effective against potato blight.
They were mainly superseded by more complex chemical remedies.
Burgundy and Bordeaux mixtures were organically approved until quite recently but are now delisted.
Now the organic grower can only hope resistant varieties will resist the strain of blight attacking and non-organic home growers have little in the cupboard to help them.
Making Bordeaux Mixture
If you prefer to make your own Bordeaux mixture here is the recipe. The quantities mentioned will make enough spray for about 2 rods of potatoes. Put 2½ gallons of water into a bucket; pour off a quart of the water into an earthenware or enamelled jug, and dissolve 4 oz. of copper sulphate in it (powdered or granular copper sulphate is preferable, as it dissolves easily).
In the bucket containing the remaining water dissolve 5 oz. of fresh hydrated lime and stir well. When the copper sulphate has all dissolved, pour the blue solution slowly into the bucket containing the lime solution, stirring all the time.
It is then ready for use and should be used the day it is made. To avoid clogging your sprayer, it is worth while straining the solution through a piece of muslin. Immediately after use always rinse the bucket or other container, as well as the sprayer, with clean water in which a little washing soda has been dissolved.
Points to Remember
- You can use a stirrup pump, if you obtain a fine spray nozzle for it.
- A misty spray is best, as it wets the foliage easily.
- If you have no sprayer, you can use a watering can with a fine rose.
- Make certain that both sides of the foliage as well as the stems are thoroughly wetted.
- Choose a fine day so that the spray has time to dry before the next fall of rain.
- It is much easier if you can cooperate with some friends or neighbours and spray several batches of potatoes on the same day.
Earthing up celery
Before you earth-up, tie the celery plants loosely just below the leaflets and remove any side growths.
When the plants are about 15 in. high, earth-up slightly, but see that the ground is thoroughly moist before you begin.
The second and third earthings—at three-weekly intervals— can be more thorough, until finally the soil should cover the plants right up to the leaves and should slope away neatly.
Don’t let any soil fall into the heart of the plant.