DISEASES OF INDIVIDUAL FLOWERS

Anemone

STEM ROT Attacks the tuberous roots of the plants causing them to rot. They are waxy when cut. Control Dig up and burn.

CLUSTER CUP Attacks the leaves and stalks forming spots on them from which cup-like fruiting bodies are produced later. Control Remove and burn.

Antirrhinum

LEAF SPOT Attacks the leaves and stems, causing pale brown or whitish spot.

Control Spray with Bordeaux Mixture (usual formula). RUST Rusty brown patches on the undersides of the leaves. Spreads very rapidly.

Control Give ample room between the plants for circulation of air. Stagnant water-laden air encourages the disease. See that the beds are well drained. Avoid watering the foliage. Don’t leave the plants in the ground in the winter. Dust with sulphur or spray with one of the sulphur sprays at intervals.

Aquilegia

STALK AND BULB ROT A water-soaked spot appears on the stem, the leaves wither and die off.

CONTROL Remove and compost properly the diseased plants. Dig the bed deeply.

Arabis

WHITE RUST Appears as shiny raised white patches. Not generally severe.

Control Dust with a fine sulphur dust. Remove diseased flowers.

GREY MOULD Appears in patches on the leaves – pale in colour at first, turning darker later.

Control Dust with a fine sulphur dust.

Michaelmas Daisy (Aster)

WILT Enters through damaged portion of the plant. Leaves yellow and mottle in the summer, followed by com-plete browning when the whole shoot dies. Control Do not propagate unhealthy plants. Select clean shoots and take cuttings from them. STEM ROT Leaves and flowers hang down and become yellowish-green, later die off. The stem goes black. Control Do not over-manure the border; give dressings of lime at 175 to 210 g/m2 (5 to 6 oz per sq yd) once a year. Remove attacked plants.

Carnations

RUST Can be a serious disease of carnations, especially in a wet season. Yellowish-brown cushions appear on the leaves.

Control Pick off infected leaves. Have plants in a well-drained sunny spot. Do not splash leaves when watering. Spray with Captan. Centres.

LEAF SPOT Spots formed on leaves, often with black centres.

Control As for Rust above.

DIE-BACK AND WILT More prevalent under glass than in the garden. Control Do not grow carnations again in the same spot, and propagate from healthy plants.

Chrysanthemums

MILDEW White, powdery patches may be seen towards the end of the season on the leaves.

Control Spray with a colloidal sulphur wash when first noticed.

RUST Most varieties are attacked by this trouble. Rusty red spots are seen on the under surfaces of the leaves. Usually worse in dry seasons.

Control Watch out for rusty patches and spray at once with Captan. Burn all old infected plants. LEAF SPOT Dark brown patches appear on the upper surface of the leaves.

Control Compost properly badly affected plants and spray others with Bordeaux mixture.

Dahlia

WILT This disease causes the whole plant to wilt. Control Badly affected plants should be dug up and burnt. Any raspberry canes in the garden should be watched, and if they become affected they too should be dug up and burnt.

CROWN GALL Large gall-like growths appear in the base of the stalk.

Control Destroy affected plants. Plant clean in another part of the garden.

LEAF SPOT Usually appears late in the season. Light yellowish spots appear, later turning greyish-brown, from the middle. Dead tissues fall off. Disease lives through the winter in sticks or dead wood stored with the tubers. Control Plant out early in open situation. Spray attacked plants with Captan. Remove leaves in autumn. Plant least susceptible varieties.

DRY ROT Dry, unsuitable storage places seem to encourage this trouble. Control Dig up tubers before first frost. Stand upside down for several days to drain thoroughly. Protect from frost. Dust tubers with equal parts of sulphur and hydrated lime when storing. Disinfect storage place with a 2 per cent solution of formaldehyde.

Delphinium

BACTERIAL SPOT Deep black irregular-shaped spots appear on both sides of the leaves. Stalks may be affected, also seeds.

Control Collect and burn all diseased foliage. Spray regularly with Captan. In severe attacks cut down plants and burn.

MILDEW White flower-like dust is found on the leaves, stalks and blossoms. The leaves die off prematurely and the buds dry up. In severe attacks the whole plant is stunted.

Control Avoid over-manuring with nitrogenous matter. Give plenty of space between the plants. Spray with Cap-tan in warm, sunny weather.

Gladioli

BASE DECAY Reddish-brown raised spots appear on the leaves towards the base. These increase in size and may become black and pitted.

Control Destroy all diseased leaves by burning. Do not plant corms in heavy, wet soil. Only store healthy corms.

SMUT Black cushions appear on the corms, leaves and stalks. Corms become completely destroyed.

Control Remove and burn all infected plants. Dig deeply, lime heavily.

DRY ROT Corms will split and dry sunken spots appear, reddish-brown in colour. Leaves in spring turn yellow.

Stems decay at soil level.

Control Buy good clean corms. Remove scales and look for sunken spots.

HARD ROT Yellow patches, later turning brown, appear on the leaves. Dark hard spots appear on the corms. Fungus lives in the soil for four years.

Control Do not plant in infected soil. Reject infected conns.

Iris

RHIZOME ROT The rhizomes become soft, putrid and evil-smelling. Base of leaves rot away.

Control Do not apply lime as alkaline soil encourages the trouble. Burn all badly diseased specimens. Cut diseased portions from very slightly attacked plants and wash in a 2 per cent solution of formaldehyde. Replant in new or sterilized soil.

LEAF SPOT Yellowish-brown spots and stripes appear on the leaves in autumn.

Control Spray with lime-sulphur 1 litre to 100 litres of water, three or four times during the summer.

Lily of the Valley

BOTRYTIS Leaves wilt and turn brown.

Control Do not grow on infected soil. See that the trouble is controlled on pasonies and it then seldom attacks lilies of the valley.

Lilies

LEAF SPOT Reddish-brown spots appear on the leaves. Leaves will die, stem may dry up and flowers may be dis-torted. Trouble spreads rapidly.

Control Spray with colloidal sulphur two or three times at weekly intervals. In severe cases give the surface of the soil a good soaking with Captan and spray the young growths when they first appear in the spring. Plant bulbs on well-drained soil.

MOSAIC Leaves become mottled and distorted and petals remain closed. Control No known cure. Infected plants must be burned.

Lupins

ROOT ROT Attacks the roots of the plants, turning them black.

Control Do not add lime to the soil as this seems to encourage the trouble. Do not plant lupins on the same soil for four years.

Mignonette

LEAF SPOT Brown patches appear on the leaves. Usually found on plants grown on damp soil deficient in lime. Control Spray with Karathane. Give the soil a dressing of hydrated lime.

Roses

BLACK SPOT Dark spots appear on leaves and young stems. The whole bush may lose its leaves.

Control Spray with Captan directly spots are seen. Repeat the spray in 14 days. Spray next season as soon as young leaves are developed. Rake up infected leaves and compost them. Mulch the ground with sedge peat 25 mm (1 in) deep to prevent the spores blowing up from the soil.

MILDEW White powdery mildew will be found on the leaves, stems and thorns. The flower bud may also be attacked.

Control Spray with Karathane. See that the soil gets a good dressing of potash in the form of wood ashes at 280 g/m2 (8 oz per sq yd).

RUST Orange spots may appear on the under surface of the leaves. Leaves may fall in bad attacks.

Control Cut out diseased stems immediately they are seen. Spray leaves thoroughly with Captan.

Sweet Peas

STEM ROT Severe in wet seasons. Lower part of stem turns brown and rots off. Leaves turn yellow and wilt.

Control Avoid planting on infected ground. Apply wood ashes at 280 g/m2 (8 oz per sq yd).

STREAK Long brown streaks found on stems and foliage.

Plant looks sickly and very few flowers are produced.

Control Apply wood ashes at 280 g/m2 (J lb per sq yd).

Sweet Williams

RUST Reddish spots on the leaves.

Control Spray with Captan. Darker varieties seem to be more resistant to the disease.

Tulip

FIRE Scorched spots appear on leaves and stems. Pitted spots appear on the flowers.

Control Sterilize affected bulbs with formaldehyde. Immerse for 15 minutes in a 0.5 solution, i.e. 1 litre in 20 litres (1 pt in 1\ gallons). Spray with Captan when tulips come through ground, again 10 days later and again 10 days after that.

BREAKING Plant loses vigour and produces small blooms. Foliage is usually mottled.

Control Keep down insect pests, particularly aphides by spraying with liquid derris.

Violets

May be attacked by Smut, Rust, Leaf Spot and White Spot but none of these are very serious on cultivated violets and the best control in each case is to pick off the affected leaves and burn them and to spray with Captan.

FORMULAS OF INSECTICIDES AND FUNGICIDES Contact Sprays

NICOTINE AND SOFT SOAP 6 g (J oz) of nicotine (95.98%) and 50 g (2 oz) of a clear liquid detergent to 10 litres (2J gals) of water.

LIQUID DERRIS Buy the best types of this non-poisonous paralysing agent and use according to the instructions on the container.

PYRETHRUM The extract from the Pyrethrum flower, usually sold as Pysect.

Dust

DERRIS DUST Similar to a derris spray but not quite so effective.

Fungicides

LIME SULPHUR A brownish red liquid. Purchase it with a polysulphide content of 25 per cent and a specific gravity of 1.30. Never mix with soap.

BORDEAUX MIXTURE 900 g (2 lb) of quicklime and 1.3 kg (3 lb) of copper sulphate to 225 litres (50 gals) of water.

Mix the copper sulphate in water overnight in a wooden bucket or enamelled container. Slake the quicklime gradually with a little water and then add the rest of the water. Pour in the solution of copper sulphate and stir.

N.B. It is possible to buy Bordeaux in a paste and as this dissolves easily in water many gardeners prefer it. LIVER OF SULPHUR 150 g (5 oz) of liver of sulphur and 250 g (J lb) of soap to 45 litres (10 gals) of water. KARATHANE gives good control of the fungus diseases known as mildew.

CAPTAN has given good result in the control of Scab, Black Spot and Rust.

The ‘Incompletely Safe’ Fungicides (CAPTAN AND KARATHANE) Mr Dunstan Ingle reports: ‘Reading the extracts from the official literature, gardeners will see that both the fungicides are not entirely free from danger to human beings and animals. Admittedly they are of comparatively low toxicity, but they cannot be recommended completely safe for those who are very diligent organic growers. Captan is a good fungicide for the black spots like Black Spot on roses, and Rust on celery. Karathane has proved a good control of the Mildews.

Captan is of low toxicity to warm-blooded animals. May cause skin irritation. Is harmful to fish. May taint fruit for canning or quick freezing. Karathan can be irritating to skin, eyes and nose. Minimum interval to be observed between last application and harvesting edible crops – one week. Dangerous to fish.’

STERILIZATION

The Simple Copper and Bucket Method Take an ordinary bucket and perforate all over with holes about 50 mm (2 in) apart, fill with dry sifted loam. Place a fair sized potato in the middle. Hang bucket about 50 mm (2 in) above water in a domestic boiler. Turn heat full on and when potato is cooked the soil will be sterilized.

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