Diseases
There are three main groups of pathogens or disease-causing organisms that cause a range of symptoms. They are fungi, bacteria and viruses. These are all microscopic organisms, but the effect they can have on plants is very large compared to their size. They can reproduce and spread very quickly.
Fungal diseases include cankers, damping off of seedlings, mildews, galls, moulds, leaf spots, rusts, rots and wilts. Once a plant is infected with a fungus, it is often difficult to eradicate it.
Bacterial diseases include blights; leaf, flower and fruit spot; canker; rot; and die-back.
Viruses are tiny, non-living particles that infect plant cells. They cannot be controlled directly by chemicals. They commonly cause stunting, mosaics, distortion, chlorosis or yellowing, poor flowering and fruiting, and streaking. You can buy 'High Health' plants that are free of all known viruses when sold, but they are not resistant to infection later. Roses and daphne are two examples of 'High Health' plants that can be purchased in garden centres.
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Brown Patch
Brown patch is a fungal disease of lawns which enters through the root system This fungus can grow without grass being present. It is a favourite of cool season grasses such as fescue, rye grass and bent grass and prefers hot and humid weather. The best method of control is prevention. If you’ve had the problem in previous seasons, avoid the use of high nitrogenous fertilisers in spring. Remove all lawn clippings after mowing to prevent the fungus being spread to other areas. Mow regularly to prevent excess thatch build up and irrigate in the morning only.
Symptoms
Brown patch starts with small discoloured patches of grass which later spread to form irregular dead patches a metre or more in diameter. Close inspection of the roots of damaged lawn will reveal that they have turned black.
Solution
Greenguard Fungicide is a general garden fungicide that controls disease through absorption working from the inside out. It is a blend of two active ingredients which work together to prevent and cure fungal infections in a range of edible and ornamental crops.
Brown Rot
Brown rot is a problem mostly of stone fruit such as peaches and nectarines. The fungus overwinters in mummified fruit which has either fallen to the ground or is still attached to the tree. Cankers on stems and spurs are another source of disease spores. At blossom time the fruiting bodies of the fungus develops toadstool-like structures which shedmillions of spores. These spores will shed at the slightest disturbance.
Symptoms
Flowers of fruit trees wilt and turn brown. Flowers will often stay attached to the tree. Brown spots appear on fruit which expands to a powdery mass of tan coloured spores. The fruit quickly rots, and if left on the tree will dry and turn into a “mummy”.
Solution
Guardall is an all purpose insecticide and fungicide spray. It controls a wide range of pests and diseases on ornamentals and other plants iincluding tomatoes, stonefruit and cabbage. This usually helps prevent further infection from spreading to uninfected blooms. You should then remove any infected fruits, mummies, twigs, and areas of bark which show lesions. Often you can prune out the infected cakerous lesions rather than having to cut off an entire limb. However, be sure that you have sprayed first so that any spores you stir up in your pruning and removal efforts are not spread to uninfected areas of the tree.
Damping Off
‘Damping off’ is a disease caused by a soil-borne fungus and affects germinating seeds and young seedlings. It can be identified by watery rot in the taproot at the soil line and the yellowing of leaves. Damping off usually occurs under moist still-air conditions and overwatering.
Symptoms
Infection results in lesions at or below the soil line. The seedling will discolour or wilt suddenly, or simply collapse and die. Above ground symptoms of root rot include stunting, low vigour, or wilting on a warm day. Foliage of such plants may yellow and fall prematurely starting with the oldest leaves. The roots of a diseased plant will have some shade of brown or black and evidence of water-soaking.
Solution
Copper Oxychloride is a fungicide that controls a wide range of fungal and bacterial diseases on fruit, vegetables and ornamentals protecting the plant.
Downy Mildew
Downy mildew is a group of fungal diseases that affect a wide range of plants. Symptoms include dark patches on top of the leaves, often with corresponding furry or downy growth on the undersides. These tufty growths may be purplish in colour. Downy mildew occurs in humid conditions and affects vegetables, fruits and ornamental shrubs and flowers. Susceptible plants include roses, hebes, lettuce, cucurbits, grapes rhubarb.
Reduce the risk of disease developing by growing plants in open positions with good air circulation. Avoid watering over leaves. When applying a funcigide, take special care to contact the undersides of leaves.
Symptoms
Downy mildew infection begins as angular yellow spots on the upper leaf surface. Then they become brilliant-yellow. Eventually, the internal parts of these spots become brown with yellow margins. The underside of this infected leaf has fine, greyish fungal growth. Infected young shoots, fruits, and seeds have white coating of fungal spores.
Solution
Champ DP Copper Fungicide is a copper fungicide which gives protection against a wide range of fungal diseases. Suitable for use on fruit, vegetables and ornamentals.
Early Blight
Early blight (sometimes called target spot) is a fungal disease that most often affects tomatoes and potatoes. It starts by causing distortion of the new growth, followed by brown or black spots. Gradually the whole plant withers, yellows and dies. The disease is difficult to treat once established but its entry into the plant can be prevented by spraying with a protective fungicide. Early blight often occurs during humid weather and is most likely to attack plants under stress. Remove dead or damaged leaves and make sure there’s good air movement around the plant.
Symptoms
The most characteristic symptom of early blight is expressed as small, brown spots on the lower or older leaves. The circular to angular spots enlarge until they are 1/4 to 1/2 inch in diameter and soon develop dark, concentric rings or ridges, producing a "target-board" effect. Affected leaves develop yellow areas around the lesions. Spotted leaves soon turn yellow, wither, and drop off. In severe cases plants can become completely defoliated late in the season.
Solution
Copper Oxychloride is a fungicide that controls a wide range of fungal and bacterial diseases on fruit, vegetables and ornamentals protecting the plant.
Lemon Verrucosis
Also called lemon scab, this fungal disease causes raised roughened warty lesions to form on the outside of the fruit. Rough patches also appear on the stems and leaves, and fruit drop often occurs. Although the inside of the fruit is unaffected, the disease should be controlled because it gradually reduces the vigour of the tree. Damp, cool weather encourages the disease.
Remove affected fruit, twigs and leaves. Dispose of them in the garbage. Copper spray should be applied before, after and during flowering to prevent further infection.
Symptoms
Brown scabs or blisters on the fruit and foliage.
Solution
Copper Oxychloride is a fungicide that controls a wide range of fungal and bacterial diseases on fruit, vegetables and ornamentals protecting the plant.
Peach Leaf Curl
Leaf Curl is a fungal disease which over winters in the crevices of the tree bark and around the buds. One or two well timed applications for most stone fruits should control the disease. The timing of the fungicide spray varies with differing stone fruit varieties. For apricots, spraying at 90% leaf fall and again as buds show pink is recommended. For peaches, spraying is best in late winter when buds first swell (bud scales start to loosen).
Symptoms
Leaves are curled, change colours and are severely deformed. Leaves finally turn brown, shrivel and drop from the tree. Fruits may drop early, or turn reddish-purple with warty growths on the outer surface.
Solution
Bravo Fungicide is a highly effective protectant fungicide. It controls a wide range of fungal diseases on fruit, vegetables and ornamentals. Bravo is stable in sunlight and its spray deposits are redistributed during rain, giving effective control over a long period of time.
Powdery Mildew
Powdery mildew is a fungus which spreads a white or ash-grey film over the upper and lower surfaces of the leaves of plants-usually the older leaves. Powdery mildew fungus favours high humidity and dry conditions. Water splash and air currents spread the spores of powdery mildew which grows on the surface of the leaf only. Powdery mildew is a common disease of roses, crepe myrtles, dahlias, zinnias, calendulas, sweet peas, cucurbits and vine crops. Spray regularly for control in warm and humid conditions.
Symptoms
Appearance of a whitish film on leaves and buds. New growth is distorted and older leaves become blackened. Flower buds may fail to open.
Solution
Greenguard Fungicide is a general garden fungicide that controls disease through absorption working from the inside out. It is a blend of two active ingredients which work together to prevent and cure fungal infections in a range of edible and ornamental crops.
Rose Black Spot
Leaf spots are easily seen and may be serious on roses, which is very commonly attacked by black spot. Spores are easily spread by water splash and infections take hold when the water remains on the leaf for about 6-7 hours. Areas with high summer rainfall and high humidity usually have the highest incidence of black spot. Treatment of the disease is year round as the fungus over winters on stems and leaf litter. All diseased leaves should be raked up and disposed of. Diseased stems need to be pruned back to healthy wood. Spray roses with a Lime Sulphur spray in winter and start an early preventative spray program at the beginning of spring once foliage emerges.
Symptoms
Circular black spots on the leaves which are fringed with yellow margins. The spots are black and can also appear on the stems. The leaves will fall prematurely and if left unchecked can lead to defoliation of the plant.
Solution
Supershield Rose Spray controls various insects, mites and diseases on roses and ornamentals.
Rust
Rust fungus is easily identified by the many orange or red pustules on leaves or stems which break open and release masses of spores. Rust fungus grows within the leaf so there is usually a copy of the spores on the underside of the leaf as well. Different rust fungi attack different host plants so rust on gerananiums won’t spread to other types of plants. Rust is a common disease of calendulas, roses, snapdragons, geraniums, gerberas and beans. Rust can also attack turf. It has become a serious disease of willows and poplar trees.
Symptoms
Orange pustules on leaves or stems.
Solution
Bravo Fungicide is a highly effective protectant fungicide. It controls a wide range of fungal diseases on fruit, vegetables and ornamentals. Bravo is stable in sunlight and its spray deposits are redistributed during rain, giving effective control over a long period of time.
Sooty Mould
Sooty moulds are fungi which cover plant leaves, stems and twigs in a black sticky substance. In almost all cases, the sooty mould is secondary to an infestation of insects that secrete honeydew. These insects include aphids, scale, mealybugs and white flies. Treating the insects will remove the source of the honeydew and dry up the sooty mould, which will eventually fall or wash off the foliage. The mould itself does not feed on the plant, however as it covers the leaf surface, it is blocking light and reducing photosynthesis, essential for plant growth.
Symptoms
Black sooty growth covering any part of the leaf, stem or branch of plants. Usually can be rubbed off with soap and water.
Solution
Bug Oil Conqueror Oil Insect Spray Ready To Use is a ready-to-use insect spraying oil for the control of scale, mites, aphids, white fly and mealybugs on roses and ornamentals.
