Shorter persistence pesticides (that are usually certified for organic growing) are likely to be less damaging to non-target wildlife. Adult females of this species mature in September or October, they are 5-7mm long dark brown and convex, immobile and attached to host plants stems. The adult male is winged and pinkish, at only 1.5 mm longit is rarely seen. Males die after mating but the females overwinter and produce white waxy egg masses in May or June. The egg masses are usually only found on stems and the wax can be pulled out in long threads; these characteristics distinguish this species from other insects that produce white waxy coverings such as cushion scale, fluted scale, horse chestnut scale, woolly aphidand mealybug. As with other powdery mildews, these species grow initially over the leaf surface, feeding from the tissues but not killing them, and producingairborne spores which spread infection.Later the tissues die and, unusually for powdery mildew infection, drop out leaving holes and tattered edges to the leaves. An overwintering stage is of minor importance, most survival through the winter is as mycelium on the evergreen leaves. Powdery mildew or leaf spots: leaf removal is not recommended as it would cause severe defoliation. Unless very severe, these infections should be tolerated

On evergreen rhododendrons, actual growth of the funguson the lower leaf surface can be hard to detect, but infection tends to cause pale green,reddish-purpleor yellowish patches on the upper surface Powdery mildew, rustand leaf spots:The fungicides tebuconazole (Provanto Fungus Fighter Concentrate), tebuconazole with trifloxystrobin (Provanto Fungus Fighter Plus, Toprose Fungus Control & Protect), and triticonazole (Fungus Clear Ultra)are approved for the control of powdery mildew and rust diseases on ornamental plants. They would probably also give some control of rhododendron leaf spots (Provanto Fungus Fighter Plus and Toprose Fungus Control and Protect mention'leaf spot of ornamentals' on the label). Usually on azaleas, the leaves become very pale, swollen and distorted, then covered in a bloom of white fungus spores Sudden wilting and collapse of the whole plant can occur, or there can be a slower and more gradual decline The majority of the growth of most powdery mildews is found on the plant surface. The fungus sends feeding structures into the surface cells, greatly reducing the vigour of the plant. Because of this surface growth, powdery mildews are even more influenced by the environment than other plant diseases. Choosing the right plant for the right place, along with some simple measures to adjust the environment can go a long way to minimising powdery mildew issues in gardens.Where you cannot tolerate scurfy rose scale, manage them using the information above as your first course of action. For scales on deciduous plants including edible fruits, a plant oil winter wash (considered organic e.g. Growing Success Winter Tree Wash) can be used. This can control the overwintering scale nymphs in December-January when the plants are fully dormant Powdery mildew: the powdery mildew fungus over-winters in the buds and when these start to growin the spring it produces airborne spores which spread the disease. The pathogen originated in north America, but is now present wherever vines are grown. Leaf infection reduces plant vigour. When fruits are infected they split as they expand and this allows secondary infection by grey mould ( Botrytis cinerea).

Similar non-chemical control measures can help to prevent infection by leaf spot fungi, downy mildew and grey mould,which are all 'wet weather' diseases (see the 'biology' section, below): Petal blight: the fungus causing petal blight produces wind-dispersed spores on old infected flowers which remain hanging on the plant from the previous season. Unusually for powdery mildew infections, the brown tissue then drops out, often leaving irregular holes in the leaves, and tattered edges which look more like insect damage than disease. The marginsof the holes often have a corky, brown appearanceEncourage predators in the garden, some ladybirds, parasitoid wasps and some birds will eat scale insects.The native kidney spot ladybird, Chilocorus renipustulatus,specialises in feeding on scale insects and can naturally coloniseaffectedplants reducing populations

The RHS believes that avoiding pests, diseases and weeds by good practice in cultivation methods, cultivar selection, garden hygiene and encouraging or introducing natural enemies, should be the first line of control. If chemical controls are used, they should be used only in a minimal and highly targeted manner. Non-chemical control

Stemphyliumsp. causessmall, dark brown or purple spots on the leaves. The spots do not merge together, nor enlarge in size. The centre of the lesion can sometimesbecome pale in colour. The infected leaves shrivel prematurely and can either remain on the plant or drop off. Where you cannot tolerate scale, manage them using the information above as your first course of action. Asexual spores (conidia) of the g rey mouldfungus are always present in the air. They require leaf wetness or very high humidity to germinate and infect. Damaged or senescent plant parts are a very common way in which the fungus gains entry to the plant. The disease has a huge host range, and is active over a wide temperature range.