Powdery mildew is easily ­recognised by the appearance of a covering similar to talcum powder over the leaves, stems and flower buds.

Leaves covered with powdery mildew will become misshapen and eventually wilt and collapse. 

Flower buds will often fail to open properly. Vegetables affected by powdery mildew will give very low yields of fruit.

Powdery mildew affects large-leafed vegetables such as pumpkins, zucchini and cucumbers, as well as flowering plants, including roses, crepe myrtles and hydrangeas. 

Because the mildew results from the weather conditions, it is sometimes difficult to control and often appears very quickly. 

An older remedy that can be tried is spraying the plants with a mixture of five parts of full cream milk, ­diluted with one part of water. 

This will need to be reapplied every couple of days. 

The butterfat from the milk stops the spores in the mildew from ­germinating.

Alternatively, fungicides that have been developed especially for the control of powdery mildew can be used.

 It is important to use follow-up sprays at the recommended strength and time intervals. 

Some plants, such as crepe myrtles, have varieties that have been specially developed to be powdery mildew resistant. 

The provision of a good air flow around plants will also assist in the control of powdery mildew.

The weather conditions that result in the formation of powdery mildew may also lead to the formation of black spot on roses. 

This mildew disease appears ­firstly as black spots on the leaves. The pots then turn yellow, giving the leaves an unsightly appearance. 

The leaves will eventually shrivel and then fall from the plant. 

The fallen leaves are still covered in the fungus spores, which can then spread to other healthy leaves. 

For this reason, diseased leaves should be removed from the ground under the plants and then disposed of in the garbage. 

Certain varieties of roses have been bred to be “black spot resistant/ free”. 

A visit to local gardens or plant nurseries will indicate varieties that perform better in the weather conditions that are common in Australia at this time of the year.

Avoiding the watering of leaves on roses will help control black spot problems as the water that remains on the leaves will create the ideal environment for the formation of the spores. A good soaking, at ground level, is much more effective.

Feeding the plants with sulphate of potash, at the rate of about 100 to 150 grams per bush about four times a year, will ensure stronger, healthier plants that will be more resistant to black spot. 

Spraying the plants will still be required. There are plenty of safe and organic ways to treat black spot.

 A mixture of two teaspoons of bicarbonate of soda in five litres of water, with a couple of drops of detergent or a couple of drops of seaweed extract added to the solution, will make an effective and inexpensive spray. 

Otherwise Bordeaux mixture or one of the other copper-based fungicides can be applied.

Hanging baskets are an ideal way for gardeners to add colour and interest to courtyards, patios and outdoor living areas. 

An effective display that will last through the summer and into early autumn can be achieved in a relatively short time.

In the past, the flowers that were traditionally used required constant watering and attention, particular on days of high temperatures and hot winds. 

However, some newer plants that require less attention are now available.

One of the most colourful, and also one of the easiest to maintain is commonly known as million bells. 

These plants have been become quite widely available in recent years. 

Million bells, Calibrachoa, are ­available in quite a wide range of colours including; red, white, violet, cherry, ­golden yellow, blues and purples, peach and terracotta. 

The plant’s name comes from the ­profusion of small flowers that cover the plant as it trails over the edge of a pot or basket or spreads over the surrounding soil.

The trumpet-shaped flowers are quite like small petunias in appearance. 

Individual flowers reach about 2cm across and generally appear throughout the year, although during the warmer months the plants provide the best ­displays.

Million bells are quick growing and form a tidy, dome-shaped plant reaching 30cm in height, with a width of 50cm. 

Suitable positions range from full sun to partial shade. 

A well-drained soil is ­preferred.  

For maximum effect plants should be watered well during the growing season. 

geoffh.gardening@gmail.com

Maitland and District Garden Club