Black spot in roses is one of the most common problems gardeners have to contend with when growing these beautiful plants.
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Black spot is a fungal disease that thrives in wet, humid weather and appears as dark brown to black spots on the leaves which eventually turn yellow and drop off.
Black spot is not only unsightly but is quite debilitating for the rose, as it continually grows new leaves to replace those lost, subsequently weakening the plant.
I have found over the years there are several things you can do to curtail and gain some control over this menacing disease:
- Where possible, choose cultivars that are resistant to the fungus;
- Collect and destroy infected leaves;
- Avoid overhead watering and water only in the mornings;
- Plant roses in full sun at spacings which allows for plenty of air movement around each plant;
- Feed diseased roses with a high potassium fertiliser;
- Prune out the centre of roses to encourage air circulation
- Most importantly, begin a regular, preventative spray regime every seven to fourteen days, depending on the weather, how much disease is around and how susceptible the particular rose variety is to infection.
Ask your nursery about the copper-based fungicide products, or for a home made remedy, mix two teaspoons of bicarb soda in five litres of water to which is added a few drops of washing-up detergent.
It’s important to completely cover the foliage especially the underside.
Consistency in spraying is the key in helping combat this problem.
Pruning Climbing Plants
Climbing plants, as they develop, are often a source of confusion as to how to control prune them.
I find that most gardeners do one of two things - they either hard prune or just nibble the plants.
The methodology in pruning most climbers as a rule is to encourage side shoots from day one after planting, as these will promote the production of more foliage and flowers.
Regular shortening of long, vigorous stems is recommended and cutting stems of flowers for indoor decoration, as with picking roses, achieves the desired result.
Many of our native climbers make excellent groundcovers.
You will often find them sending out stems along the ground seeking out some nearby plants or structures to which they fasten.
If you don’t want this to happen you must cut back the offending stems, otherwise they can smother their neighbour.
To rejuvenate an overgrown plant involves removal of much of the growth, and in some cases, this may mean right back to the main stem.
But before you undertake such drastic action, keep in mind whether the plant will tolerate hard pruning.
When removing old stems, don’t just pull out long lengths, but prune them into short lengths before removing them as this prevents damaging good stems or, in some cases, pulling the whole plant and its support structure down.
Persistence and patience is required with many gardening jobs and pruning is one of them.
Diary
November 19: The Friends of the Clifford Craig Medical Research will hold a fundraising Garden Fete at ‘Jessiefield’, 678 Pateena Road, Longford, seven kilomtres from the Prospect turn off. This inspirational garden of Jenny and Peter Hughes will be open from 10am to 4pm with stalls, entertainment, refreshments and sandwiches, Devonshire teas and a sausage sizzle. Entry $5, under 16 free.
Daily: The Emu Valley Rhododendron Garden, 55 Breffay Road, Romaine is open 9am to 5pm. This magnificent garden is run by volunteers who must be commended for their tireless work in making this setting one of Tasmania’s major tourist attractions.