How to grow Techniques Rose Clinic

Rose Clinic

Symptoms, diagnosis and treatment for all your rose problems

 

Aphids

Symptoms: tiny green 1mm long insects gathering in numbers on new foliage and buds.

Diagnosis: aphids are sap-suckers that love the new growth and tender young buds of roses. They cause stems to wilt and can also cause problems by transmitting diseases from one plant to another.

Treatment: remove them with a gloved hand, or if you are squeamish, use a pyrethrum-based spray. Persistent infestations may require the use of stronger sprays such as Confidor or Mavrik. Use strictly in accordance with directions and follow safety precautions.


 

Thrips

Symptoms: a white mottled appearance on leaves, browning of petals and flower drop

Diagnosis: pale-coloured roses can be affected by thrips. These tiny threadlike insects suck the sap from the flowers, and can also spread plant viruses. If left unchecked the leaves, new shoots and flowers will become deformed.

Treatment: thrips lay eggs in unopened buds making them difficult to control. They blow in on westerly winds and infest certain light-coloured roses, then pass on to other areas. New flushes of roses will be fine.


 

Scale

Symptoms: white-crusted stems

Diagnosis: scales are small, sap-sucking insects with a hard cap which is hard to remove. Scales found on roses include cottony cushion scale, red scale and rose scale.

Treatment: Oil sprays such as Eco-oil or Pest Oil kill all stages of scale insects by suffocation and have low impact on beneficial insects.Yates Lime Sulphur is also a useful tool in reducing the population of scale; spray on to onto bare stems after winter pruning. Best treatment is prevention – scale is only found on weak roses.


 

Two-spotted mite

Symptoms: tiny insects invisible to the naked eye, but seen as webbing and silvering of new growth.

Diagnosis: this insect was formerly called red spider mite, and is hard to control. It loves hot dry weather.

Treatment: insecticidal potassium soap sprays such as Natrasoap work by blocking the breathing pores and dissolving the scale’s outer covering, causing dehydration. These treatments will not harm beneficial insects and have a very low toxicity to people and pets. The use of Mavrik should control this pest but in the case of severe infestation the use of predatory mites is helpful. Contact Integrated Pest Management. P.O. Box 436 Richmond NSW 2753. Yates Lime Sulphur is also a useful tool in reducing the population of two-spotted mite, spray onto bare stems after winter pruning.


 

Grasshoppers

Symptoms: flowers chewed

Diagnosis: in dry times grasshoppers will eat flowers.

Treatment: because grasshoppers move so quickly, they are impossible to control. 

 

 

Fungal disease

Symptoms: black spots with yellowing leaves; white or grey powdery coating on leaf

Diagnosis: fungal disease, the scourge of roses grown in humid climates, can cause major decline in the health and vigour of your roses.

Treatment: apply a fungicide once a fortnight. Spray applications should begin when the first leaves appear in spring, and continue through summer and autumn. Recommended chemical products are Rose Shield and eco Rose. These are good, used alternatively. Spray till the plant is dripping with the mixture. 

 

 

Planting for health

Avoid planting beneath trees as roses do not like competition from tree roots or shade

Avoid planting in saturated or boggy soils or after heavy rainfall

Avoid adding manures or fertilisers in the planting hole - new feeding roots will be damaged if they make contact with these materials at planting time.

Avoid planting too closely, as roses that get tangled into each other are harder to prune and more susceptible to fungal disease.

Avoid tying climber and standard roses too tightly. Figure of 8 loose ties are best

Avoid overhead watering and watering during the hottest part of the day as this will promote leaf fungal diseases.

Avoid using chemical fertilisers until the plants are in full leaf as this will burn young roots. We like organic fertilisers which can we used anytime, enrich the soils, and feed our plants.

 

 

Rose care calendar


We’re keen advocates of the ‘prevention is better than a cure’ regime for roses. Here is our annual program for optimal rose health.

 

Spring

Water: once a week give a full watering can and seaweed solution to the root systems of every rose.

Spray: every second week spray with Yates Rose Shield plus seaweed solution (Plant Health Spray), alternate every second week with eco oil plus eco rose

Feed: every six weeks with organic pelleted rose food

 

Summer

Water: twice a week give a full watering can and seaweed solution to the root systems of every rose.

Spray: every week with Yates Rose Shield plus seaweed solution (Plant Health Spray), alternate every week with eco oil plus eco rose

Feed: every six weeks with organic pelleted rose food

Pruning: trim by one-third to encourage a better autumn flush

 

Autumn

Water: once a week give a full watering can and seaweed solution to the root systems of every rose.

Spray: every week with Yates Rose Shield plus seaweed solution (Plant Health Spray), alternate every week with eco oil plus eco rose

Feed: every six weeks with organic pelleted rose food

 

Winter

Water: no watering

Spray: lime sulphur is spray useful in reducing the population of insects, disease, fungal spores and insect eggs, disinfecting the rose giving it a fresh start for the coming spring season. This must be done onto bare stems, not on leaves, so is a job for just after the winter prune

Pruning: winter prune in late July-August, depending on where you live. Tidy up climbing roses.

Feed: fertiliser is unnecessary, but you can condition the soil around your rose with seaweed (actual seaweed, seaweed granules or pellets such as Seamungus)

Other jobs: Check ties on standard roses and climbers so they aren’t ring barking the stems.

 

Text: Sandra Ross

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About this article

Author: Sandra Ross