The A-Z Plant Health Handbook for New Zealand,
   by Jon Muller.

ROSE (Rosa)

These extensively cultivated plants come in a variety of forms, such as groundcovers, bush, and climbers. Roses as a general rule need good light, and soils with adequate moisture over summer but good drainage. They also need high levels of nutrients, so addition of fertilisers, as well as compost and mulch, is essential to get good growth.

If your rose dies or you wish to replace it, don't replant the new rose in the same position. It has been found that the old rose has an inhibitory effect on the growth of the new one.

	Symptoms: Yellow spots occur on upper surfaces of leaves, with tiny orange spots under the leaves.	Cause: Rust
	Solutions Cultural: Prune out infected material and destroy it. Ensure there is adequate air movement. Chemical: Apply copper oxychloride. Apply Greenguard or Bravo.
	Symptoms: Yellow speckling occurs with white webbing underneath the leaves. Leaf drop can be severe. This pest problem is prevalent in hot, dry conditions.	Cause: Spider mite
	Solutions Cultural: Provide more shelter from sun, and adequate moisture. Remove weeds. Alternative: Use garlic spray (see recipes, p.141). Use milk spray-125ml milk, 500g flour to 23l water. Use strong jets of water under leaves. Plant onion to deter the pest. Plant cosmos and yarrow to encourage ladybirds. Avoiding miticides may encourage ladybirds. Chemical: In late winter-early spring apply oil, and miticide, e.g. Mavrik when pest is present.
	Symptoms: Powdery white growth appears on new growth. This condition is common in summer and autumn.	Cause: Powdery mildew
	Solutions Cultural: Prune out infected parts; remove and destroy them. Alternative: Spray with a milk spray (500ml milk to 1l water) or mustard spray (see recipes). Use flowers of sulphur. Chemical: Apply Fungus Fighter or Supershield.
	Symptoms: Leaves turn silver and become much smaller. Infected branches die back. Bracket -like fruiting bodies appear on dead branches.	Cause: Silver leaf
	Solutions Cultural: Remove and burn all dead wood. Prune in late summer to early autumn when the weather is warm and dry. Spores aren't released at this time. Alternative: Insert Trichodowels (dowels with Trichoderma fungus) into the trunk.
	Symptoms: Leaves show yellow mosaic patterns or lines. Stunted growth occurs, with die-back.	Cause: Rose viruses Rose virus, showing mottling on the leaves
	Solutions Cultural: Remove and destroy infected plants. When using tools such as secateurs on infected plants, don't use the same tools on uninfected plants. Alternative: Grow 'High Health' roses that are free of viruses. As these viruses are not transmitted by aphids, the plants should remain healthy for some time.
	Symptoms: Small green or pink soft-bodied insects are found on leaf and flower buds. Flower buds can become deformed and not open properly.	Cause: Aphid Aphids on a rose
	Solutions Cultural: Check your watering, as drought stress can make the plant more susceptible. Apply mulch. Alternative: Use neem oil, onion/garlic or soapy sprays (see recipes). Attach yellow sticky traps. Hose off insects or squash them with your fingers. Nasturtiums planted nearby will lure away aphids. Plant blue tansy, cosmos, coriander, lavender, sunflower and yarrow to encourage parasites and predators. Avoiding chemicals may encourage natural parasites and predators. Chemical: Use Mavrik, Target or Confidor insecticide.
	Symptoms: Irregular, reddish-purple spots appear on leaves. Leaves may develop burnt margins and yellow areas with green blotches, and may drop off. Irregular, reddish-purple spots appear on flowers.	Cause: Downy mildew
	Solutions Cultural: Remove and destroy infected plant parts. Don't compost fallen leaves. Alternative: Use washing soda in winter (see recipes). Use flowers of sulphur. Chemical: Apply copper oxychloride or Bravo.
	Symptoms: Black spots appear on upper leaf surfaces. Leaves may drop prematurely. Flower buds may be deformed and not open. Flowers have shrivelled petals. This condition is prevalent in wet weather.	Cause: Black spot Black spot on a rose
	Solutions Cultural: Remove and destroy all infected leaves, flowers and prunings, rather than putting them in compost. Alternative: Plant chives close to roots. Chemical: Apply copper oxychloride during winter and before leaf burst. Apply Shield alternating with Bravo regularly over the growing season.
	Symptoms: Hard, grey-white, scale-like insects appear on woody and green stems. Poor growth occurs, with pale, dried-out leaves.	Cause: Scale insect
	Solutions Cultural: Prune out infected growth. Keep plants healthy in ideal growing conditions Alternative: Use mustard spray at bud burst (see recipes). Plant alyssum, cosmos, coriander and yarrow to encourage parasites and predators. Avoiding chemicals may encourage natural parasites and predators. Chemical: Apply mineral oil and insecticide, e.g. Orthene or Confidor, especially when the pest is young.
	Symptoms: The stem dies back, with a dead area in part of it (known as a cankered cane).	Cause: Rose fungal canker
	Solutions Cultural: Prune cankers back to healthy growth. Chemical: Apply copper oxychloride during the dormant period.

Excerpts

Looking after Roses & Camellias

List of plants included

Key to problems

Causes & Solutions

Guide to Chemicals
&
Alternatives to Chemicals

Introduction

Table of Contents

Links

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Acknowledgement