Brochures

Plant Problems

Rose Problems

A rose problem is almost always a reflection of the plant’s environment. Poor drainage, insufficient moisture, infertile soils - are all environmental conditions that can lead to insect and disease attacks due to the plants weakened / stressed state.  All these conditions can be altered so the plant will grow and thrive.

Roses require a sunny site, with rich, moist, well-drained soil.  They require regular watering and fertilizing.  It is a good idea to mulch around the base of the plant to prevent moisture loss and keep weeds in check.

Insects

Aphids
  • soft bodied, sucking insects can be green, red, pink, brown, black and white
  • usually attack soft new growth, clustering on tips of young leaves, stems, flower buds and blooms.
  • cause disfigured or malformed leaves as well as curling
  • excrete a sticky substance called honeydew  that coats the leaves
  • the honeydew attracts ants and may develop sooty mold
  • prune off heavily infested parts of the plant
  • use less nitrogen fertilizer - so roses don’t produce an overabundance of soft new growth
  • spray rose with a strong spray of water to dislodge aphids
  • spray with an insecticide
Spider Mites
  • tiny red, brown, yellow or green   sucking insects
  • cause stippling and yellowing of leaves and in severe cases leaves will fall
  • fine, silk webbing can be seen on the leaves and at the leaf nodes
  • spider mites are worst during hot, dry weather
  • over-winter on weeds and garden   debris - do fall and spring clean up
  • spray plants with dormant oil in early spring to destroy any over-wintering eggs
  • in hot, dry weather spray down plants with water
  • spray severe infestations with an insecticide / miticide
Thrips
  • very small, long, slender light brown to black insects 
  • they suck sap from leaves causing silvery-white streaking or blotching
  • destroy and distort flowers and flower buds 
  • hard to see so take flower buds and shake over a piece of white paper — you will see tiny insects moving around.
  • spray with an insecticide
Rose Gall Wasp
  • wasps secrete chemicals that causes the swellings on the branches which contain eggs 
  • as the eggs start to hatch and larvae grow the gall swells  
  • green or red moss-like balls appear on the rose canes
  • cut out and destroy infected canes
Leaf Cutter Bee
  • perfect circular holes appear along the margins of the leaves
  • these round pieces are for making larval chambers
  • don’t really harm rose bush so     control is not necessary
Cane Borers
  • larvae from various insects enter canes through openings causing wilting, stunting, dropping buds and die back
  • can see entrance holes just below the flower buds
  • prune off infected canes just below site of infection
Pear Slugs 
  • small dark slugs are the larvae of a sawfly
  • scrape (eat) away surfaces of the leaves causing a skeletonized effect
  • damage is done quickly so act fast
  • hand pick them or spray with an insecticide

Diseases

Powdery Mildew
  • fungal disease that starts on young growth as raised blisters causing leaves to curl
  • eventually new leaves, flower buds and stems become coated with a thin, white powdery residue
  • causes stunting and distortion of buds and leaves, yellowing and premature fall of leaves and an     overall decline in plant health and vigour 
  • plant mildew resistant varieties, give plants room (don’t overcrowd), water in the morning so leaf moisture has a chance to dry
  • spray with a fungicide
Black Spot
  • fugal disease that first appears as black or brown spots on the leaves towards the bottom of the plant
  • the spots may spread to form blotches on leaves and canes
  • leaves turn yellow and drop
  • in severe cases rose bush can be  defoliated from the bottom up
  • plant resistant varieties, water around the base of the plant, clean up fallen leaves that harbour the fungus
  • spray with a fungicide
Crown Gall
  • bacterial disease that enters through cuts and other wounds
  • a lumpy tumor-like growth appears on canes or roots - most frequently at the bud union
  • causes decreased vigour, abnormal 
  • flower and leaf production and   eventually death
  • No cure, destroy entire plant!
Rust
  • fungal disease 
  • orange-red powdery spots appear on the leaves, stems and flowers
  • spots eventually change from orange to black
  • affected leaves wilt and drop off, in severe cases can defoliate bush
  • plant resistant varieties or spray with a fungicide

Cultural Requirements

Soil
  • slightly acidic
  • rich - amend with compost and well rotted manure annually
  • moist, well-drained - amend soil with zeolite to loosen heavy soils and improve drainage
  • mulch to prevent moisture loss and acts as an insulation layer for winter
Sunlight
  • a least 6 hours of direct sun a day
  • morning sun is better then afternoon because dew will dry more quickly reducing incidence of disease
Water
  • even supply of moisture, do not like to dry out
  • during periods of drought it becomes extremely important to ensure that the shrub is receiving ample water
  • If possible keep water off the leaves when watering as this will help prevent diseases
Air Circulation
  • give plants space
  • thin out crowded canes
  • need air to circulate through the branches and crown to prevent the onset of diseases
Fertilizing
  • use a well balanced fertilizer - high nitrogen fertilizers will give you lots of green growth and minimal flowers!
  • set up a fertilizing schedule from May till the end of July.

Try to supply the proper environment so that roses will grow and thrive and be better at fighting off insects and disease.  A healthy plant is going to be able to fend off pest attacks!