Tag Archives: Blight

The 6 main pest and diseases of rose & how to treat them.

Pest  and  Disease  Control  of  Roses  

Introduction  – What  is  IPC  and  its  Methods

For  those  that  have  followed  My  blog on

general  pest  &  disease  control   Will   remember  that    I  use  the  IPC  method  on  all  plants  especially  roses. So  you    will  just  need  to  skip  this  paragraph   until  you  get  to  the  one  you  that  you  know. For  those  that  are new .  I  will  briefly  explain  what  IPC  is  before  going  on to  the  Pest  and  Disease  section .

Briefly  I  P C  stands  for  :-

  • Identify  –  By  Identifying  the  pest  or  disease  you can  then  isolate  it  and   treat  it  without  harming  any  other  insects  or  predators  that  are  beneficial  to  the  plant
  • Prevention  –

Prevention  is  better  than  cure

If  you  followed  the  guide  lines  that  i  told you. You are   less  more  than  likely  to  get    infected by  a  blight  or  pest  but   like  the  common  cold  no  matter  how  much  we  keep  healthy  we  still  get  it.  so  is  very  much  like plants

in  their  case  they  will  become  less  sickly  if  we  observed  their  requirement  from  the  off  set  as  I   have  pin  pointed  in  the  first  blog  

Control   or  Monitor   methods –   And  finally  Control    With  the  pest  or  Disease on  rose    isolated  we  can  begin  the  applying  the  safe  practise  of  control   whether its  Chemical  or  Organic  or  mechanical

The 6 main pest  &  Diseases 

& How  to  treat them

The  main  6   pest  &  Diseases  of  roses  are :-

  1. Aphids  
  2. Black Fly
  3. White  Fly
  4. Mildew
  5. Rust
  6. Black Spot

There  are  others  pest  like  the  leaf  cutting  bee   thrips &saw flies   but  those  are  the  main  six

Saw  Flies

These are caterpillar-like larvae, which feed on the leaves of your roses in the spring. They are about 1 ¼ inch long and are light green, some with black spots. If you get on top of this pest right away, you should be able to control them by simply hand-picking them. Look for them on the undersides of the leaves.

Saw  Fly  symptoms

Saw fly larvae symptoms

These  you  just  simply  remove  and  incinerate as  the  caterpillar is  well  protected

Up  close  and  personal  these  critter  look  quite  menacing  a  little  like  caterpillars  but  in  a  large  abundance


Saw Fly  larvae  up  close  and  personal

Leaf  Cutting  bees


leaf  cutting  bee

Tel tail of leaf cutting bees





Thrips are tiny, slender, dark brown or black, sucking insects that damage and destroy opening rose buds turning them brown and leaving them only partially opened. They also feed on the upper surface of the leaf. They can be difficult to see outdoors. If you think that your rose may have thrips, take a cutting inside and shake it over white paper to see if any fall out. Look for a brownish black insect with a narrow body up to 1/16 inch long. They thrive in hot, dry conditions. Regularly watering your roses and spraying with an insecticide or simply cutting off the affected rose or leaf should do the job




I have   already  been  mentioned  in detail along  with  white  fly  in  the  following  blog




  1. 0258BlackFly  


Black  Fly

Black Fly

As  you  can  see  from  this  picture  these  pest  can  be  easily  Identified &  tend  to  swarm  in  colonies  attacking  anything  that  is  green  and  sappy  whether  it  your  green  beans or  bedding  plants  to  roses  that  have  been  over  feed  with  high  nitrogen  fertilizer  to  produce  sappy  growth .



The  best  way  to  prevent  your  roses  being  attacked  by  these  pest  is  to  carefully  check  your  feeding  of  roses.

As  I  said  above  these  and  other  pest  like  aphids  like  green  sappy  growth  for  their  piecing and  sucking  mouth  parts

Feeding this way causes problems for the plant: aphids can transmit plant viruses, and the sticky honeydew they exude can attract sooty moulds to grow

As  in the  case of  lime  trees  every    where

Good  hygiene  too   don’t  compost  any  infected  plants  in  winter  as  the  females  lays  its  eggs  in  the  autumn on  plants  to  feed  its  nurseries and  ounce  the  eggs  has  hatched  in  spring  they  fly  off   on to  much  better  food  supply  and the  circle  begins.

So by  either  bagging  up  infected  plants  or  burning  them  you  are  at  least  cutting  down  on  the  numbers  in  your  garden . But  since  they  can  fly  doesn’t  really  guarantee  you  that  you  are  free  them

So  we  go  to  the  next  Section

Control  or  Management 

There  are   3   methods  of  control

  1. Cultural  

By  this  mean   good  hygiene  and  feeding  regime  as  I  said  above  also  to  encourage  their  natural  predators  into  the  garden   like  Ladybirds lacewings   even  small  birds  feed  on  the  insects  now  and  again

Click to tweet   how   you  can  attract  more  predators into  your  garden  

Spraying  with  tar  oil  or  winter  washes   tends  to  work  well in  winter    when  the  female  lays  it  eggs

Click link to  learn  about  the Natural  Predators


2. Biological  Control  

is comparatively expensive, but effective – if you can create the right conditions. The main problem being that there will be a time lag between being able to source the biological control of Blackfly. Together with this, there will need to be enough Blackfly for the biological predators to act upon.

However  ongoing  research according  to  this  article  here  published  in  2005

This discovery has applications for pest management – the aphid sucrase enzyme could be a suitable target for specific inhibitors that would abolish its dual role in osmoregulation and carbon nutrition of the aphid.

that  these  pest  can  be  controlled  by  spraying  or  other  methods  not  yet  mentioned,

Current research is focussing on determining the mechanism – it’s possible that an anti-microbial with the symbiotic bacteria as the primary target may have evolved in certain plants.

As  I  already  have  gone  into  detail  about  the  use  of  chemical  as  a  method  of  culture  I  wont  go  into  detail  here  but  only  to  stress  the  dangers 

Disease  Control




The effect of Mildrew on roses

As you  can  see  from  the  picture  that  Mildew  can  be  easily  recognised  by  its  powdery  white  effect  on  leafs  and  stems .                        In  fact  Mildews  a  fungal  Disease  rather  like BlackSpot  but  cause  its  feeds  on  moisture  on  the  plant  leaves   it  easily  remedied  by  following  the  procedure


Cultural  control

If you  seen  any signs  on   your  roses  whether  on the  leaves  or  buds  its  best  to   prune  them  out  to  avoid  the  spores  from  spreading  any  further.

Good  hygiene  again  is  important  –  keep  the  center  clear  of  branches  in  the  spring  to  allow  air  flow  through  and  around  the  plant

Try  avoid  watering  from  above  or  in  between  the    branches  water  from  the  bellow ,

Avoid  watering  in  them  evening   go  for   in  the  morning    where  if  you  have  splashed  the  leaves  the  water  has  a  chance  to  dry  off

Plant  rose  far  enough  part  so  they  can  spread  out


Rose Rust


As  you  can  see  from  these  two  examples  that  rose  rust  can  be  easily  recognised  by  its  orange  flex on leaves  and buds

Rose  Rust

Rose Rust on buds

Rose  Rust

Rose Rust on leaves

And  like  Powdery  Mildew  its  a  fungal  disease  on  the  roses  but  less  severe. That  occurs  from  the  beginning  of  spring  right  up  to  summer  should  the  environmental conditions  be  right  for  the  spores  to  spread


6  Cultural  Methods of  controlling  rust  

  • Good  Hygiene  as  always  –
  1.  remove  infected    leaves  and  incinerate  to  prevent  the  spores  from  spreading    like  Black Spot   spores lay  dormant  in  the  on  the  soil  surface  until  they  are  either  splashed  up  by  the  rain  or  watering  from  above   or  carried  up  by  insects  especially  ants . So  clearing  the  ground  of  debris  around  the  plant  is  a  must.
  2. Pruning –  By  leaving  the  center  clean  and  cutting  out  crossing  branches  improves  the  air  circulation  around  the  plant  thus  reducing  the  breeding  grounds  for  the  spores  to  live  by  drying  out  the  leaves  and  buds.
  3. Weeding  –  By  clearing  any  weeds  around  the  plant  esp  oxalis  that  get  infected  by  rust  you  are  reducing  the  risk  of  it  spreading  to  the  roses
  4. Improve  the  soil  structure  of  the  soil  by  forking  over  the  ground  in  spring  to  improve  drainage
  5. Avoid  watering    from  above   always  water  from  the  base  of  the  plant
  6. Avoid  working  on  rose  beds  when its  wet  as  you  can  spread  the  spores  by  simply  walking  around .


Chemical  Control  

When  you  see  the  first  signs  of  rust    spray   the  entire  rose  bush  with  a  copper formulated  compound   examples  can  be  found  here     until  the  bush  is  cleared  giving  it  a  good  drench.

Always    go  by  the  rules  i have mentioned   for  proper  chemical  Management

Organic  Control

There  are  many  new  ‘organic  formulations’  on  the  market  you  could  try if  you are  organically  minded  one  is  the

Disease  spray

Vitax organic spray for pest and disease

Vitax  2  in  1  pest  and  disease  control  spray    Yet I  haven’t  had  the chance  to test  it  out  yet.

But  Vitax  is  reputable  firm  that  specialize  in Rose  Care  products

Black Spot.


Black Spot  spores  on  roses

Black Spot spores on roses

Finally  I  come  to  most  dreaded  killer  of  all  roses,

Black Spot  –  as  You  can  see  by  this  image    this  too  easily  recognized  by  it  instinctive black splotches  that  are  actually   spores .  The  thin  white  threads  are  in  the  roses  stem. hence once  you  see it  its  pretty  much  that  there is  no  real  cure  for  it  except  to  either  live  with it  or  destroy  the  bush  all  together.

In  cases  of  My  many  Clients  they  rather  live  with  it  until  it  dies  completely

So  what  can  be  done  to prevent  it


Cultural  Prevention

  • As  I  mentioned  at  the  very  start  of  the  Blogs  on  roses    That  when  planting  a  new  rows  always  make  sure  the  rose  gets  a  good  start
  • Mulching  around  the  roses  in  spring  with  sterilized compost  like  Cocopeat  or  peat based formulations     This  will  stop  any    fungal  spores  that  i  mentioned  above  from  splashing  up  and  infecting  younger  shoots
  • Pruning  out  any  dead  diseased  or  dying  branches  and  incinerating  it  (  Do  not  compost  them
  • Improve  the  air  circulation  around  &  inside  the  bush  by  cleaning  out  any  inward  pointing  branches
  • Don’t  plant  roses  close  together  as  one  rose  can  spread  the  disease  to  another  and  this  too  allows  air  to  circulate
  • Water  from  the  base  only

Chemical  Control  

Organic  Control


Disease Control

A potato plant infected with Phytophthora infe...

A potato plant infected with Phytophthora infestans. (Photo credit: Wikipedia)

With disease control I always apply  the  same  IPC (Identify Prevention Control  or  Management ) approach  that  I  use  on  pest  control.This leaves no  margin of  error and  the  problem  can  be  eradicated  or  at  least  controlled.

There are over at  least 100 diseases a  plant  gets  most  of  them  are caused  by  fungal  infection  black spot  on  roses, Tomato Blight,Peach leaf  curl  & powdery  mildew.

The  diseases  on  turf are  less  problematic


I will  first  deal  with  the  diseases of  vegetables


  • The  two  most  common  ones  are  Brown  spot
  • And  Blight  (early  Blight  and  Autumn)

Brown Spot

ImageHere  you  can  see  clearly  that  its  only  the  bottom  of  the  tomatoes  that  are  infected. The  blackish brown  indentation.

The  Good  new  is  that it  does  not  spread  in  the  field  or in transit  meaning  that  it  a  disease  to  that  particular  plant


In  this  case  prevention  is  better  than  cure  as  this  disease  can not  be  eradicated  by  commercial  or  organic  fungicides

  • The  cause  of  this  disease  is  the  lack  of Calcium  or  magnesium  in  the  soil
  • The  first  signs  of  this  deficiency  is  the  sickly  anaemic   look  on  the  plant  the leaves  go  a  slight  tinge  of  yellow  and  the  plants  rather  sick.

 This  caused  by  either  heavy  clay  soils  or  bad  drainage  where  the  roots  can  get hold  of  the  magnesium or calcium   in  the  soil

If  this  left  unchecked  then  your  plant  will  definitely  get  Blossom End  Rot.

Greenhouse tomato magnesium deficiency3F

  • With  recent  research  into organic  movement.Scientist  now  believe  that  to  help  the  plant  fight  of   disease an  application  of  asprin  will  do  the trick.            Although  this  seems  to  far  fetched. They  believe  that  the  chemical  pound a salicylic acid.( Salicylic acid is a monohydroxybenzoic acid, a type of phenolic acid and a beta hydroxy acid. This colourless crystalline organic acid is widely used in organic synthesis and functions as a plant hormone. It is derived from the metabolism of salicin) found  in  aspirin  will stimulate  the  plant  immune  system  so  its  ready  to  fight  back .
  • Making  note  of  the  right  environment  for  the  plant   is  the  soil  too  acidic  ,is  it  in  a  well  exposed  place  where  it  gets  full  days  sun. or  does  it  require  a  shady  spot
  •  Pest  are  there  aphids  around  – these  can  transmit  diseases  to  the  plant  by   sucking  the  sap

unfortunately  there  is  no  cure  for  blossom End Rot  the  plant  is  best  disposed  off


There  are  two types  of  blight  that  effect  the  tomatoes  one  appears  in  early  Autumn   and  the  other  one  in  Late  Autumn

Late blight

IdentificationLate blight on  stems  

  • Sign 1

As  you  can  see by  this  picture the  first tell tale signs or on  the  stems.

This  pathogen can  effect  young  plants  too.So your  best  defence  is  spot  it  early

  • Before  it  reaches  the   leaves  and  then  makes  it  way  toward  the  fruit . Then  the  plant  is  beyond  help and  best  destroyed (not  composted)


  • In  this  picture  you  can  see how  it  working  it  away  up  the  stem  to  the  fruit

Even   when  you  think  that  your  plants  safe  it  can  still  effect  ripening  fruit  and  in  no  matter  of  time  the  fruit  will  become inedible.


Sign 2

      •   As you  can  see  by  this  picture  that  the  first  thing  it  attacks  is the  leaves.

      Should  any  of  the  leaves  start  looking  like  that  its  best  to  destroy  the plant.Before  it  starts  to  infect  from  the rest  of  the  crop

      • prevention

      Since the  tomato  is related  to  the  potato family  its  very  liable  to  get  this  blight  and  ounce  its  air  Bourne  there  is  nothing  you  can  do  stop  it  effecting  the  plants

      But  there  are  cautionary  measures  you  can  take  to  give your  plant  a  chance  to fight  it

      • Hygiene I  can’t  amplify this  enough  as  with  Black  spot this  is  important  ;-
      1. If  growing  in  pots  make  sure  everything  is  cleaned  and  disinfected  first  or  use  new  plastic  pots.
      2. Use  Grow bags  compost  for  tomatoes  not  only  they  are  ideal   growing medium  but  there  cheap  too as  well  sterile
      3. As  with  Blossom End  Rot  or  BER    feed  with  a  fine  spray  of  Asprin Mix  and  also  water  into  the  soil
      4. To  stop  splash  back  and  reserve  water    apply  a  mulch  around   the  plant   and  pick  off  any  fallen  leaves
      5. Make  sure  that your    any  diseased  potatoes   are   disposed  off  and  the  soil  is  clean
      6. Choose  a  resistant  plant  species  esp  if  growing  potatoes
      7. Careful watering  try  not to  water  over  the  leaves  as  this  may  cause  the  fungus  spores  to  spread to  other  parts  of  the  plant
      • Management    at  the  first  sign  of  the  seedling  spray  with  Bordeaux mixture  or  there  alternatives
      1. Environmental  control  this  method  is  used  here  in  the  UK  where  the  farmer  keep  an  eye  on  the  weather  and  as  soon  as  the   Min temperature  reaches   50 degrees  and  the  humidity  is  at  90 %  then  he  will  spray  the  crop  to  stop  the  epidemic

      Unfortunately  ounce  the  plant  is  infected  there  is  no  cure

    • Black Spot
    • IdentificationBlack spot  on  rosesWhen  you  see  black  spot  what  you  are  really  seeing  are  the  fungal  spores  ie  Mushrooms of  the  fungus  known  as  Diplocarpon rosae.Unfortunately  this  fungi   is  resilent and   very  quickly  becomes  immune  to  anything  so  its  very  hard  to  eradicate .

      As  you  can  see  from  above  the  leaves  become  a  yellow  and  black  spotted  hence  it  name

    • A proper pruning  and  after  care  will  minimize  the  risk  of  reinfection  :-
  1. When  pruning  roses  always  cut  away  from  the  bud  in  a  slope  this  makes sure  that  any  fungus  spores  or  other  contaminates  will  run  off  and  not  go  into  the plant.
  2. Follow  the   three Ds  system  of  pruning  first  cutting  away  any  Dead  Diseased  and  Dieing  stems  and  throwing  them  away  with  the  rubbish
  3. keep  the  centre  clean  to  allow  better  air  circulation  around  the  plant  keeping  it  dry  (fungus  thrive  in  wet  conditions)
  4. In  April prune  to  the  first  out pointing  bud
  •  If  the  roses  have  any  aphids  then  spray  with  insecticide  for  full  details  on  which  insecticide  is  best   as  they  can  transmit  viruses    and  wound  the  plant
  • Buy  new roses  – But   don’t  plant  roses  in  the  same  spot  as  the  old  ones  cause  they  wont  live  long. For  some  reason  the  old  root  system  of  the  roses  send  out  a  chemical  warning  to  other  roses  saying  you  are  not  welcome  here  ie  a  Rose  transplant  disease . Also dont be disappointed after a yr or two that your roses have got that blight again .Cause as I said before this is most antiviral disease it soon gets immune to anything you throw at it
  • Use  a  fungicide  esp  for  roses  if  you  can  use  the  one  with  a  insecticide  included  these  will  at  least   protect  the  your  shoots  as  they  grow
  • After  pruning  give  them  a  good  feed  of  organic  matter  to   help  them  fight  this  fungus    or  give  them  some  pelleted  feed  esp  designed  for  roses  as  this  contains  traces  of  sulphur which  help  the  immune  system