Pests & Diseases

Fungal diseases in roses are due mainly to weather conditions and the variety of rose that you have. Cloudy, wet, humid weather is the precursor for the 3 main funguses to thrive. BLACK SPOT, POWDERY MILDEW and RUST.

The variety of your rose is also important as they can vary in disease resistance from hardly being effected at all ie: the Rugosa family of roses which are very disease hardy roses, to very disease prone most of the year. Most breeders are now aiming for high disease resistance in their breeding programs so hopefully each year roses will become even easier to grow. Your average rose is susceptible occasionally during a year and at other times can be quite free of disease e.g. Iceberg, Grimaldi, Bordure Rose, Guy Savoy are quite hardy.

Make sure your roses are in the correct position to start with - 5 hours of full sun per day, well drained soil and an open position ie: not under trees or up against other shrubs. Treatment of funguses is like treating human diseases in that if you keep treating them with penicillin, the human diseases will become resistant.Plant funguses are the same. Keep using one chemical for a year and you may get no control the following year. I always mix a preventative with a curative chemical, if possible, to broaden the control.

FUNGAL DISEASE

CONTROL
BLACKSPOT - purple blotches on leaves Mancozeb (preventative) and Triforine (curative) - Baycor is another good curative
POWDERY MILDEW- white powder all over buds & stems Lime Sulphur in cool weather ie winter only. Baycor in warmer months.
RUST  - orange dots on leaves Mancozeb and Triforine or Zineb.
DOWNY MILDEW- Die back. Black stems spreading down from the top. Ridomil Gold is a good treatment but if the die back goes too far, dig the rose out and burn it so as it does not spread to your other roses.
MOSAIC - virus yellow flecks or varieations in leaves These plants should also be dug out and burnt, if the yellowing is overtaking the rose.

INSECT PEST

CONTROL
APHIDS– small green or light brown bugs usually covering flower buds Small outbreaks – Pyrethrum based sprays as they are the safest.
Major outbreak Folimat or Confidor will stop them in their tracks.
TWO Spotted Mite – sucking insects which live under the leaves, turning them a mottled brown Winter – Lime Sulphur (kills mite eggs) & Winter Oil (use separately) to smother any eggs.
Summer – Pyranica will kill the adults. For Biological control, Predator Mites which consume Two Spotted Mites.
CATERPILLARS Confidor. For biological control, use Dipel. Orthene.
THRIP- tiny black, thin insects about 1mm long that arrive with the Summer heat. Orthene.
SCALE - tiny white shell like insect stuck to the stems and branches of roses. Non-chemical control can be gained by spraying of winter oil during the winter months. Confidor is a good systemic chemical to also control them.

CAUTION - All chemical sprays should be treated with care. Read & observe all instructions on the bottle.  Wear protective clothing, gloves and a mask when spraying. Keep all chemicals locked up and keep out of reach of children. Do not spray on windy days.