and mildew on roses
roses have persistent mildew this year. I have tried several sprays
including Bravo, Gild, Saprol and Shield. Some of the plants had
it last year but I cannot get rid of it this year. Even my most
healthy plants have it to a mild degree. I have cut the most severely
affected back and sprayed. What winter care do I do to help prevent
this problem next year?
you please tell me the cause and treatment for a white fungus that
has appeared on my topiary rose? I have tried conventional rose
spray to little effect. Could this be from watering using a sprinkler?
of the warm, humid weather we have been having, diseases have gone
rampant. Once established, mildews are hard to control. Healthy
plants have much more resistance to diseases, so regular feeding,
watering, mulching and occasional spraying does help keep them at
Clean up any fallen leaves,
petals or prunings from around the roses to prevent diseases spreading.
The key to sprays being
effective is spraying at regular 14 day intervals until the problem
is under control and alternating sprays to prevent a build-up to
Spraying at regular 14
day intervals now will help prevent spores overwintering and affecting
plants next season. Alternate with 2-3 sprays to prevent build-up
to resistance. Greenguard, Fungus Fighter (which has superceded
Bravo), and Saprol are all effective against mildews. There are
also combination sprays, Guardall, Gild and Super Shield which control
insect pests as well.
Ensure good air circulation
around the plants, and try not to wet the foliage when watering.
Avoid overhead watering to reduce the chance of mildews becoming
Spraying with Champion
Copper through winter will help control black spot but not powdery
With improved rose breeding,
there are more and more disease resistant varieties available now.
When selecting new roses, keep an eye out for ones that state "disease
resistant" on the label. Unfortunately, some varieties are susceptible
by Dr Dan Blanchon from Unitec's Diploma in Sustainable Horticulture and Bachelor
of Resource Management.
with permission from NZOOM Home and Garden content,
from the previous
The views expressed here are not necessarily those of the RNZIH