western-queensland-gardening-guide.pdf - South West NRM

Roses and other flowers
Dieback in roses
This is a fungal disease which is common in all districts. The stem dies back from a cut
end, turning dark brown or black. There is usually a purplish band between the live
and dead material.
Control '
As soon as this disease is noticed, prune well below the affected parts, dipping the
blades of the secateurs into a fungicide liquid after each cut. Then swab the freshly cut
ends with a paste of a copper fungicide, for example Bordeaux Pozi~der Fungzcide.
Vigorous plants are less susceptible to attack by this fungus, therefore correct
fertilisation and the control of insect pests help to lessen the incidence of dieback.
Caterpillars and other leaf and bud ea fing pests
These occur on most flowers from time to time. Some can severely defoliate plants and
destroy flower buds completely.
Control
A trichlorfon (Dipterex) spray is effective against most of these pests. Treat when the
pests are first noticed, and thereafter week*, or as necessary.
Powdery mildew
This is a fungus which can be troublesome on many flowers which grow in this area,
including roses, nasturtiums, sweet peas, zinnias and verbena. It starts as whitish
spots and develops into grey or white floury patches on leaves, stems and flower buds.
Distortion of the affected parts may occur and patches may die.
Control
Dust with dusting sulphur, or apply triforine or chlorothalonil and fenarimol (Zero
Fungicide), when noticed and weekly thereafter as required. When treating roses,
particular attention should be given to the underside of the leaves.
Two-spotted mites
Two-spotted mites live in colonies beneath the leaves of roses. They are very small
(0.5 mrn long) and can be seen with a hand lens. When the population is very high
their webs become visible and the leaves yellow. The life cycle is very short and in
summer populations of mites can double in about a week- this is the reason for mite
outbreaks in early spring.
Control
Mites on completely unsprayed roses are often controlled by natural enemies and are
not always a problem. If they do become a problem dicofol (Kelthane) can be used or
predatory mites may be introduced. The latter is available from Bio Protection Pty
Ltd, PO Box 35, Warwick 4370; telephone (076) 661592, facsimile (076) 661639.