PEST
AND DISEASE CONTROL:
Modern roses are almost as attractive to pests and diseases as they
are to people; therein lies much of their reputation as difficult
plants. But unless you're interested in producing prize-winning
blossoms, roses need not require a great deal of fussing. Some species
and old-garden roses seldom require intervention-all the more reason
to seek out those that do well in your area. Healthy,
well-watered, well-fed plants are far less likely to sustain threatening
damage from pests and diseases than are unhealthy plants. Good hygiene
also discourages many problems. Here are some tips:
- Water
in the morning so leaves and canes dry during the day; this helps
prevent fungal diseases.
- Remove
diseased or damaged leaves and canes as soon as you seen them.
- Clean
up for winter by stripping leaves off the plant and removing debris
from underneath it.
- After
pruning and before new growth emerges, apply a dormant spray (lime-sulfur)
to kill over wintered insect eggs and disease organisms.
A variety
of insects cause problems for roses. Some, such as aphids and mites,
can be controlled simply by washing them off leaf surfaces. Others
can be hand picked, but some require an insecticide. It can be difficult
to identify critters-the bug you find at the scene of the damage
may not be the one that caused it. And choosing the right control-organic,
chemical, or biological-is confusing. Your best bet is to consult
knowledgeable rosarians about specific problems.
Rust in the West and Southwest and
black spot elsewhere join powdery mildew as the biggest disease
problems for roses. Good hygiene and aeration help prevent all three;
chemical controls can fight outbreaks. Again, advice from experts
on the spot is most helpful.
