Telltale yellow speckling of the
leaves is the first noticeable sign of spider mite damage
on any plant.
Spider mites look
like a dust on the back of rose leaves - notice the
white dust built up along the spine of the leaf. Close
observation will show movement.
Spider mites usually appear in the dog days of
summer, when everything is hot and dry, and especially
when there has been no rain for an extended period of
time. They usually cannot be seen with the naked eye
until they are in huge, established numbers already,
and the damage to the plants is already visible. If
you flip the leaves over, this is where you will find
them. You can also see the fine webbing on the tips
of leaves and buds if they are in epidemic proportions
already. Don't fool yourself by thinking you can wait
even a day if you see them and their damage - they will
kill a plant in a matter of weeks once established,
as they suck all the juice out of the plant and dehydrate
it to the point of death.
Good old, reliable garden-grade sulfur still appears
to be the best control for spider mites, and is also
an economical, effective fungicide for control of
diseases at the same time. Sulfur can be purchased
in powder or liquid form. I find the liquid more effective,
but the limitations of spraying are often a problem
as it cannot be sprayed when temperatures are very
warm or very cool. Winds must be calm, and bright
sun hours away. This can be overcome by spraying late
in the evening or very early in the morning. The biggest
drawback of the sulfur is the smell which can last
for days.
Often it is recommended to control mites by hosing
the plants down regularly, but you may also invite
fungal problems on certain plants by doing this. We
have used Safers END ALL to control small numbers,
but sulfur works better and I like the dual action
of fungicide/miticide as a preventative measure too.
