Before you start spraying, find out what you're trying to kill! In the
panhandle of Idaho, hawthornes often defoliate during the summer to avoid
our summer drought! If your hawthorne is suffering from a fungal rust,
you may be able to help the poor thing by watering, fertilizing and
removing all infected leaves as soon as they drop from the tree (removing
future fungal inoculum). If the problem persists, the best time to treat
the plant to avoid fungal problems is in the spring after the buds begin
to open, for which a dormant oil would not help. Before you spray,
please have your problem properly identified.

Kas Dumroese
dumroese at uidaho.edu

On Mon, 11 Sep 1995 otton at cs.sfu.ca wrote:

>
> Irene writes,
>
> >At my house, the chickadees take black sunflower seeds and stuff them
> >between the planks of my house and the houses nearby.
>
> The chickadees at our house have spent the past month storing sunflower seeds
> in a dying hawthorne tree that we have considered (at one time) spraying with
> dormant oil, as recommended by the garden centre. The tree loses virtually
> all its leaves in July. It seems to be a really attractive tree for the birds,
> and it sure makes summer bird-watching easy. Does anyone know how harmful
> dormant oil sprays are to birds (if their cache has been exposed to the stuff)?
> Looking at the label on the bottle we've bought, it contains a mixture of
> 98.4% mineral oil and a lime sulphur solution.
> Thanks in advance for any info or advice.
>
> Victoria Otton
> otton at cs.sfu.ca
>