I was looking at systemic fungicides to treat dogwood anthracnose.
Would it be safe and effective to use a fungicide intended for lawns
instead of trees (spectricide immunox) that says it treats anthracnose,
on my dogwood?
According to the University of Maryland, "Fungicide should be applied
preventively at budbreak and every 10-14 days until leaves are fully
open. Repeat during cool, rainy spells and when foliage starts to turn
red in fall. Use fungicides containing chlorothalonil, mancozeb, or
Benomyl is a systemic. Chlorothalonil is the active ingredient in most
garden fungicides. I think bordeaux mixture should also work if you
don't mind the baby blue residue.
It's sad what it does to dogwoods... I have a lovely old one in my front yard
that is quite sick from it, I will be looking for the resistant variety when we
are forced to replace this lovely old friend. It will take so many years for
whatever we buy to even begin to compare to the one I have now, they grow so
Zone 5 CT
It will be the same 7-10 day spray interval. All "systemic" means in this
instance is that the leaf surface absorbs a tiny bit of the fungicide
instead of it just coating the surface, not that it's carried throughout the
plant's vascular system. And the absorbed amount still has the same half
life. Spraying trees is a PIA. Better to buy resistant cultivars. If the
tree is large and has a lot of personal significance, and arborist can come
inject a fungcide into the cambrium, but that is a every 6 week interval
proceedure, and frankly, I'm not convinced that the wounds to the tree
aren't invitations to invasions of other kinds of insects and disease. And,
BTW, if a fungicide doesn't say it treats it, it usually does a poor job,
and it's actually a violation of federal law to use a pesticide in a way not
listed on the label. Immunox doesn't work very well on anthracnose or
cercospora on roses, wheras chlorothalonil does, but with risk of
phytotoxicity, increased during the warm months. But, anthracnose prefers
cool wet spring/fall weather and usually just goes away during the heat of
summer, so you could probably get by with only spraying during spring and
fall with an registered fungicide.
Dogwood anthracnose is a systemic and progressive fungal problem. It doesn't
just "go away" with warmer, dryer weather - it is just not as likely to be
as obvious with any new foliage appearing to be free of problems. But the
pathogen remains present, but perhaps non-active during drier weather,
within the tree's internal tissues. IMO (and one that is supported by
others), treating with a fungicide only delays the inevitable.
Cultural controls will help prolong the tree's viability as well. Clean up
and destroy any debris (fallen leaves, etc.) which may harbor spores of the
fungus, avoid pruning (which dogwoods resent and which can spread the
infection) other than obviously deadwood, fertilize sparingly in early to
mid-fall (which will provide nutrients to the root system but not encourage
vulnerable lush growth) and keep well watered during summer's heat.
Dogwood anthracnose is a widespread and serious problem for certain species
across the country and Sunflower's advice is sound - it may be best to
consider replacing soon with a resistant species or hybrid. In my
experience, despite one's best intentions and expensive treatment regimens,
the progress of this disease is only slowed but seldom, if ever, controlled
and the ultimate outcome is pretty much a given.
pam - gardengal
I have a forest full of dogwoods and probably half of them have
anthracnose. I had a state forrester look at them and he said they
would eventually die no matter what I did; the best thing to do was
cut them up for firewood; and NEVER transplant wild dogwoods into town
- I'd only be spreading the disease.
If you are going to spray your dogwoods I would reccommend mixing mancozeb and
propiconazole(fertilome systemic fungicide). I take care of the spraying at
the nursery I work for and use the agrucultural strength stuff that has the
same active ingredients. Follow the directions exactly and they should be
fine. You will have to spray in spring and late fall for it to be effective.
firstname.lastname@example.org (Marley1372) wrote in message
This is why all experts recommend getting dogwoods from a nursery
rather than transplanting wild ones. When you have bunches & bunches
of wild ones, spraying is just not feasable since dead leaves, twigs,
and bark which carry the disease cannot be controlled. Any cut,
scrape, or broken twig allows anthracnose to enter the tree.
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