Powdery Mildew

SteveM · 2023-03-10T04:02:56+00:00

I always thought there were just a couple types of powdery mildew and if I saw mildew on one variety of plant then I should worry about it infecting my dahli...

calico20hill

Maybe I had a triple-whammy with this one being added to the other two. Do these all respond to being sprayed with the same kind of fungicide? My garden is surrounded by decidious trees, Mostly Oregon Ash and ornamental maples but with other trees that inhabit swampy land over in the next field.

Teddahlia

The brush under the trees in the forest is covered with PM in the Fall.

SteveM

I imagine the PM spores that infect dahlias are always blowing around. I have a tough time keeping PM under control in an enclosed greenhouse, it is much easier to control when growing in a nice, sunny field with lots of air movement. In the greenhouse I have to rotate spraying fungicides about every 10 days as a preventative.

calico20hill

If I had only realized this we could have put the raised beds for the dahlias on the upper part of the slope by the road, where there is more air movement. I just thought it would be nice to have my garden out of sight of the road for those mornings when I love to wander through the garden early in my night clothes...:-)

Krista

calico20hill I will shamelessly have coffee in my robe and inspect the plants in our backyard in the mornings. Since we’re surrounded by condos, our backyard is essentially the courtyard for our flanking and rear neighbors but I’ve decided they’ll just have to deal with viewing their local urban wildlife. 😅

Juliarugula

calico20hill . I just thought it would be nice to have my garden out of sight of the road for those mornings when I love to wander through the garden early in my night clothes...:-)

This was one of my primary motivations for putting up a privacy fence. 🤣🤣

Cosey

I've had success using Actinovate SP in the field to treat against mildew. I've heard excellent things about using it in a greenhouse. You need to use it all season long. It's $120/bag. This bag needs to be used within 6 months of opening.

calico20hill

Cosey Hmmm, that is a bit much for my small garden. I wonder if there is anyone else around to share some with.

Cosey

calico20hill Some online stores (Arbico, maybe?) sells 2oz bags for $18. I used 1T/gal and I can mix it with my foliar fertilizer which is a great 2 for 1 application. I bet you could get 6-8 gal of spray out of the 2oz bag.

calico20hill

Cosey THat sounds real good. I will look for some and have it ready if the greenhouse gets hit again this spring. I am doing everything possible to get my plants at leas ton the outside shelves before mildew gets going in the greenhouse. The main thing I am doing is to get them them started later then usual so the good weather will come while they are younger. I have quite a few seeds started now. Its been so cold that the tubers have not been showing much growth yet in the pre-start pots. IN about a month I can put them on the wire racks outside and just cover them at night or if we get a hailstorm. (Well, when we know that might be in the offing...)I finally turned up the heat in the greenhouse to see of those tubers will get a move on! We've had so many gray days that it wasn't warming enough inside. We'll be dropping back near freezing at night for the next several days.

NCDahlia

I use MilStop on everything for PM. Best one I have found. Very easy to tank mix and dual spray with fertilizer like a kelp or age old seaweed so you can add this to a 4 gallon backpack sprayer and it works very well all season long.

https://www.arbico-organics.com/product/milstop-foliar-fungicide-potassium-bicarbonate/hydroponic-soilless-growing?gclid=Cj0KCQjw2cWgBhDYARIsALggUhq7SKjCEeYFA5UJaBdAhG1thMmpaiNelq64O3-9N6S6TpuKNUyn7c0aAuZQEALw_wcB

Cosey

NCDahlia

I love learning about new products. Thanks for sharing that. It might be a less expensive foliar option. I'll have to see how it reacts to other products I use. That's the dance you need to learn when operating with IPM/beneficial fungus & bacterias & insects.

I like the Actinovate's mechanism of action. The bacteria will colonize on the roots and have long acting preventative results. You can use it as a soil drench, dust tubers before planting, and foliar spray. I soak my dahlia seedling 1 week before field planting to inoculate them. It's proven helpful if you have a known environmental mold or mildew issues.

calico20hill

Cosey, that would be fabulous if I could use it as a soil drench. I dont think my old arthritic spine is up to a back pack but a bucket in a wagon and a container to drench from would work well in my small garden. I'll look for it when I am out in a garden supply store next.

MIDahlias

Mayday!!!!! My Heron's Nest cuttings are scheduled to arrived today. I really hope they are small plants, because I have no business buying cuttings.

I bought two plants, same cultivar from someone. One came as a plant the other as a small cutting. I already killed the small, rooted cutting. The small plant cutting is growing great, but one day one leave had powdery milder. I washed it off. Over the next two days the entire plant is covered. I tried dunking it in milk it did not help.

Someone told me to cut all the leaves off except the top and let it grow.

I have isolated it from my potted-up tuber plants, so they don't get infected.

I'm sorry if I already posted this (I feel like I did, but can't find it)

What can I do for one plant? and can a plant have powdery mildew without seeing it? Did it come to me with it? (I'm not going to write the seller) I'm just wondering. I'm hoping my Heron's Nest are ok, because I ordered more than I should have. Is there something I should do to cuttings when they arrive to help prevent powdery mildew?

bloomhjelm

When I receive new cuttings, I have the following routine:

Open the packaging and let them sit in indirect light in the open air until I'm ready to deal with them (somewhere away from my regular plants, like the kitchen counter). Give them a small amount of water or tap out excess water. Remove damaged leaves.
Spray the whole plant liberally with copper fungicide and miticide/horticultural oil.
Pot in fresh soil and label. Provide a little bit of Cal Mag. Place on a shelf some feet away from my existing plants, in partial light for 24-48 hours.
After 24-48 hours place in direct light.

bloomhjelm

I should note that I purchase tubers and cuttings from dozens of sellers a season, which is a bad practice for keeping a sanitary garden. I should also note my routine is far from foolproof for keeping cuttings from passing on their faults to other cuttings or plants. But like so many others, I take the risk because I love variety and novelty.

calico20hill

bloomhjelm I had terrible mildew on the cuttings that were sent...not apparent when I opened them but it showed up shortly there after and then I had a whole greenhouse with mildew...since that awful experience I no longer take cuttings directly into the greenhouse with my dahlias I am growing in pots. When the weather is above freezing they go outside on the shelves outside my greenhouse where they are washed off by the rain, and only brought inside if the temp is going to be below freezing or a hail storm is possible. Actually, I usually cover them up good and leave them outside. I have had no more trouble with mildew since changing to that... Frequent washing, cooler temperatures and good air movement seem to be key...

MIDahlias

calico20hill Yes, this experience has left me wondering if I will buy mail cuttings again. Besides the Powdery mildew on an high priced cutting, the cuttings I received in the mail on Thursday were rooted cuttings which is what I ordered. However, since I have to wait for them to have some more growth before I can put them in the ground, Cuttings are not for me unless strongly rooted, small plants from people I know and trust. I hope to report that my Thursday cuttings all grow beautifully.

Teddahlia

I still like the idea of shipping unrooted cuttings as the postage is very cheap( if you use a padded envelope) and so cheap sending replacement ones even twice is cheaper than shipping rooted cuttings in a box with all that stuff to protect them. They are more likely to be free of fungus and vermin too.

SteveM

I am more concerned with introducing root-knot nematodes into my field with vendor tubers than I am with introducing mildew spores with vendor cuttings. I almost never plant tubers from vendors directly in my field, instead I take cuttings and plant the cuttings. Since vendors cut off all the feeder root before storing/shipping tubers, it is very difficult to diagnose a root-knot nematode infection until the tubers are dug in the Fall.

Most, if not all, of the organic fungicides are preventative for powdery mildew but do not do much for an established infection. Of the organics, probably the horticultural oils are the most effective. Sulfur (micronized) is probably equally effective but do not use when spraying any oils. My father used to swear by Compost Tea but it is tricky to make and can be dangerous if not done properly. He would buy compost made specifically for compost tea and aerate the mixture while brewing. It was quite a process but worked for him.

MissyWeitzel

SteveM a few tbsp of baking soda and a drop or two of Dawn per gallon of water in my sprayer works pretty well for me and I use it in rotation with other fungicides and hort oil. Not sure if that would be considered organic but it's certainly inexpensive and easy!