Shoveling Sand against the Tide?

digit(ID/WA)July 1, 2007

With regards to pre-emptive care: Does anyone have successful experience staving off fungal diseases in their gardens?

The delphiniums and lupins are in deep trouble from mildew - but, this is mostly my own darn fault from crowding them. I haven't bothered to spray them with a fungicide. They've just about completed their blooming so have mostly come in under the wire and can face cutback without too much weakening.

The Shasta daisies were moved this year and so are a little late but whatever causes the bronzing of their leaves has begun. Their blooming could be so much extended if whatever this is didn't beat the tar out of them. I have a rustic's appreciation for Shastas. They are so bright and look wonderful in contrast to the bold colors of other flowers (pretty in a breeze, too :o).

I've used daconil with limited success to pre-empt black spot on zinnias and rust on snapdragons. It is supposed to have some systemic value. Not sure if it is really effective in either case since weather seems to have so much to do with all these fungal diseases.

In the past, I've gotten thru entire seasons with hardly any appearance of rust on the snaps, even without spraying. Last year, I sprayed them regularly with daconil and they slowly and steadily developed rust as the season progressed. Even lost a few of the plants by late September, all the while - spraying them weekly.

Am I wasting my time? Are there other remedies or would you encourage me in my continuing regular spraying with daconil?


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david52 Zone 6

There is a systemic fungicide for ornamentals that uses an active ingredient called "Triforine", I get Ortho brand "Rose Pride". It works pretty well, particularly on stuff like shasta daisy, asters, and zinnia. It won't cure existing fungus, but it will prevent more. As a systemic, the trick is to get it on before the problem shows up. Once, usually, is enough for annual flowers. With roses, because they keep growing the new growth needs respraying before it gets attacked. If I can remember, I need to start spraying the stuff on roses bi-weekly when the humidity goes up before the monsoon season.

Daconil, I believe, just creates a barrier and is considered (by those who sell it to us) as "safe" for human consumption. Knock on wood, but by the time I get fungus in the veggie garden, Its so close to the end I just don't worry about it.

    Bookmark   July 1, 2007 at 5:11PM
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Skybird - z5, Denver, Colorado

Hi Digit,

I have a couple thoughts about powdery mildewactually, I have more than a couple, but IÂll just go into the ones that can be discussed in polite company!

The only thing IÂve had mildew onÂyetÂthis year is my blue scabiosa. IÂm not really surprised it has it, because it was SO bad last year I actually thought it might kill the plant by fall. It didnÂt, but by now all the soil around the plant must be rife with the spores, so it was pretty likely that it was going to get it this year again too. I noticed it just starting a couple weeks ago, and hadnÂt done anything about it except wash the leaves off really well when I was watering it, but since itÂs so early I really kinda wanted to try to at least slow it down this year, so the day before yesterday I sprayed it with a homemade baking soda solution. Just filled a bottle with water and spooned some baking soda in! I sprayed it late in the day after there was no chance of its being in the sun after I had sprayed it, and I pretty much completely soaked it. For the last couple days the PM looks considerably improvedÂtho I do have white residue from the baking soda on it. I tried the baking soda because I had heard it was supposed to be as good as the commercial products, and I didnÂt have any of the commercial "cures" around, and knew if I waited till I had time to go out and buy one, the mildew would be so bad again that it would be hopeless! IÂm planning to repeat the baking soda a couple times a week for the next couple weeks and see what happens.

I wasnÂt sure there was any validity at all to what I had done, so before posting this, I googled baking soda as a fungicide, and came up with a whole bunch of links. HereÂs one of the more "scientific" ones. Some of the more home-spun sites have all kinds of "recipes!" When I do it again IÂm going to add Palmolive dish washing soap as a surfactant, but nothing else! It seems to me, the more weird things you add, the more likely youÂd be to damage or burn the foliageÂand burnt foliage wouldnÂt be any better than having mildew on it! IMO!

I think this one is the same info but in html format so you can copy parts of it if you want to!

At this point I only have one plant with a problem, so I just used a spray bottle, but I donÂt see why you couldnÂt use it in a pressure sprayer if you have a lot of plants. My mildew was obvious, but not that bad yet. DonÂt know what effect, if any, there would be with bad mildew. I did keep shaking the bottle while I used it to be sure the baking soda stayed suspended.

Now to the other "interesting situation" I have this year. In past years IÂve always wound up with some degree of mildew on many thingsÂthalictrum, delphinium,violas, roses, and more, and really bad on cukes, and really, really bad on summer squash. And IÂve ALWAYS had rust really, really, really bad on my snaps which are just reseeds that come up whenever and wherever they desireÂand rust on a couple of my (5) rosesÂpretty bad too.

This yearÂknock on woodÂthe scabiosa is the only thing that has any problem at all. The lack of rust on the snaps has amazed me, because, again, since the snaps always reseed where theyÂve been growing, and the rust has been so bad by the time I pulled them out (orange hands!), the spores must be endemic in the soil. So WHY am I not having a problem this year! I had actually been contemplating this situation in the last couple weeks! The only difference this year from the last couple years is that IÂve been here every day and been watering and taking care of my garden constantly. My grass isnÂt looking too good, but my babiesÂmy perennials and veggiesÂhave been in green heaven this year with the care theyÂve been getting. ThatÂs the only difference! You always hear that healthy plants are less susceptible to diseases, and I guess itÂs really true! ItÂs kinda funny, Âcause when I was selling perennials, I used to repeat that mantra over and over to people, and now I have actually found, from personal experience, that it is apparently true! Glad I wasnÂt lying to all those people!

I hope to be able to go back to work in about a month, and itÂll be interesting to see if I notice any obvious changes when IÂm not here every day to waterÂor do whateverÂas needed. If (when?) my squash and cukes start getting PM this year, I think IÂm gonna try the baking soda/soap combo on them if it still seems to be helping on the scabiosa. WonÂt bother with the snaps since theyÂre every-which-where and would be REALLY hard to try to get them all, so IÂll just keep using the wait till theyÂve been blooming for a while and pull them out method if they get rust again. But I think IÂll try it on the roses immediately if I notice any problem developing with them. So far this year the worst problem IÂve had with the roses is the one that got flattened under 5' of snow last winter. But itÂll be back!

DonÂt know if youÂre interested in home remedies or not, but since IÂve been thinking about it for the last couple weeks, and am now experimenting, I just thot I add my two bits!

Hope youÂre cooler up there than we are down here,

    Bookmark   July 2, 2007 at 12:49AM
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Same with me for mildew in the veggie garden, David.

The black spot in zinnias starts in the oldest leaves at the bottom of the plant. Then it is a race as to which gets the tops first - the spots or a frost. Nearly always the frost wins. So here again, it isn't usually the more serious issue.

Snaps, however, can turn into rusted hulks of themselves weeks and weeks before the end of the season. Since the rust attacks the older plant parts 1st, I once cut the plants down close to the ground after their 1st blooms had come off.

That approach actually may have worked fairly well but I did manage to KILL quite a few plants with the cutback . . . the Grim Reaper in the flower patch.

I'm not sure if Ortho is doing itself or the customer a favor with its customer-friendly product names. Of course, some tongue twister may be just as confusing but calling a chemical "Rose Pride" allows me to walk right past it when I'm thinking of something other than roses.

Thanks David, I'll check into it.

Steve's digits

    Bookmark   July 2, 2007 at 12:53AM
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Hey, Skybird! (messages crossing in the Eastern Time Zone midnight)

If they'd intended to sell it for plant disease control, why did they call it Arm & Hammer? (That snapdragon technique I used could have been called Arm & Sickle. ;o)

Plants respond to care. It is simple but true and I have seen some really inferior gardeners pretend it isn't so.

I tried successive plantings of zucchini last year with good results. As the old plants were dying of mildew, the new plants were coming on. They had mildew also but it wasn't bad. Might be a time of year issue as well as a problem of duration and age.

It will soon be time to drop a few more zuke seeds into the soil and this year I'll try late cukes also. Not so much because the older vines die early but because they begin to have more and more deformed fruits during their final weeks. The 2nd planting of cucumbers has already been started in pots and will go out in about a week.

I hate spraying all the poisons so will check out the baking soda. ATTRA is an excellent source of information. Thank you.


    Bookmark   July 2, 2007 at 1:35AM
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Skybird - z5, Denver, Colorado

Well, if your snapdragon technique is called Arm & Sickle, I guess mine is called Arm & Hand! ;-)

Going to bed now!

    Bookmark   July 2, 2007 at 2:30AM
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cnetter(z5 Co)

I'd be real careful spraying baking soda on plants in this heat - it's alkaline and can actually burn.

One very useful thing I learned back in Denver Rose Society days was that dry roots really promotes powdery mildew. Since then, I've found it true even for african violets. The drip system is great for keeping the roots moist while keeping the leaves dry. I only really see powdery mildew in the fall, shortly before frost.
If I get enough rain, I might see some blackspot on certain roses. I've seen rust only once, years ago, on a particularly susceptible bourbon rose.

    Bookmark   July 2, 2007 at 9:45AM
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I believe you are quite right on this, Cnetter. It seems a little counterintuitive that a fungal disease would be encouraged by a lack of moisture but I'm buying that argument. Inconsistent soil moisture damages leaf tissue - after all, what is wilt?

Crowding of plants has provided a good physical environment for the mildew, while taxing soil moisture reserves, but dehydrated and weakened leaves provide the opportunity for fungal invasion. I must take some of the plants out in that crowded corner but maybe a drip irrigation system in my perennial garden is in the future.


    Bookmark   July 3, 2007 at 2:19PM
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Milk for mildew! 10-20% milk in water worked better than anything else I have tried. Last year the milk solution seemed to keep the mildew under control pretty good. Used it on cukes, zuchini, pumpkins and squash. I used a 10% solution in a pressure sprayer. Try to spray both top and bottom of leaves. Google 'milk powdery mildew' for more info.

    Bookmark   July 4, 2007 at 2:34AM
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I remember reading about that original study on zucchini in Brazil, Meershaum. Sounded like it might be a good choice for country people with a milk cow.

Interesting that the researcher is using "canola oil and bicarbonate once a week and then moving to a spray of whey and seaweed extract. . ." Keeping the mildew off-balance, apparently.

Also, "treatments don't work well on heavily overcast days" since sunlight is needed to create the free radicals that act as mildicides. Perhaps one could hit 'em with one thing or the other depending on the weather.

I've also got to wonder about the value of the milk or whey as a foliar fertilizer. Seems like it could be pretty good stuff.


    Bookmark   July 4, 2007 at 3:32PM
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Skybird - z5, Denver, Colorado

Ive been drenching my scabiosa with ordinary baking soda and dishwashing soap every day for the last few days, and it seems to be working for right now. Only do it when its in the shadeand lift up the foliage to get everything underneath, including the soil. Guess Im being pessimistic, but I dont expect it to keep workingand I dont plan to keep spraying it every day ad infinitum anyway!

Thanks for the milk suggestion, Meershaum. A read the article, and I think Ill try that at the first signs that the baking soda isnt working. Really interesting that it should be sprayed in the sun! Ive never done that with anything before. Itll make me pretty nervous the first time I do it. But Im to the point where the scabiosa is outta here if I cant find a way to drastically decrease the mildew, so if any of the things Im trying kill it, I guess it really doesnt matter. What Id really like to do is cut it all the way down and start spraying the new foliage as soon as it starts growing, but its right at the peak of its blooming right now, and-----well, I CANT cut all those pretty flowers off! So Ill keep experimenting with the different sprays for now.

Thanks again for the suggestion,

    Bookmark   July 4, 2007 at 5:49PM
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Skybird, if you do try the milk, let us know what your results are. Last summer was the worst year that I have ever had for mildew. When I first started using the milk spray, all the plants were heavily damaged already. The treatment seemed to work best on the cukes and zuchini, somewhat less on the pumpkins and squash. This year, I am taking preemptive action and spraying once a week mildew or not. So far so good. I hadn't thought about the foliar fertilizer aspect Digit, I will see if I notice anything.

By the way, if you are wondering if 10% milk in water will go sour, it will. Try to mix up just what you are going to use, or put the leftover in the fridge.

    Bookmark   July 5, 2007 at 2:25AM
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So what do these look like to you? Healthy snaps and zinnias, right?

At our little cutting garden across town, there has been NO sign whatsoever of rust on the snaps this year! (That's "not one" as in zero, zip, zilch, nada!) And, Ive only thrown away a single zinnias stem (thats ONE) with mildew, and 2 (count em, TWO) because of black spot!

I dont know why I stayed with daconil so long except that, since it is approved for food crops (altho I dont use it for them), I have assumed that it is fairly safe.

After Davids suggestion, I tried a system fungicide. I went with Immunox. Turns out that this fungicide is considered as having low toxicity for humans even tho it is only approved for ornamentals.

So, these fine flowers are holding up right until frost without the fungal diseases that usually plague them. Hurray!! (And, thanks David. :o)

Steves digits

    Bookmark   September 26, 2007 at 12:49AM
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david52 Zone 6

I should do my roses again now, it looks like a very mild fall on the way, and I'm getting a lot of p. mildew on the new growth. How many times did you have to spray them? I always had the impression that once, when they're just about to flower, was enough.

    Bookmark   September 26, 2007 at 8:55AM
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cnetter(z5 Co)

Over 400 roses here and no Black Spot, Anthracnose or Rust. PM on only a very few extremely suseptable ones such as Orpheline de Juliet. No spray, just plenty of good, consistant watering and plenty of wind lately.

The only thing that has lots of PM here is the bindweed, which I try not to water.

    Bookmark   September 26, 2007 at 9:56AM
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aliceg8(CO 5)

Oh boy, a new baddie I didn't know about.

I have this mildew on my zucchini leaves. I wasn't worrying about it because the plants were still producing, but now it seems that this mildew could drop spores to the ground to infect next year. So I guess I should spray too, even though the season is almost over? I'm going organic with the veggies, so I guess it's the baking soda solution for me.

Also, I would guess that I wouldn't want to compost these leaves, right?

    Bookmark   September 26, 2007 at 10:43AM
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cnetter(z5 Co)

Powdery Mildew shows up even in very clean, controlled environments, such as indoor growing of AVs, if the plants are poorly taken care of. It seems to be in the very air around us, just waiting for the right opportunity. Which means composting the infected leaves is not going to make a big difference.
I'm kinda surprised I haven't seen it on my summer squash this year, but I have seen it in the fall in the past, as the plants are shutting down. Maybe it'll come later if the weather holds up and doesn't freeze.
But I've never ever seen it on younger plants in the peak of production.
When it does hit my squash, it's always as the plants are shutting down so I just consider it part of the fall plant death process and ignore it.
Same with the roses - if it hits, it only hits shortly before I get a killing freeze anyway.

    Bookmark   September 26, 2007 at 12:10PM
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David, I only worried about the snaps and zinnias altho' it sure would have been a good idea to do battle with the mildew on the delphiniums and lupins in the Spring (too slow on the draw). The delphiniums would have been back much better right now if I'd done so.

So I started in early July just adding the systemic fungicide for the S & Z's to the systemic insecticide that I use weekly on all the cut flowers. Discontinued spraying about 2 weeks ago when everything began tooo ssslllloooowwww ddoooowwnn - (including, one hopes, the bugs).

The roses had very little mildew this year and none of those other "baddies," Cnetter. I guess I commented on my overcrowded perennials above - some of them have GOT to go! Overhead sprinklers are likely to remain, unfortunately.

The real, real, real killer is rust on the snaps.

Alice, I've never sprayed veggies for fungi, ever. But, mildew is usually so bad on the zukes that they keel over by about the 1st of September. Very limited mildew this year - a different variety may have made the difference. I don't know about spores. As Cnetter points out, the weeds have got it EVERYWHERE! I'm trying to think of what weed it was I was looking at that had so much mildew it should have just DIED, instead of hanging on at the edge of the garden just to spite me. What was it . . . Kinda like the potato bugs eating the deadly nightshade down to nothing before they go on to the eggplants and potatoes . . . So if they like it so well, why can't they completely kill the darn stuff?

Late planting really helps with the mildew. My succession planting of sunflowers was so late I was afraid they wouldn't have time to bloom but thanks to the long Summer, they have. Those plants are absolutely the healthiest sunflowers I've ever seen.

The same is pretty much true with the late planting of Summer squash - beautiful, healthy plants. Since the early zukes didn't succumb to the mildew, the only thing that saved me from a Summer squash "avalanche" was that I didn't get that late planting in until about the 10th of July. So late that I'm getting like 1 or 2 squash off each plant but soon, all my pretty squash . . . will . . . freeze . . .

Next year, that broccoli and early cabbage is coming out the FIRST of July and those squash seeds are goin' into the ground! Or, Ill squeeze them in between the broccoli and cabbage during their final weeks, if necessary. (Then I can suffer from abundance instead of guilt. That'll teach me . . . ;o)


    Bookmark   September 26, 2007 at 12:10PM
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cnetter(z5 Co)

Ooh shoot, the poorly taken care of part was mostly just about AVs, which I occasionally get sick of, don't water enough, and then they get sick.
I think PM in the garden is more of a seasonal/environmet/weather thing.

    Bookmark   September 26, 2007 at 12:19PM
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(Did you hit that "submit" button at 12:10:02 or 12:10:03, Cnetter? ;o)

It may be hard on the zukes because of the wounds from harvesting - not sure. Ya gotta know, I'm really pounding on my plants right thru the year. Even staying out of them when they are wet isn't always possible.

And, pushing the planting season probably just sets them up for trouble. But, that could work both ways with me trying to grow lettuce and such in the heat of Summer. They are saying, "I'm just going to make a little seed and die now . . . so sorry."

(I'm kind to dogs and small children, however. :o)


    Bookmark   September 26, 2007 at 12:27PM
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