Author Topic: Powdery Mildew: what's "high" humidity, spraying open flowers, w/ nutr. spray??  (Read 504 times)

JakeFruit

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I lost nearly all my panicles to Powdery Mildew last year so I'm determined to fight it this year. I've bought Bonide's 90% micronized sulfur, planning on mixing 1.5 tbls of it per gallon of water in a small pump sprayer.
I've watched half a dozen (Har) videos on the topic, I understand the general conditions where PM thrives (70's or lower temps, still/dry conditions, paired with high humidity), but I'm left with a few unanswered questions. I think I'm in danger of PM now, need to spray ASAP; hoping someone can fill me in on the questions

  • What percentage of humidity should I consider as high? I'm looking at 91% tomorrow overnight, does that qualify?
  • I have panicles with open flowers on them currently, is it safe to spray them with sulfur now?
  • Does sulfur deter flies/bees/etc.,? I know not to spray when they are active, just curious if they'll avoid recently sprayed flowers.
  • Would mixing a nutritional spray in be beneficial/harmful? I have some SouthernAg citrus spray I was thinking of using.

Thanks, anybody!

Galatians522

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I am seeing PM on some ornamental plants, so it is going strong in my area. Sulfer is only preventative, as I understand, so you need to spray now (before you physically see PM). Regarding nutritional spray, I recently heard that Monopotassium Phosphate (MPK) increases the fungicidal properties of sulfur when the two are applied together. No clue whether Southernag will help any. I think Har has answered similar questions on several occasions if you check the last few pages of the mango psets and diseases thread.
« Last Edit: January 10, 2022, 09:51:06 PM by Galatians522 »

sbtropic

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I have used bonide Sulfur, and nutritional sprays for powdery mildew of the mango. Generally, I use the nutritional foliar sprays trough the season and well before the panicle emerges. I feel that they help to reduce the problem. Then as soon as the panicles emerge but before flowers, you can apply sulfur. As soon as peas size fruit appears, then you can continue using fungicides. If no powdery mildew is present, then apply sulfur again. If its present consider switching to Potassium Bicarbonate. Sulfur is a preventative but Potassium Bicarbonate is an eradicant. Sometimes if I see powdery mildew before the fruit is formed I use Potassium Bicarbonate. But I only do this if I have to.

Galatians522

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I have used bonide Sulfur, and nutritional sprays for powdery mildew of the mango. Generally, I use the nutritional foliar sprays trough the season and well before the panicle emerges. I feel that they help to reduce the problem. Then as soon as the panicles emerge but before flowers, you can apply sulfur. As soon as peas size fruit appears, then you can continue using fungicides. If no powdery mildew is present, then apply sulfur again. If its present consider switching to Potassium Bicarbonate. Sulfur is a preventative but Potassium Bicarbonate is an eradicant. Sometimes if I see powdery mildew before the fruit is formed I use Potassium Bicarbonate. But I only do this if I have to.

Thanks for posting that I didn't know about the Potassium Bicarbonate.

JakeFruit

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Har briefly mentions leavening in fighting PM once it appears in one of his videos. Sodium bicarbonate sounds like it would also work, but excessive sodium accumulation in the soil being a big negative, he recommends potassium bicarbonate (PB). That put me on investigating exactly how to use PB against PM; sounds fairly simple, I purchased a 1lb bag from Amazon for $8.99. I also read about several other potential weapons to use against PM once it sets in, the craziest being whole milk!  ???

weiss613

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2 ways I go.
First is 98% mineral oil and baking soda(arm and Hammer) for 100 gallons of water I use 1.5 gallons mineral oil and 7 lb  baking soda. The oil is to control scale and other pests and powdery mildew and the baking soda is to kick ass on powdery mildew.
My alternate spray which I do 2-3 times a season is what I learned was the #1 treatment for the prevention of anthracnose and powdery mildew problems. I got it from a plant pathologist at a lecture at Fairchild Garden sponsored by the Rair Tropical Fruit Council. The Dr said they tested every anti fungus treatment and combination of treatments and this was the best and here it isÖÖ.
Per 100 gallons again
15.5 ozs of Azoxystrobin and 16 ozs of Nu Film 17. Take a look at this short video and you will see how nice it works. Iím not answering questions at this time.
https://youtu.be/AFmhih1I5io

JakeFruit

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Those sure are some pretty fruit!

Azoxystrobin sounds promising, but Nu Film 17 looks pretty pricey (considering my needs). I'd probably try pairing the Azoxystrobin with the surfactant I recently purchased, but once I get enough trees in my yard, Nu Film 17 sounds like the way to go with whatever I'm spraying. A long-lasting surfactant (requiring few applications) is definitely appealing.

I wonder now if Azoxystrobin plus the potassium bicarbonate (I just purchased) would be of any additional benefit....or harm.

The few panicles I currently have are all flowering (never been so happy to see flies), so I'm thinking the safest path is to hold off on any spraying until any set fruit get pea-sized. Hopefully this week of cold weather will prompted a bigger flush and I can spray in 2-3 weeks, before any next round of flowers open.

weiss613

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Jakefruit. If you spray with 98% mineral oil and Azoxystrobin you will be getting fungus plus scale. It doesnít kill all scale but greatly reduces the population plus many other pests including another mode of action against fungus. Donít mix the baking soda with Azoxy but can if only spraying mineral oil.

JakeFruit

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That sounds cheaper!  ;)
Do you use a special nozzle to spray mineral oil or does it spray well through standard spray heads?

 

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