[Microbeman]

Actinovate;

Originally Posted by Microbeman
Actinovate is Streptomyces lydicus (bacteria). I'd be very interested to know if it is effect against PM

Well you're in luck. I just found some PM near my cool air intake and I have some Actinovate. Trial test this week,I'll let you know what becomes of it. I'm assuming it will be one of those things where continued applications are needed every few days..who knows.

[Microbeman]

I hope I did not jump the gun starting up this thread. If Cheese and George have not already placed their posts elsewhere, please put them here.

Controlling Powdery Mildew (PM) is a giant deal. There are many strains/species of the family Erysiphaceae and some ones introduced to North America in the past 15-20 years. To fight something, I believe it is best to understand it and unfortunately PM is relatively complex, changes stages and is apparently hybridizing.

From a bit of research today it 'appears' the species 'mostly' effecting cannabis/hemp are;
Podosphaera macularis [aphanis]
(formerly Sphaerotheca macularis) First seen in the west in 1996 in Yakima valley where it destroyed crops of hops and has since spread throughout the west and has opened up its appetite to include some other crop species and some species of weeds. In its aphanis variation it effects strawberries.
AND
Leveillula taurica (anamorph; Oidiopsis taurica)
introduced to Florida 1971; effecting chili and bell peppers, tomatoes, cotton, globe artichoke, onion. Leeks, tomatoes and can also infect weed species.

Although Actinovate (Streptomyces lydicus) claims that it can control PM, I could find no direct evidence by way of trials to support the claim yet. [a certain member who used to get peer reviewed papers for me is no longer with us] I've attached a paper which outlines some fungal pathogens it was effective against. I also attached a document from UC Davis about PM. It appears that Actinovate is effective against some fungal pathogens and it has been determined (hoped for) that it may be a broader fungal pathogen antagonist. If it works, it works. Be mindful that just spraying water on PM controls it (or some species) to a large degree.
https://pmep.cce.cornell.edu/profiles..._reg_0305.html

My opinion is that PM is encouraged by higher amounts of nutrients but that is only a speculative hypothesis at this point. To beat back an outbreak of PM, I think what is needed is an organism which devours it. I am (slowly) working on two angles to this, one bacterial, one fungal.

Our PM problems in our greenhouse a number of years back subsided when we stopped using fertilizers and used compost tea consistently. Because we had no control for comparison, it cannot be determined that this was causational.

Serenade - Bacillus subtilus

AQ-10 - pretty sure the original company distributing it went down but another bought the rights and available somewhere.

Ampelomyces quisqualis isolate M-10 is a naturally occurring hyperparasite of powdery mildews. This parasitism reduces growth and may eventually kill the mildew colony. The mycoparasite is not restricted to powdery mildews. In vitro work indicates that it can be parasitic on Botrytis cinerea Pers. Ex. Fr., Alternaria solani (Ell. & Mart.) Sor., Colletotrichum coccodes (Wallr.) Hughes, and Cladosporium cucumerinum Ell. & Arth (Jarvis & Slingsby, 1977) There is no information indicating that A quisqualis shows infectivity or pathogenicity to any organisms beyond this relatively narrow taxonomic range of fungal pathogens. Indeed, its life history strategy as a hyperparasite, would tend to preclude a wide host range.

It infects and forms pycnidia (fruiting bodies) within powdery mildew hyphae, conidiophores (specialised spore-producing hyphae) and cleistothecia (closed fruiting bodies of powdery mildews). Having penetrated into the mildew hyphae, the fungus produces pycnidia, in which form the pathogen can survive adverse periods e.g. winter, in and around the host plants of the mildew fungi. The pycnidia produce spores, which require favourable conditions for successful germination e.g. in terms of temperature, moisture and in particular the presence of the appropriate host. Over-wintering pycnidia can also be produced saprophytically in vascular plants e.g. in mildewed clover leaves and in cucumber leaves (Yarwood, 1939). The infectivity of the spores produced by the pycnidia rapidly diminishes under field conditions (e.g. 24 to 48 hours), although this can be extended under appropriate conditions.

Sundheim and Krekling (1982) demonstrated that A. quisqualis produced specialised appressorium-like penetration structures on powdery mildew. Penetration of the host cell was probably due to mechanical and enzymatic processes. Furthermore, enzymatic digestion played a major role in the invasion of the host cell and the destruction of cytoplasm. Invading hyphae penetrated the host cells through the septal pores of the host. Beuther et al (1981) studied the effects of extracts from the hyperparasite on growth, sporulation and conidial germination of the host. They found no evidence of toxin production.

Calcium deactivates the pectolytic enzymes produced by powdery or downey mildew condida and stops the PM from 'rooting' even deeper/more into plant tissue. The condida spread in between plant cells where pectin predominates, and I could be a bit off there, can be inhibited with increased calcium levels. Visible PM is the mushroom (fruiting body) of the hyphae (mycelium). While that may not be the correct scientific way of describing things I think people get the picture.

I'm a bit rusty on the hyphae/condida thing.

Foliar calcium for PM helps! As a plant matures in the flowering cycle it's under stress and basically dying so PM becomes more prevelant the deeper you get to flower...IMO. Serenade always seemed to work great early on but the more you used it, and also the more mature the plants were (deeper in flower), the less effective it seemed.

My opinion is that PM is encouraged by higher amounts of nutrients but that is only a speculative hypothesis at this point. To beat back an outbreak of PM, I think what is needed is an organism which devours it. I am (slowly) working on two angles to this, one bacterial, one fungal.

I have heard that when N is used to excess it can promote PM issues. Instead of the 'higher amounts of nutrients' thing the flip side of sorts is having unhealthy plants which are disease and pest magnets. A treatment can also be looked at as a bandaid.

[Microbeman]

link for the quote? Sp; condida = condidia

Originally Posted by Microbeman

Our PM problems in our greenhouse a number of years back subsided when we stopped using fertilizers

What were the fertilizers?

Originally Posted by Microbeman

link for the quote? Sp; condida = condidia

I'm not so technical like you about these things regarding proper scientific lingo. I looked and actually it's conidia. I remembered it as condida that were the roots penetrating but guess that's the hyphae. I think you have it from here cause I seem to be pretty wrong.

[Microbeman]

Originally Posted by Nondual

I'm not so technical like you about these things regarding proper scientific lingo. I looked and actually it's conidia. I remembered it as condida that were the roots penetrating but guess that's the hyphae. I think you have it from here cause I seem to be pretty wrong.

yes I mispelt it too; haha

[Microbeman]

Do you have a link for your quote? BTW, I'm not arguing with you in the slightest. Don't stop posting.

[Microbeman]

Yeah conidia is just sort of another word for spores

[Microbeman]

Originally Posted by Nondual

What were the fertilizers?

Our PM problems in our greenhouse a number of years back subsided when we stopped using fertilizers and used compost tea consistently

Prefer the whole quote. Any and all fertilizers; zero zilch nadda

We had experimented with many types of fertilizers, typical & organic (OMRI certified)