What is Podosphaera macularis?
Along with Botrytis cinerea (gray mold), another thorn in the side of the plant kingdom at large is the microorganism called Podosphera macularis, perhaps better known as white powdery mildew. Formerly known as Sphaerotheca macularis, the scientific community reclassified itopen_in_new with its current name around 1980. While this mold can cause disease among humans, it is most damaging to the plants it infects. In particular, it is a major threat to the success of industries that cultivate strawberries, cannabis, chamomile, and hops. This relentless microorganism may attack at three different stagesopen_in_new of cultivation: the vegetative stage, the flowering stage, and the drying/curing stage.
Where is it Found?
How Does it Spread?
What Does it Infect?
Preventing the spread of Podosphaera macularis
Podosphera macularis thrives in places of overcrowded, over-watered plants and high humidity. Within cultivation rooms, the best practice to thwart Powdery mildew is clean air circulationopen_in_new. Adequate space between plants is essential, increasing a harvester’s yield. Humidity levels must be regulated to prevent the air from becoming too saturated. While the moisture naturally transpired by plants is necessary for them to thrive, it can build up — creating an opportunity for pathogens like Podospaeris macularis to grow and spread. Also remove dead leaves and any standing water near your crop.
Since this stubborn pathogen has a tendency to resist synthetic fungicidesopen_in_new, alternate methods of controlling its spread are necessary for the healthy yield of crop — such as germicidal ultraviolet irradiationopen_in_new, as described below.
Get More Protection with UV Disinfection
In addition to the above preventative measures, Germicidal Ultraviolet (UV-C) air and surface disinfection can inactivate Podosphaera macularis in greenhouses and for the cannabis industry — including growing rooms, drying rooms, and laboratories.
Learn about these applications:
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Indirect UV models are designed for occupied spaces. Direct disinfection models (with lamps exposed) are only for use in unoccupied areas where plants are not present. Shop our products at AtlanticUltraviolet.comopen_in_new.
Our germicidal lamps produce ultraviolet wavelengths at 254 nanometers, the region of maximum germicidal effectiveness. Read our FAQ blog post to learn more. See dosage data below.
Podosphaera macularis: Classification & UV-C Dose for Inactivation
| Organism: | Alternate Name: | Type: | Disease: | UV Dose*: |
|---|---|---|---|---|
| Podosphaera macularis | Sphaerotheca macularis | Mold | Powdery Mildew | 16.9 mJ/cm2 |
* Nominal Ultraviolet dosage necessary to inactivate better than 99% of microorganisms. See sources below.
Podosphaera macularis Symptoms
The most common symptoms associated with Podosphaera macularis are as follows. After infecting a plants leaves, it spreads to other areas.
- Presence of white powdery mildew
- Purplish patches or blisters on upper leaf
- Damage to stalks, leaves, stems, and buds
- Discolored plant tissues
- Rotting smell
- Hindrance of newer growth
Sources on Podosphaera macularis
The above information can be found on the following pages.
- University of California: E-Journal of Entomologyopen_in_new
- Trifecta Natural: How to Treat and Cure Powdery Mildew on Cannabisopen_in_new
- Clean Leaf: Preventing Powdery White Mildew on Cannabisopen_in_new
- APS Publications: Powdery Mildewopen_in_new
- Wikipedia: Podosphera macularisopen_in_new
Dosage Source
Ultraviolet Light for Suppression of Powdery Mildew (Podosphaera Macularis) and Botrytis Fruit Rot (Botrytis Cinerea) Of Strawberry. Paulo Pinto De Mello Neto, University of Florida, December 2021.
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