There’s nothing worse than pouring time, energy and money into growing the best, healthiest, most aromatic plants imaginable, only to spot signs of fungus and disease threatening to wipe them out. It’s certainly not the end of the world, though it can seem so at first glance. But depending on the seriousness of the infestation, it could be the end of the individual plant’s world.
While there are many types of plant disease and fungi, this article will focus on two of the more common ones – the dreaded powdery mildew (or PM) and gray mold, otherwise known as Botrytis. Treatment methods, along with tips on keeping your plants in tip top shape so they’re not susceptible to such ailments, will also be covered.
Starting with the oldest known plant disease on record, powdery mildew is also one of the most common and easily recognized. The fungal disease creates patches of white to gray powder on plants’ leaves, stems, flowers or fruit and, while generally affects leaves’ upper sides, can also take over their undersides.
To avoid PM, steer clear of conditions that favor it, such as cool, damp environments with little circulation. Make sure your plants aren’t crowding each other, that they get enough sun or artificial light and have enough room and air to breathe. It’s best practice to water plants in the morning before full daylight, so they’ll have the remainder of the day to dry out, which discourages disease establishment. Hopefully they’ll thank you later by producing sweet, tasty fruit.
If cultural practices fail and your plant becomes infected with PM, the best bet is to remove and destroy all infected plant parts, or the entire plant, depending on the severity of its spread. But don’t make the mistake of tossing the debris in the compost, as hot temperatures are needed to kill the fungus, which generally doesn’t happen.
After destroying infected plant parts, you can try and control PM’s spread by pruning the plant, which boosts air flow while reducing humidity and infection. And when feeding your plants, avoid using nutrients high in nitrogen, as it promotes tender, succulent leaf growth, which are easy targets for PM infection.
Homemade sprays high in sulfur (garlic cloves can be crushed in water for this) are another option when initial signs of PM are noticed, and there are plenty of organic brand-name treatments on the market. Keep in mind, however, that continuous, regular spraying is needed to prevent and control disease, but it won’t kill the fungi.
Onto the sickly gray mold, which if ingested, can cause illness. Another fungal disease, there are many Botrytis species that can severely affect plants, though the most common is Botrytis cinerea. It can invade nearly every part of the plant, with the exception of the roots, and spreads most rapidly in humid, relatively cool conditions. The disease initially appears white, but soon darkens to gray. Dust-like spores form and are quickly spread by natural forces (wind or insects) or through watering.
To avoid contamination altogether, follow all the best practices listed above for PM, and be methodical in the grow room or garden. This means removing all dead and dying plant matter from the plants themselves and from the soil, then destroying it.
The gray mold mainly lives on dead plant material and spreads to susceptible living plant material via wind and water, therefore it’s imperative to stop the spread of spores. Another best practice is to cover the infected part with a plastic bag before removing, to decrease the risk of spores spreading. And when removing such plant parts, be careful to do so during dry conditions, as wet, mold-ridden plants are more likely to spread fungal spores.
So while there aren’t any cure-alls for these fungal infections, controlling their spread is key in preventing a full-on outbreak.