Jul 14, 2017

Powdery Mildew: Biological Controls

Biological controls are living organisms used to prevent and treat pests in your garden. One great benefit of utilizing biological controls is that it allows you to be approved for certified organic gardening due to the absence of chemicals.

Why Should I Use Biological Controls?

Compost teas and products like Serenade contain numerous microorganisms (microbes). When you spray them onto your plants, these beneficial little lifeforms fight the good fight against the pathogenic ones. In addition to killing fungi, like powdery mildew, they can also prevent them in the following ways: increased overall plant health, improved disease resistance, and establishing beneficial microbial colonies which occupy space and consume plant byproducts that could otherwise end up supporting disease. In other words, you use these little buggers to create a militia of good guys that kick out the rowdy ones that would otherwise be hanging around and eating your goods.

Can it Be Harmful to My Grow?

Biofungicides can be used throughout a plant’s life cycle, but there are some important points to consider. While they safely treat numerous diseases on many different plants, the look and feel of some fruiting/flowering crops may be affected. If this idea scares you a bit, we recommend mixing a weak solution, testing it on a small area, and then adjusting your mixture as necessary. Or, stop using it entirely in the latter stages of growth. When using compost teas, it is very important to eliminate the possibility of human pathogens being applied to an edible crop.

What’s in the Water?

If you’re familiar with the benefits of beneficial microbes in the root zone, then you probably also know that they should not be combined with chlorine or chloramines. Chlorine and chloramine are present in every city’s tap water. Accordingly, use distilled or dechlorinated water when mixing biofungicides.

How do I Apply Them?

Make sure that you apply for thorough coverage but do not spray plants directly under high-intensity bulbs. Give your plants a break by turning off some lights and/or raising lights when applying your solution. Resume regular light intensity once the spray has evaporated and there isn’t any standing water remaining on the foliage. The goal here is to prevent burn spots on leaves, as well as to create favorable conditions for the microbes to get established. Click here for more application tips or the “Secrets of Foliar Spraying” provided by the makers of Bountea.

Biological controls can be an effective tool in an integrated disease management plan. Since they work in several ways, they present a win-win situation; in addition to proactively treating powdery mildew, you can also provide your plant's nutrients. By increasing overall plant health, diseases like PM stand less of a chance. Treatment is most effective when you start it early in a plant’s life and maintain it regularly. When you use this combined with the cultural controls covered in previous posts, biological anti-fungal controls can help you avoid serious PM outbreaks. Unfortunately, PM can’t always be prevented so make sure you know about chemical controls that can be used to combat powdery mildew once your grow has already been invaded.