Basil Downy Mildew appearing in 2018 spring gardens

Basil Downy Mildew, or BDM for short, is a disease that is steadily impacting both commercial growers and home gardeners. You likely have seen it but didn’t realize what it was. BDM appears as dark grey water-soaked marks on basil leaves, and it slowly spreads over the whole plant and onto others, thanks to rain and overhead watering. Once your basil gets BDM, you’re pretty much out of luck. Harvest what you can and rip up the plants and bag them so you don’t spread the disease.

In years past I have seen BDM in my own community garden, appearing in the hot and humid months, so later in summer. Just this past April I spotted it on every single potted basil plant in my (local to Boston) Whole Foods’ produce section. And I also spotted it on basil plants at a big box store on Long Island. BDM is getting an early start this year!

DMR Varieties

Needless to say, BDM is a problem. Luckily some plant breeders have been doing some work to find basil varieties that exhibit DMR, or downy mildew resistance. I have heard of four options.

If you grow flowers you are likely aware of the Proven Winners brand. This year marks Proven Winners’ first foray into edibles with the introduction of Amazel Basil. Developed by researchers at the University of Florida (talk about hot and humid conditions!), they claim Amazel Basil is resistant to basil downy mildew. It’s also late to flower, they say, which means a longer harvest before having to pinch out those flowering heads.

The next three options are all out of the Rutgers University breeding program. They are Rutgers Obsession DMR (sweet basil with the added benefit of being highly resistant to fusarium wilt), Rutgers Devotion DMR (better for potted plant use and for fresh markets) and Rutgers Thunderstruck DMR (good for field and garden use with slightly ruffled leaves).

The question is, where do you find these plants? The Proven Winners website is a good place to start. They are very responsive when it comes to queries about their products. Also let your local garden center know you are interested in Downy Mildew Resistant basil varieties. They can then do the search-and-find process for you. Keep in mind that these are still relatively new plants. While a few many be available this year, look for a better availability of them in 2019.