So many people ask us about the beautiful yellow carpet of mustard flowers in the vineyard each spring. I thought that I would let our “expert” field that question. Garrett Buckland, from Premiere Viticultural Services, is part of our Vineyard Management Team. He brings an amazing wealth of knowledge to us (think Mr. Science in a vineyard) and helps us to make the best decisions possible as we create our Farm Plan each year. Our goals are always the same — we try to grow our grapes in the most sustainable way possible to produce the world-class fruit that you expect to be the foundation of our Baldacci Family Vineyards wines — but each year, Garrett helps us to responds to the changing natural environment (more or less rain, frost, etc).
I asked Garrett “why is there mustard in the vineyards” and he edited my question to address the mustards that are both naturally occurring and planted in our new vineyard block. Read what he said … you might need a dictionary!!
Why we have Mustard in the new blocks at Baldacci by Garrett Buckland
At Baldacci we have encouraged the mustard growth to help suppress nematode population and we have planted our own varieties that are specifically bred to have high levels of Glucosinolate compounds, or are “extra spicy.” These include, Black mustard, Nemfix mustard, IdaGold Mustard, Oilseed radish, Diakon radish and wild radishes. When we incorporate these plants back into the ground they will break down just as the first populations of nematodes are gearing up to do damage to our young vines, which usually coincides well with a soil temperature of about 60 degrees F.
Like all farmed crops, young grapevines can be very sensitive to plant parasitic nematode populations which can cause lots of problems in proper development of a vineyard. It’s very important to use all of the cultural techniques when we can to naturally reduce harmful nematodes rather than applying costly and dangerous chemicals to accomplish the same goal. In this situation we can let the right winter cover crop do the work for us.
Most members of the Brassica genus like rapeseeds, radishes, and mustards contain high levels biofumigants that suppress nematode populations. There are several different products that are released when mustards breakdown in the soil that disrupt the reproductive cycle of nematodes, and some that act as biofumigants similar to commercial fumigants used today. The compounds that work the best in reducing populations are the Glucosinolates, which degrades naturally into the soil into methyl isothiocyanate, a strong bio-nematicide. In general the more Glucosinolate compounds mustards have the better a nematicide they are. Glucosinolates are the class of compounds that provide the “spiciness” to mustards and radish species and the pungent flavors and odors to popular food products of mustards and horseradish. In Napa the most common “endemic” mustard is black mustard, with many different species present up and down the valley, always with bright yellow flowers. Also quite common and endemic to this region is wild radish, which can have a variety of colors in its flowers from white to pink to almost purple.
You often see these mustards spring up in fields when they haven’t been there for 10 years or more. Mustard seeds have been known to persist in soils for upwards of 20 years, and can often spring up where they haven’t been by simply discing a field at the right time. Here at the winery most of the wild mustard has already bloomed and set seed, while most of our planted species will continue to be bloom for another month or so.