To Cover Crop or Not To Cover Crop: Is it a Question?

What I really know and understand about the benefits of cover crops could fit nicely into a thimble. But with some required reading and research on the subject I found that there's an abundance of commentary on the issue, and as I was assigned in my Viticulture course at UCC, an article I wrote on the subject. So, I wanted to share it with my wine swirling, slurping audience how cover cropping or not cover cropping can benefit or be a possible detriment to what eventually ends up in that bottle of wine you may have just uncorked.

Summary: The ins and outs of cover cropping, the benefits, the pitfalls looked at, examined, pulled apart and weighed. Past farming techniques measured against current philosophy and approach, collectively we see the rewards outweigh the cover cropping risks. Cover crop research is imperative before starting a regimen, don't be afraid to reach out to local experts, neighbors, and become familiar with the preferred timing of mowing during dormancy and the late spring.

To cover crop or not to cover crop is no longer the question. In today's grape farming world, cover cropping is part of the path to a healthy vineyard. But not everyone agrees on the correct method to reach the desired outcome. This disagreement is likely due to the fact that not all vineyards are created equal; thus one approach is unlikely to achieve the goals of the vineyardist.

Since you've become convinced that cover cropping is the way to go, what to do now? There are so many options, a variety of choices and even more pitfalls if the wrong determination is made. It's best to consult an area expert for an informed decision, in the form of local farm advisor, they often know what works best in your area. For example, your farming practices will be very different if you're growing Cabernet Franc in Virginia versus the Napa Valley. Even mowing practices will be widely divergent, as Virginia wineries see much more rainfall in the summer than do wineries on the valley floor of Napa, along highway 29. For these many reasons, it's imperative to do some thorough research before getting started down that path.

The benefits of cover crops can be enormous and are often reaped for years to come, like the residual checks paid to actors and actresses after their popular sitcom has gone off the air.

Soil Erosion: If you have steep slopes in the vineyard, previously unused because of erosion and other concerns, the right cover crop can make the difference between a few more productive acres, which bodes well for a bit more longterm profit where margins are already razor thin.

Dust Control: The correct cover crop applied correctly can significantly reduce the amount of airborne dust, which can be kicked up during farming operations in the vineyard.

Water Infiltration and Evacuation: Again, providing the right cover crop is essential. Not all vineyards suffer from the same issue; primarily west coasters are concerned about increasing moisture while east coast vintners have more moisture than they know what to do with it. Thus east coast vineyards are less likely to mow unsightly overgrowth down the lanes of their vineyard during the summer months, while west coast vineyardists are mowing away to keep cover crops from competing with the vines for scarce water, especially those who dry-farm.

Nematodes: With less availability of chemicals to combat harmful nematodes, some vineyardists are using a rotation of various cover crops to help reduce their impact. Not all nematodes are harmful, but for those that are, applying cover crops which negate their activity is a useful tool.

Chemicals: If there is a desire to reduce the impact of chemicals in the vineyard, planting creeping red fescue could be an excellent choice, as it handles tractor use well and it chokes out competitor grasses. Of course, crabgrass is also a good choice if a less aggressive grass would suit the site better. With these choices of cover crop and others, it's possible to reduce the need for fungicides and other sprays significantly, and possibly increase a healthier beneficial insect population.

Beneficial Insects: Another possible, though not thoroughly studied to provide unimpeachable evidence, it has been suggested by some growers that cover cropping with appropriate choices for the site can significantly increase the populations of beneficial insects, like spiders and mites.

Nitrogen Health: Every grower eventually has to think about how to best manage Nitrogen [N] in their vineyards. It's a crucial nutrient for fruit quality, too much and vines can produce extra canopy, too little and it limits photosynthesis and thus reduce the quality of the fruit. One of the places ground can lose nitrogen is from heavy spring rains which can leach out, but with the right cover crop in place can help to recover N for recycling back into the soil. While it is cheaper to spray nitrogen than to depend on the cover crop [CC] for assistance, other added benefits of CC like cation enhancement and water infiltration cannot be minimized. There's also the fact that cover crops, for example, Barley Crop which uptake excess N and it may mean it's not polluting downstream water supplies.

Cover Crop Inoculant: Many may not even consider the need for an 'inoculant' I know I didn't until I thoroughly read this article, but without it, you may find your efforts of planting CC are all in vain. Most seeds today come pre-inoculated, but for those that are not, it's imperative to have the beneficial bacteria on the seeds being planted for CC; otherwise, the plants may grow poorly or just plain die.

Weed Control: The effectiveness of cover crops as a weed [aka native vegetation] control mechanism cannot be overstated. This means less need for spraying.

Vigor Control: Hedging may only do so much to help control vigor, by having a semi-permanent cover crop, it will compete with the high-vigor vines and ultimately give back control and bring balance. But of course, moderation is key in using cover crops to overcome excessive vigor issues, if too competitive, it could jeopardize vine nutrition.

Mowing: The decision to mow the cover crop can be crucial, but when is the question. In the winter, during vine dormancy, a CC over 18 inches could potentially retain cold air, whereas bare ground or minimal CC will more readily reflect daytime heat preventing vine damage on cold nights. In the spring and summer, mowing too early can lead to summer grass issues, it's best to follow tried, and true mowing SOP [standard operating procedure] and a thick shock of legumes is a smart defense.

There are many factors which need to careful consideration before employing cover crops, it’s imperative to do proper research in advance, and don’t be afraid to consult others who’ve gone down that road before, there’s no need to reinvent the wheel. Cover Crops used correctly can have unexpected long-term benefits far into a vineyards future, and on the flip side, it can make the difference between a good harvest and an excellent vintage. It may ultimately change the profile of your favorite winery or producer. There more than a few knobs, levers, and buttons to push, pull and rotate, before dialing in the perfect formula of viticultural success.