Video Clip: Weed Em and Reap Part 2. Living Mulch System: Disease Suppression


Weed 'Em and Reap Part 2: Reduced tillage strategies for vegetable cropping systems [DVD]. A. Stone. 2006. Oregon State University Dept. of Horticulture. Corvallis, Oregon. Available at: (verified 17 Dec 2008).


This is a Weed 'Em and Reap Part 2 video clip.

Watch this video clip at


Helen Atthowe, BioDesign Farm. Stevensville, MT. 

Audio Text

Disease Suppression

We’re seeing disease suppression, which is something we don’t entirely understand yet. There are many theories about what could be causing this disease resistance. But particularly the last two years, we’ve seen a very small amount of cucumber mosaic virus or pepper mosaic virus, which is a virus which attacks 800 species of plants, both monocots, grasses, and dicots, vegetable plants, and in fact, weeds as well. Our favorite weed, this Malva neglecta, is a place where the virus over-winters.

If I had seen this 10 years ago, I would’ve been scared to death, because cucumber mosaic virus can cause stunting of plants and diminished yield. But here we have this on our older leaves, mostly, and the plants outgrow it and in fact, are extremely vigorous. If we have any more peppers on these plants, you can see that the plants are falling over because there are so many peppers on this plant. And yet, if you look closely throughout all these plants, you see that there’s a small amount of this cucumber mosaic virus within the population of this living mulch field, yet it never seems to get to a point where we see a diminished yield.

So, the possibility is that these plants are kicking in with their immune system and in some way suppressing the cucumber mosaic virus. There are some theories that plants are encouraged to kick in their immune systems with microbial interactions, with soil microbe interactions, that may be enhanced by organic matter and organic residue additions which is what we think is going on here, but its still a new area and we’re not entirely sure.


Published January 19, 2009

This is an eOrganic article and was reviewed for compliance with National Organic Program regulations by members of the eOrganic community. Always check with your organic certification agency before adopting new practices or using new materials. For more information, refer to eOrganic's articles on organic certification.