Herbicide Contamination?

Sunflowers stunted by herbicide contamination.

Hi folks! It's been a long time since we posted anything new. We've been feeling challenged by a number of things and will write a more comprehensive post soon but wanted to get word out about a situation we had with many of the 'starts' we planted from seed this spring. Many of them were severely stunted or died from what appears to be herbicide contamination in our potting soil (which we made from combining last summer's compost and some composted horse manure).

We're posting this to our site in the hopes that people reading our posts about the deep mulch method of gardening and folks using grass clippings, animal manures, or hay or straw for mulch, or to build their compost piles will use discretion in acquiring those materials. Some herbicide chemicals can remain toxic for several years in plant materials and manure.

Herbicide-contaminated tomato plants

We always knew that farming chemicals can have damaging and long-lasting effects in the environment but didn't think we would be effected as we use no chemicals directly on our lawns or gardens.

It is ironic that, after championing the use of "local", organic materials to create garden fertility (instead of imported, concentrated fertilizers that are often mined and produced unsustainably) that we experienced such devastating results.

Of the hundreds of tomato and pepper seeds we started this year, not a single one was unaffected and all had to be thrown out!

If you are still using chemicals to fight weeds, we urge you to stop. Herbicide contamination is another reason to only eat organic foods as they minimize the use of these chemicals in our environment.

Here are links to two excellent articles we found on the topic:

(LINK) - Gardener Alert! Beware of Herbicide- Contaminated Compost and Manure

(LINK) - Herbicide Carryover in Hay, Manure, Compost, and Grass Clippings

We encourage you to do research of your own and share your comments below if you have relevant experiences.

Here are the details of our situation:

Right from the start, some of our seedlings did great but other varieties would do fine until they began putting on their second set of leaves and the leaves would begin curling in a distorted manner, never fully unfurling so the plants couldn't photosynthesize (get energy from the sun). We also noticed that some of the plants formed gold-colored nodules right below the soil-level where the roots begin to branch and on their root tips.

Onion starts did fine!

Some of our seedlings did fine:

• cabbages and kales
• cucumbers, squash and melons 
• onions
• artichokes

 But many of them did poorly or died altogether:

• tomatoes
• peppers
• peas, beans
• lettuce
• sunflowers, zinnias, marigolds

In many cases we started seeds three, and four times. It took us awhile to discover the likely source of our plant failures. For several months we thought our plants were suffering because it was so cool, wet and overcast; the Pacific NW - where we live, set records both for rainfall, and consecutive days of cloud-cover this past winter and spring. Plants sometimes develop a condition called "damping off" - (LINK) where they rot at the soil-level. 

Starting seedlings - before we knew our soil was contaminated.

After an on-line search, we found the articles listed above that outline the symptoms we were experiencing and they attributed the problems to soil contamination from a class of herbicides commonly used on golf-courses and other large public lawns, and on fields that are destined to be planted in grass-seed, livestock and horse-feed, and grain crops (such as wheat). These herbicides target broad-leaved weeds but do not kill grasses and grains. We haven't had our soil tested so we can't be sure but we feel it is likely that the wheat-straw we purchased to mulch our garden and build up our compost-piles might have been tainted with one of the products listed in the article (Clopyralid and aminopyralid, or something similar). It is also possible that one of the loads of composted horse manure that was donated had not been composted long enough and still contained herbicide residue.

OSU students sifting compost and manure to make potting soil.

Compost Contamination: This is the first year in the Sharing Gardens that we made our own potting soil. We've always purchased it in the past. For many years Chris has had experience making his own potting mix (prior to the Sharing Gardens) and always had good success with it. Last summer (2016) we made a huge amount of compost. It was made primarily from grass-clippings, wheat straw and leaves. For the first time since starting the gardens, we had enough excess compost after planting Fall crops, to save it for making potting soil.

Our recipe:

•  2-parts of our compost
•  1-part of composted horse manure/sawdust and 
•  a small amount of coffee grounds.

We don't know if the contamination came from manure that wasn't composted long enough or the wheat-straw we used to build our compost pilesl. We've checked with all the people who have donated large quantities of grass-clippings and none of them used any herbicides last year on their lawns so we feel confident that grass-clippings were not the source.

The reason we think it was our potting soil that was contaminated is that none of our seeds planted directly in the ground showed any of these same signs of distress.

Compost bins(left) and grass-piles (center) for garden fertility.

Note:

• Do not use contaminated compost or manures to make "compost tea" if you are going to be pouring it on any of the families of plants listed above. In addition, potatoes (in the same family of plants as tomatoes, peppers, eggplant and tomatillos - solanacea should not be grown in contaminated soil or had tea applications. Lettuce may also be susceptible).

• Some chemicals can remain active in the soil. compost or manure for two years or more.

• They can harm vegetable and flower plants in concentrations as low as 3 parts-per-million!

• While it is unlikely that enough of these chemicals would be present in lawn clippings from a residential source to contaminate your compost or mulch-pile, there are several herbicides available from garden-stores that do contain aminopyralid or clopyralid.

      -- Here is a list of herbicides and their active ingredients organized by trade names.

      -- Here is an alphabetical list of herbicidal active ingredients, with trade names following.

We encourage you to do research of your own and share your comments below if you have relevant experiences.

Carrots (front) and nasturtiums (back) are thriving this year!

Once we discovered the source of our plants' distress, we bought some regular potting mix and have successfully started lettuce and most of our flowers. It's too late to start peppers and tomatoes.  The only pepper plants we have are ones we purchased at a nursery; unfortunately we won't have many peppers to share this year.

Steve Rose, in a previous year, with tomato plants he donated to the Sharing Gardens and Monroe's Food Pantry.

We're grateful to our friend Steve Rose for dropping off dozens of tomato plants he started from seed. If not for him and the tomatoes that "volunteered" in our greenhouses from fruits that fell on the ground last fall and sprouted this spring, we'd have no tomatoes. We've managed to dig up and transplant almost eighty tomato seedlings and even have had a few dozen to give away. Thank goodness for volunteers! (This is another great reason for only growing heirloom/open-pollinated seeds: if we had grown hybrid varieties of tomatoes, the "volunteers" could not be counted on to "grow true".)

Thank goodness for kale! Delicious, nutritious and unaffected by herbicide contamination.

On a happier note, it's now mid-June and we have most of the gardens planted. It's been a challenging winter and spring but we're feeling optimistic for the Summer and Fall to be able to fulfill our mission of providing bounteous harvests of vegetables to our local food charities.

LINK to Herbicide Contamination Update