Regional Gardening Reports :: National Gardening Association

In the Garden:
New England
September, 2006
Regional Report

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Although bagged spinach is off the shelves, local farmer's markets may have fall plantings to keep you in the green.

Respect Manure

We'd just had a spinach salad with dinner when we heard the news. The bag of spinach in the refrigerator went into the trash, and fortunately, we didn't get sick. But I've been following the ensuing discussion of the E. coli-contaminated spinach. The scare is prompting talk about the safety of the production and handling of food, and I think it's all to the good if more precautions are taken as a result to prevent contamination of food before it reaches consumers. I've had friends suffer through severe sickness from salmonella (mayonnaise in a store-bought sandwich) and cryptosporidium (imported raspberries). And I've been sickened from tainted seafood in a restaurant.

The situation has also raised questions about organic agriculture in general, given its dependence on manure. This is where things can get muddled.

I've used manure for many years from various sources, and while I wear gloves and gardening footwear when working with it, I haven't generally viewed it as a risky material. Then this past summer my son developed a nasty foot infection from a bacterium that's present in manure, but he wasn't working with manure or compost at the time and the source was never determined. Nevertheless I started researching and found a case of someone getting dangerously ill from accidentally puncturing her foot with a manure fork.

The fact is, manure is biologically active and capable of causing disease. But we don't need to throw out the baby with the bath water (synonymous with the proverb: Do not remove a fly from your friend's forehead with a hatchet!). We just need to be smart about handling it safely.

Manure Guidelines
The National Organic Program rules mandate that on land used to grow crops for human consumption, any raw animal manure must be composted, or incorporated into the soil at least 120 days prior to the harvest of a crop whose edible portion has contact with the soil (such as root and leafy crops). The Canadian Organic Growers have stricter guidelines calling for aging uncomposted manure for at least one year before use.

Some experts recommend not using uncomposted manure at all on edible crops. A report from Colorado State University Cooperative Extension says that, to be on the safe side, the manure should be hot composted at 130 to 140 degrees F for at least five days. Then the hot composting should be followed by a curing period of two to four months to get rid of any pathogens that survived the heat.

For those of us who make compost without manure, the heating and curing are not critical because E. coli is not a concern. And bagged composted manure from a reputable source should also be safe (check with the company about their process).

The tricky part comes if you use manure fresh off the farm, and then the above guidelines are important. Avoid using dog, cat, or pig manure because the parasites they contain can survive composting. We also could be smarter about taking precautions, such as wearing shoes and gloves when working with compost and manure (the woman who contracted the serious foot infection was turning her compost barefoot!), and, of course, not socializing in cow pastures (yes, I read of a case where 300 people became ill with E. coli after partying in a cow pasture).

Handling Produce
In addition, here are some suggestions for handling fruits and veggies to reduce the risk of exposure to a range of soil-borne diseases:

1. Thoroughly wash raw vegetables and fruits in running water right before eating -- even fragile fruits such as raspberries.
2. Use a vegetable brush to scrub foods with a thick skin or rind, such as melons, cucumbers, and citrus. Otherwise, any pathogen on the skin can find its way into the edible portion when you cut it open.
3. Peel root crops like carrots and potatoes.
4. Washing contaminated leafy produce doesn't make it safe because the bacteria are tightly attached, says the FDA, but it does reduce the risk.

It's unfortunate that organic agriculture is taking a hit with this latest disease outbreak because, to me, what this case highlights is the difference between food that's mass produced across the country or the world and handled by who knows how many people with many opportunities for contamination, and food grown on a smaller scale closer to home. Or at home. Even in New England we have a choice for much of the year. With indoor grow lights, we can extend the season even further. I'm now starting a crop of spinach in my tabletop light garden.

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