Until recently, the term "safe" vegetables meant mainly that they were free of harmful chemicals or contained them in such low concentrations that they didn't threaten anyone's health.

There was, and still is, a lot of emphasis on using only pest-control chemicals approved for vegetable crops, applying them at the prescribed concentrations and frequencies, and allowing for ample waiting periods before harvesting.

These safeguards are still essential in helping keep garden vegetables safe.

Prevent, Reduce Contamination

In the late 1980s and '90s, a number of produce-related illness outbreaks prompted the 1997 start of a federal program to help keep fresh produce safe.

This new initiative stressed preventing and reducing the contamination of fresh produce with human pathogens (living things that make people sick).

The concept of safe food was broadened to include being free of disease-causing microbes such as Salmonella, E. coli 0157:H7, Shigella, etc., and parasites such as Cryptosporidium and Cyclospora.

Producing "safe" fresh vegetables in the garden is fairly easy, because vegetables aren't a primary source of human pathogens. Fortunately, the bacteria, fungi and viruses that sometimes make plants sick don't make people sick.

How Veggies Get Contaminated

How do garden vegetables get contaminated with the "bugs" that make people sick?

The most likely source in the garden is animal manure. But animal manures are good for the garden. They contain essential nutrients that help plants grow. And their organic matter improves soils.

The good news is that gardeners can reap manures' many benefits and still grow vegetables free of human pathogens.

Use composted manures.

The heat generated during the composting process destroys human pathogens. Besides making the food safer, properly composted manures are much more helpful to the garden than raw manures.

Must Be Properly Composted

Keep in mind, though, that improperly composted manures are likely to contain as many pathogens as raw manure. Don't use them.

If you aren't sure the manures you want to use have been properly composted:

• Apply them only after the vegetables have been harvested.
• Fully incorporate them into the soil.
• And wait at least three months before planting food crops in the garden.
• Don't use them on perennial vegetables and root crops.

Speaking of animal manure, living animals often visit the garden. Pets, deer, racoons, rodents and birds can carry human pathogens and may contaminate the garden with fecal matter.

Be aware of this potential problem. Keep on the lookout for the telltale signs that they've been active in your garden. If animals or birds do visit your garden, take measures to keep them out.

By applying chemicals properly, using composted manures and keeping animals out of your garden, you can help make sure your picture-perfect vegetables are not only fresh and nutritious, but also safe to eat.