Most celery has about nine hundred parts per billion of two natural carcinogens.
But one variety might have two thousand parts per billion, another two hundred parts. Someone just introduced a new celery into the United States with nine thousand parts per billion. Farmers, regardless of whether or not they use synthetic pesticides, have made use since agriculture 's beginnings of crop varieties that are resistant to insects and diseases. Many morphological characteristics have been used in plant breeding to reduce pest abundance and damage. The relationship between plants and insects is an ancient and fascinating one.