I just returned from an international conference on integrated pest management. Since my last two articles were on soils and composting. I was excited to learn that the trend in pest management is to manage soil quality.
One thing the scientists pointed out was that systems with higher amounts of nitrogen have greater insect problems. They said that organic matter (OM) in the soil buffers this effect, because it reduces the need for large amounts of nitrogen and encourages beneficial micro-organisms in the soil. These soil critters may induce a systemically inspired plant resistance to insects. They called this "plant defensive signaling."
Soils high in OM also help plants resist diseases, because the beneficial microbes act as antibiotics, parasites or competitors to the disease organisms. One speaker called the appearance of good soil "chocolate cake soil."
One of the key points of the conference was that overuse of chemical pesticides causes resistance in pests such as insects, diseases and weeds. Home gardeners and commercial growers have traditionally overused pesticides. There are now more than 500 insects, 150 diseases and 320 weeds resistant to chemicals, so we have far fewer effective chemicals available.
For example, glyphosate has become the most widely used herbicide in the world with a $4.5 billion market out of a total herbicide market of $9 billion, outselling the next 15 chemicals combined. However, after only five years of use, many weeds became resistant to products containing glyphosate, the active ingredient in Roundup, Kleenup and other products. Twenty states now have weeds resistant to glyphosate.
Resistance is not as critical a factor for home gardeners as it is for food producers. Homeowners can weed by hand, remove diseased plants or wash insects off. Commercial growers cannot afford these labor-intensive techniques. More than 205 million acres of cropland were treated with glyphosate in 2008.
Resistance to this product could have a significant effect on world food availability.
Controlling pests is a reactive rather than a proactive process. Building the soil to make plants grow better and be less susceptible to pests is a proactive approach. As gardeners, we are pushed into thinking we have to use insecticides, fungicides and herbicides by industry media.
Last week I listed a link for compost at Cornell: http://www.cfe.cornell.edu/compost. An astute reader let me know that the link has been changed to www.css.cornell.edu/
compost/outdoors.html
- JoAnne Skelly is the Carson City/Storey County Extension educator for University of Nevada Cooperative Extension. For information, contact Skelly, at 887-2252 or skellyj@unce.unr.
edu, your local University of Nevada Cooperative Extension office or at www.unce.unr.edu. Ask a Master Gardener at mas
tergardeners@unce.unr.edu.