WHAT IS CGM
It a natural byproduct of wet-milling corn during the corn syrup process. Corn gluten meal is used in the production of taco shells, pet foods and corn chips etc. Corn Gluten Feed is an animal feed.

Corn Gluten Meal CGM is both a pre-emergent herbicide and a natural source of Nitrogen fertilizer, making it an all natural weed and feed product. There are no pesticide or synthetic fertilizers in it. There are products available on the market that have other additives making them fertilizers with CGM. When a product has a nitrogen level of less than 10 (10-0-0), it is less expensive and also less effective. The fillers used in CGM where the NPK level is less than 10-0-0 have little to no fertilizing effect on flora. According to studies and research done at IOWA State University on CGM synthetic additives or fillers can result in a diminished pre-emergent effect on weed seed germination.

CGM is a 60% protein material containing 10% nitrogen. It has the following amounts of Nitrogen, Phosphate and Potassium; 10-0-0.

It can be a fine yellow powder or a golden pelletized product. Both are pre-emergent herbicides. Pelletized product provides ease of application and effectiveness for up to six weeks, unlike powdered product.

The first patent for CGM was in 1991 as a natural pre-emergent herbicide.

WEEDS THAT CGM CONTROLS
In Ottawa, CGM is used primarily to control crabgrass, but will also reduce the germination rate for curly dock, dandelions, knotweed, lambs quarters, pigweed, and plantain (in alphabetic order).

WHERE TO USE CGM
Lawns, flowerbeds, bulb beds and vegetable gardens

WHEN TO APPLY CGM
Three times a year is best but the spring and fall applications are the most important. Fall application prevents weed root systems from establishing over winter, while the spring application will control the germination of weed seeds from the previous fall.

The first application can be done in early spring, after the snow has melted, since the corn gluten pellets slow release life is about six weeks. This annual application occurs from mid April to mid May. Apply the CGM before the tulips go dormant. This application is effective at reducing crabgrass germination. If used annually it is 80-100% effective.

The summer application should be from the middle to the end of June; this will reduce the weed seeds that blow in, in late May, such as the dandelions.

In July to mid August, the lawn will be dormant or semi dormant depending on the temperature and rainfall. Let the lawn go dormant by not giving it additional water. This reduces the survival of recently germinated weed seeds and the eggs of lawn insects such as the European Chaffer Beetle, Japanese Beetle and June Beetles (lawn grubs).
Overseed from late August to the end of September if the lawn is not robust. Grass seed needs at least 6 weeks to establish before winter arrives. CGM can't be applied until it is established.
The third CGM application is done in October, after the grass seed is established, and late enough to be active in the very early spring.

HOW TO APPLY CGM
It is applied to the soil surface for lawn weed control. Broadcast the product using a fertilizer spreader at the recommended application rate. Water the product thoroughly after application to press it to the soil surface. The watering or rain releases the proteins in the CGM, which are toxic to root growth in seedlings. Every time it rains these proteins are released until the pellets decompose.

Mix it into the top 1.4" of soil before transplanting flats or container grown annuals, perennials or vegetables. These plants will not be harmed by the CGM because they have a large strong root system. With less weeds in your Garden, nourishment from the soil will be directed to desirable plants instead of strengthening weeds.

The CGM in pellets is easier to apply than the powder form, will not cake when it is watered and will not blow away upon application.

Suggested application rates are in the order of 2 Kg / 10 m2 to lawns or gardens

Buy the quantity needed for each application and if there is any left over keep it dry otherwise it may decay.

RESULTS
When it is applied annually in the spring there is up to 98% control of crabgrass germination. The plants do not grow so with repeated use there are less seeds on the soil to germinate
CGM won't damage the lawn, or soil because it is a natural product. People and pets can enjoy the greenspace or yard immediately after application because CGM is non- toxic.
In fact the Nitrogen is in the form of a slow release fertilizer, so the plants will be lush, leafy and dark green. Some companies have added other nutrients to make it more of a broad based fertilizer, but to be effective as a pre-emergent herbicide it must be 98% CGM. (10-0-0)

HOW IT WORKS
The natural plant proteins (dipeptide) in Corn gluten meal stops root growth when seeds germinate causing the plants to die. This is especially effective if the soil dries out shortly after germination.
In the future new products will be marketed. Research into hydrolyzed proteins from corn and other grains can be applied as sprays and have higher herbicidal potential.

ADDITIONAL INFO
http://www.gluten.iastate.edu/
Environmental Factor (Oshawa) www.environmentalfactor.com

Other Natural Herbicide Products
There are new environmentally friendly contact herbicides that use pelargonic acid a fatty acid found in plants and animals. They rapidly lower the pH of any plant sprayed weakening the cell walls and killing the plant in about 2 hours. They are not systemic nor selective so they cannot be used on lawns Weed Eraser TM, Scythe TM Natures Glory, fast acting Weed, Grass Killer contains acetic acid (vinegar) and lemon juice Ecoval Company sells a commercial formula which is 25% acetic acid.

http://attra.ncat.org/attra-pub/PDF/weed.pdf

Source: http://www.ottawa.ca/city_services/yourhealth/environmental/lawn_2_h_en.shtml