Question
QUESTION: i read that granulated sugar will kill dollarweed.  just to sprinkle it on and water it in.  it is growing under trees i don't want to kill.  will it kill only the dollarweed or other vegetation also?

ANSWER: Dear Judy:

Granulated sugar will kill weeds as confirmed in the excerpted article shown below: "A Sweet End to Weeds" (by UK author: Margrit Beemster, December 2005).

"Sugar has the potential to control annual weeds according to recent research trials conducted by researchers from Charles Sturt University. The researchers, ecologists Dr Suzanne Prober, Dr Ian Lunt and Dr Kevin Thiele, have applied sugar to trial plots for a project funded by the NSW Environmental Trust on how to restore understorey species in endangered Grassy White Box Woodlands.

Trials on a private property 揥indermere? and a travelling stock reserve 揋reen Gully?near Young in central NSW have provided dramatic results, with Paterson抯 Curse and Wild Oats flourishing in untreated plots whilst plots treated with sugar had far fewer annual weeds.

The researchers have found that sugar provides a good, short-term non-chemical and ecologically friendly method of weed control. "It appears sugar is a tool we can use to help change a system back to one dominated by native species rather than weeds,?says Dr Suzanne Prober who has been working to conserve and restore grassy white box woodlands for the past 15 years. Nearly all of the woodland belt, from southern Queensland to north-east Victoria is now used for agricultural purposes, principally wheat and sheep.

So why does the sugar work? Because it is one of the fastest ways of reducing soil nitrate levels. Dr Prober抯 compared soil nutrients in undisturbed woodlands and disturbed, degraded sites. She found the most striking difference between the two was in nitrate levels, which were extremely low in undisturbed remnants and high in degraded remnants."
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"How to Get Rid of Dollar Weeds"

(By The Raytown Post, eHow Member)

Step 1

First off, it's important to understand one thing about the dollar weed(and most weeds in general); Weeds thrive in poor soil and are a good sign that your lawn is either over fertilized or has unhealthy soil. The richer the soil, the more difficult it is for weeds to survive.

Now, dollar weeds may not be a problem in your entire lawn, but if you have them in any significant portion of it I would recommend treating your entire lawn as described in Step two.

Step 2

Divide the area of your yard you will be treating into sections of about 250-300 sq ft (about 17' X 17'). Spread a 1 lb bag of household sugar (or dry molasses, if available) over each section of the yard until the entire yard has been treated. Be sure to complete the entire area you plan on treating before watering your lawn.

Step 3

After the lawn has been treated with sugar, water the treated area(s) thoroughly. Be sure to water the sugar in well the same day or else you might be opening yourself up to another infestation: ants. Continue your regular lawn care regimen (mowing, edging, weed eating, etc...) but try to avoid over fertilizing or switch to an organic formula. Over the next two weeks you should begin to see a SIGNIFICANT decrease in the dollar weed population and, after a few more weeks with regular mowing, the weeds will likely be gone altogether.

You should treat your lawn with sugar twice a year, once in the Spring and once in the Fall.

Best regards,

Mack Jean
AllExperts
Master Gardener
Tennessee

---------- FOLLOW-UP ----------

QUESTION: If I understand correctly, nitrate is the end of the nitrogen cycle. food, amonia, nitrite, then nitrate.( in my saltwater reef tank)  So, does the sugar neutralize the nitrate?  Is the sugar harmless to the tree roots in the ground underneath?

Answer
As I understand the chemistry of this process, the sugar does in fact neutralize the nitrate.

My best educated guess is that sugar treatment of a lawn will not harm tree roots generally speaking, but certain species of trees might be susceptible and would advise proceeding with caution and perhaps completely avoiding application of sugar within the inside perimeter of the drip line of the tree(s)in question.