A nice yellow track is visual 3 to 5 days after the UV treatment.

Then small grass and weed starts to grow slowly. 

Weed having stored resources underground in a large root system,
is growing faster and several treatments are necessary during the
growing season to dry out their underground storage.

After 10 days, the track is still nice yellow but after 2 weeks green
grass and weed are coming up from below.

After 2.5 week, grass and weed is regaining power and the
treatment has to be repeated in the growing season.

 

The photo from may 3, 2007 below shows the conditions 2.5 week
after the 2. UV treatment this year.

UV light did stop the thick layer of lawn moss, but straws of grass
are getting tall.
It is time for the 3. treatment this year to dry out the weed and
grass, so it remains tiny as in the black spot.

The photo below taken on may 13, 2007, and shows the conditions 10 days after the 3. UV treatment this year.

The dry dead lawn moss has been gently removed manually before the 3. UV treatment.
Next the lawn has been cut by a lawnmower to shorten grass and weed outside the track.

The 3. treatment this year were a major setback for the weed.  10 days after, the photo shows no weed.
Getting my glasses, I did find a few - 1mm high.

The first two days were dry but during the following 8 days the weed  received 34 mm rain.

The weed will come up in a few days but it will probably remain tiny until the next UV treatment.

The photo is taken on may 21, 2007 and shows the conditions 2.5 week after the 3. UV treatment this year.

The photo is taken on may 29, 2007 and shows the conditions 26 days after the 3. UV treatment this year.

The photo is taken on June 7, 2007 and shows the conditions 35 days ( 5 weeks ) after the 3. UV treatment this year.

The photo is taken on June 26, 2007 and shows the conditions 2.5 week after the 4. UV treatment this year.

2.5 week after the last photo only little weed has been added in the UV treated track.

Normal rain is 60 mm a month, but we got 201 mm since the last photo.

The photo is taken on August 4, 2007 and shows the conditions 2.5 week after the 5. UV treatment this year.

The grass were cut by a lawnmower 5 weeks ago.
38 mm of rain since the last picture.  38 + 132 = 170 mm since last UV treatment 5 weeks ago.

The grass were cut by a lawnmower 2½ weeks ago.
39 mm of rain since the last picture. 

The grass were cut by a lawnmower 6½ weeks ago.
68 mm of rain since the last picture. 

The grass next to the track were cut by a lawnmower.
8 mm of rain since the last picture. 

It were a major setback for the weed to be exposed to 7 UV treatments this year.

The grass next to the track were cut by a lawnmower 5 weeks ago.
45 mm of rain since the last picture. 

It is a major setback for the weed to be exposed to 7 UV treatments this year.
The temperature is now so low that further growth is limited for some time.

259 mm of rain during a mild winter since the last picture. 

It were a major setback for the weed to be exposed to 7 UV treatments last year. 
Money can be saved if a long pause can be taken during "winter time" where tractors can be used for something else.

May 3, 2008:   1 UV treatment in 2008.
The grass next to the track were cut by a lawnmower

Giant Hogweed,  Heracleum mantegazzianum, has been planted down the track outside the picture frame.
Their growth rate is extreme, so they will need UV treatments quite often in order to dry them out.
The ones planted has roots at the size of big carrots - small ones would have been more realistic.
 

13 mm of rain since the last picture. 

Giant Hogweed,  Heracleum mantegazzianum - shown on the picture below, has regain strength 5 days after a visit by the lawnmower.
However the plants radiated by UV light has a slower re-growth.

Japanese knotweed is planted at the end of the track ready for experiments later this year.