I looked up an MSDS for Weedmaster.
(Chloridazon). The toxicity data looks like a second application would be
OK from that standpoint. You might check with the label on the product to
see if it is listed for your other problem. It may be that the other weed
responds better to a different chemical. Your county agent should be able
to help you with identification of the weed and when it is best to
spray.
It is common to get say 90% control of a weed, so
go after the remainder next year.
It is also common to find that seeds from an
established weed population continue to sprout for a number of years. You
can't kill them until they sprout. Spotted knapweed is notorious for
this. My ag agent says some seeds will sprout for up to 5
years.
I was walking my hay field last week and found some
baby Lupine where the worst infestation was last year. I will have to
spray them again next spring, or things will be bad in another couple of
years.
Lupines are also a good example of the difficulty
of defining a weed. Lupine is native to our area, so it does not fit the
definition as an imported pest. It is pretty, and gardeners like it, so
you can't eliminate it on the basis that it is ugly and unpleasing to the
eye. It does spread and successfully compete with a desirable plant
(grass) which can make it a weed by some standards. The real reason that
it has to be eliminated is that it can poison cows and horses!
My high school biology teacher defined a weed as a
plant in the wrong place. Corn in a soybean field is a weed. Lupine
in a hay field is a weed.
Ed
Ed & Wendy Hauser 2994 Mittower
Road Victor, MT 59875
