Hy Liliana!
Here in the south of Chile it is comon for us to have grass grub in our rye
grass pastures.
This type of insect only eat roots, so it is hard to get there with some
insecticides; we have good results using: clorpirifos 10 % dust, 5 Kg/ha,
mixed with the fertilizers and put in the soil with a no till seeder.
Another good control is Imidacloprid 70 %, using 200 grams per 25 Kg of rye
grass seed, and seed with a no till seeder. Depending of the stage of grouth
of the insect, it is posible to control some population, using a high
concentration of animals to squeeze the insects in the soil; it helps only
to reduce the population, no to control 100 %, and you can get some
compactation problems, depending from your soil.
Hope this helps.
Regards
Dieter Uslar
Agronomist
COLUN Ltda.
www.colun.cl
duslar@colun.cl
----- Original Message -----
From: "liliana Sotomayor" <whitsot@uio.satnet.net>
To: "Graze-L@Witt. Ac. Nz" <graze-l@witt.ac.nz>
Sent: Wednesday, April 28, 2004 7:22 AM
Subject: [Graze-l] grass grubs
> Dear List members,
>
> I would be grateful for any comments on the management of ryegrass
pastures
> that are infested with grass grubs. Here is my situation.
> We have been using NZ ryegrass seed for more than 20 years now and
> constantly improving soil fertility. Soil tests for P are around 30-35,
> great organic matter content, but we still have a bit of S and Mg to add.
We
> are located at 3000 m above sea level. In the past 5 years we have seen
the
> ryegrasses being pulled by the cows as they graze to the point that
pasture
> persistence is diminished to 3 years. Since kikuyu is present it readily
> takes over. Examination of the root structure reveals poor root
penetration
> to deeper parts of the soil, although examination of the soil profile
> indicates no level of compaction ( and water drains freely). Grass grubs
are
> present at rates of 2 to 10 per area of 20 square cm. which I have been
told
> is a level of action in NZ.
>
> If treatment is needed for the pasture the question is with what. I have
> thought of using systemic insecticides that are sprayed on the grass and
its
> transported to the roots where it will kill the grub. I do have access to
a
> sprayer. Application of insecticide granules on to the soil is a bit
harder
> as I will need a seed drill with discs.
>
> I think the grubs are a problem but that maybe grazing management would
help
> control them. At this point I HAVE to do something drastic to save some
of
> the better paddocks. What would be the insecticide to use (generic name
for
> ingredient, please), rate, when to apply, when to graze again.
>
> Thanks so much for any comment.
>
> Liliana Sotomayor, DVM
> Casilla 17-12-245
> Quito, Ecuador
>
>
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