nematodes and cover crops was Edible Bulbs

We do not bring in any live plant material into our farm, all plants are sourced from seed propagation. Been growing Camas and lilies for 20 years in some parts of our fields and have not seen disease yet, ahem - knock on wood-. Nematodes are not an issue - yet - but keeping soil healthy is big concern. We summer, and or winter cover crop with sunflower,vetch, buckwheat, rye and sometimes mustard on 2 year cropping cycle. Improvement in soil OM and weed regime has been noticeable. Disease - we have no data but need to maintain best practices.

Janos

Thanks for information about marigold

clip from page 26

Using brassicas and many grasses as cover
crops can help you manage nematodes. Cover
crops with documented nematicidal properties
against at least one nematode species include
sorghum-sudangrass hybrids (Sorghum bicolor X
S. bicolor var. sudanese ),marigold (Tagetes patula ),
hairy indigo (Indigofera hirsuta ), showy crotalaria
(Crotolaria spectabilis ), sunn hemp
(Crotalaria juncea ), velvetbean (Mucuna
deeringiana ),rapeseed (Brassica rapa ),mustards
and radish (Raphanus satiuus ).
You must match specific cover crop species
with the particular nematode pest species, then
manage it correctly. For example, cereal rye
residue left on the surface or incorporated to a
depth of several inches suppressed Columbia
lance nematodes in North Carolina cotton fields
better than if the cover was buried more deeply
by moldboard plowing. Associated greenhouse
tests in the study showed that incorporated rye
was effective against root-knot, reniform and stubby
root nematodes, as well (20).
Malt barley,corn,radishes andmustard sometimes
worked aswell as the standard nematicide to control
sugar beet nematode in Wyoming sugar beets, a
1994 study showed. Increased production more
than offset the cover crop cost, and lamb grazing of
the brassicas increased profit without diminishing
nematode suppression. The success is conditional
upon a limited nematode density. The cover crop
treatment was effective only if there were fewer
than 10 eggs or juveniles per cubic centimeter of
soil. A moderate sugar beet nematode level was
reduced 54 to 75 percent in about 11weeks,increasing
yield by nearly 4 tons per acre (231).
On Nov 6, 2011, at 3:42 PM, J. Agoston wrote:

I have never seen in Holland to rotate the fields between crops. The prices
of field is so high there that they would not be able to afford it, they
cannot even buy field there, just rent it for 99 years, and relatives
cannot inherit fileds, as I know.

Most nematodes like Meloidogyne hapla and Ditilenchus dipsaci are
polyphagous. They can live on other plants as bulbs or root crops, they
also survive on weeds.
If you ever have a nematode problem you cannot eliminate it. We have
nematicids, but they are not 100% effective as methyl-bromide was, or
steaming the soil. But with those technologies, still nematodes survived in
lower soil levels. Rule of thumb is as long as a root can penetrate the
soil the nematodes will go down there. So it is a bit like the case with
viruses.
I have rented a field this year, and there was nothing just weeds for 7
years, before that potato was there. Upon harvest I noticed nematodes in
the crop I sown from seed.

Just think about it, why did the dutch swithched to isolated production of
vegetables and cutflowers? They had a seroius nematode infestation in their
greenhouses, so seroius that they couldn't control it with chemicals
anymore.

Sowing Tagetes is a good biological way to reduce the nematodes, but you
cannot eliminate them. You have to keep Tagetes on the field for at least 2
months, the longer the better. It is used mainly for the control of
Meloidogyne. The eggs will open if the Tagetes roots get near to them. The
invasional larvae (J2 - juveline nematodes) will enter the roots at their
tips, but this plant is not their host, so they will die within days. If
ther in nothing in the soil, the eggs wil lay there waiting for a host
plant's root for years.
There was an experiment with Globodera rostochiensis. After 8 years of
keeping the soil free from host plants my collegues still have foung viable
cysts.

Janos,
Hungary
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