[Arid_gardener] RE: Root knot nematodes

[Linda Drew]

Hi, Marcia

Crop rotation and solarization can be used to control
root knot nematodes:
http://ipm.ncsu.edu/urban/cropsci/c06disea/nematode.html
http://ag.arizona.edu/PLP/plpext/diseases/vegetables/melon/melonrknot.htm

A Google search seems to indicate that most varieties of
marigold may be helpful, especially if used as a cover crop:
http://www.louisianalawnandgarden.org/en/lawn_garden/home_gardening/
flowers/Marigolds+Effective+Against+the+Southern+Rootknot+Nematode.htm

Bean are in the legume family and roots have nitrogen fixing
nodules that look similar to root knot nematode. I would check
first -- here are some pictures of what to look for:
http://helios.bto.ed.ac.uk/bto/microbes/nitrogen.htm
http://www.backyardnature.net/econitro.htm

Linda Drew
Master Gardener

>From: "Marcia" <boahiss at earthlink.net>
>To: <arid_gardener at CALS.arizona.edu>
>Subject: [Arid_gardener] RE: Root knot nematodes
>Date: Tue, 15 Aug 2006 15:58:44 -0700
>
>
>In a previous message, the following was part of a discussion on 
>controlling
>root knot nematodes:
>"In India, African marigolds (Tagetes erecta) planted with tomatoes or okra
>were found to be effective for reducing six kinds of nematodes including 
>the
>root knot nematode and for increasing the quality and quantity of crop
>yields. Some substance exuded from marigold roots interrupt the nematodes'
>life cycle because the nematode larvae have difficulty penetrating marigold
>roots and nematodes were unable to develop once inside marigold roots.  
>They
>say mulches made from marigold leaves and stalks have also helped reduce
>nematode populations."
>
>Can anybody tell me whether other species of Tagetes, such as the Mountain
>marigold (T. palmeri/lemmoni), which is available locally in the nurseries
>in Tucson, will also do this? I have a terrible problem with these 
>nematodes
>that I have battled with for years. I just pulled up a row of green beans
>that were finished producing and either dead of dying, and boy were the
>roots knotted! These nematodes really go after beans. So now this whole 40'
>X 6' area has definitely got them bad. I wanted to try planting the
>marigolds to see if this would reduce the numbers. I would need a lot of
>plants, so would prefer to find seed. So 2 questions:
>1. will Tagetes palmeri/lemmoni or other species of Tagetes work, such as 
>T.
>lucida, Mexican tarragon)? And
>2. anybody know a seed source for Tagetes erecta, and will it grow well in
>Tucson? Is it the same marigold that is sold in "eastern garden-type" seed
>catalogs, such as Park's and Burpee's?
>
>Thank you,
>Marcia
>
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