Some months ago, I was wondering why one of the new pumpkin plants was looking so sickly. When I investigated the plant, I noticed that some of the roots were exposed, and was horrified to see many nodules along them that indicated the presence of the dreaded root knot nematode (RKN) – microscopic parasites that attack roots of plants. Wikipedia says this of them:
Root-knot nematode larvae infect plant roots, causing the development of root-knot galls that drain the plant’s photosynthate and nutrients. Infection of young plants may be lethal, while infection of mature plants causes decreased yield.
Horrible infestation of root knot nematodes on the roots of a pumpkin plant growing in a pot.
There are a few ways to try to manage a RKN problem. Thanks to Mother Weed, I had neem fertiliser, and I wasted no time in scattering lots of it in the area.
Marigold sprouts. Never expect them to grow directly in your garden because snails cannot resist their succulent red stems – even when the plants are bigger…
A prettier but less immediate solution is to grow marigold plants – specifically, the French marigold, or tagetes patula. The roots of this plant are said to contain a chemical that kills nematodes. First, you have to grow lots of the plants. At the end of their growing season, you are supposed to till them into the soil. This soil is now clear for planting other things, and the following growing season, you are supposed to grow the marigolds where they weren’t grown the first season.
Yes, it sounds complicated, but just look at these flowers:
The French marigold cultivar we currently have growing here. Gorgeous, isn’t it?
I can’t wait until we have bushes and bushes of them blooming everywhere! Besides, I’ll take biocontrol over the use of chemical pest control whenever I can.
The only problem is that snails find the plants delicious, and we’ve already had casualties. This has made me quite anxious, because you know how it is when you buy seeds - sometimes you get way too many, and other times there are so few that they become precious, like gold. Of course I feel like I don’t quite have enough marigold seeds for the RKN treatment, which I probably do, if all of them grow, but if they don’t… 
However, with the first group of plants growing, it’s safe to start sowing more precious seeds. Besides that, I hope that the ones that have started blooming will be able to provide us with seeds to grow more plants. It’s time to wage war on the snails again.
© 2014 curiousgardener.com All rights reserved.
