Nematodes, the plant eating kind

[Tucson Grower]

In case some of you are having issues with these kinds of critters, such as "root knot nematodes". There is a natural way to slow them down, besides crop rotation. That is a product called Chitosan; rather the source of the product is the key. The source being the rinsed , dried, and ground shells of certain kinds of seafood. Those being: crabs, lobsters, and shrimp. The shells of these sea creatures are composed, primarily of chitin. As an asside: chitin is also the main ingredient in the skeletons of most insects.

When this powdered chitin is added to your garden soil, its decomposition adds some plant nutrients to your soil - and nothing bad (as long as any salt residue is rinsed off before drying and powdering). Then certain microorganisms, namely certain bacteria and fungi, which are likely already present in your soil, finding the added chitin to their taste, flourish and multiply. And this is why that is so important -- all nematodes, the good ones as well as the bad ones, lay eggs. Guess what their egg shells are made of; that's right, chitin. So boosting the populations of microorganisms that find chitin  an irresistable meal, does, definitely reduce populations of endemic nematodes that could adversely affect our crops.

[Tucson Grower]

Update: During my recent efforts in shopping for a good deal on this product - dried, ground, crab/lobster/shrimp shells. I discovered additional information, of which I had not yet been aware. Apparently besides increasing the populations of miocroorganisms that eat chitin, the microorganisms create an enzyme called chitinase, which they use to digest/eat the chitin, earthworms, among other creatures, also create chitinase when they eat the shell meal. Anyway, this enzyme, chitinase, persists in the soil (for an indeterminate amount of time - depends on many environmental factors), helping to guard our plants from growing populations of detrimental nematodes. And, the presence of the enzyme chitinase is a trigger that activates a plants natural defenses against insect pests. So, apparently it's a win, win, win - and perhaps even more wins.

[Tucson Grower]

Now, the back story: For quit some time I have been fascinated by the various, insect eating plants. There are quite a few more of them than most people realize. One group of them, commonly called, "Orchid Flowered Butterworts", really got my attention. I tried growing my first ones in the early 1970's. Though I experienced limited success, at that time, I was determined not to give up. I kept researching this group, and finally discovered that some nematode species found them to be ideal subjects to use for their nurseries. The nematodes modus operandi were to chew holes in the roots and leaf bases (the parts of the leaves having ground contact), then inocculating them with disease bacteria and laying there eggs. The rotten dying plants provided nourishment for the baby nematodes - yuck. So now I had to research how to control nematodes. It was helpful to know, that, while this malady did affect the plants, in nature, it was quite rare. I learned that nematodes are inhibited by UV light and chitin/chitinase in the soil root zone for these plants. Because these plants primarily grow in the American tropics, and at high elevations, such as pine forests, where they sometimes even experience sub-freezing temps. Their exposure to UV was quite high. Since they are adapted to have a high tolerance for being dry, most contemporary growers kept them on the dry side in order to reduce the incidence of this nematode - rot. The second important factor was; these plants attract insects to their leaves and trap them there, where they digest and absorb the soft parts of the insects, then rain washes the insect skeletons (chitin), down into the root zone.

Fast forward: It's now the 1990's and I began experimenting. I set up shelves with banks of cool white fluorescent lights (fluorescent lights leak UV) and captured large quantities of native insects, dried them and ground them to a powder. I began obtaining various species and hybrids of the "Orchid Flowered Butterworts" and kept them in shoebox sized plastic trays, in small plastic pots, using various innert media (such as perlite, vermiculite, pumice, cat litter, silica sand, etc.) under the fluorescent lights and floating in water, while I frequently fed them by sprinkling the leaves and soil surfaces with the powdered insects. My collection quickly grew, and in the ten or so years that I did this, I think the nematodes got about 3 plants, total. At that point I had tens of thousands. My electric bill, just for the lights, was more than $100 per month.

And that's why I know that chitin works to supress nematodes.

[Tucson Grower]

One final point of interest: nematode mouthparts are also chitin - a wammy point.

[amyinowasso]

Do root knot nematodes fll into this category?

[Tucson Grower]

Yes, I believe they are the root knot type. They just have a more immediate and devastating effect on the "Orchid Flowered Butterworts", than they do on our more robust garden plants. And, since the morphology of most nematodes is similar, if not the same - the use of chitin supplements should be just as effective on the majority of them.

It would be like us, swimming in a mix of stomach acid and digestive enzymes. We might be able to endure it, for a few minutes, but eventually it will do us great harm.

It certainly creates a hostile environment for the nematodes.

[Tucson Grower]

Considering how relatively expensive crab, shrimp, and lobster shell meal is I've been contemplating other potential sources of chitin. My initial experience using the dried ground bodies of endogenous insects caught in plastic buckets hung beneath electric bug zappers and wrapped with 1 inch chicken wire to keep lizards and birds from stealing the insects. I then dry them on a dedicated cookie sheet in the oven at 100F. for about 15-20 minutes. I then grind them in a dedicated electric coffee grinder, until they are a powder, then store them in labeled airtight containers until use. They last almost indefinitely. It's amazing how many pounds of dried insect powder I can accumulate in one season, even here in the desert Southwest, with only a single collection device. I was also thinking that an even larger collection device, that might also catch some grasshoppers could be set up using a strong fan, a net, and a blue light source. 

Another potential source is bat guano collected from insectivorous bats. Though these bats do digest chitin, their diet is so rich in the stuff, that much of it is passed in their guano (stool). Besides they digest it by producing chitinase enzyme, and perhaps some of that too is pased in their guano.

[amyinowasso]

This made me laugh. The lengths we gardeners will go to. I enjoyed the "dedicated" cookie sheet and coffee grinder, LOL. There was a similar idea back in the 80s (?). In Organic Gardening magazine or maybe my encyclopedia of Organic Gardening. You picked up all the dead bugs you could find, let's say the problem is grasshoppers. So all the dead grasshoppers, put them in a little water in a blender grind them up, strain and spray where they're eating. The idea being dead bugs probably died of disease and maybe it will be spread. I've not seen this suggested recently, so maybe it doesn't work or maybe it takes a very dedicated gardener to grind up bugs.

[heavyhitterokra]

I found out during the grasshopper plague here that grasshoppers climb anything they can find at night and 'roost' up off the ground a few feet high. I could go out at night with a flashlight and harvest thousands of grasshoppers from my tomato cages, fence posts, corn stalks, and fruit trees. We've gathered as many as 3 pounds of grasshoppers in one night using that method. They don't fly when you shine a bright light on them, but if you bump the thing they are roosting on, they will all jump away and escape, so you have to harvest them swiftly and gently or you will lose the entire hoard in an attempt to grab one grasshopper.  Sometimes, that's hard to do when they are so thick that they are touching one another as they sleep or whatever it is that grasshoppers do at night.

[macmex]

Joseph (Tucson Grower), that is an incredible amount of original investigation you've done!

[Tucson Grower]

heavyhitterokra,
Maybe they would make a good fertilizer, or compost ingredient, even if you didn't have nematode problems. Perhaps a vacuum could be used to gently and quietly suck them up. If it could somehow be run quietly enough so as not to disturb them while they're resting. I have a spot beneath my 12 foot tall Eucalyptus seedlings, I'm growing some Alfalfa beneath the trees and that's where the majority of the grasshoppers feed. Though sometimes a few of them move a ways to feed on some of my other irrigated plants, like Radishes, Beans, and Lettuce. My own shopvac is nearby. I think, tonight I'll give the grasshopper round-up a try.                                                                                                             

[Tucson Grower]

amyinowasso,
Yes, I remember that info from OGF, but, for me I garnered the info about insect-soup from back in the late 1960's. I feel it is very pertinent, even today. I believe part of the premis was that disease is present in every population and the insect-soup helped to increase its virulence and presence in the local insect populations, thus reducing those populations. By spraying it on their feeding grounds, more of them were exposed to possible insect diseases.

[heavyhitterokra]

George and I have both tried using a wet vac to suck up grasshoppers at night before. For me, it sucked up too much foliage to be very effective, so we ended up placing it in a strategic location in the garden and duct-taping the hose, pointing up, to receive the grasshoppers that we caught by hand.

It worked very well for that, due to the fact that we were catching them so fast and in such quantities that there was no good place to put them all. We caught as many as 3 pounds of grasshoppers per night, but eventually just gave up on it because there were so many grasshoppers that we were not making a noticeable dent in their population.

[Tucson Grower]

heavyhitterokra,
Thanks for that update. I wish that would have worked for you guys. For me, at my location, there are many fewer hoppers (most likely less than 100, total) and most are less than an inch long, a rare few being 3-4 inches long. Most of them stay in or around my patch of Alfalfa, where it's hard to notice any damage.