Benefits
Nematodes are very inexpensive to use and provide fairly fast results. The first host death will occur within 48-72 hours of host penetration for Hb nematodes, 16-24 hours for Sc and within 24-36 hours for Sf. Results can usually be maintained for 6-15 weeks. Not all will work right away, though (see Drawbacks) and most will scatter soon after being put out unless there is a lot of host larvae available. Using new planting medium will probably spark the need for additional applications, though, especially if a sphagnum peat-based product is being used, as this tends to be the international source of fungus gnats. Other causes of shorter performance periods can include: allowing containerized plants to dry, bone-dry, completely; ultra violet light (UV) exposure (see Advisories); and the use of a nematicide. (Nematodes are compatible with most other substances.)
Nematodes are very versatile. They can be applied a number of different ways, through both automated equipment and manually. They can be put through just about any irrigation setup and they’ll withstand up to 300 p.s.i. I’ve heard of people using buckets, watering cans, hose-end sprayers, pump-up handheld sprayers, backpack sprayers, boom trucks and all sorts of application vehicles. So how one applies nematodes is basically up to the user.
Versatility extends beyond the flexibility of their application. The “little worms with a big attitude,” as I sometimes refer to them, attack a huge segment of the pest species which bother growers. This one feature allows them to often be used successfully in cases where everything else has failed. Sometimes a grower will encounter a situation where I haven’t a clue of what to offer as a remedy — and chemicals have proven themselves worthless. I’ll do some research with the grower and find out the pest spends part of its life underground (as 90% do). I then might suggest the grower explore the nematode option, experimentally. He or she does, and sometimes we all win! One arborist wanted to try them against a species of borer by spraying them on the trunks of large trees instead of on the soil. He applied them at night. Apparently the nematodes liked the borers, their holes and the rough bark of the trees, because they performed much better than expected.
Please note, however, as much as their versatility is beneficial, it can also be a detriment (see Drawbacks).
Most nematodes can be stored. In-vivo or life-host-reared nematodes may typically be held for 2-3 months in the refrigerator. Some other formulations may be in long-term suspended animation for up to 6 months or more sometimes. Short-term storage does not hurt athletic, healthy-to-begin-with nematodes. They simply live off of their lipids, or fat cells. Long-term storage may have undesirable effects to the overall quality of nematodes, but it depends a lot upon their initial pre-storage health (see Advisories). In many cases you’ll just apply a huge concentration of nematodes as many are mortally-challenged.
With healthy nematodes, buying in quantity and storing can be to your advantage. You might be able to save on shipping, handling and product costs, if volume breaks are offered and met. If repeatedly applied, nematodes will provide maximum results.
Lastly, nematodes will not harm people or animals, not even earthworms — they’re kin. [Intro]
Drawbacks
These nematodes don’t seem to establish themselves (many disappear quickly ) to such a degree as to continue getting pest control two years down the line in sod. The Hb species will bear up to 200,000 young ‘uns beginning in as little as 9 days, the Sc species can have the same number beginning in about 14 days, and Sf can bear 100,000 to 150,000 young beginning in about 12 days. Despite this, though, reapplications are usually necessary at least annually, or even at shorter intervals for containers, depending upon pest pressure, conditions, and attractant/host material. Another factor affecting this is the fact that these nematodes don’t all go to work at the same moment and many will scatter soon after release. With 100% live and healthy nematodes, the most to immediately go to work, typically, is 40%. Mother Nature always thins things out. She tries all the time to even the playing field. She’s looking to achieve eventual equilibrium — balance. This is why the nematodes can’t remain in the numbers we need for sustained control, not without physically barring the pests from the plant material or removing it all together. Good thing nematodes are reasonably priced!
Hb/Sc/Sf nematodes have a wide host range. To say the least! This is true because the nematodes are nonselective. They shouldn’t be used with the aphid midge, Aphidoletes aphidimyza, for this reason (they are okay with the soil-dwelling mite, Hypoaspis miles and the rove beetle, Atheta coriaria). Other beneficials, some natural ones, and some of the other commercially available species, can sometimes fall victim to nematodes, but not to an extent which may render a program ineffective. This should only be a minor concern (if at all), but it’s one you should be aware of.
Some pests I can positively say they don’t parasitize, which in itself is a drawback, are other nematodes, the pernicious plant pests: lance, root-knot and dagger nematodes, for example.
The application of nematodes can be an arduous task without some sort of equipment. Doing it by watering can is a very effective method, but it’s time-consuming. Fertilizer injectors, boom sprayers, etc., make it much easier. For small outdoor sod applications, certain hose-end or tank sprayers work like a charm and are of little cost. [Intro]
Scouting
Parasitized grubs will be, 1) dead, 2) partially deteriorated — depending on how long after initial host entry they were discovered — and/or 3) discolored. The victims of the Hb nematode will be tinged orange-red, and those of the Sc will be only be a slightly discernible yellow to tan. And Sf nematodes will color their host a darker tan color.
But before anything can be parasitized, the nematodes must be alive and ready for action. My company has an easy way that you can test sponge-carried units when you receive them:
Sponge Nematode Inspection Procedures
- Remove the sponge from the bag.
- Apply a tiny amount (a pencil-point amount) of the nematodes (the off-white to yellowish material on the sponge) to the outside of the plastic bag in which they came.
- Add 1-2 drops of room temperature water to the nematode sample.
- Wait 1 to 2 minutes.
- Place the plastic bag against a smooth, dark surface.
- With a hand-lens, and sometimes with the naked eye if conditions and your eyesight are perfect, you should be able to detect movement in the droplet. With 10x and up, individuals should be seen “swimming.”
- This process should work with any nematode product. The difference will be how the nematodes are collected and suspended, i.e., a granular material will have to be soaked in water to allow the nematodes to swim, or sink, freely. Moreover, concerning non-in-vivo nematodes, a resurrection period of up to 72 hours may be needed before movement [life] is noticed. [Intro]
Advisories
As previously explained, repeated drying and re-hydrating of nematodes can adversely affect them. The same holds true for UV (ultra-violet light) exposure. They’re soil-dwelling critters and can’t handle a good tan. Direct sunlight will first sterilize the nematodes (this takes only about 7 minutes), then it will kill them. It is for this reason that nematodes should be applied in the evening or night, or during overcast weather. Outdoors, a good time to apply these organisms is during a continuous light rainstorm (heavy rains will cause surface runoff and your nematodes will take up whitewater rafting). For one thing you won’t have to worry about UV light and, second, you won’t have to use so much water to properly wash them in the soil. Speaking of water, if you wish to determine how much water you’ll need, figure the saturation to a depth of two inches of one square foot of medium-friable soil will use .66 gallons of water so you’ll need up to that amount. (But you don’t have to saturate, just make things wet.)
An important advisory concerning nematodes is they way they are reared and supplied. Many nematode-based products today are made of nematodes artificially reared (in-vitro) on an artificial host and a diet of nematode chow. The nematodes are then placed in a state of suspended animation, where the vital functions of the organisms are all that remain. Clinically speaking, many of these undead nematodes are actually, well, dead. These typically come packaged by the billions in a gel or water dispersible granules. The vast nematode numbers compensate for the dead nematodes, and the sluggish behavior of the survivors. These products are designed for shelf-life so they can be sold through normal distribution channels and handled as an inventory item, complete with up-front manufacturers’ profits.
Most of these are satisfactory products which work as indicated on their labels, just not as well or as economically as nematodes which are reared in-vivo, typically using an actual insect host: the larva of the wax moth (G. mellonella), a.k.a. the wax worm. One quality manufacturer allows their nematodes to hatch out of the host themselves and, by their own means, slither to a collection point — which confirms their vigor. This keeps the nematodes in peak condition, searching, tasting, sampling, hunting and killing. (This can’t be done with an artificial diet and host). In-vivo nematodes go to work immediately. They don’t have to wait 24-72 hours to resurrect themselves. They can even be tested easily before you put them out to ensure the product is good (see Scouting).
Nematicides, as their name implies, kill nematodes. Products with this quality should not be used on or near areas where parasitic nematodes are being employed. [Intro]
Usages
Greenhouses, fields, interiorscapes, orchards and gardens. I’ve seen the successful implementation of these species in just about every conceivable situation. This includes just about every conceivable media: soil/sod, peat-lite mixes, bark products, rockwool, etc. [Intro]
Rates, Instructions, and Purchase
Need more information? Check out our sponge rates (also solid rates) or our short-term storage, handling, and release sponge instructions (solid instructions). You may also purchase Hb on sponges, purchase Sc on sponges, purchase Hb/Sc combos, purchase Sf on sponges, purchase Sc flea packs, or purchase Sf in solid form. [Intro]
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