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Beneficial Nematodes - FAQs

What Are Beneficial Nematodes and How Do They Work?
Beneficial Nematodes are microscopic, non-segmented roundworms that occur naturally in soil throughout the world. Inside the nematode's gut is the real weapon — beneficial bacteria that when released inside an insect kill it within 24 to 48 hours. The nematodes enter the larvae via the mouth, anus, respiratory openings, or directly through the body wall of the pest. Next, nematodes eject their bacteria inside the pest's body. These bacteria multiply and cause blood poisoning of the pest, leading to death. They also convert host tissue into nutrition for the nematodes to feed on and multiply. As the food resources within the dead pest become scarce, nematodes exit the pest and immediately start searching for a new host. Haz clic aquí para preguntas frequentas en Español.

How Do I Choose the Right Nematodes?
Use our complete Beneficial Nematode Selection Chart to select the proper species by pest. If you are unsure about which nematode to use or your target pest is not listed, please call us and one of our sales representatives can guide you to the correct species.

What's the Application Rate?

  • 5 million treats 1,600 sq. ft.
  • 10 million treats 3,600 sq. ft.
  • 50 million treats 1 acre.
  • 250 million treats 5 acres.
  • 500 million treats 10 acres.
It is best to make at least two applications, separated by 7-10 days in order to stagger the life cycles of the nematodes and to assure complete coverage. In cases of severe infestations, applications should be made every 7-10 days or until infestation subsides.

When Should They Be Applied?
Nematodes should be applied in morning or evening when soil temperatures are 42°F – 95°F. Beneficial nematodes remain effective up to 95°F, but no longer parasitize prey above that. Please Note: one hard freeze will not harm beneficial nematode populations; however, prolonged freezing temperatures will.

Apply early in the morning or predusk when temperatures are cooler and the sun is not as bright (UV rays harm nematodes). Timing of applications during the year can be pest-specific to what is being controlled and their life cycle. Remember, beneficial nematodes control soil-dwelling life stages.

A second application of beneficial nematodes is recommended for best results. This follow-up can be done around 1-2 weeks after the initial application; or, it may be better applied during fall months in the case of pests with overwintering, soil-dwelling life stages. In the presence of high pest populations, applications should be made every 7-10 days or until infestation subsides.

How Long Can Nematodes Be Kept Before Use?
Beneficial Nematodes should be used as soon as possible. If you need to store them, it is best to store them in a refrigerator for no longer than 2 weeks.

How Are Nematodes Applied?
The solution can be applied using a watering can, Hose End Sprayer, backpack or Pump Sprayer or through irrigation or misting systems. Mix nematodes into water and gently agitate. Apply when the sun is low on the horizon as the nematodes are photophobic and do not like direct light. See our video on how to apply nematodes here.

To determine the mix rate of nematodes to water:
The mix rate of nematodes with water is highly variable due to water pressure, differences in application equipment, how fast or slow you walk while applying, how long your stride is – all of these factors play into the 'how to' of applying beneficial nematodes. The bottom line is that you need to do a small experiment first and it will be simple after that!

Here's the Test Run:

  • Place a small amount of food coloring in the hose end sprayer container that you will be using to make the application. Make it a bright color so you can see it as it dilutes in your experiment.
  • Mix this with a specific amount of water of YOUR choosing
  • Go out to the area you need to spray. Then walk and spray until the food coloring is gone. Eyeball what percentage of your area was covered – was it 10%, 25%, 50%?
  • Once you figure out how far that initial mix went you can easily do the math to determine how much of the nematode package to use with each re-load.
  • If you have nematodes left over after the first round, just re-do the process and increase the mix rate of nematodes to water.

For best results use a Hose End Sprayer that allows you to set the mix rate. Do not use a hose end sprayer that does not have the ability to spray in controlled doses.

Should The Soil Be Moist After The Nematode Application?
The soil should be moist at time of application and lightly watered immediately after application. After application, regular watering of the treated area will provide sufficient moisture. Generally speaking, water every 3-4 days if rainfall does not occur.

How Long Does It Take To See Results?
Noticeable changes in pest populations are not evident until around two weeks after application. Beneficial nematodes need time to fully parasitize and kill their host, then move onto the next host. Nematodes kill the pests from the inside out. You will not see dead insect bodies as you would with a chemical knockdown. Adult pest populations should gradually decrease as the nematodes continue to kill infected life stages.

How Often Should Nematodes Be Applied?
Nematodes are recommended for use whenever larvae or grubs are present. Generally, this is during the spring and fall months. Because larvae feed on plant roots, beneath the soil surface, severe damage can be done before realizing there is a problem. Look for signs of an adult insect, such as leaf-notching. If adult insects are present, their eggs will be hatching soon. Keep in mind, one application may not eradicate a population of insects that has become established over a period of years.

Will Nematodes Live Through The Winter?
In general, harsh winter weather in most parts of the country almost guarantees a significant decline in the population of the nematodes. In most cases, nematodes (just like insects) will become dormant during cold weather. Any survivors would be few in number to provide adequate insect control. If your insect pest returns the following year, another application may be necessary.

When Nematodes Are Applied To One Area Will They Move To Other Areas?
Nematodes, due to their microscopic nature have limited range of movement. Generally NemAttack™, our formulations of Steinernema will stay where you put them, but NemaSeek™ (Heterorhabditis) will continue moving through the soil until they find a pest to infect.

How are Beneficial Nematodes Shipped?
REFRIGERATE UPON ARRIVAL. Remove nematode tray(s) and sleeves from insulated shipping container or packaging and place in refrigerator until ready to use. The Beneficial Nematodes are shipped in an easily dissolved formulation that you mix with water.

Will the beneficial nematodes harm my dog?
Beneficial nematodes can be used around and will not harm mammals, aquatic life, birds, reptiles or amphibians.

Additional Nematode Information


ARBICO Organics Guarantees Live Beneficial Nematodes Upon Arrival of Product. Call us at 1-800-827-2847 with questions. We look forward to speaking with you!

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