I have Grubs in the Garden- Help!

I have grubs in my separate Vegetable garden raised beds ( 3 x 7) 

What are grubs,? Why are they there,? Do I need to change the soil in the entire box?

Or how do I get rid of them?  How harmful are they to your vegetables and plants?

thank you for your advice

JoAnn

Grubs are the larval stage of many different beetles, including the Japanese beetle and masked chafers.  The grubs live below ground and feed on the roots of tender vegetable plants and especially lawns and it will damage them.  You will find their damage around summer time or fall.  These grubs are attracted to any moist soil.  Usually, they are found in your lawn, but they can also be found in your garden or raised beds.

During the feeding period, female beetles burrow  3″ into the soil and lay their eggs.  Usually around 30 or 40 eggs per female. They prefer moist soils because it is easier to dig in. A raised bed is perfect for this.

The best time to control grubs is in late spring.

I teach the law of cause and effect. So here goes:

You are having grubs in your vegetable garden because there is something wrong with your soil. A healthy soil will not have the grubs.

Sooooo:

I am thinking that:

When was the last time you added live compost to the raised bed? You cannot buy live compost in the stores. Must be purchased freshly made from local source. Anything sealed is not alive. Must have been made with animal manures and rock dust. Live compost will be your microbial Army that will destroy the grubs as well as other pests (yes ants too) and diseases.

You do not mention if you are organic or conventional (I love that word, basically hides the chemical use).

If you are using chemicals, I can’t help you.

If you were organic, then you would not be having this problem. But being organic doesn’t mean much if you do not follow basic organic principles.

Organic fertilization provides a complete balanced nutritional source as well as microbiological sources that help keep the soil alive.

Trace minerals are also essential since the grubs will love mineral deficient plants to eat (natures way of cleaning up).  So when was the last time you added rock dust?

I am guessing that you have not replaced the soil in the raised bed and that it is primarily dead now. You need to replace the soil in the raised bed once a year for best results. Usually, you can do this in several different ways to rebuild the soil:

         a. Replace the soil entirely. Remove all of the soil, add to the compost bin to recompose it. Add new live compost, fresh organic potting soil, new organic fertilizers, new microbes. That is why it is always better to have several raised beds. You can rotate the beds every year that you work on the soil.

         b. Use a cover crop to replenish the soil. Just only grow a good cover crop like peanuts or oats or a cover crop blend. When the plants are fully developed, turn it all over and allow to decompose properly. Add rock dust and organic fertilizer and live compost and turn it all over. Allow sitting for a month or two.

          c.  You can cover the raised bed with black plastic so it will heat up during hot days. Allow a week. While this will kill the grubs, it will do nothing to bring your soil back to life so you will need to remove some of the soil and add new live compost to it after you have done the plastic covering. Plus organic fertilizer and rock dust.

7. Biological white grub control using  Bacterial Milky Disease, Bacillus popilliae Dutky. You will need to add this every year in early spring. This is effective after the first year and becomes more efficient over time.  You can use this if you have no time to do the right thing and help the soil get back to life. However, the soil will get worse and worse if you do not pay attention to the health of soil so this will be effective only if you start taking care of the soil. You will not need this after the first year if you take care of your soil.

8. Biological white grub control using Entomopathogenic Nematodes. Parasitic nematodes are from may online sources. My favorite is from Arbico Organics. There are many products that have the  strains  Steinernema carpocapsae (Biosafe, Scanmask), and they have been effective against these grubs. Preparations containing Heterorhabditis spp. are also effective.  An excellent organic gardener will apply these once every few years anyway as a preventative. Usually, your neighbor’s garden will become a problem if their yard is infested with the grubs as it will naturally overflow into other areas. If your garden is organic, the larvae will not be able to establish themselves, but you will still see their damage signs.

9. Biological control using compost tea. Make compost tea or buy from local sources. A good live compost tea blend will help to increase microbial activity in the soil.

White grub prevention:

The best way to avoid having a grub problem in your raised bed is as follows:

Keep your soil happy and alive with microbial life. The greater the diversity of microbial life in your soil, the fewer grubs and other soil pests and diseases.

Control your watering. Allow the garden to dry out in-between watering. Grubs need moist soil.

Plant earthworms (I like African nightcrawlers). The earthworms will be your mineral factory. They also will produce earthworm castings. This will natural acidly the soil. You need to have a ph of 6.5 to 6.8. A ph of 7 is ok too. Anything else, the microbial life will start to get reduced the farther away you are from the magic ph of 6.8.

any questions?

Leave it in the comment box and I will answer it asap.

Thanks!

andy Lopez
Invisible Gardener