Wednesday, March 31, 2010

Grubs in my Cabbage? Cauli? Broccoli? Not any more!

I would like to offer a little credit where it is due.  Our sales rep Di was getting increasingly frustrated at seeing moth eaten (literally) brassica (Cabbage, Cauliflower, Broccoli) vegetables wherever she went so she did something about it.

Di went out and bought some 2 litre pressure sprayers...
  Just like this one, nothing fancy.  We supplied her with a small quantity of Dipel (Bacillus thuringiensis, Bt) in a plastic screw top container and instructions to mix 1 teaspoon of Dipel in 2l of water.  Oh and some kitchen measuring spoons.  Di started doing a quick spray on the vegies at garden centres where she called weekly and presto the grub problem disappeared.

I feel like I bang on about Dipel.  The product has been around for years and I think some people regard it with some suspicion because of it's 'Eco' tag.  There has also been some controversy around Bt's because big chemical companies have been breeding the bacteria into some hybrid crops.  But this product is safe, naturally prevents insects developing resistance to its effectiveness and it works better than anything else on grubs.

I have a few quick tips.
1.  Keep it refrigerated.  Bt's are living organisms and they will last longer in the fridge.  Just make sure the packet is sealed and clearly marked.
2.  Use it regularly.  Usually I prefer to monitor pests and spray as required.  Grubs are a little different.  Once the grub season arrives (January-May) particularly the warmest period, the life cycle of a Cabbage Moth is less than a week and they can fly in from anywhere.  The Bt works when the caterpillar eats some some foliage that you have smothered with Dipel, the bacteria becomes active in the caterpillar's gut and kills it from the inside out.  Dipel has to be applied weekly to keep it fresh and to catch each new generation of grubs.
3. Try to get the Dipel spray on the underside of the plant's foliage.  You know where the grubs hide, so take a little extra care to spray under the foliage.
4.  Remember Dipel is only effective on grubs.  All sorts of grubs yes, but it won't do anything to protect your plants from Aphids or Thrips.
5.  Dipel is safe, but treat it with respect.  I prefer our staff to use protective equipment whenever they handle chemicals, it's just good policy.  I am constantly amazed at the contempt familiarity breeds with some common garden chemicals, particularly snail bait.  Please wear gloves, shoes and at least a dust mask when using these products.

Thanks Di.  Good job, well done!


  1. Why can't you just pick the eggs and grubs off the leaves?

  2. Thanks BollyBlog. Eggs and grubs can be picked off but it's very time consuming. I know what Di would tell me to do with the grubs!


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