Thursday, 8 October 2009

Organic Pest and Weed Control

written by Gavin from The Greening of Gavin


As I attempt to grow my vegetables in line with organic farming principles, without artificial fertilisers and petrochemical pesticides or herbicides, sometimes after a really hot day my broccoli and other brassica get attached by cabbage moth caterpillars. You see, the heat makes the usually strong plants wilt and I don't know if they have an immune system like up, but I do know that this is when the beasties are more likely to attack.

I started picking off the caterpillars at night with a torch by hand and throw them over the fence for the magpies (they love them). That works for a few days and then it is out with the torch again for another caterpillar throwing contest.

There had to be a better way, I thought. There must be some friendly way of deterring the little buggers (no pun intended). I performed a little research and there were only a few products on the market that are organically certified. I went to our local Hardware store to check out the pesticide section. I was gob smacked with the so many types of poisonous products on the markets just to grow vegetables. I can just imagine all of the harmful chemicals that you would ingest if you used these sprays and powders. 

I found only two organically certified pest control products out of about 60 that were available. Some people must not understand the issues with using these type of poisons, or they wouldn't buy them and the chemical companies would stop making them. Anyway, the two type available were Derris Dust and a product called Beat-A-Bug. Derris Dust is made from the Derris root which is native to Central and South America and contains a compound called Rotenone. It is long lasting and relatively safe for humans. It is a poison in large quantities, so follow the instructions on the label. I have found it very effective on brassica and silverbeet. It stops the caterpillars in their tracks. Just make sure that you don't use it if rain is expected as it is water soluble.

Even though Derris Dust is a good deterrent, it is not very good for sorting out aphids which is another pest I have to deal with. Aphids suck the life out of the new growth and they stunt the growth of just about all the plants they attack.  They are usually moved around by ants, so watch for them as well. This is where the Beat-A-Bug would come in handy, but it is quite expensive for a 1 litre bottle, so I make my own version. It is called the "All purpose onion, garlic and, chilli pest spray", and I found the recipe in a gardening book called "The Organic Garden" by Jeffrey Hodges. The spray is also a mild fungicide, antiseptic and antibiotic and has a very strong odour, just like someone opening their lunch box on a hot day that contained onion & garlic sandwiches! Here are the preparation directions;

"Combine 2 finely chopped onions and 6 cloves of freshly crushed garlic with 1 tablespoon of hot chilli powder (or 6 finely chopped red chillies), cover with 2 cm of water, stir well and allow to steep for 24 hours. Dissolve 1 cup of pure soap flakes in 5 litres of warm water, and then add the strained onion, garlic and chilli mixture and stir well. Use within 24 hours."

Now with most things there are some safety tips.

  • Always use gloves and wear a long sleeved shirt and trousers, as the chilli in the spray really stings on bare skin.
  • Make sure that if you do get some spray on your skin to wash it off immediately with soapy water.
  • Don't spray in windy, rainy, or very hot conditions. The best time to spray is early in the morning as the bugs are less active.
  • Don't harvest sprayed plants for about 2 days. Natural sprays will breakdown after about 12 hours unlike petroleum based sprays. And of course you don't want you fresh vege to stink of garlic and onions.
I make the pest spray up whenever I need it and spray the next day. I have also found that the plants go through a growth spurt a few days after spraying for pests, so the plants must absorb some of the nutrients in the spray! An beneficial side effect in the best possible way. I use the spray about once a month to keep things under control and hand pick caterpillars or aphid damaged vegetation in between sprays. If you really don't want to mix up this potent natural pest spray, try Beat-A-Bug instead. I think that the only extra ingredient it has is pyrethrum so it is a good alternative if you can afford it.

Now that you know about organic pest sprays and powders, the weed control is so much easier. Mulch is the answer to all organic gardeners problems. Mulch thickly in spring and summer and the weeds hardly get a chance to germinate. Any of the few that do get through, I pull by hand and throw in the compost bin. Any grasses that manage to pop through the weed matting under my paths are simply killed off by pouring boiling water on them. They die within a week as their cell walls bust and the plant wither and expires. I use left over cooking water or boil up a kettle of water. It works well and beats having to pull them out by hand. It is also very friendly on the garden and is so much better than using glyphosate (roundup and zero manufactured by Monsanto) which is harmful to all life and causes cancer in humans.

By using these easy tips, I hope you avoid the poisons and switch to organic pest sprays, and that you have a successful and healthy organically grown garden just like mine!