Safe Pest Control - Step 3 and 4

Best-practice pest-control for food-gardeners involves six steps (in this order):

1. Make your food garden as healthy as possible 
2. Don’t please your pests 
3. Keep them out 
4. Catch and remove 
5. Is further action needed? 
6. Use a low-impact pesticide 

Step 3 and 4 are discussed below.

Step 1 and 2 were discussed here.

Step 5 and 6 are discussed here.

I would like to thank Marg M, Margaret W and Jan R for proofreading and commenting on my drafts and for additional information they provided.

Step 3 - Keep them out

Keeping pests away from your plants can be done in many ways, for instance:

• Keep wildlife out of your food garden by erecting effective fencing (see Wildlife and Food Gardens ).

Cute, but very destructive when not kept out of your food garden

• Put netting, or a cage, or ‘plastic drink bottles without bottoms’ or or fine-wire waste baskets (see photo below) over plants or beds.

Marg M keeps out Cabbage White Butterfly with Reject Shop wire baskets

This slippery barrier is good protection against snails

• Observe good food garden hygiene.  For example, sterilise secateurs with turpentine or methylated spirits when you finish pruning one fruit tree, before starting on the next one.  Make sure to clean garden tools that may have been in contact with diseased material, especially if you took them to someone else’s garden.

• Inspect new plants you buy or are given, before you put them in your garden, and do not add to your food-garden plants any that look unhealthy or are affected by a pest or disease.

• Do not put diseased/pest-ridden fruits or vegetable left-overs or clippings on your compost heap.

• Do not allow into your garden mulches, composts, soils and manures that are likely to contain garden pests.

• Solarisation is the simple environmentally-friendly method of using the sun to kill garden pests, weeds and seeds in mulches, composts, soils and manures. Worth considering if you suspect material you are about to add to your food garden contains a pest you want to keep out.  In summer (in Tasmania temperatures may be too low in other seasons) spread a layer of up to 30 centimeters thick on the ground and cover it with black plastic. Make sure the black plastic covers the area at all times. Six to eight weeks later (4 – 6 weeks in warm conditions) a wide range of pests will have died in the heat generated under the plastic.  For more information see for example Soil Solarization for Gardens and Landscapes and Gardens Alive.

'Easier said than done’ you may think, and you are right.  Five years ago I did not have Oxalis in my garden.  Now I have.  It must have arrived with a plant in a pot or in soil, compost or manure I got from elsewhere and I never realised it was there.

It may not be easy to deny access to pests, but if you realise that YOU are the gatekeeper, you stand a better chance.


Step 4 - Catch and remove

Sometimes you simply won’t be able to keep pests out. Insects and fungi, for instance, can simply ‘blow in’ on a windy day, and there is nothing you can do about that.

In other cases the pest was already in your garden, but you did not realise it was there. It was dormant in your soil or in last season’s debris.

Here are some examples of what you can do to trap and remove pests:

• Remove old branches, twigs and dead leaves, so pests can’t use them to spend the winter or lay eggs. This will especially be the case in autumn. If you suspect that materials might be used for this purpose, only put them on your compost heap if you do ‘hot composting’.

• If a pest has only affected a few leaves of a plant, the solution can simply be to remove the few affected leaves from the plant and remove them from your garden. Don’t put them on the compost heap, just in case they survive or even thrive there.

• Put codling moth trap bands around the trunks of your fruit trees. Then, later in the season, remove these bands and remove them from your garden. For more info see Beating Codling Moth

• Decoy plants are a good way to trap and remove pests. After picking my broccoli in August, I left the plants in the ground and put lettuces around them. Snails and slugs preferred the broccoli plants and left the lettuces alone.

• Yellow insect glue traps (see photo below) are an excellent way to trap whitefly, aphids, fruit flies and other nasties. The glue is not poisonous. Disadvantage of glue traps is that they will also trap beneficial insects such as bees, so don’t put them in areas of your garden where you want bees or know there are bees.

An insect glue trap in action

• Install beer traps for slugs and snails. Remove and refresh regularly.

• Slugs and snails are mostly active at night an hide in sheltered spaces out of the sun during the day.  Consider creating some lovely shady moist shelters for them (a terracotta pipe or space under bricks or ... ) and then collect them during the day.

• Go ‘slug and snail hunting’ at night.  Go out with a torch and remove snails and slugs wherever you find them in your food garden. If you don’t like ‘crushing’ them, dump the snails and slugs in a bucket with salty water and they die instantly.

• There is a period from late autumn to early spring when there are no slugs and snails because it is too cold. When night temperatures gradually go up in late winter, and there is rain, there is a sudden 'population boom' of slugs and snails in my garden. It is important to go slug and snail hunting at this time because in doing so you avoid major damage. I have sometimes found (and crushed) over a hundred snails and slugs in ten minutes and this is why I believe this to be far more effective than for instance beer traps.

Just two small snails, but they will finish this leave in no time

• When I mulch a garden bed with lucerne hay, after dark slugs and snails travel from far and wide to feast on this wonderful sweet-smelling stuff. It is a great way to catch them in great numbers. Just be aware that therefore lucerne hay should only be used on empty beds or around mature plants. If you plant young seedlings and cover surrounding soil with lucerne hay, you put them right in the middle of slug and snail paradise.

• Caterpillars are a very hungry pest that can completely ruin cabbage, cauliflower and broccoli plants, especially young seedlings. Look for eggs on the under-side of leaves. If you squash these with your fingers, you remove this threat before caterpillars hatch and begin to be a problem.

• Aphids can often be removed from a plant with no more than a strong jet of water from a sprayer or by squashing them with your finger if there are not many.

• If scale is only just beginning to establish itself, simply squash them with a finger. Also consider removing affected leaves or branches if the infestation is not all over the plant.  Put those off-cuts in the bin, not your compost heap.

• Possum traps may seem a good way to get rid of possums, but my own experiences and those of others tell me that, if you trap one possum, you are likely to trap many more there after, because you are probably hosting a possum extended-family. In my opinion, the best approach to not have possums in your food garden is not trapping, but keeping them out in the first place, ie. fencing.

This series of blog posts on safe pest control continues with Step 5 and Step 6 here.