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Archive for October, 2011

OK, green side up is a good start! And take it out of the pot too. Don’t laugh it has happened!

Seriously though how should you plant something to ensure it has the best chance of survival?

Choosing the right plant is a good start. For the situation that is. If a plant needs full sun then planting it under a tree is a good way to get a leggy, lopsided plant. Likewise if it needs shade, then come summer it will likely get burnt. Also be aware of what situation the plant was in when you bought it. If it was under shadecloth then be careful about putting it out in full sun in the middle of summer. Plants need acclimatising and that takes a few weeks of gradually moving it and adapting it to its new environment.

Having a healthy plant to start with is also important. That means buying your plant from an accredited nursery look for the NIASA logo. This helps ensure you are not bringing disease home. Nurseries with this logo follow strict guidelines for hygiene such as keeping plants away from contact with any possibly infected soil ( so plants must not be directly on the ground). Water sources must be from a source that will not carry disease (such as a bore) or it must be treated to ensure it is free from disease (eg dam water). Nurseries also should not use fungicides that will mask signs of root diseases such as Phytophthora (dieback) because as soon as you get them home and they run out of their fungicidal protection they will likely succumb and die, infecting your soil and garden in the process.

Look out for cheap plants. You generally get what you pay for. Throw-away lines are usually root bound and although they may grow initially they will soon strangle themselves and die. Don’t think that slashing and ripping roots apart solves the problem – it doesn’t. About the only thing those plants are good for is growing on long enough to take cuttings from and then discarding.

When buying larger plants that appear to have plenty of room for the root ball it is still possible for problems to exist sight unseen. If that plant was root bound in the tube and then potted on once or twice, then that root bound portion of the root ball still exists and will still give problems down the track. Another reason from buying from a reputable accredited nursery. Consider buying tubestock where its easy to look at the root ball and see what condition it is in. Small plants are capable of growing fast and will often catch up to larger ones – possibly because they do develop much better root systems in the ground if put into the right environment.

When you get your plant home, make sure it is well watered if you are not planting it straight away. And don’t YOU keep it until it is rootbound before planting.

When you get to planting time make sure you excavate a hole bigger than the plant requires and as you fill the dirt in around the root ball tamp it firmly with your fingers at the base of the hole and back fill. A good watering and you’re done! NEVER fill the hole and tamp it all from the top. You need the ground to be uncompacted at soil level for good moisture penetration.

Should you add other stuff into the planting hole? Well I seldom do. But then I plant mostly natives that come from an environment that is pretty devoid of anything. And my soil is foothills soil so I have a bit of clay around. You certainly may need to use something to ensure the soil is wetting well and evenly. There is a bit of controversy about the value and longevity of some wetting agents (in another one of my blogs) so I’ll leave that up to you. A bit of clay works well and is longer lasting. Just mix it into the profile. Composts and other sources of organic matter can be useful for several reasons. They provide some nutrients but beware of those that are fresh because they may contain ammonium or high levels of phosphorus, both of which can be harmful. A well-made compost should smell earthy and not generate heat if left in a pile. Most composts also have a low nitrogen to phosphorus ratio which means your plants will still require additional nitrogen. Contrary to popular belief, the nutrients in composts and manures are largely water soluble and can leach quickly if you overwater.

However, given that most potting mixes are largely bark/sand/sawdust etc, then incorporating some potting mix/compost like materials around the planting hole can be useful. It provides a gradient for the roots so they don’t suddenly come from the highly organic potting mix out into a hostile gutless sand – an environment where there is a relatively high water-holding capacity into one which dries out very quickly. The trap being that you may be watering the root ball and thinking it is moist when under the ground, the roots are getting out into sand and being subjected to drought conditions.

Should you put fertiliser in the base of the planting hole. My belief is NO. In our sands, the only way fertiliser goes is down so with no roots below, it will be wasted. I prefer to see fertiliser applied closer to the surface. Controlled release fertiliser should be applied (dibbled) below the soil surface to minimise fluctuation in temperature which will see its release rate go sky high.

Seasol and other seaweed products. These contain small amounts of cytokinins which help promote root growth but just remember most are NOT fertilisers, you will need to use fertiliser as well.

Now what if you’re planting a larger tree. The trick is to not plant too deep. The flare of the roots should be visible at the surface. If you buy a tree and cannot see the root flare at the base at the potting mix surface when it is in the pot, you must clear away that excess mix first in order to find the correct level. There is an excellent series of powerpoints with the finer details of planting large trees at this website.

Mulching? If you want to mulch, make sure your irrigation will penetrate below the mulch. Preferably driplines should be below the mulch. Use a coarse mulch, don’t have it too deep, it needs to be in proportion to the plant and keep it away from the base of the plant so you don’t induce collar rots. There are articles on mulching elsewhere in this blog. Meanwhile, there are some trials going on as we speak that I hope will give us some insight into what happens down in the root ball under various depths of mulch, especially with respect to soil moisture. More on that later.

Finally, remember that your plants were probably watered in the nursery once or twice a day so coming into your garden and subjecting them immediately to lesser regimes may not be a good idea. Again you will need to acclimatise. Give your plants time to get out into the soil and develop a bigger root system before you start restricting water to them.

Many highly organic potting mixes, if they dry out can be hard to rewet and many also dry out quite quickly because they have been designed for the environment in a pot, not in the ground. The way water behaves in a pot is quite different to the way it behaves in the ground. This is why its not a good idea to use soil as a potting mix. Drainage and water movement is quite different. You can get a perched water table at the base of a pot, pots also heat up more than the soil and depending on the shape of the pot there can be big variations in capillary movement which mean a pot may or may not drain well. This is why low, wide pots or trays drain poorly compared to taller slimmer pots.

Wow! I think that’s about it, this has been a long one but there is a lot to cover. I hope you find it useful.

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This was inspired by a talk I gave last Sunday.  By chemicals I mean the things you use for pest and disease control.

Firstly I’d like to point out that at least one of the chemicals registered for use in organic gardening is actually quite toxic to humans.  Rotenone or derris dust has been implicated in both Alzheimers and parkinsons disease recently so maybe best avoided.

If you are looking to use chemicals that don’t harm beneficial insects and other non-target organisms then you need to stay away from any organophosphates eg malathion or Rogor.  In fact, Rogor has just been withdrawn so you won’t be able to buy it in the future.  All carbamates such as carbaryl are also dynamite on beneficials including bees.  Confidor, used as a foliar spray and Lebaycid, used for fruit fly are also bad.  All synthetic pyrethroids and even natural pyrethrum are bad news for beneficials.  While sulphur is used widely, it can be hard on non target organisms eg predatory mites.  Copper kills earthworms it if gets into the soil in sufficient amounts

Chemicals that are generally OK to use include:

  • Neem – NOT registered for use on food crops in Australia. Insecticidal and antibacterial, antiviral and antifungal. Prevents insect feeding and oviposition, and act as a growth regulator. Active against whitefly, thrips and mealybug. Relatively harmless both bees and earthworms.
  • Dipel (Bacillus thuringiensis) – low toxicity.  Used for caterpillar control.  Needs to be kept in fridge and has a short life.
  • Insecticidal soaps – Contain fatty acids derived from plants or animals. To be effective must contact pests directly.  Can burn in hot weather. May also kill beneficials but are not residual.
  • Spray Oils. Kill insects and mites and eggs of both on contact. Act by suffocation and can therefore also kill beneficials but not residual.  Many plants are burnt by oils.
  • Eco carb/Eco fungicide (potassium bicarbonate).  Used for powdery mildew control.  Relatively non-toxic.  Not residual so needs to be applied frequently.
  • Milk.  Good for powdery mildew. 1:5 to 1:10 dilution.  Too strong and you get sooty mould. Low fat milk is less effective than full cream milk. Use at 7-10 day intervals.  Good coverage is essential.
  • Natural Pyrethrum. Often mixed with piperonyl butoxide to make it more effective. Contact only, paralyses pests. High toxicity for some beneficials, eg Encarsia formosa, predatory mites. Three to 10 day residual effect.
  • Garlic and chilli – relatively non toxic.  Good for aphids.
  • Derris dust (rotenone). Human LD 50 of 300 to 500 mg/kg , implicated in Parkinsons, highly toxic to fish and marine animals.  Degraded by UV so lasts less than a week.
  • Diatomaceous earth –milled from the shells of fossilized diatoms. Abrades soft-bodied insects, so they lose fluids and dry up, therefore works best in dry weather.  Contact only, insects take up to 12 hours to die. Irritating to lungs. Kills bees.
  • Ryania. Derived from the roots and stems of Ryania speciosa, More persistent selective than rotenone and pyrethrum. Generally not harmful to parasites and predators, some  toxicity to predatory mites.
  • Sabadilla Dust. From the crushed seeds of a tropical lily. Can be mixed with water and sprayed, but clogs nozzles.  Not very residual, little effect on most predators and parasitoids. Highly toxic to Typhlodromus pyri, a predatory mite active in some apple orchards. Kills bees.
  • Success.  A new class of chemical called strobilurins made from actinomycetes.  Generally safe for use with beneficials but hard on wasps and bugs.

Just to finish a couple of recipes for home made sprays.  The Solanum recipe comes from an African paper (The effectiveness of home made organic pesticides derived from wild plants (Solanum pindiriforme and Lippia javanica), Garlic (Allium sativum) and Tobacco (Nicotiana tobacum) on Aphid (Brevicoryne brassica) Mortality on Rape (Brassica napus) Plants.  Mhazo ML, Mhazo N and Michael T. Masarirambi.  2011.  Research Journal of Environmental and Earth Sciences 3(5): 457-462. They used Solanum panduriforme but I’m sure other species would work just as well.  Just watch where you leave any fruit or spare spray, we don’t want any pets or children getting poisoned.  I haven’t listed the tobacco recipe as it didn’t work on aphids.

Garlic and chilli spray: 1 garlic bulb, 1 L water, 1 medium onion, 1 tablespoon cayenne pepper, 1 tablespoon dishwashing soap.  Crush garlic finely. Add finely chopped onion to the mixture and rest of ingredients except soap. Wait for 1 hour before adding the soap to the mixture. The spicy ingredients must sort of stew or steep almost like tea. Add the soap, the non-toxic spray is ready to use. Spray can be stored in the fridge for a week.

Garlic Buttermilk spray (called so because it has paraffin oil in it as a wetter.  It is more effective but more apt to burn in warm weather).  1 pint (568 mL) water, ¼ cup dishwashing soap, 2 teaspoons paraffin, 6 tablespoons chopped garlic. Soak whole garlic in liquid paraffin for at least 24 h. After a day finely chop the garlic, add dish liquid and water. Shake very well and strain the mixture. Store in a glass jar lasts around a week.

Solanum spray: 10 Solanum fruits, 1 L water, 1 tablespoon dishwashing soap.  Chop Solanum fruits and put in container. Add waterand allow mixture to set for 24 h. After a day strain, add liquid soap. Spray can be stored in a glass jar in the fridgefor about a week.

Solanum buttermilk spray: 1 pint (568 mL) water, ¼ cup dishwashing soap, 2 teaspoons paraffin, 6 tablespoons chopped Solanum fruits.  Soak whole Solanum fruits in liquid paraffin for at least 24 h. After a day finely chop the Solanum, add dish liquid and water. Shake very well and strain the mixture. Store in a glass jar lasts around a week.

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