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Lesson 10 – Part A: GARDEN FRIENDS AND ENEMIES
Lesson 10 – Part B: ORGANIC PEST CONTROL
Lesson 10 – Part C: ORGANIC PEST AND DISEASE TREATMENTS
PREPARATION FOR LESSON 10:
Please read through Lesson 10 text for students.
A couple of magnifying glasses would be useful for this class so that students can observe at close range the variety of insects and other creatures they may encounter in the garden. If you do have any pest or diseases in your garden, you will need a hand trowel to dig a hole beside the roots of affected plants.
The beneficial wildlife in this lesson includes only the most common species. Observation will reveal other beneficial creatures in your garden. Further information on some species and organic pest control can be found in the 'Solving Problems Naturally' chapter (Easy Organic Gardening and Moon Planting pp 411-434).
Encourage students to look for wildlife in their garden and keep a record in their garden diary or journal of the different species in your local area.
The website 'Brisbane Insects' that was created by Peter Chew and his family is very educational and although it contains information about insects and spiders in Queensland, many of the species are found in other states of Australia.
The 'Brisbane Insects' website includes a fascinating 'Ladybird Field Guide' that shows both juvenile and adult forms of a wide range of ladybirds. Many ladybird larvae and pupae are accidentally killed because they are mistaken for pests.
We encourage your garden class to visit this website, so that students can become familiar with the many beneficial insects and pest predators in Australian gardens.
http://www.brisbaneinsects.com/pchew_brisbane/index.htm
http://www.brisbaneinsects.com/brisbane_ladybirds/LadybirdFieldGuide.html
Another interesting site for students is the database of all species of Australian frogs on the Frogs Australia website.
http://www.frogsaustralia.net.au/frogs/froglist.cfm
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Many conventional gardeners believe that pests and diseases are inevitable in gardens, but this is not true. The truth is that only stressed plants are vulnerable to pests and diseases, and there will always be a physical reason for gardening problems. The organic methods taught in this program have been designed to keep plants naturally healthy, and you should have few pests or disease problems in your garden, particularly as the health of your soil improves.
However, if a problem has occurred, discuss with students what you can see that is wrong with the soil where pests or diseases occur, and ask what they think could be causing the problem. Identification of the cause will help them to avoid problems in the future.
This lesson includes a few environmentally-friendly remedies for only the most common vegetable garden problems.
The key word in organic pest control is 'control'. Pest predators will not entirely eliminate a pest because they would be cutting off a future food source but, in a healthy garden, they keep pest numbers so low that damage is not noticeable. Widespread research has confirmed that biologically-diverse gardens are healthier than those that use preventative spraying.
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Organic gardeners work with the environment to control pests, giving pest predators an opportunity to control the problem before resorting to organic allowed pesticides because many "organic" pest and disease treatments will also kill some pest predators, and some are poisonous to humans, or can irritate the eyes or skin.
If your school has registered to participate in this program by completing the Registration Form on the Home Page of this website, you can receive gardening advice for any garden problems by e-mailing details of your problem to:
education@bfa.com.au
Questions from registered schools will be directed to the most relevant of BFA's panel of experts to provide personal e-mail advice, including the most suitable organic-allowed treatments to use for severe pest or disease problems.
Derris dust
Derris dust (rotenone) is an organic pesticide made from the roots of several species of tropical plants. It works by shutting down energy production in cells, which makes it a neurotoxin. Derris dust is popular with organic gardeners for the control of caterpillars, aphids, thrips, and to some extent, mites. It also has a long history of use as a fish poison.
The Australian Pesticides and Veterinary Medicines Authority (APVMA) allows rotenone to be used as a pesticide, and it is allowed as a restricted input under Australian organic standards.
However, Canada and the United States have now banned the sale of rotenone for all uses except poisoning fish, and Japan does not allow its use in organic production. Rotenone is packaged as a dust that must be applied frequently to be effective, and the dust can be inhaled, absorbed through the skin, or ingested with food that has been carelessly washed.
As children are more vulnerable to all neurotoxins and other pesticides, we do not recommend the use of this product in school gardens.
Oil sprays
Oil sprays can burn plants when temperatures are high, or when plants are water stressed. Organic-allowed oil sprays are suitable for adults to use during milder conditions when pest predators aren't active.
Soap sprays
If soap is recommended as an ingredient to help an organic-allowed spray to adhere to plants with glossy or waxy leaves, the correct soap to use is one with a potassium base. These soaps are available from garden departments. Ordinary soaps or detergents will damage plant leaves and have, on occasion, killed plants. All soaps that kill pests can also kill pest predators. Soap sprays should only be used by adults.
Aphids
If your students are old enough to understand, you can explain to them that the electricity in lightning turns nitrogen and oxygen in the air into nitrous oxide (laughing gas), which dissolves in rain and falls on the soil as nitrates, a form of nitrogen that plants can use for food. The extra usable nitrogen combined with extra water can result in a rush of new growth after a period of stormy weather. However, most of the work of changing nitrogen gas into plant food is done by soil bacteria in organic gardens.
You only need a very tiny amount of clay to make a spray, and it must be fine potting clay - not clay soil, as this can cause a different set of problems.
Snails and slugs
Only use plastic jars for traps, as glass jars can shatter in hail storms.
Snails and slugs are extremely fond of the smell of beer, and they don't mind stale, flat beer. If Vegemite is not enticing your pests into the trap, try using a third of a cup of beer, instead. Beer slops can be stored in a screw top jar in the fridge, and used to top up the trap, when necessary. Avoid spilling the trap contents on the soil though, as beer in soil will kill earthworms.
Caterpillars
There are good organic-allowed caterpillar treatments available for severe pest invasions. Contact the BFA Helpline for advice on the most suitable treatment for your particular caterpillar problem.
A good plant tonic
Please note that some plants with furry leaves, including lavender and sage, do not like foliar feeding with liquid seaweed. It can cause the leaves to blacken.
Generally though, organic-allowed seaweed extract is an excellent supplementary fertiliser. However, it does contain considerable amounts of potassium and too much potassium can block the absorption of some other minerals. Problems can occur if it is used very frequently.
Mildew diseases
Chamomile tea (one teabag to one litre of water) is a good remedy if 'damping off' affects seedlings. The foliage works even better than the tea bags, which contain only flowers. If you have a lot of seedlings to care for, it might be worthwhile to grow some German chamomile at a suitable time of year to make your own brew. Dry the foliage by hanging a bunch of stems upside down, indoors. Crumble the dried foliage and use a teaspoon of the crushed leaves to make the tea. Strain tea before adding to the spray bottle.
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