Plant protection

To protect our peas, beans, broad beans and corn from birds, we have to net the beds. We have started using supports made from lengths of polypipe slipped over the ends of metal star stakes, or strong wooden stakes. These arches can be left in position to provide support for netting or shade cloth, as required. Shadecloth will also provide some protection from frost.
Stakes 1.8 metres (6′) in length are suitable for beds that may contain climbing plants or corn. Star stakes measuring 2.25 metres (7′ 6″) can be used for small trees or larger covered areas. For star stakes you will need (2″) 51 mm *** diameter polypipe. Wooden stakes can be used when only (1 1/2″) 38 mm polypipe is available. A semicircular arch is reasonably strong, and this is the easiest to produce for smaller areas.

*** Please Note: Flexible polypipe is still sold in imperial measurements of (1 1/2″) and (2″). Polypipe sold as 50mm diameter is high pressure pipe. It is thicker and less flexible.

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This structure over our pea and bean bed was made from 1.8 m. wooden stakes embedded in soil to 30 cm, which is as far as they would go in our soil. This resulted in 1.5 m. of the stakes left exposed. The stakes were positioned on each side of the bed, 1.5 m. apart, with approximately 1.5 m. – 1.8 m. between arches. We used the taller arches here to allow the remaining popcorn cobs to complete drying on the plants. This spacing provided arches with a height of approximately 2.2 m. The structure was erected very quickly and is easy to move if necessary.

To get an idea of the size of the arch canopy you will produce, measure the width of the bed, and divide the measurement by two. Add this measurement to the height of the stakes above the ground. For example, if you are using 1.8 m. stakes, buried 30 cm, you will have 150 cm of stake exposed. If your bed is 1.2 m. wide, half this measurement is 60 cm. Add the two together and you have 210 cm, or 2.1 m. – about 30 cm lower than the average ceiling. If you need a taller arch, use longer stakes.

To calculate the amount of polypipe you will need for each arch, multiply half the width of the bed by 3.1428 (or “pi” if you have a calculator with pi), then ADD 90 cm to allow at least 45 cm to slip over the top of each stake. For a bed 1.2 m. wide, 60 cm x 3.1428 = 188.5 cm plus 90 cm = 278.5 cm. Rounding it off, each length of polypipe would be cut to 280 cm or 2.8 m.

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This is an example of a more permanent structure across a series of beds. It is approximately 6 metres wide. The arches are quite flattened and require support in the centre of the polypipe lengths. The gardener has used a strip of flat steel along the centre of the roof, welded to the tops of several galvanised iron pipes set in the ground.

Crop rotation

Crop rotation is the practice of allowing a minimum of three years between growing a particular family or group of plants in the same patch of soil. This practice is essential to maintaining healthy soil because it prevents the build-up in soil of pathogens that cause soil-borne plant diseases. Plants weakened by diseases also attract pests. Many modern farmers have forgotten the importance of crop rotation. The trend is towards monoculture and these farmers have to rely on stronger and stronger chemicals in an effort to cure plant pest and disease problems.
There are eight main groups of plants that are commonly grown in vegetable gardens. Some groups can be grown together but others, such as legumes and the onion family, don’t make good neighbours.
If you find that pests and disease are repeatedly affecting your vegetables, and crops are disappointing, try the crop rotation below and you will find that your garden rewards your efforts. This rotation has six sections and includes a green manure grain, plus a legume green manure if you don’t want to grow your own peas and beans. The green manures are included because they recycle nutrients, replenish organic matter in topsoil, and help inhibit soil pathogens. In this rotation, legumes precede the tomato family because broad beans inhibit a fungal wilt that affects tomatoes. Organic matter assists in keeping soil healthy because it provides a habitat for beneficial microorganisms that keep disease organisms under control and improve soil structure.
Section 1:
Legumes – peas, beans, broad beans, or a green manure legume.
Section 2:
Solanaceous – Tomato, capsicum, chilli, eggplant, pepino, potato. (Some tomato family diseases can also affect Strawberries.)
Section 3:
Crucifers – broccoli, Brussels sprouts, cabbage, Chinese cabbage, cauliflower, horseradish, kale, kohlrabi, mizuna, mustards, radish, rocket, swede, turnip.
Section 4:
Green manure grain – such as barley, cereal rye, corn, millet, oats, sorghum, or wheat – depending on the season. Sweet corn can be grown in Section 4 if you have plenty of compost and don’t need to grow a green manure grain.
Section 5:
Chenopod family – silver beet, beetroot. (Winter spinach can follow a summer crop of beets as long as this group is not grown in the same bed for another 3 years.) Also the Aster group – lettuce, chicory, endive, globe artichoke, Jerusalem artichoke and sunflower.
Section 6:
Umbrelliferous – carrot, celery, coriander, dill, fennel, parsley, parsnip. Also the Allium family – all chives, garlic and onions.

Cucurbits – cucumber, gourd, marrow, pumpkin, rockmelon, squash, watermelon, zucchini. These, except for pumpkin, can be sown with group 5 or group 6, but not both. Pumpkins are best grown on their own because the vines are very vigorous and the roots give off compounds that can deter some other plants. Dill can also be grown with Section 3 to deter cabbage pests. Sweet corn is a good companion for cucumber or beans.

When the legumes are finished, group 2 can be planted in that bed. Group 3 replaces group 2 and so on, with all the groups moving up one bed. If you only have three or four beds, divide some of the beds proportionately, to suit your food preferences. Once your soil is restored to health, you can adjust the rotation to a three or four year one that suits the type of vegetables you prefer to grow, as long as you allow at least three years between the same group.
Crop rotation should also be practiced with flowering annuals and some perennials. Cinerarias and zinnias are related to the lettuce family, petunias are related to the tomato family, and stock and wallflower are crucifers. These plants can succumb to the same diseases that affect the vegetables in that group. Carnations and dianthus can be affected by a wilt disease if they are always planted in the same soil, and carnations, dahlias and irises can also suffer a stem rot disease if crop rotation is not practiced.

Oleander butterfly

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In autumn, caterpillars of the Oleander Butterfly visit my potted Weeping Fig. The Oleander Butterfly has a wing span of 7.5 cm and is very dark brown or black, with white blotches on both wings and body. The caterpillars arrive in an amusing little caravan formation, travelling head to tail, then spent about a week munching on the fig foliage before each forms a chrysalis. I don’t know where they breed because we don’t have any Oleanders, but they seem to enjoy leaves from plants that have milky sap. I leave these creatures in peace because they do little damage to the tree, and the chrysalises are so pretty.

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Slaters and earwigs

Slaters and earwigs feed on decomposing organic matter. If they are becoming a pest around your vegetables, you have probably added immature compost or uncomposted manures to your topsoil, or have a lot of semi-decayed organic matter in your soil. We get slaters in our compost heap but we don’t worry about them there as they are contributing to the composting process and dining in the heap keeps them away from the vege patch. Slaters and earwigs are attracted to stressed plants. Give your vege garden and any affected perennials a drink of seaweed extract tea (Acadia, Eco cweed, or Natrakelp) at weak black tea strength. This will make plants more resistant to pest attack.

Slaters, which are not insects but related to prawns and lobsters, congregate in rotting timber, heaps of rotting vegetation, rock heaps, and shady, dark places. Remove breeding sites from the garden, and turn your compost heap regularly.
Someone told me that they are having great success drowning slaters in beer baits that I recommended in my book for snails and slugs. The slaters are attracted to the yeast smell of beer, as fermenting organic matter has a yeast smell (See post).
Jackie French recommends mixing one part pyrethrum powder to two parts plain flour, and placing baits in, or near, the dark places that slaters shelter in during the day. Try putting the baits in jar lids inside pots laid on their sides with loosely crumpled paper in the top to darken the interior.

Earwigs are slender insects with a set of pincers on the tail end of the body. They can be reddish-brown or black. These little pests will also feed on flower buds and fruit. They like to hide in confined areas in rocks, bark, timber and under debris. Earwigs can be trapped by putting crumpled newspaper into flower pots and leaving the pots on their side in garden beds. In the morning, drop the crumpled newspaper into a half bucket of soapy water to drown the insects, then refill the traps with fresh paper. Remove debris from around your garden to restrict their hiding places. If an earwig refuses to budge when disturbed, it is most likely protecting eggs laid in the soil beneath it. Dig down and dispose of the pale oval eggs.

Frogs

After many years of drought, we had a lot of rain earlier this year. It was impossible to keep our pool chlorinated, so we waited until the sky cleared before attempting to clean the pool. To our surprise we found the pool contained many hundreds of tadpoles. Frogs are very welcome on our property because they eat insects and spiders. They are also a sign of a healthy environment. Many pesticides and herbicides are toxic to frogs and tadpoles.
The tadpoles were feeding on the algae on the sides of the pool, and looked quite healthy. Apart from providing some shade for them over part of the pool, and providing some ramps for froglets to get out of the pool, we left them to do what tadpoles do best. An old window screen prevents them from being sucked into the filter when we run the pump. I haven’t fed them because I haven’t had any lettuce growing, and I didn’t want to feed them lettuce that could contain systemic pesticides.

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There appears to be three types of tadpoles, one brown, one black, and a very shy type that is a pale, almost translucent, olive. These tadpoles don’t look the same as the small green tree frogs that bred in our small frog pond, as they were quite green by the time their tails had been absorbed (see below).

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The first to become froglets were the brown tadpoles; the other two types still have tails.
These mottled frogs with a dark stripe down each side, aren’t particularly nervous around humans and will allow me to get close enough to photograph them. In sunlight, the tops of their heads look almost like burnished copper, but at other times they look grey-brown. It appears that these froglets belong to the tree frog group because they have no trouble climbing the tiles at the edge of the pool. I spotted one of them hiding in a Birds-nest Fern the other day but most of the frogs are treating our backyard like Club-Med, and spend the day lolling around the pool. I have no idea what kind of frog they are, and would be grateful if someone could enlighten me.

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Ladybirds

Ladybirds, except for the leaf-eating 26 or 28 spot ladybirds, are an asset to any garden. Both adults and larvae consume a considerable quantity of pests such as aphids and scale, and one type of ladybird feeds on fungus.
Most people know what adult ladybirds look like but ladybird larvae are strange looking creatures and many people confuse them with garden pests. As a result many of these hardworking pest predators are killed by pesticides, including organic sprays, and a decline in ladybird numbers is always followed by a pest outbreak. A common victim is the larvae of the Cottonycushion Scale ladybird which disguises it self so well, it is often mistaken for scale. A Brisbane web site has an excellent range of photos of ladybirds and their larvae. Check before you spray so that ladybirds won’t become an endangered species.
http://www.brisbaneinsects.com/brisbane_ladybirds/index.html

The cabbage family

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This family, called the Brassicas, tend to be more susceptible to attack from the Cabbage Moth and the Cabbage White Butterfly when conditions are too warm for them or when the soil they are growing in is too acid for their liking, especially while the plants are young.
The cabbage family includes Brussels sprouts, Chinese cabbage, cauliflower, horseradish, kale, kohlrabi, mizuna, mustard greens, swede, tatsoi, turnip, watercress and stock, and is also related to radish. These plants need both boron and molybdenum for healthy growth and these are only available to plants when the soil pH is close to neutral. If you know that your soil is acid, and your Brassica plants are being attacked, give the bed a drink of dolomite or agricultural lime. Dissolve a generous handful in a full watering can and apply this to each square metre of the bed. Repeat the application if pests are still hanging around in two weeks.
In the meantime, remove all pest eggs from under leaves and leave crushed caterpillars on the leaves. This helps to deter further egg laying.