Karen is new to organic gardening and is wants to know what to do about the green vegetable bugs that are attacking her tomatoes.
The green vegetable bug is a sap-sucking pest. They use weeds as hosts and attack vegetable plants that are stressed in some way. Of the chemical sprays required to kill these bugs, one will poison any birds that eat the bugs, and the other is deadly to bees and other beneficial insects. It can also metabolise in humans to a more toxic chemical, and is currently under review.
Chooks show no interest in eating these bugs. The best way to get rid of these organically is to put some methylated spirits into a soup tin or similar container. Put on gloves to protect your hands from any smelly juice they excrete and use a stick to knock them into the tin. Then get rid of weeds and plants that have finished bearing to prevent these pests continuing to breed.
To prevent further attacks (and this is the most important part of the treatment) have a look at why your tomato plants are stressed, and correct the problem. Some gardeners find it difficult to understand that pest and disease attack are only symptoms of unsuitable conditions for a particular species, but it is true. I noticed yesterday, that similar bugs are attacking some silver beet plants we have. We decided after picking the first of this silver beet that we did not like this variety as much as ‘Fordhook’ and decided to just feed the plants to the chooks, a plant or two at a time. Consequently, the silver beet did not receive the same attention as the other vegetables and, before long, these bugs moved in. The bugs are not attacking other vegetables that are receiving normal care.
When pests attack plants, the answer is always in the soil. It may be too dry or poorly drained. If water is in short supply in your area, hill up your tomatoes about 5 cm at a time. They will produce more roots along the stem and allow them to access water more efficiently. Tomato plants need a deep watering (under mulch) several times a week in dry weather, rather than a light daily watering.
Or, the plants may be short of the nutrients they require to produce pest-deterring pheromones. If you have skimped on fertiliser, after a thorough watering, give each plant a light feed of complete poultry-based fertiliser and a drink of seaweed extract tea.
Or, the soil may be too acid or alkaline for the plants and the nutrients they require can be locked out and unavailable to the plants. This can be difficult to determine without testing, except that, with tomatoes symptoms of phosphorus deficiency (purple colouring under leaves and slow growth) are a clue that soil is too acid or alkaline if you have applied adequate complete fertiliser. If soil is too alkaline, put some well-rotted horse or cow manure under the mulch around the plants. If soil is too acid, water in some dolomite or lime around the base of each plant. See Changing soil pH.
This post has been revised due to recent research. Click here.
The larvae of this group of moth borers do damage to a range of stressed native trees. Some eat bark and can ringbark stems, causing death of the section. Others eat leaves, which they drag to the entrance of tunnels. The bark-eating larvae form nests of bark and droppings bound together by a web (see photo).
To get rid of these pests, prune off the webbing and destroy the larvae. Also remove damaged sections of bark. If twigs and foliage are damaged, prune them off and look for tunnel entrances. Poke a piece of fine wire into the holes as far as it will go. Remove the wire, and then seal the holes with putty, Blu Tack, or fine clay.
Attack by this pest is an indication that the plant is stressed and low on nutrients. Apply a complete fertiliser suitable for natives. Give the tree a drink of seaweed extract tea. Do not allow grass to grow close to the tree. Check drainage, and improve watering, if necessary. Use leaf mould as mulch around these plants.
Strawberry crowns sold by nurseries are certified as being free from virus disease. Virus diseases that affect plants are usually incurable, and this is certainly the case with strawberry virus, which is spread by a particular aphid. If you are starting your strawberry patch with crowns from a friend, make sure the crowns are not infected before planting.
Symptoms of strawberry virus are: stunted growth, small and uneven leaf size, and small misshapen fruit. Any plant showing these symptoms should be removed and destroyed. Plants produced by runners (offsets) from infected plants will also carry the virus. To avoid diseases in strawberries, maintain a regular fertilising and watering program to keep plants growing strongly, as stressed plants are less able to resist disease. But, avoid over-fertilising with high nitrogen fertilisers as soft, sappy growth is very attractive to aphids, and may encourage crowns to produce runners instead of fruit. An application of seaweed extract tea mid spring and autumn can help make strawberry plants more disease resistant. Replace plants at least every three years, in a new patch of soil. This will reduce the risk of soil-borne diseases and maintain good cropping, as older strawberry plants are less productive.
Strawberry crowns can be quite expensive. You can purchase some to get you started, and increase the number of plants with offsets after the first fruiting season. Use only offsets from your healthiest plants, planting out during Full Moon phase.
These sap-sucking pests are can be found on the twigs and branches of a range of plants, including fruit trees. The pests themselves may not attract much attention unless the plant is heavily infested because they are reddish-brown in colour with black hairs, and only 5 mm in length. The part we notice as a pest is actually the scale’s egg sac – a grooved, white, wax structure, larger than the insect itself. The egg sac will contain up to hundreds of red eggs. (See photos below).
Before treating these pests – check that you haven’t confused them with the larvae of the mealy bug ladybird, which are also white and fluffy. Ladybirds and their larvae consume an enormous amount of scale insects and aphids, but many of the larvae are killed when they are confused with pests. Many pest predators are killed where copper sprays are routinely used, and scale infestations commonly follow spraying for other pests.
When the cottonycushion scale prepares to lay her eggs, she fixes herself to the twig. Give the white structure a poke, if it doesn’t move, it’s scale – ladybird larvae will scuttle off. When temperatures are below 24° C, and pest predators are absent, cottonycushion scale can be suffocated by spraying with white oil at 10 ml per litre of water. This will not kill the eggs, and the spray will have to be repeated in two weeks, to catch the newly hatched scale.
In warmer weather, suffocate spray with enough fine potter’s clay dissolved in water to make it cloudy. Pest infestation is a sign that plants need an improved fertiliser and/or watering program, or that you need to adjust your soil pH.
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.
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.
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.