Thursday, 16 February 2017

Biological methods of PEST CONTROL

I have spent years practicing organic gardening and I know how important is companion planting to prevent pests. I have faced common pests like cabbage worms and cabbage white butterflies are prevented by planting thyme, garlic and tagete around. Or slugs, which are disencouraged by garlic and mints too, but most effectively by reducing mulching and their access to sensitive plants.

Spider mites, mildew and aphids are common glasshouse pests, as ventillation is the best prevention against them. I notice that neem may prevent spider mites. But overall, moving plants outdoors is the best solution. The same goes for mildew.

Yarrow, lemon balm, garlic, artemisias are excellent species to include in your garden.

Recently I found onion scarlet lily beetles, potato beetles and squash bugs. They are prevented by planting respectively carrot-family species, ground ivy, and tansy.

Slugs: protect plants with plastic bottle rings or even half-cut plastic bottles, surrounded by sand, ash and/or coffee, removing any mulch, and then surrounding the area with a second plastic slug barrier. You still need to cut grass around to keep slugs under control. Inverted plastic bottles work well with lettuce and with seedlings of pumpkins and zucchini. Mints, garlics and carnation repels them, to some degree. Perhaps fennel. Some suggest spraying with chili. Go slug hunting in early morning or in rainy weather. Use ducks until all slugs are gone (before they start eating your garden). Using chicken tunnels (fenced) around your garden, and they will clean all slugs that could move towards your gardens. I haven´t tried sawdust which is also suggested. Planting in greenhouses is also a good solution. Finally you might avoid sensitive crops like lettuce and carrots, and instead plant more resistant crops like kale or spinach. Plant the sensitive crops in well-sheltered beds.

Slug fences work! But remember to trim grass around them!

Inside the fence, protect plants by using plastic bottles or plastic rings. Be creative! But remember to remove these, when hot weather is forecast.

Cabbage pests: spray compost tea. Plant in polyculture! Plant: garlic-family plants, thyme, sage?, nasturtium?, artemisia and tansy repels them; mustard, radish, tagetes, borage, eucalyptus, sage, mints and dill also potencially good. Carrot family plants attract predatory wasps and zinnias attract ladybugs. Hyssop is a trap crop.

Potato beetles: vetches, ground ivy and tansy repels them. also coriander, flax. Plant early, in raised beds, to allow good growth before plants are defoliated by them, to reduce crop losses. Remove them by hand.

Squash bugs: nasturtium, tagete, and tansy repels, catnip and dill also, radish might work.

Mice and moles: artemisia, garlics, euphorbia, rue, fritilary, bury an inverted bottle (wind noise scares them). Cats are also effective.

Onion scarlet lily beetles: carrot-family plants attract predatory pests as well as catnip or mints, also goldenrod and milkweed, nasturtium (repels them). Remove them by hand. Plant onions in raised beds and well separated from each other, possibly in polyculture.

Scarlet lily beetles attack onions

Corn earworm larvae/moth: geranium, thyme, cosmos. Store corn grain in glass jars, and preferably in duplicate, to avoid losing seed.

Ants: coffee, mints and pennyroyal, lemon skins, sugar mixed with borax (not so ethical and healthy)

Codling moths (fruit trees like apples and pears): nasturtium, chives, lavender (but not so effective). More effective: in winter, clear all fallen fruit. In early spring (15°C), setup moth traps and solar lamps with oil, to capture them (this is just to indicate you that they are there, it does not remove the problem). In late spring, when petals fall, spray fruit with organic bacillus thuringiensis, garlic spray or other organic products, before larvae enters the fruit. Repeat every week for a month, until no more moths are trapped. Alternatively, use nematodes against the catterpillars. Place grease bands around the trunk to prevent creeping catterpillars. Keeping chicken under the trees during winter also works quite good.

Citrus worms: use neem oil


Aphids: Very frequent indoors. Keep plants healthy and not water-stressed or too much nitrogen. Use good ventillation, washing them (rain or a jet of water or with soapy water). Plant mints, garlic, nasturtiums

Spider mites: devastating pest indoors. Use mostly good ventillation; good watering and rain (Expose plant outdoors if possible). Keep plants healthy and not water-stressed. Plant perhaps neem and coriander/dill. Ensure plants are under bright light, and not water-stressed. If necessary, keep plants in isolation and wash them frequently, immersing them in soapy water.

Mildew: ensure good ventillation, expose plant outdoors if possible.

Gnats (small mosquitos): an indoor pest. Avoid organic matter. Cover with a layer of sand over the soil. Keep soil dry. Use vinegar to attract and drown them. Use oil on surfaces or sticky surfaces. Expose plants outdoors or repot plants in sterile new soil.

Root rot: use fine organic matter, use peat, use sterile soil, avoid irregular watering or too moist, do not add too much sand or clay to the soil mix. Keep plants healthy and under good light.


Deer: Use fencing, both high and with vegetation. Setup obstacles. Protect young trees. Plant sensitive crops further away from the edges of property. Floating row cover. Spread hair around crops (this might work against other pests too). Some suggest hanging scented soap bars. Another method might involve placing rottening eggs or spraying eggs diluted in water over your crops. If necessary, setup electric fences.

Wild boar: Dogs can provide some prevention. Wild boar is probably more of a problem in early spring when wild food is scarse. It can also be a problem with you have, for instance, a monoculture of corn. Setup fences. Setup obstacles like sticks or branches around sensitive crops like root vegetables.

Birds: Floating row cover. Cats are effective control. Protect young seedlings with inverted bottles. Place baloons, cds, scarecrows around the garden (though this might not be as effective as you think). Buy birdbusters (make artificial noise). Nevertheless, in my experience I haven´t had much damaged from birds, as I see them as beneficial against other smaller pests such as slugs.

Rabbits: Setup fences (60cm high). Remove habitat where they could hide and cover from predators like shrubs. Cats and dogs scare them. Garlic, garlic clips or fish emulsion. Plant alfalfa and clover just for them. Floating row cover.

I decided to include a few other gardening problems.

Forest fires: plant rows of cypress or poplars, at angle, to stir the fire away from your property. Plant ice plant barriers. Clean vegetation in the edges, or setup water lines.

Drought: add a pond. Thick mulching! Beds filled with organic matter or even hugelkultur! Sunken beds. Dense planting. Plant under a tree. Shrub edges to create shade. In desert areas, create an oasis, by creating depressions, swales, and planting desert species like date palms, olives, carobs, mesquites, honey locust and acacias.

Frost: Thick mulching, by adding thick insulating layers of leaves, grass, straw and peatmoss. This way, one can insulate down to -15°C. Use plastic wrapfoam during minor freezes (with straw inside). This can even protect small trees. Use fleece covers during minor frosts.

Cool summers: Plant against a south-oriented wall. Raised beds sloped towards south. Sandy soil, with plenty fluffy organic matter (like straw), to warm rapidly. Add some fresh compost to generate warmth. Setup windbreaks! Use well-adapted varieties from cold countries in the Arctic. Start seedlings indoors. The easiest solution is of course to grow under a polytunnel.

Tomato fruit drop-off. Add calcium to the ground. Avoid irregular watering, too wet or too dry. Add compost tea. Reduce dew moisture in morning, by growing them under a polytunnel, in raised beds or in containers. Use locally adapted varieties.

Plant around: phacelia, lemon balm, tagete, calendula, broad beans, yarrow, chamomile, valerian, dandelion, nettle, horsetail, mugworts and wormwood, aster-family flowers, clovers and lupins.

Also see my previous post in 2011: