Dealing with Garden Pests and Diseases – Container Gardening

Dealing with Garden Pests

Most people do not give a thought to the possibility of garden pests and diseases until their hanging flower baskets are in full swing and window planters burgeoning. Then one day, probably while watering, we may notice a sticky substance on some of the leaves and two days later it is clear we really have got greenfly. Or the birds we have fed all winter suddenly attack our early peeping primroses, nipping off all the buds, and it is obvious something must be done. Insect pests such as greenfly can be deterred greatly by routine weeding and good cultivation. A strongly growing plant will more easily cope in the early stages of insect attack. Always take off every dead or dying leaf and flower.

garden pests and diseases

Keep the plants clean and fresh with overhead spraying during dry spells. If only one plant is being attacked, it still pays to treat all the other plants in the same container at the same time. There are proprietary brands of sprays and powders on the market to deter most pests nowadays – including pepper dusts to put off cats! The big manufacturers seem to be constantly bringing out new products, so ask at your garden shop. I have found that an aerosol can is usually all that is required to deal with an insect attack, and this saves having to mix a large quantity of insecticide.

Many garden pests tend to hide under foliage, and so are very easily detected in hanging baskets and window planters, where they are more visible than on plants in the garden. When only one or two plants are involved, you can even brace yourself to rub out greenfly and other insects by hand in the early stages of an attack. One of the few advantages of a windy site is that aphides are unlikely to be much of a problem.

Ants can be another problem. These garden pests, apart from the possibility that they may come indoors, do encourage aphides, often introducing them to plants, on which they ‘farm’ them. They also tunnel about in the soil of pots and boxes, make nests, and disturb root systems of plants, which often die as a result from lack of moisture. Fortunately there are proprietary ant killers available, and if you buy one sold for destroying ants in the home it will be non-poisonous.

Other pests you may find on plants in a container include red spider, whitefly, blackfly, and scale insects. You may not realise your plants have red spider, which are difficult to see, until foliage mottles and growth becomes deformed. In severe cases the mites spin tiny webs over the stems and leaves. Regular overhead spraying with water not only keeps the foliage clean but the addition of 1 teaspoonful of common salt to a gallon of water helps deter red spider. Sunroom gardeners often think the scale insects, which are small blister-like objects, are part of the plant itself, and I have known people watch with interest for some months to see what happens next! In fact, these insects are feeding on the plant.

Whitefly are related to both scale insects and aphides. Like minute white moths, they rise from the plant when disturbed and can be difficult to deter because they have five stages in their life cycle from egg to adult — you may think you have got rid of them at one stage but there may still be eggs waiting to hatch. Control with a pyrethrum-based product sprayed on two or three times a week for about a month.

It is a good general rule to take immediate steps against any insects you find on your plants, except ladybirds and bees. If not dealt with promptly, insect pests are unlikely to go away ; on the contrary, they will increase and become more difficult to deal with.

The early spring can put the container gardener right off birds! And so, for that matter, can the summer, if you grow strawberries in a basket or tub out of doors. Many birds peck off buds and flowers and in the spring have been known to almost pick plants to pieces. So try to be one step ahead, particularly if you grow primroses and polyanthus. Buy a bundle of unobtrusive green-painted pot plant stakes and carefully slit down the top 1/2 inch of each. With these make a barricade all round the container or basket you wish to protect. Space them evenly and stretch black cotton, not thick thread (birds can get dangerously entangled in strong thread) between the stakes; criss-cross the cotton over the container. The idea is to deter the birds, which detest feeling with their legs or wings something they cannot see, not to trip them up! A covering of chicken wire over a container will deter cats, where these are a problem.

Where slugs and snails are concerned, I find the best answer is Liquid Sluggit, which gets right down to the business when watered on. It kills the pests beneath the soil as well as on top.


Plant Diseases

Botrytis is a fungus or grey-coloured mould which thrives in moist conditions, usually first attacking old discarded leaves. It is an obvious advantage to keep all plants in a clean condition as a first line of defence.

Damping off is when a young plant rots at soil level, by which time it is really too late to do anything about it. But resolve next time to use a sterile compost and not to over-water.

Mildew is due to lack of movement of the air and is therefore something which occurs with containers in very sheltered positions. This disease is easily recognisable, appearing as a thick grey dust over the surfaces of leaves.

Rust looks exactly like metal rust, and can attack fuchsias and geraniums as well as things like garden hollyhocks, on which it is commonly seen. In addition to controlling with a suitable spray treatment, take off and burn all affected leaves.

Proprietary treatments are available for dealing with all the common plant diseases which are likely to trouble the container gardener. As with pesticides, new products frequently come on the market so it is best to look and ask at a garden shop or the garden products counter at the chemist’s.


Premature Plant Leaf-Fall

When most of the leaves drop off a plant prematurely, or the leaves turn yellow, the reason may well be poor growing conditions. The soil may be too wet — or it may be too dry. The plant may not have been fed sufficiently, or it may be suffering from lack of light. The cause may even be that it has outgrown its container. Sudden alterations in temperature, particularly in spring, also cause leaf colour change. With these possibilities in mind the reason in a particular case should be obvious, and the remedy likewise.

None of these reasons necessarily means that the plant will die, though certainly it may be considerably weakened. In very severe cases, cut the plant back a little to see if it will shoot again. If and when it does shoot, mild feeding will aid its recovery.


05. September 2010 by Dave Pinkney
Categories: Garden Management, Pests and Diseases | Tags: | Comments Off on Dealing with Garden Pests and Diseases – Container Gardening

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