Pests & Diseases Affecting Aubergines

In temperate climates, aubergines will not suffer from many troubles; in the list that follows the main ones are likely to be grey mould (botrytis), red spider mite and slugs. However, in tropical conditions, Colorado or potato beetle may cause a lot of damage, as aubergines belong to the same plant family as potatoes. Although it is very unlikely your aubergines will be troubled with Colorado beetle, it is generally a good idea to grow this crop well away from your potato crop. There are also several wilt fungus diseases which are soil -borne and infect the roots, but these can be avoided if the crop is rotated, ie. not grown on the same site in two or more successive years.

Red spider mite: this is the most serious problem you are likely to encounter with aubergines, particularly those grown under glass, or when the weather is hot and dry outdoors. The main symptoms of red spider mite infestation are leaves turning speckled grey-green and then bronze. If the infestation is severe, the leaves will wither and fall prematurely. Another indication of red spider mite is fine silken webbing covering the leaves and sometimes the stems. The best preventive measure in very hot, dry conditions is to syringe the leaves daily with warm water, or, better still, with a solution of soft soap. Both indoors and out, cut off and burn all badly infested leaves, and step up the application of water, both to leaves and roots. If the infestation is in the greenhouse, fumigate with azobenzene, or similar insecticide. Slugs: these familiar garden pests attack a wide variety of plants, ormanental as well as vegetable. They feed chiefly after dark, both above and below ground. The leaves, stems and low-hanging fruit can be attacked.

During the day they hide away in dark, moist cool places. Their favourite haunts are decaying vegetable matter, and soils rich in humus and moisture.

Trapping slugs is an effective method of ridding your garden of these pests, but it is time-consuming, and calls for daily inspection of traps. Use wet sacks or heaps of damp vegetable refuse, such as lettuce or cabbage leaves or orange peels, and place them at the base of the aubergine plants. Remove and destroy all trapped slugs daily.

Alternatively, use proprietary slug pellets, based on methiocarb or metal-dehyde. Remember, though, that slugs have the ability to cast off poisons or irritants which may fall upon them by excreting slime; to be completely effec-tive, you should repeat applications of slug pellets on successive nights. Greenfly: these small green insects are usually found in colonies on or near the growing points, or under the young leaves. Infested leaves turn yellow or pale green, become distorted and wither, while infested growing points may die completely, so that the plants and or side shoots stop growing and are -stunted. Control greenfly by smokes or sprays of malathion, bioresmethrin or derris. Whitefly: these insects, which look like tiny white moths, are more trouble some years than others. They thrive in hot, dry, weather, and whitefly attacks in these conditions can be ruinous. Like red spider mite, they live and feed on the undersides of leaves, where they suck the sap. The leaves become greyish green and wilt; in a bad attack the plant ceases to grow and becomes a horrible mess of insects, sticky discoloured leaves, and sooty mould. They also exude honey dew and it is this which encourages secondary infection by sooty mould. Spray thoroughly with bioresmethrin as soon as the first signs of whitefly appear, particularly the undersides of the leaves and again as the makers instruct. Repeated sprays are usually required to deal with immature whitefly missed by previous applications. Capsids: these bright green, quick-moving insects occasionally attack the growing points of aubergine plants. From mid-spring onwards, they pierce the leaves and stems, and suck the sap. As they are relatively large, mechanical damage can be quite severe; infested leaves will be misshapen, puckered and tattered; infested growing points may die completely, so that the plant or sideshoots stop growing. There can be a second generation of capsids in midsummer, so it is doubly important to deal with them thoroughly as soon as you see signs of their presence. Capsids are exceedingly active and quick-moving insects, so you are far more likely to see symptoms of capsid infestation than the capsids themselves.

Control capsids by spraying or dusting with malathion, or derris plus pyrethrum. Capsids drop to the ground when disturbed, so remember to treat the soil around the plants as well. Botrytis (grey mould): this fungal infection is a very common garden problem, and attacks a wide range of fruit and vegetables. It is usually associated with cool, damp, overcrowded growing conditions. The symptoms of grey mould are fluffy, grey growths on the leaves, fruit and occasionally the stems. Aubergines grown under glass are particularly vulnerable. The disease enters the plant through a wound or through dead or dying tissue, and hence infection often occurs on the fruit where the blossom was joined to it. Because botrytis spores are constantly present in the air, poor growing conditions can quickly lead to a severe attack, and an entire crop can be ruined. The best precautions are to ensure that seedlings and young plants are not overcrowded, and that air can circulate freely. Quintozene applied to the soil just before planting gives some measure of protection. If there is an outbreak of botrytis, remove and burn all infected leaves and fruitlets. Improve the growing conditions, by raising the temperature both night and day, giving more ventilation, and removing shading from glass, if previously applied. Badly infected plants should be removed and destroyed, as it is unlikely they will recover.

Gardening Tips:

Making the most of cloches

As mentioned in CHOOSING AND USING CLOCHES3 the method of cultivation known as strip-cropping is the best way to make use of a set of cloches. A group of crops are grown next to each other in strips or rows of equal width, and the cloches are used to cover the crops in succession. One set of cloches could be used on two or three strips. The two-strip system is the simplest one to start with. The breadth of each strip will depend on the width of cloches used, the ultimate amount of space needed by the crop, and the necessary working space for proper cultivation. Where, for example, a single row of cloches is used, a convenient breadth of strip is the width of cover plus a ‘path’ of 30 cm (12”). Crops suitable for strip-cropping can be divided into four major groups, depending on the time of year for which they are cloched. The first group consists of hardy spring crops cloched from mid-winter to mid-spring (eg spring cabbage, peas); the second group is of half-hardy crops either sown in heat and planted out mid to late spring, or sown under cloches mid-spring (eg cucumbers, tomatoes); the third group is of tender crops that are cloched all summer (eg tomatoes, peppers); the last group is of crops that are cloched from mid-autumn to early winter (eg endive).

Intercropping

In addition to the main crops being grown in the two and three-strip schemes, extra crops which require little space, are quick growing, or mature later, can also be fitted in under the cloches at the same time. For example, spring onions, quick-maturing carrots, radishes and garden peas can all be intercropped with lettuces. French beans can be sown on both sides of a single row of sweet corn, or a row of lettuces beside tomatoes, making full use of large cloches. This will not adversely affect the tomatoes, provided that watering and feeding are not neglected.

Strip-cropping enables you to use all your cloches to their full capacity, so that each cloche covers as many crops as possible during the year. By this method, you can make 30 m (100’) of cloches cover 120 m (400’) of crops, which is obviously far more economical than having to buy 120 m (400’) of cloches to do the same job.

With strip cropping, too, there is no need to wear yourself out carrying cloches from one end of the garden to the other; it is simply a matter of moving them a few feet to the next strip.

Accurate marking out of the rows is of the utmost importance in strip-cropping. To make the job easier, construct the simple measuring device shown in the diagram. Take a strip of waste wood and after painting it white, measure out the widths of cloche rows, gaps and paths along its length and mark them by means of shallow saw cuts, filled in afterwards with black or red paint.

Cloche cultivation notes

Here are some basic notes on how to use cloches in relation to a variety of vegetables and fruit.

31. August 2013 by admin
Categories: Fruit Gardening, Uncategorized, Vegetable Gardening | Tags: , , , , , , , | Comments Off on Pests & Diseases Affecting Aubergines

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