This section is from the book "Commercial Gardening Vol4", by John Weathers (the Editor). Also available from Amazon: Commercial Gardening, A Practical & Scientific Treatise For Market Gardeners.
The insect pests afflicting Tomatoes are not numerous, but some of them are exceedingly troublesome. Young plants are sometimes afflicted with Aphides and Ghost Flies, but these are easily checked by dipping or syringeing with a solution of quassia chip, soft soap, and nicotine (see pp. 216, 217, Vol. I.). Red Spider sometimes appears when the atmosphere is too dry, and is best kept down by gentle syringeing.
These are often very troublesome to market growers. One kind (Heterodora radicicola) attacks the roots, causing large warty or pea-like swellings on them. The presence of these Eelworms is indicated by the leaves drooping and turning yellow, and the whole plant becoming limp sooner or later. As the young Eelworms are very small - 1/75 in. in length - they can only be seen with the aid of a good pocket lens or microscope. They resemble minute eels, pointed at each end, and easily pierce the tissues of the tender roots. Wounds are caused on these, and with the exudation and coagulation of the sap the knotty swellings are produced. As the Eelworms suck and destroy the tissues the sap is unable to flow upwards to the leaves, hence the ultimate collapse of the plants. In due course the eggs of the pest hatch into tiny Eelworms, which pass into the soil, seeking the roots of other Tomato plants. They will, however, attack the roots of Cucumbers, Peas, Beans, Potatoes, Beets, Cabbage crops, Lettuces, and others, so that it would be dangerous to grow any of these crops after Tomatoes in the soil that is already infested.
Several remedies have been suggested, amongst them the following:
(2) Mix fresh gas lime thoroughly with the soil, which must then be left uncropped for at least six weeks. Quicklime may be used instead.
(3) Water the soil thoroughly with lime water.
(4) Water the soil with Little's Soluble Phenyle, 1 oz. to 6 gal. of water.
(6) Remove all the soil from the house and treat it outside; in the meantime thoroughly wash the house with a solution of 1 part of carbolic acid in 8 parts of water, or give the walls a good coating of freshly made lime-wash.
These remedies are more or less of the "hit-or-miss" type, and may or may not be successful or partly successful in destroying the pest. As a first precaution the injured plants should be taken up carefully and burned immediately. After the crop is over, it would be a laborious and costly task to take out all the soil and replace it with fresh material which might also contain Eelworms. Sterilizing the soil by steam or boiling water is perhaps the only effective remedy, and once done thoroughly there would probably be no further attack. In addition to this the soil should be turned up deeply - to a depth of 2 or 3 ft. - if possible, so as to bring the lower layers into cultivation, and give the upper and perhaps worn-out layer a rest for a season or two. Soil treated, or rather cultivated, in this way is not likely to be too rich or rank in organic material; and if it should be, that drawback can be easily rectified by adding either slaked lime or basic slag (2 oz. to the square yard) at the time of planting.
These voracious pests are the larvae of beetles known as Click Beetles and Skip Jacks. They are generally found in large numbers in freshly broken ground. It is therefore risky erecting greenhouses on land that has been under pasture, or has not been cultivated for some years, until the ground has been well ploughed or dug and exposed to the air for one season at least. In this way the Wireworms will be exposed to their natural enemies - the starlings, blackbirds, thrushes, rooks, etc. These will destroy more in a day than any number of "traps" or insecticides will in a month.
When amongst Tomato plants, Wireworms will attack the roots and pierce the stems, causing the leaves to wilt badly. One of the commonest methods of catching Wireworms is to cut up pieces of carrot or beetroot into 1 1/2- to 2-in. cubes, and insert them at the base of each plant just below the surface of the soil. The Wireworms are very fond of these juicy traps, and will be found boring into them. The pieces of carrot or beetroot should be examined every other day, and all Wireworms found should be destroyed.
Other remedies consist in dressing the soil, at least six weeks before planting, with fresh gas lime, or a week or two before with quicklime at the rate of about 1/2 bus. to a square rod. Kainit (about two-thirds of which is salt) may also be worked into the soil three or four weeks in advance, at the rate of 4 lb. to the square rod, to allow the salt time to work. Superphosphate of lime has also given good results. Sterilizing with steam or boiling water would be most effective when possible; in addition to which the soil should be deeply trenched.