Experiments on the mode of action and factors influencing activity of the synthetic compound 1, 3, 5 tricyano-3-phenylpentane are reported. The mobility in plants of various naturally occurring and artificially introduced substances is discussed, and examples are given of groups of compounds having biological properties which could indicate new leads to systemic nematicidal activity.
INHIBITION OF ROOT-KNOT DEVELOPMENT ON TOMATO BY SYSTEMIC COMPOUNDS BY F. C. PEACOCK I.C.I. Ltd., jealott's Hill Research Station, Bracknell, England PEACOCK (1959) described a technique for culturing the root-knot nematode lVleloidogyne incognita (Kofoid and White) under controlled conditions. One object of this technique was to study the effect on parasite development and host plant reaction (i.e. gall formation) of test substances introduced into the nutrient medium in which excised host (tomato) roots were cultured. Experiments were made to test theories of possible mechanisms of interference with the normal nematode/host root complex. Test substances were also introduced into intact tomato
The reniform nematode (Rotylenchulus reniformis Linford & Oliveira) has been observed on a wide range of food crops in the Gold Coast, and can maintain itself under fallow conditions on at least two common weeds. Measurements differ slightly from those given by LINFORD and OLIVEIRA, but it is considered that the same species is involved, the differences being accounted for by development on a different host. The life-cycle appears to be as short, or a little shorter than, LINFORD and OLIVEIRA'S theoretical minimum period of 25 days. Susceptible and resistant host species have been noted, and a particularly heavy infestation on tomato is recorded.
The use of sodium azide and organic acid azides for the control of potato root eelworm has been investigated: in suitable conditions they were effective both in greenhouse tests and in field trials. The biological activity of azides has been shown to arise from liberation of undissociated hydrazoic acid. The acid is only liberated in effective quantities in acid soils, but in such soils it is decomposed with formation of nitrogen. Organic acid azides are decomposed by a wide range of dust diluents and by soil, and there is some evidence that in diluents the main decomposition reaction is the formation of isocyanate by the Curtius rearrangement, whereas on wet soils extensive hydrolysis occurs giving hydrazoic acid, which is subsequently decomposed.
Abstract It is shown that the residual benzene hexachloride (BHC), determined analytically in a loam soil, is a function of the amount of benzene hexachloride (13% y ‐isomer) (referred to in this paper as BHC‐13) applied per acre and the time elapsing after application. A significant correlation was found between the level of residual BHC and degree of tainting of potatoes grown in the same soil. The taint measurements involved in the present work are in agreement with the much more numerous and independent measurements that formed the basis of an earlier paper. BHC‐13 thoroughly worked into the top six inches of a loam soil, at rates up to 8 lb. per acre, was lost at an exponential rate of approximately 50% per annum over the period of the trial. Provided that the application of BHC‐13 to the soil does not exceed 1/4 1b. /acre annually, the risk of growing tainted potatoes on loam soil in this country seems slight; surface application at rather higher rates may also be safe.
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