AUTOMATED COLORIMETRIC PROCEDURE FOR THE DETERMINATION OF TOTAL AND UNCHANGED UREA HERBICIDE RESIDUES IN SOIL

Summary. An automated colorimetric method has been described for the determination of both total and unchanged herbicide residues of the urea herbicides fluometuron, metobromuron, chlorbromuron and chlortoluron. The method is based on the well-known Bratton-Marshall diazotization-coupling reaction for aromatic amines and is also applicable for other phenylureas as well as for N-phenylcarbamate and anilide herbicides. The procedure is especially useful when large series of soil samples have to be analysed, for instance in connection with leaching experiments. Manual work and working time have been reduced with this method by up to 50%.     

Air Pollution and Plant Health

Plant injury due to chemical air pollutants (SO₂, HF, NO₂, ethylene, ozone and PAN) is a well-known phenomenon in densely industrialized and urbanized areas. Studies on this subject form the major part of this publication. Less is known about the influence of air pollutants on the development of parasitic plant diseases and insect pests and only in exceptional cases has the effect of the presence of certain pathogens in plant leaves on symptom-expression resulting from chemical air pollutants been investigated.     

Aerial Application of Chemicals at Low and Ultra-low Volume Against Main Pests of Citrus and Olive Trees in Tunisia and Libya

Encouraging results were obtained in low and ultra-low volume aerial applications against Ceratitis capitata Wied. in Tunisia (Malathion LV 96%) and against this pest and against Dacus oleae Gmel. in Libya (with Malathion LV, phosphamidon 50 and 100% a.i. and dicrotophos 100%). The mixture rates of insecticide and bait were also considered.     

CONTROL OF WEEDS IN MARROWSTEM KALE BY EPTC AND SOME OTHER HERBICIDES

Summary. Two experiments on chemical weed control in marrowstem kale are reported. In the first of these three herbicides applied before sowing were compared; in the second experiment four herbicides were studied, one applied before sowing and the others applied after emergence. Of all the herbicides examined, EPTC, applied before sowing and incorporated into the seedbed, was the most satisfactory in terms of both weed control and yield of kale. Neither endothal + propham nor dinoseb + TCA proved satisfactory as pre-sowing treatments. The three herbicides applied post-emergence (all methylmercapto triazines) were ineffective for the control of Polygonum spp. and Poa annua , although fairly effective against Stellaria media and Chenopodium album . They caused considerable damage to the crop and reduced yields by at least 25%.
Le désherbage du chou moellier par l'EPTC et quelques autres herbicides     

THE EFFECT OF IRRIGATION AND STOCKING RATE ON THE OUTPUT FROM A SWARD

The dairy-cow results are presented from an experiment in which the response to grass irrigation was measured at two stocking rates. The method and herbage results have already been described (1).
Over two years, with an average application rate of 5·5 in of water per year, the main effect of irrigation was to increase the number of grazing days obtained by 35%. Neither yield per cow nor milk quality was significantly affected by the treatments.
The data emphasize the importance of high stocking rates for the full exploitation of irrigation. The practical implications of the results are discussed; they suggest that in the right circumstances of herd potential and grassland management, irrigation for milk production can be highly profitable.     

AN INTERNATIONAL EXPERIMENT ON THE EFFECT OF AGE AND STORAGE CONDITIONS ON VIABILITY AND DORMANCY OF AVENA FATUA SEEDS

Summary. Freshly collected ripe seeds of Avena fatua were first kept out of doors on the surface of the soil for 0 to 3 monehs, and then stored dry in the laboratory for 0 to 6 months before testing for dormancy and viability. Results from six European countries agreed well. Only 10% of ripe seeds germinated immediately alter collection and germination rose to 50% by December or January in all countries except Denmark. Viability was scarcely affected by age or storage conditions, except that many seeds died out of doors during winter in Denmark and Germany. The percentage of dormant seeds in December was greater in Denmark than elsewhere, possibly because the seeds were of a different type. Seeds may not behave the same in normal agricultural conditions as they did in this experiment.
Une expérience internationale sur l'influence de l'âge et des conditions de conservation sur la viabilité et la dormance de semences d'Avena fatua