156 



Charlock Spraying. 



[JUNE, 



the charlock entered into the rough blade, or when the plants 

 were about the size of turnips ready for singling, but, as a matter 

 of fact, it was done on charlock at all stages of growth. This 

 was necessitated by several of the days originally arranged 

 turning out quite unsuitable for spraying. A calm day is 

 necessary for success, when the fine spray descends naturally on 

 the outspread leaves of the charlock, and a minimum of it falls 

 on the upright corn blades. Whereas with wind, besides 

 uneven distribution, the spray is carried in a horizontal direction, 

 so that the greater part of it is caught by the waving corn and 

 very little of it by the plant for which it is intended. Rain is 

 equally undesirable, for it either materially weakens the solution 

 or washes it off the plants entirely. 



At a few of the centres the demonstrations were proceeded 

 with although the conditions were not all that could be desired, 

 but to avoid disappointment and waste of money the operation 

 should be undertaken only when the weather appears settled, on 

 a calm day — sunless, if possible— and when the majority of the 

 plants are just in the rough leaf. With regard to the time when 

 spraying is most effective, it was found that no necessary relation 

 existed between the size of the plant and the stage when it 

 could be most easily destroyed. In cold, backward seasons, such 

 as 1902 and 1903, and on poor or exposed lands, it is not 

 unusual to find charlock coming into flower while less than 

 3 inches in height. Such charlock is slow grown, stunted, hard 

 and wiry, and much more difficult to kill than when the plant is 

 young and succulent. Cases of this kind were successfully met 

 by making the fluid 4 instead of 3 per cent., but experience 

 showed that charlock is most successfully and economically 

 eradicated by spraying when the plant is young, succulent, and 

 in the rough leaf. One spraying in favourable circumstances 

 will kill the charlock, but this is entirely dependent on its being 

 properly done under suitable climatic conditions ; and two 

 sprayings within ten days of each other may, in certain circum- 

 stances, be required to completely eradicate charlock from a 

 growing corn crop. 



