lo March, 1910.] Aiiszvers to Correspondents. 191 



Killing Trees with Arsenic. — W.T.C. writes :— •' I have been usin<i, witli 

 success, dissolved arsenic applied immediately after ringing, for the killing of 

 eucalypts. Before proceeding further I wish to know — (i) What form is the 

 arsenic likely to be in when it becomes mixed with the soil, after the trees are 

 grubbed and burnt and the land cultivated? (2) Is the presence of arsenic in this 

 form, and in the quantity of about i{ lbs. to the acre, likely lo materially affect 

 the fertility of the soil?" 



Answer. — (i) For the purpose mentioned, arsenic is usually applied in the 

 form of arsenite of soda. It will remain in this form in the soil, but as it is 

 soluble in water it will gradually disappear through the action of rain and drain- 

 age. (2) The presence of arsenic in the form of arsenite of soda, at the rate of 

 li lbs. per acre, would not affect vegetation or the fertility of the soil, and 

 consequently would not destroy eucalyptus trees. If ig lbs. to the tree is meant, 

 the soil in the vicinity of the tree would be affected. 



Inter-crops in Young ORCH.iiiD. — Merrigum states that he is iilanting a voun,' 

 orchard and would like to know what could be grown, under irrigation, in the 

 way of inter-culture, for the Melbourne markets. 



Anaivei'. — As an inter-croji between voung trees, strawberries have been grown 

 in your district with highly payable results. The lime, manure and water neces- 

 sary to strawberries would all be helpful to the voung trees. Tomatoes would also 

 be a very profitable crop, especially if the seeds were sown in March or April 

 under glass, and planted out early. A crop of onions would probably be pro- 

 fitable, although your district is rather warmer than ordinary onion districts; this 

 vegetable has. however, been grown with very good results in the Goulburn Valley. 

 Whatever crop is grown between young trees, it should be kept out from the trees, 

 So as to allow the growing roots to spread as far as possible. Any breaking or 

 cutting of the voung roots b\- cultivating implements will cause a very severe 

 check and will inevitably dwarf the tree. 



Food for C.^LVES. — E.J. asks for the formula of a good food for calves. 



Ansik cr. — The best of all foods for voung calves is without doubt fresh 

 milk. When this cannot be used an effort should be made to supply the con- 

 stituents as near as possible. This may be done by using fresh skim milk, to which 

 is added an oil to take the i)lace of the butter fat removed. Possibly the best of 

 all in this respect is cod liver oil, well shaken with the milk so as to make a fine 

 emulsion. Some of the calf foods on the market are quite satisfactory if the directions 

 given are properly carried out. 



Stack ("over. — W.W.J, states that he has tried a mixture of sugar of lead 

 and alum for a stack cover made of common hessian and found it good. As ^ugar 

 of lead is a poison he wishes to know whether his cattle are likely to be affected 

 if they eat the hay. 



.Answer. — Sugar of lead is decidedly jjoisonous, and the upper layer of hay 

 would undoubtedly contain a certain amount. It would depend upon this amount 

 as to whether injurious symptoms were produced. 



Poisonous Qu.ai.ities of Millet. — J.W.H. asks whether millet has been 

 proved effectual in poisoning rabbits. Also whether there is any danger to stock 

 through eating millet. 



.Answer. — Growing millet for rabbit extermination has been tried with very 

 indifferent results, principallv on account of the presence of other food. The 

 idea may have originated from the well-known fact that sorghums contain during the 

 leaf and flowering stages, a variable quantit}' of prussic acid and cyanide of 

 potassium, two substances of recognised poisonous cjualities. It has been specially 

 noted that if the growth of the plant is stunted, through dry weather or any other 

 natural cause, the amount of the poisons referred to is increased. Stock should be 

 kept away from millet until it is cut and allowed to wilt in the open for at least 

 36 hours, during which time the injurous elements disappear. 



Converting Pyrethrum into Insecticide. — L.r.D. inquires as to mode of 

 converting Pyrethrum into insecticide. 



Answer. — To obtain the best results from Pyrethrum it is advisable to cut 

 Ihe plant just as the flowers are beginning to open, as its value as an insecticide 

 depends on its oil content, which is most abundant at this stage of growth. The 

 oil is very volatile, so the cut portions must not be exposed during drying to direct 

 sun heat or to a high temperature. When dry, grind into powder and place in 

 air-tight receptacles, otherwise it will quickly lose its strength. It may be either 

 used in solution or as a powder. The ordinary method is to mix one ounce to three 

 gallons of water when used as a solution. As powder, dr\- without dilution, or 

 mix with flour or any light material in the proportion of one part of the powder 

 to from six to thirty of the dilutant as mav be desired. 



