52 



Pomona College Journal of Economic Botany 



AMMONICAL SOLUTION OF COPPER CARBONATE 



"Put 3 gallons of water in a wooden or an earthen vessel, pour 3 pints of 

 ammonia (26°B.) in this, and stir it to mix the two evenly. Take 8 ounces 

 of copper carbonate and shake it into the ammonia water, stirring the liquid 

 for awhile. If a considerable part of the copper carbonate remains un- 

 dissolved, the liquid may be left to settle ; if, however, nearly all of the 

 copper carbonate is dissolved, more of it should be added in the manner 

 previously described until a considerable amount remains undissolved ; then 

 it is set aside, as stated before. After the precipitate has settled, use the 

 clear blue liquid. The undissolved copper carbonate may then be treated 

 with more ammonia and water, fresh copper carbonate being added whenever 

 the residue becomes less than an ounce. The solution should not be kept 

 for more than a day or two, and when used one gallon should be diluted 

 with 15 or 20 gallons of water."— Prof. Rolfs, in Bull. 52, p. 17, U. S. Dept. 

 Agrcl., 1904. 



This spray has never been given a test in this county, but during the present 

 spring extensive tests will be made by this office as well as many other 

 fungicides not yet tried. 



PRUNING 



Because of the fact that the fungus has never killed the limbs of the 

 lemons outright and it was difficult to ascertain just which wood was infected, 

 the matter of pruning has never been taken up. Then, too, the disease was 

 so general that the possibilities of eradication or control seemed hopeless by 

 means of so slow a method. 



The pronounced attack upon the orange trees was so great that the cost 

 of pruning would far exceed anything in the form of sprays. 



The fact that the disease had never shown up to any degree upon the 

 twigs before makes it seem to us that pruning would do little good on such 

 large trees. However, in consideration of the facts presented so strongly 

 by Prof. Rolfs and Mr. Fawcett in regard to this method, some checks 

 are to be made to test this advice. 



If fungicides applied to the diseased twigs are capable of holding the dis- 

 ease in check and prevent its spreading, we can save much by their 

 application over pruning. 



It would be useless to attempt to prune it out of a lemon orchard, where, 

 as stated above, the point of infection on the limbs cannot be definitely as- 

 certained, because only the discolored leaves, spotted fruit and dropped 

 bloom are the only indications. If future observations are able to show 

 just where the infection takes place on the lemon trees as it does on the 

 orange, pruning may be resorted to. 



Winter Pruning for Wither-tip. is well described by H. S. Fawcett, in 

 Press Bull. 133, Florida Agricultural Experiment Station, December 11, 1909: 



"Wither-tip is one of the worst fungus diseases of citrus trees in Florida. 

 In the winter season, diseased trees may be distinguished by the yellowing 

 and falling of their leaves, the dropping of their fruit, and the dying of 



