February 24, 1892.] 



Garden and Forest. 



91 



any one to test copper sulphate and copper carbonate as well 

 as Paris green in regard to their purity : 



Copper sulphate, if pure, should dissolve completely in 

 water, making a clear solution, free from sediment or sus- 

 pended matter. 



Copper carbonate should dissolve completely in nitric acid, 

 commonly called aqua fortis. If it does not dissolve com- 

 pletely, it is impure and probably adulterated. Copper car- 

 bonate, if pure, should dissolve completely, or very nearly so, 

 in a considerable quantity of strong ammonia-vi'ater. I3oth 

 tests should be used. Of course, copper carbonate could be 

 adulterated by using powdered copper sulphate, but this could 

 easily be detected, since copper sulphate easily dissolves in 

 water, while copper carbonate does not. 



Paris green should, if pure, dissolve completely in strong 

 ammonia-water, used in liberal quantity. 



Such simple tests as the foregoing may be applied by any 

 one, and they will serve as a fairly reliable guide regarding the 

 purity of the compounds mentioned. When adulterants are 

 added they have been found by common experience to e.xist 

 in the form of some finely powdered white substance, as 



in appearance there may be seen the dark fruiting spots of the 

 fungus, where the spores are borne in large numbers. Tliis 

 form of damping-olTis particularly contagious, on account of 

 the rapidity with which the spores germinate. By actual test 

 cases of inoculation, fully developed spore-bearing spots have 

 been produced upon healthy Carnation-stems in three days 

 when these stems were kept moist, as are the portions of cut- 

 tings below and at the surface of the sand, (lardeners have 

 frequently observed that some stock is much worse than 

 others with this cutting-trouble, which, in large part, can be 

 accounted for on the ground that the fungus is not uniformly 

 distributed in mature plants. Stock fi-ee from it will be apt to 

 remain free, but diseased stock, in like manner, is quite sure 

 to decay in the sand. 



The failure of Rose-cuttings to grow may be due, of course, 

 to various causes, but the one that has been most frequently 

 met with of late is fungus belonging to the genus Gloeospo- 

 rium. This fungus forms minute pimples in the bark of the 

 diseased wood, followed by an exudation of a gelatinous spore- 

 mass from each pustule that is, at first, rose-tinted, becojiiing 

 almost brick-colored. The branches of many Rose-plants in 



Fig;. 16, — Clematis paniculat i. — See page 90. 



barium sulphate, for example, which is insoluble in water, 

 alkalies or acids. 



Fruit-growers who have to use large quantities of copper 

 compounds should, for the sake of economy, buy the sepa- 

 rate ingredients and do their own mixing. Persons who have 

 occasion to use only small amounts of spraying mixtures may 

 tind it advantageous to purchase prepared compounds ready 

 for use, if they can be sure that the preparation is reliable in 

 strength and not extravagantly high in price. 



Fungous Troubles in the Cutting Beds. 



TOURING the past few weeks particular attention has been 

 ^-^ paid to some diseases in the cutting beds. Among those 

 found dead or badly decayed are cuttings of Carnation, Rose, 

 Clematis, Passion Flovv'er and Chrysanthemum. In the Car- 

 nations, for example, the cuttings begin to decay at the sur- 

 face of the sand, the outer leaves soon rot at the base and fall 

 to the ground. This is due to an anthracnose of the genus 

 CoUetotrichum, and long before the cutting has become ruined 



a feeble condition have been examined microscopically, and 

 this fungus has been detected. Wiiile we have not found it 

 naturally upon the foliage there was no difficulty in inoculat- 

 ing leaves with the Gloeosporium, by placing them in contact 

 with diseased stems in a moist chamber. Rose-wood that is 

 only slightly diseased with this anthracnose when made into 

 cuttings would probably fail, because the new conditions 

 would be particularly favorable for the growth of the fungus. 

 As in the case of the Carnations, the obvious precaution is to 

 use healthy wood. 



Many Chrysanthemum-cuttings have failed, and an examina- 

 tion of a considerable number of these leads to the identifica- 

 tion of at least two fungi, either one of which is sufficient to 

 account for the trouble. During the past year Chrysanthe- 

 mums have suffered a good deal from the presence of a fun- 

 gus of the genus Septoria, which caused the severe blighting 

 of the foliage in some instances, almost defoliating the plants. 

 This same Septoria is present in abundance in the cuttings that 

 have damped off. Other plants, obtained from other green- 

 houses, and appearing in the same plight, have a Phyllostiata 



