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THE TROPICAL AGRICULTURIST. 



[December i, 1882. 



It is at least curious that coffee leaf-disease first ap- 

 peared on the eastern side of the mountain, while 

 this pest seems, as yet, confined to the western. 



Dr. Trimen, whose scientific position is very emin. 

 ent, may be right and we may be wrong on the 

 question of the power of a badly affected tree to 

 infect another ; but if abnormal meteorological con- 

 ditions are sufficient to set up a chemical action in 

 the juices of a plant calculated to blotch and kill tlie 

 leaves and to swell and canker the branches and 

 twigs, so that many trees succumb, is there, we 

 again ask, anything unphilosophical in the supposi- 

 tion that wind-carried drops of the diseased juices or 

 particles of the diseased bark and wood tissues, may 

 convey the disease to and infect previously healthy 

 trees ? As to the climatic conditions which produce 

 the disease — apart from excessive moisture and the 

 cold resulting from evaporation of that moisture, 

 analysis of the rain water might have revealed some- 

 thing significant, had we only thought of testing it 

 diu'ing the prevalence of the South-west monsoon. 

 Abbotsford is nearer CO than 50 miles, in a direct 

 line from the south-western seaboard, and there 

 is besides the distance, the objection of elevation 

 (4 650 feet to 6, 100) against the idea of sodium 

 chloride being carried by the monsoon winds in 

 sufficient quantity to inflict injury. While a moder- 

 ate proportion of salt in the atmosphere is favour- 

 able to vegetation, which it stimulates, salt-storms 

 can be deadly in their effects. Any one who doubts 

 this has only to look at the young coconut pahns 

 on the seashore anywhere near Colombo. In the 

 height of the south-west monsoon, 



When the wrathful spirit of storms 



Has made the tops of the waves his own ; 



and masses of bitter brine are carried inland, the 

 leaves of the young palms are blackened and killed 

 as if fii'e had passed over, and scorched them. 

 The natives resort to very deep holes in order 

 to shelter the young plants, but neither this ex- 

 pedient nor any other mode of shelter which would pay, 

 as we know from experience, can prevent the destruc- 

 tion of a considerable per-centage of young coconuts 

 annually, by that which Is deemed, and no doubt 

 correctly, beneficial to the palm when properly and 

 moderately administered, — salt. Now sea water con- 

 tains other salts besides sodium chloride, notably 

 salts of magnesia, and we submit that it is just 

 possible that an excess of some salt ; ammonia, 

 sodiimi chloride, magnesium chloride, or magnesium 

 sulphate, in the atmosphere may have injuriously 

 affected vegetation on our hills ; the source of all, save 

 the ammonia, being the ocean over which the winds 

 had swept, absorbing moisture and with the moisture 

 the salts contained in the sea, as they passed onwards or 

 were drawn forwards? We are not dogmatizing, but 

 throwing out suggestions for the consideration of 

 those who have studied such subjects. The com- 

 position of sea water varies according to position 

 and climate and for our purpose we look at the 

 analysis of the water in the Bay of Bengal. In 

 1,000 parts, we get 



Water ... ... 966-75 



Sodium chloride ... 26 '06 



Magnesium do. .. 2'81 



Potassium do. ... r20 



Magnesium sulphate ... 1'82 

 Calcium ... 1 "36 



Most of the above ingredients would be rather bene 

 ficial than otherwise if properly applie<l. But they 

 would be injurious in excess, and excess might be 

 predicated of minute quantities applied for long-con- 

 tinued periods, as well as to over-doses given at once. 

 In a most va,luable book recently published (the Hand 

 Pook of Salt, second edition, by I)r. J. J. L. Katton of 



the Madras .Salt Department ; Higginbotham & Co., 

 Madras. ) there are several accounts of damage inflicted 

 on vegetation by salt storms, one of which occurred on 

 April 29th of this year. It was a severe gale from the 

 South- West, doing considerable damage to vegetation 

 in tlie south of England for many miles inland. Its 

 effects were attributed to salt, crystals of wliich were 

 distinctly noticed. And now comes the statement to 

 which we specially wish to direct attention. At a 

 meeting of the Royal Horticultural Society, May 23rd, 

 1882, Dr. Church explained his experience on the sub- 

 ject of salt storms carried on for 15 years : — 



"He found from.'j to|7 grains of salt per gallon of rain, 

 brought from the west by autumnal gales ; whereas 

 ordinary rain water contained only half a grain to the 

 gallon. He mentions tliat the exposed sides of the 

 trees in Oakley Park were injured by the salt, which 

 could be seen sparkling on the trees a few days after a 

 gale, if no rain followed ; and this at a distance of 25 

 miles from the sea. He thinks that salt acts by abstract- 

 iiig moisture from the leaf cells, and forming a concen- 

 trated solution, which in a manner pickle^ the leaf. Differ- 

 ent trees were differently affected ; but it was the 

 general opinion of the meeting that this was due to 

 different degrees of hardiness in the frees. Assuming 

 that ordinary rain water in England contains half a 

 grain of salt to the gallon, an inch of rain, would 

 yield 1 1,315 grains per acre, and with an annual rain- 

 fall of 30 inches, 339,450 grains or 44ths. per acre." 



In an account in the LinniEan Transactions of a salt- 

 storm which raged for several days in Jauuary 1803 

 the very word which Dr. Trimen uses as a synonym, 

 for "canker" is applied to the effects of the wind- 

 carried salt on vegetation, thus: — " The most remark- 

 able phenomenon noted in connection with this storm, 

 was that it withered the leaves of plants and mortified 

 their top branches for a space of seventy miles from 

 the sea." This disposes of the difficulty of distance, 

 for Abbotsford is not quite sixty miles inland. 



But, once again, — let us look at the recorded effects 

 of a salt storm in New England in 1815, and noticed 

 in the American Jonrnal of Science : — " At New Lon- 

 don, ,Salem and other places, both on the coast and 

 several miles in the interior, tlie leaves of many trees 

 appeared as if they had been scorched." And then 

 comes confirmation of our position that the mischief 

 might be the result of tlie long continued action of 

 wind-carried moisture containing only muiute portions 

 of salt : — " The injury to plant life produced by salt 

 storms, seems to be in direct proportion to their in- 

 tensity and DURATION. It is a question of the violent 

 [italics in the original,] application of saltsjiray to 

 plants, for a certain len/ith of time." 



We submit that we have made out a strong case for 

 at least the full investigation of our salt-spray tlieory of 

 the new leaf-scorcliing and brauch-and-stem-mortifying 

 disease. Salt has undoubted merits in agriculture. 

 But wliile a moderate application of this substance 

 stimulates vegetation, there is no more deadly applica- 

 tion to growing plants than salt in excess. ' ■ Gard- 

 eners and agriculturists are much better acquainted 

 with its poisonous than with its fertilizing proper- 

 ties." Gardeners use salt to kill weeds and grass on 

 pathways, and farmers employ salt in largest quan- 

 tities for the improvenient of weedy lauds by the de- 

 struction of the weeds. Not even fire is destructive 

 to vegetable tissue and plant-life. 



If salt existed in the 50 iuches, of rain which fell 

 at Abbotsford in the two months of June and July, 

 at the rate of even 3 grains to the gallon, our readers 

 can imagine what its piclding effects must have been, 

 and quite consistent with tlie opinion of those who 

 attended Dr. Church's lecture us to effect being in 

 proportion to hardiness of tree, is the fact that while, 

 the delicate eucalypts and cinchonas have suffered 



