79 



ORIGINAL AND OTHER COMMUNICATIONS ON GARDENING, 

 FLORICULTURE, &c. 



♦ 



BLISTER-BLIGHT. 



Peach and Nectarine trees in some situations are liable to what is called the blister- blight 

 during May and June, that is, many of their leaves become of a thick fleshy substance, which 

 in some cases extend even to the young shoots. They are more affected in ungenial springs, 

 and the disease is likely to be very general after the late unpropitious spring. The leaves so 

 affected soon curl up, forming a receptacle and food for various kinds of insects, which if once 

 allowed to get established are not easily got rid of during the remainder of the season. The 

 most effectual remedy is to pinch off the affected leaves as they appear, and also to cut off the 

 young wood buds so affected ; which will, if persevered in, prevent insects from getting established 

 by means of these diseased leaves ; and the trees in most cases ultimately push kindly, and by 

 July would not by a casual observer be suspected of having been affected with the blister-blight. 



ON THE EFFECTS OF LIGHT, &<$., ON VEGETATION. 



Many years ago the beneficial effects of light on vegetable substances was ascertained, by 

 accident, by the late distinguished Philosopher, Dr. Priestley, and by him detailed in a simple 

 and clear manner in the third volume of his work, intitled " Experiments and Observations on 

 all kinds of Air," and which have been confirmed by all succeeding Vegetable Physiologists. 

 For the information of those who may not have a copy of the work we will quote the passage. 

 He says, " that having a large trough of water, full of recent green matter, giving out air very 

 copiously, so that all the surface of it was covered with froth, and jars filled with it, and' inverted, 

 collected great quantities of it very fast ; I filled a jar with it and inverting it in a basin of the 

 same, I placed it in a dark room ; from that instant no more air was yielded by it, and in a few 

 days it had a very offensive smell, the green vegetable matter with which it abounded being 

 then dead and putrid." Vol. 3, p. 295. These experiments have been further confirmed by 

 Sir H. Davy, in his Agricultural Chemistry, p. 205. Indeed so beneficial is light to all healthy 

 vegetation that it cannot be dispensed with unless by the plants sustaining more or less injury ; 

 yet if plants be placed in too great a heat and light, as occurs in the midst of summer in hot- 

 houses, it is hurtful, their colour is extracted, carbonic acid is given out entire without decompo- 

 sition, and the plant becomes weak and languid, a fact which is well known to all gardeners, 

 who to prevent it, when the sun is too strong at mid-day, take the precaution to cover the top 

 with blinds, which are sometimes attached to the tops of the houses for that purpose. Plants 

 made to vegetate in the dark are always of a yellowish white colour, weak, and without firmness, 

 in consequence of carbon, the necessary food of plants (and, as we may say, their very muscle) 



