40 REPORT OF THE COMMISSIONER OF AGRICULTURE. 



boue black, this being tbe proper quantity for an acre. If the trees are 

 in an advanced stage of the disease, more muriate of potash is to be 

 added, giving about 4 pounds of this salt to an average-sized tree. It 

 is very safe to remark, however, that no person ever succeeded in re- 

 storing a tree in an advanced stage of the disease of yellows, and no 

 one who has had any experience with it will ever make the attempt. 

 The assumption that this disease is caused by a deficiency of particular 

 elements in the soil cannot be sustained. 



It is a common observation that, when trees become weakened from 

 impoverished soil, their foliage assumes a yellowish color. This is ob- 

 served not only in the peach, but also in the pear, cherry, orange, &c. 

 In fact, a yellow coloring of the leaves is a common index of a weak- 

 ened condition of a plant. On grape-vines seriously aifected by phyl- 

 loxera at the roots, the young growths will assume a stunted, 3-elIowish 

 appearance, which is perceptible from a considerable distance. Peach 

 trees on poor soil have been seen to make yearly stunted growths 

 with yellowish foliage, while yielding small, prematurely-ripening fruit, 

 and in fact, looking very similar to a tree having the yellows ; but such 

 trees are probably as far as possible removed from any likelihood of 

 contracting that disease. It is quite in accordance with the every-day 

 experience of those engaged in the cultivation of plants, that the best 

 method of restoring weakly trees, such as those just alluded to, is to 

 enrich the soil, and it is also good practice to allow those that are iu 

 an advanced stage of poverty a more generous allowance than that given 

 to those not so much in need ; hence the benefit which has seemed to 

 result from the application of potash, &c., to the roots of peach trees 

 having yellow leaves may lead to doubt whether the color indicated a 

 result of impoverished soil only, or arose from the disease known among 

 peach-growers as the yelloics. The latter is understood to be contagious 

 and can be communicated to a healthy tree by pruning it with a knife 

 previously used iu cutting a diseased one. 



One writer observes that when the "symptoms of yellows are mild in 

 character and limited in extent," the trees should be limed and manured 

 vigorously. He adds : " Follow this up with a little judicious pruning, 

 and you have done all that seems jiracticable towards preserving, if not 

 curing, your aflected trees." 



There is a difference of opinion regarding this contagious feature, 

 some holding to the opinion that the disease is transmitted by contact, 

 while others are equally convinced that it is not so transmitted. 



These seemingly conflicting opinions may arise from the supposition 

 that all yellow indications of foliage result from one cause, which is not, 

 we take it, the case; for all agree that when yellows is accompanied by 

 a multitudinous growth of wiry, yellowish shoots on the older branches 

 and stems, it is incurable. It may, therefore, be strongly suspected that 

 in cases where an enrichment of the soil has cured trees of a disease 

 supposed to be the yellows, the yeUow appearance of the leaves has 

 been due to impoverished soil alone. ^ 



Another cause of yellowness in peach leaves is that of the borer, which 

 oftentimes does great injury by destroying and girdling the bark jus'^ 

 at or below the surface of the ground. The result of this insect deprt 

 dation is often mistaken for yellows. 



J. Fitz, in his work on peach culture, says : "The ravages of the yel- 

 lows, as far as I know, seem to be confined to the l^orthern and Eastern 

 States and some portions of the West." 



Fulton, in his work on the peach, remarks that " the yellows is very 



