252 STATE HORTICULTURAL SOCIETY. 



DISEASES MISTAKEN FOR YELLOWS. 



Having defined yellows, it will now be proper to state what it is not; i. e., 

 to describe somewhat carefully those abnormal appearances for which it has 

 been mistaken. This is the more necessary because many growers, and even 

 some writers upon the subject, have never seen genuine yellows, and because 

 some of these abnormal appearances are likely to be found in every peach 

 orchard and to cause unnecessary apprehension. 



(1) The borer. — The larva of ^-Egeria exitiosa, Say, devours the inner 

 cortex of the tree at the surface of the earth, or immediately above or below, 

 often causing extensive destruction, and uol in frequently girdling the trunk. 



If these injuries are slight the tree is not harmed, but if they are extensive 

 there is a marked yellowing of the entire foliage, the leaves being also more or 

 less fcilded sidowise, upward, along the midrib, and curled downward end to 

 end. The fruit in some cases also ripens prematurely. Thus injured, the 

 tree presents a very sickly appearance, and generally dies in a year or two, 

 the symptoms being not markedly different from those manifested by any 

 tree wlien some portion of the trunk-cylinder is deprived of the whole or 

 greater part of its bark. 



This disease is easily distinguished from yellows. If the foliage is very 

 yellow, an examination at the base of the trunk will show that a large part of 

 the inner bark has been destroyed, and will often discover the larva still at 

 woik. If such trees are vigorously shaken in July or August the yellow 

 leaves will fall in a shower; but no amount of shaking will dislodge the 

 leaves of a tree infected by the yellows. So tightly did the latter stick to 

 the branches that, even in September, when I undertook to remove them 

 from some of the much-branched secondary shoots, considerable force was 

 necessary. Indeed the process was likened not inaptly by one farmer to pick- 

 ing pin-feathers from a starved chicken. 



The prematurely ripened fruit, so far as I have seen, is natural in color and 

 resembles that produced by the gardener's devise of "ringing" or girdling, 

 being found only on nearly or completely girdled trees. It is never red spotted, 

 never asso'jiated with dark-green foliage, and never connected with those 

 hasty, much-branched and feeble summer growths which are always found on 

 trees badly diseased by yellows. Usually also this fruit ripens only a week 

 or two in advance of the normal time and retains its normal flavor. The 

 only case in which the two diseases can be confounded is where they both 

 exist in the same tree. 



(2) Tlie roofs apJiis. — A very shining dark-brown or black aphis, which 

 corresponds nearly to Aphis chrysantheini, Kosh, but which I have not been 

 able to identify with certainty, infests the roots of the peach often in such 

 vast numbers as to interfere seriously with its growth or to kill it outright. 

 This insect is common to parts of New Jersey, Maryland and Delaware, par- 

 ticularly on sandy land. It frequently so stunts trees that at three or four 

 years of age they are but very little larger than when first set. The insect 

 occasionally infests whole nurseries, and may be distributed in this way. 

 Possibly this may be an explanation to the fact that peach trees are most 

 likely to suffer from root aphides the first year or the second year after they 

 are set. Such trees are said to be "Frenched." The foliage partakes of the 

 universal stunting and is usually samewhat yellowish. Iq districts where 

 yellows has not appeared I found this (ii.-jease called by that name, and have 

 no doubt it has often been misLakeu for it, particularly in Njw Jersey. 



