YELLOWS, IN THE PEACH. In the Mid dle States, especially upon sandy soils, peach trees have been subject for a long time to a dis ease known as Yellows, a remedy for which has not so far been found, except that of grubbing affected trees and burning. The applications that have produced most good have been iron filings, scales from the blacksmith's anvil, and hot wood ashes applied at the rate of a shovel full about each tree. Salt is also reported to have been beneficial. Trees grown from the seeds of affected fruit, will sometimes show the disease at one year old. Often it is not notice able until the tree has borne one or two crops of fruit, when it is indicated by slender, erect branches starting up from the larger limbs, a general sickly appearance of the tree, and a dull color of the foliage. The fruit also becomes discolored. and So changes from the natural taste and appearance of the variety as not to he recog nizable as the sanae. When first attacked, a single branch only is sometimes affected; but by the following season it spreads over the whole tree, which struggles feebly for life for a season or two, producing small, immature, and flavor less fruit. The yellows is a contagions disea,e, and is imparted to other trees by contact or pro pinquity, as well as by a knife used in pruning trees affected, from buds taken from infected trees, and from the soil in which such trees have grown. The cut will show the appearance of an infected branch. The disease has been known in the West for many years, but does not appear to make much headway except on the loess formation or other sandy soils. On the light sands of the Michigan lake shore region, long famous for its excellent peaches, it has of late years made such ravages that the legislature of the State has been obliged to pass the most stringent laws, involving the destruction even of whole orchards where found, and the appoint ment of commissioners to see that the law is car ried into effect. In relation to this disease, the microscopist of the Departnaent of Agriculture reports to the government experiments as follows : A series of experiments by the moist process with the bark of a peach-tree affected with the yellows, showed as follows: lnto five glass receivers I placed respectively, a few drops of water, just sufficient to form a moist atmosphere in each. Into No. 1 I put a piece of bark affected with the yellows; into No. 2 a piece of bark from a healthy peach tree; into No. 3 a handful of peach leaves from the unhealthy tree; into No. 4 a similar quantity from the healthy tree; and into No. 5 portions of bark from the healthy and unhealthy trees mentioned.
All the specimens were secured from the out ward atrnosphere. The temperature of the room in which the specimens were kept was frequently at 90° Fahr. These conditions were highly la,vorable to the development of such fungi-germs as mature under excess of heat and moisture. Previous to arranging the specimens in the receivers they were examined minutely with a low power but no signs of fungi were visible. On the fifteenth day The unhealthy specimens in Nos. 1 and 5 exhibited on their external surface a spotted appearance. When viewed by a power of seventy five diameters they were seen to consist mostly of a translu cent, yellowish-brown, spiral, thread-like fungus, genus Ncemaspora. When a portion about .03 of an inch is placed under an object-glass of one inch, and secured in the usual manner by means of a disc, with dilute gum water, the spiral forms are seen to dissolve gradually, and ulti mately to form a yellow stain. On viewing it with a power of one-eighth, it appears to be a mass of curved spores, resembling in form caraway seeds, but invisible to the naked eye. Each spore ha,s a life-like motion confined to a center of its own. When they are treated to the action of nitric, muriatic, and nitro-muriatic acids, no immediate change is observable; and in those strong acids the life-like motion tinues, which, I think, proves that the motions are not the result of any form of organic life, but simply what is known as Brownian motion, which is frequently seen when minute particles of inorganic matter are placed under a high power. When the spores are combined either
with concentrated sulphuric acid or caustic potash they become completely destroyed, ing a homogeneous mass, and their organic structure is no longer visible. The figures in the cut, page 1047, represent a sectional view of the bark, showing fungus growth; 6, Ncemompora; 7, the same, when placed in water or acid, except sulphuric; 8, a very highly magnified form of the spores contained in 6. About the twentieth day mycelium was fouud in dance growing from the spiral threads, bling double-celled Puccinia, the spores varying in number from one to ten, and so small that a power of one-eighth was required to give good definition. Since contact with water dissolves this form of Ncemaspora without troying the life of the spores, it is evident that the action of rain or washes of pure water will only tend to diffuse the spores over the body of the tree and roots, while the applications of solutions of sulphuric acids and alkalies will destroy them. Hence a remedy may be found for peach-yellows in the application of alkalies and phates, and their compounds, to the bark and roots of the trees. Statements have frequently been made that the application of hot lye has been known to cure yellows when applied to the bark and roots. My observations seem to confirm these common rumors. In receiver No. 5 the healthy bark was not contaminated, seemingly, with the Ncemospora, standing its immediate contact ing several weeks with the healthy bark. As might be pected, the common molds, as Penicillium and Mue,ors, grew all over the surface of the specimens, healthy and unhealthy. The leaves in Nos. 3 and 4 were next ined. They had been subjected to the same treatment as the bark. The healthy leaves, although fined during four weeks in a moist atmosphere, at a temperature ranging from 80° to 90°, exhibited no signs of mildew. A split branch to which the leaves were attached exhibited a small portion of Mucor fruit, and Mycelium on the sap-wood and pith; but the unhealthy leaves were completely covered in two weeks with Mycelium, (mold,) and the fruit of the common blue, yellow, and black lium and Mucors. I have repeated these experi ments several times, always with the same results. It is evident that the healthy leaves possess an antiseptic substance, which prevents the growth of the common molds on them. A portion of healthy and unhealthy leaves from the trees above mentioned was analyzed in the laboratory to determine the respective amounts of moisture, organic matter. and ash in them, and gave the following results: The fact of the absence of ash or solid matter and of the increase of moisture in the unhealthy leaves, would of itself account for their greater tendency to mold. Since leaves do not absorb earthy matter from the atmosphere, it is evident that the cellular strueture of the tree _ _ ha,s in some way failed to perform its functions; for, had the ascending sap carried with it potash, lime, or other earthy matter, the leaves would have been stored with them, since the leaves have no power to evaporate them. The deficiency of earthy matters in the leaves may also account for the ab sence of ash in the fruit. If the theory is well founded that the leaves elaborate juice for the growth of the fruit. the leaves being deprived of proper nour ishment, the fruit can not mature. It has been long observed that trees af ected with the yellows fruit earlier and mature prematurely, and soon decay. The presence of a larger amount of sap in the unhealthy than in the healthy, indicates an earlier and greater flow than in that of the healthy tree. The presence of watery sap in the leaves, twigs, and buds would induce naturally an early growth of fruit and premature decay. From these and other observa tions the disease seems traceable to the body of tbe tree or roots. Applica