EXPERIMENT STATION BULLETINS. 257 



has exterminated the peach orchards of Maryland and northern Delaware, 

 and is gradually spreading southward. It appeared in Berrien Co., Mich- 

 igan, in 1866, the germs being presumably brought in nursery stock from 

 New Jersey. For a few years it spread very slowly, but after 1875 it became 

 very destructive and showed itself in nearly every orchard in the county. 

 In 1874 there were fully 650,000 peach trees in Berrien county, and in 1877 

 the shipments were more than a half million baskets, but such was the vir- 

 ulence of the disease that after 1875 few orchards were planted, as young 

 trees were carried off within two or three years. The attack was so severe 

 and so widespread that the number of trees in the county fell to 50,000 in 

 1884, and in the townships of Benton and St. Joseph, where it first appeared, 

 hardly a tree remained. It worked northward and appeared at South 

 Haven in 1869 and at Paw Paw about 1877. The disease was not particu- 

 larly destructive at South Haven until 1875, but from that year until 

 1880 it increased in virulence. The fruitgrowers of South Haven, profiting 

 by the experience of their neighbors at the south, waged a war of extermina- 

 tion and, where it was followed up, the loss was quite small. In some cases 

 the proper precautions were not taken and entire orchards were destroyed. 

 The history of the disease is about the same in Allegan, Kent, and Ottawa 

 counties, where it appeared later. While it has undoubtedly appeared in 

 other counties it has done little harm. It behooves the peach-growers in 

 all parts of the state to be on the watch and on its first appearance to 

 stamp it out. With our present lack of knowledge of the real cause of yel- 

 lows, we can do no more than to subject the trees to such conditions as will 

 be most likely to keep them healthy. We should, then, use trees free from 

 taint of disease; plant upon high, well-drained soil; avoid the use of excessive 

 quantities of nitrogenous manures, supplying necessary plant food for the 

 most part in the form of chemical fertilizers; give frequent, regular cultiva- 

 tion; cut back and thin out the trees to secure a strong growth; remove all 

 surplus fruit while still small and thus prevent it from drawing needlessly 

 upon the trees; fight early and late against the borers and other insects, the 

 curl-leaf, rot, and other fungous diseases. This treatment should give us 

 strong, vigorous trees that will be more likely to escape the attack of yellows 

 than those grown under opposite conditions would be. While it is believed 

 that favorable conditions for the growth of the trees will render them less 

 susceptible to this and all other diseases, it is not claimed that the trees 

 will have entire immunity, and it is not likely that a case of yellows can be 

 cured if it once appears in a tree; but if yellows makes its appearance in an 

 orchard where some of the conditions are unfavorable, it is probable that, 

 if the diseased trees are at once removed and the remaining trees are given 

 proper care, they will be less liable to attack than if nothing had 

 been done except to remove the diseased trees. From the fact that we have 

 no definite information, as has been previously stated, regarding the exact 

 nature of the disease, the above can not positively be stated to be correct, 

 but from our general knowledge of plant physiology, and the fact that 

 plants as well as animals that are in a healthy condition and with con- 

 genial surroundings are less subject to disease, than those that are 

 weak and exposed to unfavorable conditions, it will be well for the prac- 

 tical fruitgrower at least to hold to this belief until it has positively been 

 demonstrated to be false. The course recommended is the one that will be 

 most likely to give profitable returns, and if in any way it aids in warding 

 off the disease it will be so much gained, while if it fails to do this there 

 will be no loss. 

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