EXPERIMENT STATION BULLETINS. 473 



in such large numbers on the roots that they are easily detected. These 

 insects suck the sap from the roots, giving them a tlabby appearance, and 

 the effect upon the foliage is so marked that one familiar with their work 

 can readily detect their presence by this alone. The leaves are generally 

 more or less drooping, and are of a dark yellowish-green color; they are 

 generally smaller than the leaves on healthy trees and are folded and 

 wrinkled. Another characteristic is that numerous red spots, due to the 

 work of fungi, appear on the leaves. Later in the season, the injured 

 portions fall from the leaves, which appear as if perforated with a charge 

 of shot. Trees having the appearaDce given above, will almost certainly 

 be found affected with the aphis, but in a few cases the same appearance 

 has been noticed wmere the trees were planted deeply, especially if they 

 were in hard-pan or a cold, wet soil. Most, if not all, of the Michigan 

 nurseries are free from this insect, but it may appear unexpectedly in any 

 of them, or upon trees brought in from without the state, and, as it is 

 so destructive, it will pay to take precautions to destroy the insects if 

 they should be on the trees. This can be done by dipping the trees in 

 strong tobacco water, made by soaking one half bushel of stems in a bar- 

 rel of water. If, later on, it should appear upon the trees growing in the 

 orchard, the cheapest and most effectual remedy will be the application of 

 from one half to one bushel of unleached wood ashes about the trees. 

 It will be more effectual if the soil is scraped back over a circle as large as 

 the branches of the tree, and replaced after the ashes have been scattered. 

 Tobacco stems or tobacco dust may be used in the same way and, like 

 the ashes, will both act as an insecticide and furnish a large amount of 

 plant food to the tree. The Black Peach Aphis is most troublesome on 

 light sandy soils but may be found on the stiffest clays. For the most 

 part, the insects are wingless and cannot move from tree to tree, though 

 they are probably distributed by ants and other insects. They are found 

 upon the roots during all of the year and in early summer they are found 

 upon the young shoots and leaves; having been, perhaps, brought up from 

 the soil by ants. The effect of the insect is particularly severe upon young 

 trees, which are often, in nurseries and newly-planted orchards, killed by 

 them. On old trees the effect is less severe and, if the trees are well 

 cultivated and fertilized, they may be able to escape with a slight check to 

 their growth. This insect is probably more generally distributed than is 

 supposed, and may account for many of the failures in young trees which 

 have been placed where old orchards have been taken out. In case it 

 becomes desirable to replant with peaches, the land should be used for at 

 least two years for some other crop, and an attempt should be made to 

 increase the humus of the soil by turning under clover or other crops. 



THE WOOLLY APHIS. 



In several parts of the state apple trees are badly infested with the 

 woolly aphis, which attacks the roots as well as the branches, causing 

 knots and swellings to appear. If they are very numerous the fruit, 

 when produced at all. will be small and imperfect and the trees will make 

 but little growth. The root form can be treated with wood ashes or 

 tobacco dust, and those on the branches can be destroyed with the kero- 

 sene spravs or strong tobacco water. 

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