478 STATE BOARD OF AGRICULTURE. 



apple, pear and plum, as well as on the raspberry and blackberry. An- 

 other form of gall, which appears as small nodules upon the roots, is due 

 to the work of the "eel" worms (nematodes), but these are quite distinct 

 both in their appearance and nature. 



BLACK KNOT. 



The swellings upon the branches of the plum and cherry trees, to which 

 the name of "Black Knot" has been given, have been found very de- 

 structive. While in some seasons the growth is but slow, in others they 

 develop rapidly and destroy entire orchards. The development of the 

 knots begins during May and June, when, upon the branches that are one 

 or two years old, a slight swelling will be noticed and the outer bark will 

 crack, showing the green layer beneath, which will soon take on a russet 

 appearance. Upon the surface an olive-green mould will soon appear, 

 which is due to the development of summer spores of the fungus. These 

 are borne about by the wind and serve to scatter the disease. The de- 

 velopment of the spores continues and, by autumn, the surface will be of a 

 black color, covered with innumerable minute pimples, in which the win- 

 ter spores of the fungus will be developed. These will ripen in Febru- 

 ary and thus the disease will secure another start. The old " knots " are 

 dry and hard and each year extend both ways along the branches, until 

 they reach a considerable size. By carefully examining the trees during 

 the early summer, the "knots" can be detected in the early stages of 

 their development and, if at once cut off and burned, further spread of the 

 disease will be stopped. In removing infected branches, the cuts should 

 be made, if possible, a foot or more below the knots, in order that the 

 diseased portions may be destroyed. When the knots are upon the trunks 

 or main branches of small trees, where it would be impossible to cut them 

 off without destroying the trees, the diseased tissues may be cut away 

 and, if the wounds are painted with linseed oil, or tincture of iodine, the 

 danger of stopping further growth of the tree or branch will be prevented. 

 While the removal of diseased branches is the only remedy that can be 

 depended on to prevent the spreading of the disease, yet, if the trees are 

 thoroughly sprayed with Bordeaux mixture, it will be impossible for the 

 spores to obtain lodgment upon the healthy branches. In several portions 

 of the state, it is reported that the knots are becoming very troublesome 

 and that they have destroyed many plum trees. In case the owners do not 

 take prompt action to check the disease, the fruit growers of the locality 

 have in their hands the power to see that the knots are destroyed, as it 

 only requires a petition of ten free-holders to secure the appointment of 

 commissioners whose duty it will be to secure the destruction of all knots 

 and of the trees if badly affected. 



PEAR BLIGHT. 



The fire blight or "frozen sap blight" of the pear comes under the 

 operation of the yellows and spraying laws. This disease is of a bacterial 

 nature and is very troublesome in some seasons, particularly upon rapid- 

 growing trees, or on land that has been heavily manured, or that is natu- 



