63 



The remedies were applied with the " Eureka Sprayer" and the ap- 

 plications were made on May 29, June 4, June 22, July 2, and July 11. 

 On the treated vines the loss did not exceed 5 percent., while vines in 

 adjoining rows not treated lost from 90 to 95 per cent, of their crop. 



BLACK-KNOT OF THE GRAPE. 



I send with this several specimens of grape vine affected with a peculiar disease. 

 Any information in regard to the matter will be thankfully received. — (C. Gere, 

 East Springfield, Erie County, Pa.) 



Auswer. This is a disease which the French have named Broussins, 

 the Germans Krebs or Schorf, and the Italians Malattia dei tubercolL 

 The first name, "Broussins," meaning excrescences, is descriptive of the 

 disease, and is the one we will adopt. Professor Viala, in his work on 

 the Maladies de la Vigue, pp. 441, 442, has clearly described the dis- 

 ease in question, and illustrated it with two excellent figures. His 

 description is very complete, and the cause to which he attributes the 

 malady appears most reasonable, and we can not do better than to 

 translate in full what he has written : 



Under the action of the frosts of autumn and winter, and especially those of spring,, 

 peculiar malformations are developed upon the roots, the root crown, the side 

 branches, and the shoots left after pruning. Upon the roots they appear as little nod- 

 ules the size of a pea, more rarely as large as an egg, which are soft and spongy 

 when moist, but become firm and hard when dry. They have a warty surface, being 

 formed of smaller uodules, which run together where they unite with the root. Upon 

 the crown of the root there is sometimes produced a proliferation of tissues, compar- 

 able to the Broussins of the root, but which may arise from other causes than early 

 frosts. These spongy masses, harder and less warty than those on the roots, some 

 times grow to a great size; specimens have been seen which had a radius of 3^ inches. 



Upon grafts the adjacent layers of generative tissues some times multiply to an un- 

 usual extent, giving rise to a spongy swelling, having the form of Broussins. But it 

 is especially upon the young branches and side shoots that these formations are most 

 frequent. Broussins usually appear at the insertion of the shoots upon the side 

 branches, but it also occurs over the whole length of the interuode, or even several 

 successive nodes, entirely changing their normal appearance. There are formed sev- 

 eral masses of irregular excrescences, composed of a large number of shapeless nodules. 

 The wood thus covered is often enlarged to four or five times its proper diameter. 

 The bark is torn and often stretched in narrow strips over the irregular groups of 

 nodules. The latter are soft and spongy, but become very hard when dry. 



The anatomical structure of these nodules has only been imperfectly studied. It 

 appears, however, that frosts have destroyed the generative cell-layers at certain 

 points and that about these points the unaltered bark and cambium cells multiply in 

 an abnormal manner, producing the tuberculous malformations which constitute 

 Broussins. 



By some it is believed that the latent buds, which are very numerous at the inser- 

 tion of the shoots upon the old wood or of the roots upon the crown, can, when influ- 

 enced by the same phenomenon, make similar excrescences by all growing out at the 

 same time. Others contend that the excrescences on the vine are not composed solely 

 of cellular tissues. Von Thumen has tried to show in this disease the action of a 

 parasitic fungus which he has assigned to the genus Fusisporium, the development 

 of which he has not been able to follow. He is the only author who has given ex- 

 pression to this opinion, which now seems to be erroneous. 



The branches and main stem should be cut off down to the healthy part ; this is 

 the only means of arresting the unhealthy change of tissues. 



