202 EXPERIMENTAL FARMS 



5-6 EDWARD VII., A. 1906 



The injury done to clover and alfalfa by the dodder is by actually sucking their 

 elaborated sap from them. When the young seed first germinates, a slender yellow 

 thread is pushed up from the soil, which swings round slowly as it grows, and, as soon 

 as this thread touches a living plant, it twines itself around it and throws out from the 

 surface which touches its host, many rootlets or suckers which grow into the tissues 

 of the host plant and draw from it its sap. The host soon becomes dwarfed and in 

 time dies. The dodder plant, however, in the meantime has thrown out a very much 

 branched tangle of fine stems which have spread to other plants in the neighbourhood, 

 from which it is also drawing its nutriment. As soon as the young dodder plant has 

 attached itself to a suitable host, its connection with the soil dries up and ceases. The 

 flowers of the dodder are not produced until the plant has attained a considerable size, 

 when it may form a thick mat from two to four feet across. The flowers are borne in 

 thick conglomerate clusters along the stems and are sometimes so abundant that they 

 almost hide the yellow or reddish stems. Although the plant belongs to the Con- 

 volvulus family, the tiny five-lobed corolla does not very much resemble the well 

 known shape of the flowers of the Morning Glory. The seed pod, however, and the 

 shape of the contained seeds show the relationship. The separate seeds found in clover 

 seed are variable in size, some being about the same size as Red Clover seed, others 

 much smaller. They are obtusely triangular, of a pale greenish or yellowish brown 

 colour, with the surface finely granulated. 



It is probable that the large seeds, nearly as large as those of clover are of a differ- 

 ent species from those usually found, which I take to be Cuscuta epithymum. Mr. G. 

 H. Clark, Seed Commissioner of the Department of Agriculture, tells me that ' owing 

 to the shortage in the clover seed crop of last year some of our seed merchants im- 

 ported a lot of clover seed which had originally come from Chili, but was procured 

 through European merchants. This seed was badly infested with Clover Dodder and 

 Wild Carrot. The supply of lucern seed sold in Canada usually comes from Utah, and 

 generally contains some dodder seed. If properly cleaned, however, lucern can be made 

 practically free from dodder seed.' 



Mr. Clark also writes me as follows : ' Since discussing the matter of the identity 

 of the different-sized dodder seeds found in clover and alfalfa seed, I have gone more 

 carefully into it and now believe that this recently introduced large dodder seed is 

 Cuscuta racemosa. Mart., var. chiliana, Eng., of which you will note considerable re^ 

 ference made in the reports of French, German and Swiss botanists as a species of 

 dodder found in clover seed imported from South America. We have been able to 

 secure a specimen of seed that was grown by Dr. Stebler, of Zurich, which he classifies 

 as racemosa, and which we believe to be almost identical with the "dodder imported into 

 Ontario during the past season. We have yet to learn whether this dodder will stand 

 our Canadian winters, but it seems that G. epilhymum may become a nuisance in the 

 south-western part of the province of Ontario.' 



The following is cited from Mr. Miller's article in the Farmer's Advocate and 

 refers probably to the worst occurrence "of the Alfalfa Dodder which has ever been 

 noted in Canada: 



' As a good example of the injury this weed may accomplish when it once becomes 

 established, let me mention a case in St. Mary's, Ont., where a fifteen acre field of 

 alfaKa w.as in two years practically destroyed by this weed. The writer had the op- 

 portunity of visiting this field several times during the past summer, and thrv>ugh 

 the courtesy of the owner secured the following information : The field was seeded 

 down in 1902 with alfalfa, oats being used as a nurse crop. Conditions being favour- 

 able, it gave a beautiful stand in 1903, being cut twice and giving a total yield of 

 about six tons per acre. The first indication of dodder was noticed June 1, 1903, when 

 the owner found a^bout a dozen small round yellowish patches, which he attributed 

 to the bursting of drainage tiles. In about two weeks, however, these had spread 3o 

 as to attract special attention, and, upon examination, he found masses of tendrils. 

 In 1904 it had spread so as to produce a blight throughout the field. The alfalfa iras 



