1906.] 



Dodder. 



335 



C. Gronovii. — Besides attacking lucerne, and without doubt 

 other leguminous plants, it is stated to infest chicory, potatoes, 

 and beet. 



C. monogyna infests vines and some other plants ; and 

 C. corymbosa not only develops on lucerne but on various other 

 leguminous plants. 



Prevention and Remedy. 



1. As it is so harmful when once established it is very 

 important that dodder should not be allowed to obtain a footing 

 on clean farms. This is undoubtedly only rendered certain by 

 taking great pains that no seed is sown in which there is any 

 trace of dodder. Bearing this in mind the purchaser should only 

 deal with reliable firms, and should always insist, among other 

 things, on a guarantee that all his seed is absolutely free from 

 dodder, 



2. If the purchaser is not satisfied as to the purity of any 

 seeds he may have purchased an excellent plan is to sift clover 

 and lucerne seeds, using a sieve of twenty meshes to the inch. 

 Although the seeds of Large American Dodder are not 

 removable in this manner, those of other dodders are separated 

 with comparative ease. According to Nobbe's experiments, 

 however, this method is not always entirely satisfactory owing 

 to variations in the size of the clover and dodder seeds. In the 

 case of white clover, for instance, the seeds may approximate in 

 size to those of dodder. To make a cheap, serviceable sieve for 

 the purpose the American Agriculturist lately* recommended 

 the construction of a light wooden frame about 12 inches square 

 and 3 inches deep, over the bottom of which a 20-mesh wire 

 screen (made of No. 32 English gauge, round wire) should be 

 tacked. In this one-fourth to one-half a pound of seed may be 

 placed at a time and vigorously shaken for half a minute, A 

 man should be able to deal with from 5 to 10 bus. per day. It 

 may be remarked that where much seed is to be dealt with a 

 larger sieve would be more useful. 



3. In the case of all seeds the purchaser will be well-advised 

 to consider the question of submitting samples to some authority 

 for expert examination and approval. 



* Ap. 28th, 1906. 



