100 MAINE AGRICULTURAL EXPERIMENT STATION. I909. 



ties which thus far have prevented its successful culture can be 

 surmounted, it will more than recompense the cost of the many 

 hundreds of trials that have been given this plant in Maine dur- 

 ing the past 25 years. 



WiED Mustard. 



During several years, beginning with 1904, the writers endeav- 

 ored to kill wild mustard in sown grain crops by spraying with 

 copper sulphate and with iron sulphate. The first season's 

 experiment w^as markedly successful. The second year an 

 attempt was made to repeat the experiment on a large scale in 

 Aroostook County and while the plants were stunted it did not 

 result in destroying the weed. While it has been generally recog- 

 nized throughout the State that wild mustard or charlock is one 

 of Maine's worst weeds in sown crops it is not generally known 

 and was not known to the writers in 1905 that there are two 

 plants which differ so little in appearance that they are both 

 known as wild mustard. One of these is the wnld mustard 

 proper, Siiiapsis arvensis, which is also frequently and properly 

 called "charlock." The weed which very closely resembles it 

 and is sometimes called jointed or white charlock is the wild 

 radish, Raphamis raphanistnini. Young wild mustard plants are 

 readily killed b}^ spraying with a solution of either copper sul- 

 phate or iron sulphate. The wild radish is very resistant and in 

 experiments made at this Station has even defied treatment with 

 20 per cent solution of iron sulphate reinforced with 5 per cent 

 of sulphuric acid. In the first year's experiments conducted on 

 the College Farm at Orono the weed that was killed was wild 

 mustard. In the second year's experiments in Aroostook County 

 the failure to kill was due to the weed being wild radish. 



It is perfectly possible to kill wild mustard by spraying. The 

 only discouraging thing about spraying for wild mustard in 

 Maine is that so much that is commonly called wild mustard is 

 wild radish, and while it has been claimed by investigators 

 in Germany and France that they have killed wild radish by 

 spraying with a 20 per cent solution of iron sulphate, it is more 

 than probable that they were wrong in identifying the plant. 



