EXPERIMENT STATION BULLETINS. 483 



right stalks again which produce another crop of seeds. Just how long 

 the same plant will remain alive has not been determined. 



Yellow Rocket resembles wild mustard quite markedly, which is not 

 to be wondered at, as it belongs to the same family. Its flowers are not 

 distinguishable from those of the mustard except that they are smaller. 

 Mustard does not have so many upright stems, usually having one main 

 stem, branching freely ; it is also much later as it is an annual and does 

 not have the benefit of a start the previous season. The root of 

 mustard retains its tap-root nature to a large extent while that of 

 Yellow Rocket in its second season is greatly divided and branched. 

 Tt is also usually more or less hairy while Yellow Rocket is free from 

 hairs. The leaves of mustard do not have so large or rounded a termi- 

 nal lobe and so small lateral lobes as do those of Yellow Rocket. 



As it lacks long underground running roots or stems like Canada 

 thistle, milkweed, etc., yellow rocket need never be feared on land that is 

 under cultivation constantly or at rather frequent intervals. Its chief 

 harm is in meadows, pastures, etc. ; i. e. where the land is left two or 

 three years without cultivation. Thus in fields of alfalfa it is a serious 

 pest, as it multiplies from year to year with the greatest rapidity. So 

 also a grain field in which a few plants occur will be thoroughly seeded 

 to yellow rocket before the grain is harvested. The clover the remainder 

 of that year will show only the low tufts of leaves of the weed but the 

 next spring the field may appear yellow, so numerous are the plants. 

 This of course, greatly reduces the value of the field, both because of 

 the direct injury to the clover crop due to the loss of plant food and 

 water and because of the inferior hay that results from the presence 

 of the yellow rocket. 



The smooth shining epidermis makes spraying with any of the milder 

 herbicides useless, — and the location of the weed in meadows, clover 

 fields, etc., makes it impossible to spray with poisonous sprays which 

 would be injurious to animals feeding upon hay from that field. 



Spudding out the plants before they go to seed is the most practical 

 method of fighting this weed, provided it is not too abundant. In the 

 latter case the field should be plowed. In any case this ought to be 

 done before the end of May as seed production begins about the first 

 o^f June (or earlier or later, depending upon the season). Careless plow- 

 ing without subsequent harrowing or cultivation will not always destroy 

 all of the first year plants and these will manage to regain their foot- 

 hold and grow until fall, producing the seeding plants next year. 



Mowing, although destroying the tops of the plants, and accordingly 

 thousands of flowers, is not to be recommended as very short branches 

 are then formed near the root and these produce flowers and seeds be- 

 low the reach of the mowing machine and fill the ground with seed to 

 make more trouble next year. 



SUMMARY. 



YelloAv rocket, a native of Europe, is one of the mustard family and 

 a very serious weed. 



It is a biennial or perennial and does not blossom and seed until the 

 second season, being inconspicuous the first year. 



