FIELD CHOPS. 737 



length of time required for Keruiinatioii is determined in tlie usual way. It 

 is pointed out that by this method the difficulty of separating empty and fully 

 developed seeds is avoided and thereby the i*eliability of the results in germi- 

 nation tests is increased. The percentage of germination is based on weight 

 and is, therefore, more readily comparable with the cpiantities of seed bought 

 and sold. Furthermore, the mathematical impossibility of comparing per- 

 centages of weight and i>(>rc(Mitagcs of number is avoided. 



Notes on eradication of weeds, with experiments made in 1907—8, L H. 

 Pammel and Charlotte M. King {Iowa Sta. Bill. 105, pp. 265-300. figs. 19). — 

 Notes are given on the annual, biennial, and perennial classes of weeds, the 

 character of root systems of weeds, the dispersal of weed seeds, and on spray- 

 ing machinery, and reports on experiments in weed eradication are i)resented. 



In studying the root systems of weeds the root of common milkweed was 

 traced for a distance of 14 ft. through the soil. The depth and sjircad of roots 

 of some common weeds are shown in tables. 



\A\v\y in the summer of 1908 seeds of 31 different weeds and cultivated 

 pl.iiits were placed in horse manure and left for 5 weeks. After this treat- 

 ment 1 per cent each of the seeds of chess, large ragweed, squirrel tail, curled 

 dock, and sunflower, and i per cent each of the seeds of lamb's quarter, corn, 

 and Rugel plantain germinated. In all the other samples no germinating seeds 

 were found. The percentage of germination in samples of these seeds not so 

 treated ranged from S to 9S per ceut, except in the case of field thistle, with 

 which no seeds grew from either the treated or untreated sample. 



The report on the results of experiments in weed eradication is prefaced by 

 notes on the destruction of weeds by the use of copper suli)hate, sodium chlorid, 

 carbolic acid, sulphuric acid, slaked lime, formaldehyde, corrosive sublimate, 

 sodium arsenite. sodium arsenate, and iron sulphate. In 190T-S, 2 weedy oat 

 fields were sprayed with a solution consisting of 100 lbs. of iron sulphate to a 

 barrel of water. The fields were sprayed on June 20 and 21, the weather being 

 cloudy and heavy dews following the spraying. This treatment blackened the 

 leaves of oats to a considerable extent and was effective on mustard, greater 

 ragweed, smaller ragweed. Pennsylvania smartweed, slender knotgrass, lamb's 

 quarter, artichoke, Spanish dagger, and wild buckwheat. The oats recovered 

 from spraying as did also milkweed, morning glory, cockle bur. meadow sun- 

 flower, germander. Indian hemp, pigeon grass, and foxtail. In the second field 

 the sjiraying was effective on ground-cherry, cress, pepper grass, five-fiuger, 

 ellisia, and evening primrose, but not effective on dock, boltonia, and meadow 

 sunflower. A test of spraying weeds along a roadside showed that this treat- 

 ment is not effective in the case of many weeds and is injurious to red clover. 

 The results of other experiments showed that while young mustard was killed 

 by spraying, plants which had already formed pods at that time produced seed. 

 (Ireater ragweed treated with the iron sulpliate solution did not average more 

 than 2 ft. high at harvest time, while the untreated specimens were from 3 to 

 4 ft. high. Changing the strength of the solution indicated that the injury 

 from double strength and half strength solutions was proportionate to the 

 injury from the normal solution. 



Observations made in the greenhouse on the growth of quack grass indicated 

 that the larger proportion of the roots of this plant are between 2 and 4 in. 

 below the surface, and it is concluded that deep plowing will prove an effective 

 method of eradication. An acre of ground in a cornfield was hoed July 7, 11, 

 14. IS, 24, 2H, and 31, August 8, 12, 17, 21, and 26, and September 2, 9, 1(5, 29, 

 and 30, when practically all of the grass was killed. In a similar experiment 

 au acre of corn ground was spaded and the quack grass roots carefully removed. 



