436 EXPERIMENT STATION RECORD. 



wild mustard, by spraying with iron sulpliate solution is given and the results 

 obtained at the station and elsewhere are briefly reported. The solution used 

 was of about 20 per cent strength. 



It is found that the best results from spraying are obtained when the grain 

 and the weeds are from about 6 to 10 in. high, or just before the mustard 

 plants begin to bloom. In several of the tests the work of spraying was con- 

 ducted at the rate of 25 acres in 5 hours. It is stated that a powerful pressure 

 is absolutely necessary in order to develop the proper fineness of spray, and 

 that favorable weather is also highly important. Spraying just after the dew 

 is off on a bright sunshiny day is considered most favorable to successful w^ork. 

 A description of successive steps in the appearance of sprayed leaves is given 

 and the physiological action of the sulphate is interpreted. " The main action 

 involved seems to be that the water in the leaf is drawn out of the cells by the 

 flakes of salt dried on the surface." 



The grain suffered a little setback but permanent injury did not result on 

 account of their indeterminate growth which left only the tips of the older 

 leaves exposed to the action of the sulphate. The following weeds were entirely 

 killed under favorable conditions of spraying: Wild mustard (Brassica arven- 

 sis), ragweed (Ambrosia artemisi(vfo1ia). king-head or greater ragweed (A. 

 trifida), bind weed {Convolvulus sepium), marsh elder {Iva xanthifoUa), milk- 

 weed {Asclepias sp.), peppergrass (Lepidium virginicum) , pigweed (Amarantus 

 sp.), and sweet clover (Melilotus alba and M. officinalis). Those more or less 

 badly injured included Russian thistle (Salsola kali tragus), sunflower {Helian- 

 thus sp.), dandelion dock (Rumex crispus), thistle {Carduus sp.), white clover 

 {Trifolium repens), red clover [T. pratensc), and alfalfa (Mcdicago saliva). 

 The results of spraying for the eradication of dandelions were not so favorable 

 as those reported by other experimenters. Young plants with a small root were 

 generally entirely killed with only 1 application, but large strong plants re- 

 quired 3 and even more applications at intervals of 3 or 4 weeks. Cutting off 

 the crown of dandelion plants and applying a 20 per cent sulphuric acid solu- 

 tion to the cut surface generally killed the dandelions. Kerosene applied in a 

 similar manner also caused the roots to decay, but gasoline was without effect. 



According to an estimate given the total cost of spraying 300 acres is ap- 

 proximately $1.25 per acre. 



Weed work, H. L. Bolley {'North Dakota Sta. Rpt. 1908, pt. 1, pp. 42-U).—A 

 general review of the weed work carried on by the station is presented. 



The work of spraying the lawTis of the college campus with iron sulphate 

 to reduce the growth of dandelions is described. On the sprayed areas no 

 dandelions produced seed and many of the large roots totally disappeared, while 

 young plants coming from seed were completely destroyed. The sprayed lawns 

 made a strong growth of grass through the season. This better growth was 

 apparently associated with a deeper green in the color of the grass, which 

 result was found to be largely due to the elimination of certain destructive 

 parasitic diseases of blue grass, such as common mildew, smut, common rust, 

 and other less common parasitic enemies. 



In summarizing the results the belief is expressed that iron sulphate or 

 copper sprays increase chlorophyll production under certain conditions, and 

 that the spraying of a wheat crop ipiproves the growth by leaving the crop 

 more open to light and air at the proper time. The sprays showed themselves 

 to be destructive to germinating spores and parasitic fungi. Certain elements 

 of proper weed destroyers have a fertilizing value. Some of the substances 

 may act as growth stimulants, and some of the sprays seem to extend the 

 period of vegetation as observed with the spraying of wheat, oats, and lawn 

 grasses. 



