58 THE MONTHLY BULLETIN. 



that it will cover an acre with 52 gallons. No harm will be done if the 

 solution is put on heavier but the cost of material will be more. 



Spray with a power sprayer, special types of which have been devel- 

 oped for this work. The time to spray is when mustard is about 8 to 10 

 inches high, that is, when nearly all the seeds have sprouted. Spray on 

 a sunshiny day to get best results. 



The ordinary orchard spraying machine can be converted into a field 

 sprayer by connecting a cross pipe, fitted with several spray nozzles, to 

 the outlets. The object of this is to cover a larger area. The spray 

 should issue as a mist, and not in drops as from a sprinkler. The force 

 is used to penetrate the hairy or waxy coating of the weed leaves and 

 reach the vital parts of the plant. 



Johnson Grass (Sorghum halapense). — Where Johnson grass does not 

 occur, the thing to do is to keep it out. Sow Clean Seed ! The method 

 of procuring clean seed has already been given. There is great danger 

 that sowing Sudan grass will spread Johnson grass, and the State Com- 

 mission of Horticulture has investigated the possibility of procuring 

 pure Sudan grass seed. The most satisfactory information we received 

 came from the United States Department of Agriculture, and is given 

 below : 



"There are no varieties of Sudan grass seed recognized at the 

 present time, though there is some difference in regard to seed. 

 This is mainly due to hybridizing influences. The Texas station 

 has attempted to differentiate between pure and mixed or hybrid- 

 ized seed by indicating the former as 'cream hull,' or that which 

 has a decidedly golden cream color. Seed with darker glumes or 

 that tending to a reddish color, or even black, is more likely to be a 

 mixture or hybrid seed. This can not, however, always be de- 

 pended upon. The only safe method of procedure is to purchase 

 seed that is grown in districts free from Johnson grass. 



The letter supplied the names of growers of Sudan grass seed which 

 could be guaranteed practically free from Johnson grass. AVe would 

 advise those intending to plant Sudan grass to communicate with Mr. 

 Roland ]McKee of the Bureau of Plant Industry, U. S. Department of 

 Agriculture, or with this Commission. 



The Johnson grass problem in California is already a very serious 

 one. Thousands of dollars have been spent in its attempted control and 

 still it remains one *of our worst weed pests. Hundreds of acres have 

 •been completely abandoned to it. If the most rigid care is not taken by 

 prospective grain planters and seed men, still greater areas will be 

 ruined. AA^itness the misfortune of the rice growers and take warning. 



The only practical method of eradicating Johnson grass, so far recom- 

 mended, is thorough plowing, raking and burning. Turn hogs into the 

 field and they will root out large quantities of the rootstocks. Rotate 

 crops, using hoc crops wherever possible. 



Keep ditch banks, roadsides and other waste places free of the weed. 

 Do not allow it to go to seed. Screens in the headgates and ditchgates 

 will keep out large quantities of the seed. Johnson grass and other 

 w^eeds growing along the ditch banks are a serious means of spreading 

 weed seed. 



