DEPARTMENT OF AGRICULTURE BULS. 826-850. 



Department Bulletin No. 829. — -The Mosaic Disease of Sugar Cane and 



Other Grasses — Continued. p age . 



Secondary symptoms 10 



Injuries resembling mosaic 12 



Varietal susceptibility 12 



Other hosts .'...- 15 



Nature of the disease 16 



Infection phenomena 16 



Transmission of mosaic in diseased seed pieces. 18 



Transmission of the disease by carriers 18 



Soil relations 19 



Relation to disinfectants -. 20 



Relation to fertilizers 20 



Control 20 



Elimination by roguing 21 



Elimination by grinding all cane and securing clean seed 22 



Exclusion 22 



Eradication 23 



Elimination by planting immune varieties 24 



Department Bulletin No. 830. — Effect of Temperature on the Resist- 

 ance to Wounding of Certain Small Fruits and Cherries: 



Experimental work 1 



Description of the method employed 2 



Conditions of the tests 3 



Discussion of results 5 



Department Bulletin No. 831. — Spillways for Reservoirs and Canals: 



Spillways 1 



Overflow spillways 4 



Spillway control 9 



Flashboards 11 



Sliding gates 11 



Tilting or centerweighted gates 12 



Rolling dams or barriers 13 



Siphon spillways 15 



United States Reclamation Service siphons 28 



European practice 31 



Huntington Lake siphon spillway 32 



Conclusions 38 



Acknowledgments 40 



Department Bulletin No. 832. — -The Flow of Water in Dredged Drain- 

 age Ditches: 



Introduction 1 



Field measurements 2 



Computations 4 



Tabulated results 6 



Description of channels 7 



Accuracy of results 9 



Description of experiments 9 



Conclusions 59 



Department Bulletin No. 833. — Chrysanthemum Midge: 



General description 1 



Historical 2 



Distribution in the United States and Canada 3 



Varieties affected 4 



Economic importance 4 



Technical description 6 



Life history and habits 7 



Natural enemies 13 



Experiments in control 14 



Summary of control and recommendations 21 



Preventive measures 22 



Literature cited 23 



