CONTENTS / 



Page 

 Department Bulletin No. 1237. — Organization and Development of 

 a Cooperative Citrus-Fruit Marketing Agency — Continued. 



Appendix 49 



Organization and marketing plan adopted by the southern Cali- 

 fornia fruit exchanges -- 49 



Articles of incorporation of California Fruit Growers Exchange. 50 



By-laws of California Fruit Growers Exchange 51 



Form of crop contract 56 



Form of contract between a district exchange and local associa- 

 tion 58 



Form of contract between a district exchange and the exchange. 59 



Grade specifications 64 



Tables 1, 2, and 3 65-66 



Literature cited 67 



Department Bulletin No. 1238. — The Cankerworms: 



Introduction 1 



Economic history 2 



Scientific history 3 



Synonymy 4 



Common names 4 



Differences between the species 5 



. Food plants 5 



Distribution 6 



Fall cankerworm 6 



Spring cankerworm 6 



Means of dissemination 6 



Economic importance 8 



Fall cankerworm 9 



Descriptions 9 



Seasonal history and habits 11 



Spring cankerworm 20 



Descriptions 20 



Seasonal history and habits 22 



Natural control 28 



Weather conditions 28 



Diseases 29 



Starvation 29 



Birds 29 



Insect enemies 30 



Other enemies 31 



Control measures 32 



Cultivation 32 



Spraying : 32 



Mechanical barriers 33 



Summary 35 



Literature cited 36 



Department Bulletin No. 1239. — Studies in the Physiology and 

 Control of Bunt, or Stinking Smut, of Wheat: 



Physiologic factors affecting the development of bunt 1 



The problem of soil infestation 2 



Duration of viability of bunt spores in the soil 6 



Physiologic response of spores of Tilletia to temperature 8 



Relation of soil moisture to infection 11 



Morphologic response to pathologic conditions 12 



Relation of temperature to the germination of bunt spores and 



wheat kernels 15 



Control of bunt 18 



Nursery studies in seed treatment 18 



Relation of depth of seeding to bunt production 21 



Relation of rate of seeding to bunt production 23 



Breeding and selection studies of varietal resistance to bunt 25 



Summary 27 



Literature cited 28 



