CONTENTS. 



Page. 



Introduction 



Symptoms of curly-top 



External symptoms 



Internal symptoms H 



Symptoms in seed beets 12 



Only one symptom really characteristic 13 



Cause of the disease 13 



Theories 13 



Preliminary experiments 



Isolation cages 



Nymph of beet leafhopper more harmful than the adult 18 



History of an outbreak of curly-top in the experimental field at Garland, Utah . 18 



Early sowing advantageous in preventing curly-top 19 



Extraction of plant juices not sufficient to account for the disease 20 



Conditions favoring an outbreak of curly-top 21 



Natural and artificial barriers to leafhopper invasion 22 



Host plants of Eutettix tenella 22 



Description of the beet leafhopper 22 



Beet growers should be able to recognize the leafhopper 24 



Serious nature of curly-top - 4 



A consideration of curly-top in seed beets 24 



Several types of leaf-curl on seed and sugar beets - • - 28 



Affected seed beets almost nonproductive 29 



Percentage of loss of seed beets 29 



Severe outbreaks not frequent in a locality 31 



Progeny of the diseased seed beets healthy 31 



General character of early-top 31 



Summary °° 



Conclusion 



Recommendations 3o 



Bibliography °' 



Description of plates "*" 



Index 43 



181 5 



