CONCLUSION. 35 



leaves following the seed harvest have frequently been known to 

 develop the symptoms. 



Few affected seed beets are capable of producing seed, and then 

 only in very small quantity. The seed yielded by affected seed beets 

 will, however, produce healthy sugar beets, which, in turn, unless 

 in the mean time attacked by more leafhoppers, are capable of be- 

 coming good seed beets. 



It has not been found possible to communicate the disease from an 

 affected plant to a healthy one. 



CONCLUSION. 



In cooperation with the Bureau of Entomology, the writer has 

 already carried on some spray experiments in the hope of devising a 

 method of holding the destructive beet leafhoppers in check. It was 

 found that, if it can be thoroughly applied to the insects, a strong 

 kerosene and whaleoil-soap emulsion will kill them. However, the 

 time is so short when the spray might efficaciously be applied that it 

 is not yet certain that spraying will be practicable. Then, too, it 

 is not easy to apply a spray to the beet leafhopper, because its wings 

 thoroughly protect its body and thus prevent the emulsion becoming 

 effective. 



Possibly some form of " hopper-dozer " used at the right time will 

 prove more serviceable. More experimental work is needed along 

 these lines. 



At the suggestion of the Bureau of Entomology, the following 

 recommendations, found in Bulletin 66, Part IV, of that Bureau, 

 pages 47—48, are quoted: 



More should be known about the places of hibernation and early spring his- 

 tory of this insect. It could not be found in the rubbish around the fields in 

 early spring, and only a few specimens were found in waste places up to the 

 time they appeared on the beets. When once the place where the greater number 

 of them pass the winter is discovered, it may be possible to destroy them 

 there or on their spring food plants before they migrate to the beets. After 

 they have appeared on the beets it will be necessary to be very pi*ompt in the 

 matter of remedies if the injury is to be prevented. A thorough spraying with 

 kerosene emulsion at a strength of 1 part of the stock solution a to 5 parts of 

 water would destroy most of the insects that it hit, and by using a drag in 

 front of the nozzles to turn the leaves over and cause the insects to jump, most 

 of them could be reached. Where the insects were coming in in numbers this 

 spray would need to be followed by a second one ten days later. 



Several mechanical devices have been used to catch different leafhoppers, 

 and no doubt several of these could be used against this insect with advantage. 

 The tar pan, or " hopper-dozer," drawn over the beets two or three times in 



"For directions regarding the preparation and use of kerosene emulsion see 

 Farmers' Bulletin 127, U. S. Dept. of Agriculture, pp. 20-21, and Circular 80, 

 Bureau of Entomology. 

 181 



