NOTES ON VARIOUS PLANT DISEASES/ 



F. C. Stewart. 



SUMMARY. 



I. During the season of 1898 a bacterial rot caused heavy 

 losses to the onion growers in Orange Co., IST. Y. The onions 

 were found to be affected at harvest time. One or more layers 

 of the onion would be soft rotten while the adjacent layers were 

 sound. Sometimes the rotten layers were on the interior, in which 

 case the affected bulbs might be difficult of detection; or the rot 

 might be confined to the outermost fleshy layer, producing the 

 so-called slippery onions. Although this rot is quite certainly due 

 to bacteria, it is not readily produced by inoculation, vsdth diseased 

 tissue except in the presence of water. This shows that water is 

 an important factor in the rot and that th,e unusually large amount 

 of rot in 1898 was due to the excessively wet weather which oc- 

 curred in July and August of that year. ThorougTi drainage and 

 clean cultivation are recommended as preventive measures. 



II. Leaves of field cucumbers affected with a powdery mildew 

 have been received from Athens, Pa. This is believed to be th^e 

 first record of the occurrence of powdery mildew on field-grown 

 cucumbers in America. In greenhouses it is not uncommon. The 

 identity of the fungus is uncertain, but it is probably different 

 from the powdery mildew occurring on squashes and pumpkins. 



III. A dodder, Cuscuta gronovii Willd., has occurred on green- 

 house cucumbers at th.e Station. Plants affected with this parasite 

 should be immediately destroyed to prevent it from spreading. 

 It is very aggressive. 



Reprint of Bulletin No. 164. 



