-7- 



To design an oil with this potential, specifications called for a highly 

 refined petroleum oil low in unsulfonated residues and with a short residual. 

 The unsulfonated residues are highly toxic to plant tissues. Injury can also 

 be eliminated or greatly reduced if the oil does not persist on the foliage after 

 completing its pesticidal action. 



Since the mode-of-action of the highly refined petroleum oils are largely 

 or wholly mechanical - causing death by asphy^ciation, they preclude the develop- 

 ment of resistance characteristic of organophosphorus and other pesticides. If 

 use of the 60 second oil can be extended to include the cover sprays for the 

 control of such pests as the European red mite, a new era in mite control may 

 result. Furthermore, since petroleum oils, as used, are exempt from a tolerance, 

 they present no residue problem on fruit. 



Besides the European red mite, oil sprays have been used effectively to 

 control scales, aphids, mealy bugs, and psyllids. They are also effective 

 ovicides for codling moth, oriental fruit moth, leaf rollers, and cankerworms. 



H. E. Wave 



Department of Entomology 

 and Plant Pathology 



I I I I I I I I I I I I I I I I 



X- DISEASE OF PEACH 



Twenty years ago X- Disease of peach was common in many orchards and caused 

 extensive and serious losses. Systematic removal of diseased trees by growers 

 and eradication of chokecherries, which carry the disease, near orchards has 

 brought the disease under control. An occasional tree with X-Disease is still 

 found but, frequently, reports of X-Disease turn out to be other troubles which, 

 at least in part, cause similar symptoms. 



Names, Cause and Plants Attacked ; 



The disease was first reported from Connecticut in 1933 and was called 

 X-Disease because the cause was not knovra. The name still persists but other 

 names for the disease are eastern X-Disease, yellow-red disease, yellow-red 

 virosis and eastern yellow-red virosis. 



Stoddard, in 1938, worked with the disease in Connecticut and reported the 

 cause to be a virus and that, "as far as is known, X-Disease occurs in nature 

 only on peach, nectarine and chokecherry" . It has also been found on sweet and 

 sour cultivated cherries and has been transmitted artificially, by budding and 

 grafting, to many plants related to peach, cherry and plum and even to unrelated 

 plants such as tomato, carrot, parsley and periwinkle. Wild black or rum cherry 

 ( Prunus seroti na) and beach plum (P. maritina) could not be infected and are 

 considered immune. 



