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HOW TO KEEP THOSE STRAVfBERRIES VIRUS-FREE 



Almost all strav/berry plants gro^dng in the northeast are infected wth one or 

 more virus diseases. It is very likely that wild stravirberries also are infected. 



At least three species of aphids^ knorm to occur in the northeast, serve as 

 virus carriers. After feeding upon diseased plantethese aphids may transmit the 

 viruses to healthy, virus-free strawberries. Certain other ai:^ids, also found on 

 straviTberries occasionally, have transmitted vimses experimentallyo 



Virus-free strav/berry plants grovm for fruiting next season , AMD WXT SEASON 

 ONL^i do not require protection from aphids. Viruses contracted by these plants — ' 

 Wrough aphid feeding should have little or no effect upon their growth or yield. 



Plants grgym in nurseries for subsequent sale as virus-free plants , MUST BE 

 PROTECTED from aphids in the nursery to keep them in a virus-free conditiwu This 

 becomes even mere important in stock beds from Tiiiiich the nurserymai vdll set his new 

 stock beds and plant beds for succeeding seasons. 



Virus-carrying aphids must not feed on plants which the nurseryman or anyone 

 else wants to keep virus-free . 



How Aphids Move From Field to Field 



Winged forms are produced in some generations of most aphid species. In straw- 

 berry aphids, only the vdnged forms are able to move from one plant bed to another, 

 (An exception would be the movenent of plants, infested virith wingless forms, from 

 place to place,) 



This Is the Problem 



Our problem then is (l)to prevent cringed aphids from developing on knovm virus- 

 infected plants or on plants which may have virus, and (2) to prevent any vdnged 

 aphids that do develop on such plants from establishing colonies or even feeding upon 

 cur virus-free plantings, 



TiHiat the Nurseryman Can Do 



¥inged apliidsdo not travel great distances unless carried by wind or \3y some 

 other means; therefore: 



(1) Locate virus-free stock and p]a nt beds in places isolated from possible 

 sources of aphids and virus - 3000 ft, is suggested as a reasonably 

 safe distance - any distance is better than none. Such isolation is 

 helpful but distance in itself does not guarantee immunity to aphids and 

 virus. 



Winged qshids restilt -vtien strawberry aphid colony reproduces rapidly and becomes 

 overcrowded. They occur principally during Ilay and Jiine aid again in September, 

 October and November, Some may be found during summei«months also, therefore: 



