Stnaa^ennlc^ 



CAN BE VIRUS-FREE 



By JOHN S. BAILEY, Department of Pomology, The Cranberry Station, East Wareham 



NINETY-EIGHT percent of all 

 strawberry plants are infected by 

 virus. Since it is not selective, the 

 virus attacks wild plants as well as 

 cultivated ones. It weakens plants 

 considerably, stunts their growth, and 

 decreases yields. To strawberry grow- 

 ers, this means severe financial losses. 

 Through the efforts of research 

 men of the U. S. Department of Ag- 

 riculture at the Beltsville Station in 

 Maryland, several million virus-free 

 strawberry plants are now available. 



Virus Carried b/ Aphids 



Where do the viruses come from? 

 Can we get rid of them? The viruses 

 are carried from diseased plants to 

 healthy ones by aphids or plant lice 

 (mostly of the genus Capita phorus) . 

 Although present all year round, 

 aphids are active only during the 

 time between the first bloom and the 

 first hard frost. 



Chemical Dust Effective 



A good aphid killer, such as para- 

 thion or malathion dust, will keep a 

 strawberry bed aphid-free and almost 

 virus-free. To protect newly set beds, 

 it is necessary to dust every 10 to 14 

 days from the time growth starts in 

 April until July 1, and again during 

 September and October. During July 

 and August, dusting is sufficient every 

 three or four weeks. Parathion and 

 malathion should never be used on 

 bearing beds during bloom nor 

 within two weeks of harvest. Placing 

 the bed at least 3000 feet from other 

 strawberries helps to keep it virus- 

 free. 



Virus Tested by Grafting 



How will the nurseryman who is 

 trying to sell his plants protect them 

 from aphids? The researchers at 

 Beltsville obtained vigorous, healthy 

 strawberry plants from all over the 



**vi' 



A typical screenhouse used 

 for producing virus-free and 

 nematode-free plants. 



-■^ewflp^. 



