-5- 



STRA^/BERRY VIRUS 



Stravrberry virus troubles ai'e still serious in Massachusetts as elsewhere, 

 Ihey will ccntinue to cause considerable loss to g rowers until virus-free plants 

 are available in adequate quantity. 



Dr. G. '.;, Darrow and his associates in the U. S, D, A, have located virus- 

 free plants of a number of varieties and made them available to nurseries. It is 

 the responsibility of the nurseries to increase the supply of plants ard keep them 

 virus-free. Several nurseries have accepted this responsibility and appear to be 

 doing a good job so that virus-f3r«e plants of several varieties will be offered to 

 growers this winter and next spring. The supply is limited and may not meet the 

 demand. 



Virus-free plants are being produced by nurseries in Delaware, Maryland and 

 Tennessee, One of the high points of the trip to BeltsvilHas was a two-day visit 

 to several strawberry plant nurseries in Delaware and Eastern Maryland. It is quite 

 a sight to see a single field of 60 to 70 acres of strav/berry plants. Tliese plant 

 fields will average about l^O^OOO plants per acre. Some of t he better will yield 

 300,000 plants. Such fields are really covered with stravfberry plants. It is es- 

 timated that virus-free plants, because of their increased vigor, should yield 

 i;00,000 plants per acre. 



Many of the plants I saw were virus-free or nearly so. The folloT;-ing sub- 

 stantially virus-free varieties are now available to growers: Albritton, Anncre, 

 Blakemore, Catskill, Howard 17, Klondike, Klonmore, Massey, Sparkle, Tennessean, 

 Tennessee Beauty and Tennessee Shipper, In the winter of 19^h-19S^) it is hoped 

 that plants of Big Joe, Dunlap, Missionary, Robinson and Verr:iilion vd.ll be available 

 and, in 19^5-1956, plants of Fairfax, Gem, Midland, and Redstar, 



Where virus-free stock has been compared with ordinary, virus-infected stock, 

 the growth of the virus-free stock has been much better. It should be worthvdiile 

 for a grower to get some virus-free plants to make his ovm comparison. If the plants 

 are to be fruited only once, there is probably little to be gained from dusting for 

 aphid control. On tlie other hacj?, there is the possibility that if virus-free plants 

 are kept free of virus, their superior vigor can be maintained and they can be fruit- 

 ed several times to advantage. 



To keep plants virus-free requires thorough and regular dusting to control 

 aphids. There are in Massachusetts plenty of the three aphids vriiich tp read the 

 virus. Either parathion or raalathion vrill do a good job. Actual field experience 

 on a large scale shovred that where dusting vfas properly done, aphids vrere extremely 

 hard to find. In nearby undusted fields, plenty could be found. 



Dusting of the virus-free bed only is not enough. ApMds must be prevented 

 from migrating in from surrounding infected fields. Since it is estlniated that 99% 

 of the strawberries presently g rown are virus infected, it is a good bet that nearby 

 old beds are infected and need dusting, Vifild strav/berries, also, have been found to 

 be virus infected. Therefore, to keep virus-free plants free of virus v/ill require 

 thorough and regular dusting of both the new virus-free plants and all old plants 

 in the vicinity and either dusting or eliminating wild plants, 



J.S.Bailey 



