SMALL FRUIT DISEASE CONFERENCE 



A small fruit disease conference was held on February 18 and ly at the U.S.D.A. 

 Research Center at Beltsville, Maryland. About a hundred small fruit specialists, 

 growers and nurserymen from all over the United States and Canada were in attendance. 



The strawberry virus situation was discussed in considerable detail. It 

 was apparent that from the standpoint of the research man this is a very complex 

 problem. Much work is being done, but much more is needed. From the viewpoint 

 of the grower the essentially virus-free stocks are so much better than the non- 

 virus- free that every grower should demand them. 



At present the difficulty is to maintain these essentially virus-free plants 

 in that condition through the several years it takes tc multiply them sufficiently 

 so that all growers can be supplied. Eight states, California, Tennessee, Michigan, 

 New Jersey, Ohio, Maryland, Delaware and Arkansas have established, or are in the 

 process of establishing, a system of inspection and certification or registration 

 of essentially virus-free strawberry plants. In these states there is some super- 

 vision over the production, and control over the sale, of such plants. 



In Massachusetts there is no such arrangement. A few plant grov;ers, because 

 of carelessness or ignorance, are offering plants for sale as essentially virus- 

 free which are not. The progressive plant growers are doing a good job of 

 supplying quality plants v;hich are essentially virus-free. It is up to the straw- 

 berry grower to be sure that he deals with the latter kind of nursery. 



Attempts are being continued to produce virus-free plants by heat or chemical 

 treatments. So far heat treatment has been successful in inactivating some but 

 not all viruses. One case has been reported of inactivating a virus with a zinc 

 salt. 



The fight against root infesting nematodes in strawberries continues. The 

 root knot and meadow nematodes which work in the roots continue to be the most 

 general and worst offenders. In Florida the sting nematode which works on 

 the outside of the roots is their worst offender. 



A new nematocide 1, 2-dibromo-3 chloropropane (sold under the trade names 

 Fumazone and Nemagon) received considerable attention. This material is not 

 toxic to strawberries as arc the commonly used soil fumigants DD and ethylene 

 dibromide. On the other hand it is much slower acting. It has been found to 

 be very effective against root knot nematodes. It is being prepared in granular 

 from which makes it much easier to apply. 



Red Stele was discussed briefly. Two or three more strains of the disease 

 have been found in northwestern Canada, making a total of 5 or 3 strains. The 

 only control measure is still the use of red stele resistant varieties. 



Verticillium wilt of strawberries was discussed at some lengbh. It is the 

 most serious disease of strawberries in California. It can be controlled by 

 fumigating the soil with chloropicrin, but this is too expensive at present 

 price levels out there. As a result, some strawberry land is going out of 

 production. This fungus attacks red raspberries, potatoes, tomatoes, egg plant 



